chore: 1.2.0-beta.1

Merging #88 left two `@Update fun update(alarm: TaskAlarmEntity)` declarations in `TaskAlarmDao`: one returning `Int` from the release branch, and one returning `Unit` from the feature branch. `release/v1.2.0` doesn't compile with both. This keeps the `Int` one, which `ProviderWriter` uses.

Co-authored-by: Jean-Luc Makiola <business@jeanlucmakiola.de>
Reviewed-on: https://codeberg.org/jlmakiola/agendula/pulls/89

.forgejo/PULL_REQUEST_TEMPLATE.md

@@ -26,14 +26,14 @@ Which of these ran green, and anything you exercised by hand. On-device notes
 are especially useful for UI changes, and for anything touching the provider
 read/write paths (OpenTasks / tasks.org installed).
 
-  ./gradlew lintDebug :app:testDebugUnitTest :app:assembleDebug
+  ./gradlew lintFullDebug lintOfflineDebug :app:testFullDebugUnitTest :app:testOfflineDebugUnitTest :app:assembleDebug
   python3 scripts/check_translations.py
 -->
 
 
 ### Checklist
 
-- [ ] `./gradlew lintDebug :app:testDebugUnitTest :app:assembleDebug` passes locally
+- [ ] `./gradlew lintFullDebug lintOfflineDebug :app:testFullDebugUnitTest :app:testOfflineDebugUnitTest :app:assembleDebug` passes locally
 - [ ] New domain logic comes with JVM unit tests under `app/src/test/`
 - [ ] Provider details stay inside `data/tasks/`
 - [ ] No `values-*/strings.xml` touched (Weblate owns those; new English strings in `values/` are fine)

.forgejo/workflows/ci.yaml

@@ -127,10 +127,12 @@ jobs:
 
       - name: Setup Java
         if: steps.scope.outputs.code == 'true'
+        # JetBrains 21 is what gradle-daemon-jvm.properties asks for; installing it
+        # here keeps Gradle from downloading it via foojay.
         uses: actions/setup-java@v4
         with:
-          distribution: 'zulu'
-          java-version: '17'
+          distribution: 'jetbrains'
+          java-version: '21'
 
       # Fully qualified on purpose. Codeberg resolves bare `uses:` refs against
       # data.forgejo.org, Forgejo's own action mirror — actions/checkout,
@@ -178,18 +180,18 @@ jobs:
 
       # No --no-daemon: the daemon lives only as long as this job container
       # and lets the following steps skip JVM startup + reconfiguration.
-      - name: Lint (debug variant only)
+      - name: Lint (debug variants only)
         if: steps.scope.outputs.code == 'true'
-        run: ./gradlew lintDebug
+        run: ./gradlew lintFullDebug lintOfflineDebug
 
       # :dav is a plain JVM module, so it has no testDebugUnitTest — naming only
       # that task would compile the vendored suite and run none of it, which is
       # the whole safety argument in dav/PROVENANCE.md.
       - name: Unit tests
         if: steps.scope.outputs.code == 'true'
-        run: ./gradlew testDebugUnitTest :dav:test :caldav:test
+        run: ./gradlew testFullDebugUnitTest testOfflineDebugUnitTest :dav:test :caldav:test
 
-      - name: Assemble debug APK
+      - name: Assemble debug APKs
         if: steps.scope.outputs.code == 'true'
         run: ./gradlew assembleDebug
 

.forgejo/workflows/translations.yaml

@@ -2,7 +2,7 @@ name: Translations
 
 # Fast, SDK-free parity check for translation resources, so Weblate PRs (which
 # only touch values-*/strings.xml) get quick feedback without the full Android
-# build. The deeper checks still run in CI via lintDebug (ExtraTranslation).
+# build. The deeper checks still run in CI via lintFullDebug (ExtraTranslation).
 #
 # Runs on every PR (no path filter) so the required "Translations / check"
 # status is always reported — like the `ci` job. A path-filtered workflow is

.gitea/workflows/beta.yaml

@@ -3,7 +3,7 @@ name: Beta — Codeberg pre-release
 # A beta is cut by pushing a release branch whose committed versionName is
 # X.Y.Z-beta.N (see docs/RELEASING.md). Same model as release.yaml: the
 # committed version is the trigger and the vX.Y.Z-beta.N tag is an output. If
-# no tag exists for that version yet, this runs the unit tests, builds and
+# its Codeberg pre-release doesn't carry the APK yet, this runs the unit tests, builds and
 # signs the APK with the app key, records a Gitea pre-release (with the R8
 # mapping) and publishes a Codeberg pre-release with the APK + SHA-256.
 #
@@ -27,7 +27,7 @@ jobs:
   detect:
     # Gitea only; see the same guard in release.yaml.
     if: github.repository_owner == 'makiolaj'
-    runs-on: docker
+    runs-on: light
     outputs:
       is_beta: ${{ steps.v.outputs.is_beta }}
       version: ${{ steps.v.outputs.version }}
@@ -36,58 +36,28 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
 
-      - name: Resolve version and whether it is a new beta
+      - name: Resolve version and whether it still needs publishing
         id: v
-        env:
-          # Codeberg, not Gitea: see the same lookup in release.yaml.
-          TAG_API: https://codeberg.org/api/v1/repos/jlmakiola/agendula
         run: |
           set -e
           INFO=$(bash scripts/version_info.sh)
           echo "$INFO"
           echo "$INFO" >> "$GITHUB_OUTPUT"
-          VERSION=$(echo "$INFO" | sed -n 's/^version=//p')
-          BASE=$(echo "$INFO" | sed -n 's/^base_version=//p')
-          if [ "$(echo "$INFO" | sed -n 's/^channel=//p')" != "beta" ]; then
-            echo "versionName $VERSION is not a beta — nothing to do."
+          if [ "$(bash scripts/version_info.sh channel)" != beta ]; then
+            echo "Not a beta — nothing to do."
             echo "is_beta=false" >> "$GITHUB_OUTPUT"
             exit 0
           fi
-          # Fatal on anything but a clean 200/404, as in release.yaml: guessing
-          # "no tag" during an outage would re-cut a published beta.
-          tag_status() {
-            curl -s -o /dev/null -w '%{http_code}' "$TAG_API/git/refs/tags/$1" || echo 000
-          }
-          # A beta of a version that already shipped stable would carry a lower
-          # versionCode than the stable one: nobody could install it over it.
-          case "$(tag_status "v$BASE")" in
-            200)
-              echo "v$BASE already shipped as stable; a beta of it is pointless. Bump the version." >&2
-              exit 1 ;;
-            404) ;;
-            *) echo "Codeberg tag lookup for v$BASE failed — refusing to guess." >&2; exit 1 ;;
-          esac
-          STATUS=$(tag_status "v$VERSION")
-          case "$STATUS" in
-            200)
-              echo "Tag v$VERSION already exists on Codeberg — nothing to release."
-              echo "is_beta=false" >> "$GITHUB_OUTPUT"
-              ;;
-            404)
-              echo "No tag for v$VERSION on Codeberg yet — cutting the beta."
-              echo "is_beta=true" >> "$GITHUB_OUTPUT"
-              ;;
-            *)
-              echo "Codeberg tag lookup for v$VERSION returned HTTP $STATUS." >&2
-              echo "Refusing to guess: treating this as 'no tag' could re-cut a published beta." >&2
-              exit 1
-              ;;
-          esac
+          # Done only once its Codeberg pre-release carries the APK, so a failed
+          # publish is redone by the next push; refused unless newer than the
+          # latest stable release.
+          GATE=$(bash scripts/release_gate.sh)
+          echo "is_beta=${GATE#cut=}" >> "$GITHUB_OUTPUT"
 
   beta:
     needs: detect
     if: needs.detect.outputs.is_beta == 'true'
-    runs-on: docker
+    runs-on: gradle
     env:
       ANDROID_HOME: /opt/android-sdk
       ANDROID_SDK_ROOT: /opt/android-sdk
@@ -100,10 +70,12 @@ jobs:
           submodules: recursive
 
       - name: Setup Java
+        # JetBrains 21 is what gradle-daemon-jvm.properties asks for; installing it
+        # here keeps Gradle from downloading it via foojay.
         uses: actions/setup-java@v4
         with:
-          distribution: 'zulu'
-          java-version: '17'
+          distribution: 'jetbrains'
+          java-version: '21'
 
       - name: Setup Android SDK
         uses: android-actions/setup-android@v3
@@ -156,7 +128,7 @@ jobs:
           grep -E 'versionName|versionCode' app/build.gradle.kts
 
       - name: Unit tests
-        run: ./gradlew testDebugUnitTest
+        run: ./gradlew testFullDebugUnitTest
 
       # The real app key, same as a stable release: a beta has to update in
       # place to the next beta and to the stable version.
@@ -175,7 +147,8 @@ jobs:
           storeFile=upload-keystore.jks
           EOF
 
-      - name: Build release APK
+      # Both flavors; the offline one goes to Codeberg only (issue #39).
+      - name: Build release APKs
         run: ./gradlew assembleRelease
 
       # Notes = a `## [X.Y.Z-beta.N]` section if there is one, else
@@ -190,7 +163,8 @@ jobs:
           bash scripts/release_notes.sh "$VERSION" > release-notes.md
           cat release-notes.md
           TAG="v$VERSION" PRERELEASE=true NOTES_FILE=release-notes.md \
-            MAPPING=app/build/outputs/mapping/release/mapping.txt \
+            MAPPING=app/build/outputs/mapping/fullRelease/mapping.txt \
+            MAPPING_OFFLINE=app/build/outputs/mapping/offlineRelease/mapping.txt \
             bash scripts/publish_gitea_release.sh
 
       # The point of the whole workflow, so NOT continue-on-error.
@@ -202,5 +176,6 @@ jobs:
         run: |
           set -e
           TAG="v$VERSION" PRERELEASE=true NOTES_FILE=release-notes.md \
-            APK=app/build/outputs/apk/release/app-release.apk \
+            APK=app/build/outputs/apk/full/release/app-full-release.apk \
+            APK_OFFLINE=app/build/outputs/apk/offline/release/app-offline-release.apk \
             bash scripts/publish_codeberg_release.sh

.gitea/workflows/release.yaml

@@ -48,7 +48,7 @@ jobs:
     # secrets. repository_owner differs between the two forges regardless of
     # URL, proxy or instance rename, so this closes it permanently.
     if: github.repository_owner == 'makiolaj'
-    runs-on: docker
+    runs-on: light
     outputs:
       is_release: ${{ steps.v.outputs.is_release }}
       version: ${{ steps.v.outputs.version }}
@@ -62,17 +62,6 @@ jobs:
 
       - name: Resolve version and whether it is a new release
         id: v
-        env:
-          # Tags are read from Codeberg, which is canonical — deliberately NOT
-          # from the Gitea API this workflow runs on. The Codeberg -> Gitea sync
-          # is a push mirror, i.e. `git push --mirror`, which deletes refs the
-          # source does not have. A tag minted here on Gitea is therefore wiped
-          # by the next sync (Codeberg does not have it yet) and only reappears
-          # once the tag push at the end of this workflow propagates back.
-          # Asking Gitea inside that window would report "no tag" for a release
-          # that already shipped, and cut it a second time.
-          # Public repo, so this read needs no token.
-          TAG_API: https://codeberg.org/api/v1/repos/jlmakiola/agendula
         run: |
           set -e
           # versionName -> versionCode, channel and the pre-release flag (set
@@ -94,30 +83,11 @@ jobs:
             echo "versionName $VERSION on main is a beta. Set the stable version before merging to main." >&2
             exit 1
           fi
-          # A tag for this version already existing means the release shipped on
-          # an earlier push; do nothing. Absent => this merge cuts the release.
-          #
-          # Anything other than a clean 200/404 is treated as fatal rather than
-          # as "no tag". A Codeberg outage or a network blip would otherwise
-          # read as absent and re-cut a release that has already shipped —
-          # republishing to F-Droid. Failing here is recoverable; a duplicate
-          # release is not.
-          STATUS=$(curl -s -o /dev/null -w '%{http_code}' "$TAG_API/git/refs/tags/v$VERSION" || echo 000)
-          case "$STATUS" in
-            200)
-              echo "Tag v$VERSION already exists on Codeberg — nothing to release."
-              echo "is_release=false" >> "$GITHUB_OUTPUT"
-              ;;
-            404)
-              echo "No tag for v$VERSION on Codeberg yet — cutting the release."
-              echo "is_release=true" >> "$GITHUB_OUTPUT"
-              ;;
-            *)
-              echo "Codeberg tag lookup for v$VERSION returned HTTP $STATUS." >&2
-              echo "Refusing to guess: treating this as 'no tag' could re-cut a shipped release." >&2
-              exit 1
-              ;;
-          esac
+          # Tags are read from Codeberg, the canonical forge, by exact name: its
+          # git/refs/tags API matches by prefix, so v1.1.0-beta.1 would read as
+          # v1.1.0. A lookup error is fatal rather than read as "no tag".
+          GATE=$(bash scripts/release_gate.sh)
+          echo "is_release=${GATE#cut=}" >> "$GITHUB_OUTPUT"
 
       # Before a single Gradle task runs: F-Droid truncates the in-client
       # changelog, so an over-long one would reach users cut off mid-sentence.
@@ -135,7 +105,7 @@ jobs:
   release:
     needs: detect
     if: needs.detect.outputs.is_release == 'true' || github.event_name == 'workflow_dispatch'
-    runs-on: docker
+    runs-on: gradle
     env:
       ANDROID_HOME: /opt/android-sdk
       ANDROID_SDK_ROOT: /opt/android-sdk
@@ -150,10 +120,12 @@ jobs:
           submodules: recursive
 
       - name: Setup Java
+        # JetBrains 21 is what gradle-daemon-jvm.properties asks for; installing it
+        # here keeps Gradle from downloading it via foojay.
         uses: actions/setup-java@v4
         with:
-          distribution: 'zulu'
-          java-version: '17'
+          distribution: 'jetbrains'
+          java-version: '21'
 
       - name: Setup Android SDK
         uses: android-actions/setup-android@v3
@@ -212,7 +184,7 @@ jobs:
       # Test the exact commit being shipped (only on a real release).
       - name: Unit tests
         if: env.IS_RELEASE == 'true'
-        run: ./gradlew testDebugUnitTest
+        run: ./gradlew testFullDebugUnitTest
 
       - name: Setup Android Keystore
         if: env.IS_RELEASE == 'true'
@@ -230,7 +202,9 @@ jobs:
           storeFile=upload-keystore.jks
           EOF
 
-      - name: Build release APK
+      # Both flavors. Only full goes to F-Droid and Play; the offline one
+      # (issue #39) is a Codeberg release asset and nothing else.
+      - name: Build release APKs
         if: env.IS_RELEASE == 'true'
         run: ./gradlew assembleRelease
 
@@ -286,7 +260,7 @@ jobs:
         run: |
           set -e
           mkdir -p fdroid/repo
-          cp app/build/outputs/apk/release/app-release.apk "fdroid/repo/agendula_v${VERSION}.apk"
+          cp app/build/outputs/apk/full/release/app-full-release.apk "fdroid/repo/agendula_v${VERSION}.apk"
 
       # Per-version "What's New": ensure this version's changelog exists in the
       # fastlane tree (committed at release-cut time for the official repo; this
@@ -348,7 +322,8 @@ jobs:
           set -e
           bash scripts/release_notes.sh "$VERSION" > release-notes.md
           TAG="v$VERSION" NOTES_FILE=release-notes.md \
-            MAPPING=app/build/outputs/mapping/release/mapping.txt \
+            MAPPING=app/build/outputs/mapping/fullRelease/mapping.txt \
+            MAPPING_OFFLINE=app/build/outputs/mapping/offlineRelease/mapping.txt \
             bash scripts/publish_gitea_release.sh
 
       # Publish the release on Codeberg, which is canonical for tags and
@@ -371,7 +346,8 @@ jobs:
           set -e
           [ -s release-notes.md ] || bash scripts/release_notes.sh "$VERSION" > release-notes.md
           TAG="v$VERSION" NOTES_FILE=release-notes.md \
-            APK=app/build/outputs/apk/release/app-release.apk \
+            APK=app/build/outputs/apk/full/release/app-full-release.apk \
+            APK_OFFLINE=app/build/outputs/apk/offline/release/app-offline-release.apk \
             bash scripts/publish_codeberg_release.sh
 
       # Play takes an App Bundle, not the APK: a second artifact from the same
@@ -386,7 +362,7 @@ jobs:
       - name: Build release AAB
         if: env.IS_RELEASE == 'true'
         continue-on-error: true
-        run: ./gradlew bundleRelease
+        run: ./gradlew bundleFullRelease
 
       # NOT actions/upload-artifact@v4: its client refuses any non-github.com
       # server as unsupported GHES (go-gitea/gitea#36024). This fork drops that
@@ -398,7 +374,7 @@ jobs:
         uses: https://github.com/ChristopherHX/gitea-upload-artifact@81f940d004763f986ba3582c007fd842dd5cb0d7 # v4
         with:
           name: release-aab-${{ needs.detect.outputs.version }}
-          path: app/build/outputs/bundle/release/app-release.aab
+          path: app/build/outputs/bundle/fullRelease/app-full-release.aab
           if-no-files-found: error
           retention-days: 14
 
@@ -492,7 +468,7 @@ jobs:
         run: |
           set -euo pipefail
           # Absolute: a lane body runs from fastlane/, not the workspace root.
-          AAB="$GITHUB_WORKSPACE/dist/app-release.aab"
+          AAB="$GITHUB_WORKSPACE/dist/app-full-release.aab"
           test -f "$AAB" || { echo "No AAB at $AAB — the artifact handoff failed." >&2; ls -la dist || true; exit 1; }
           bundle exec fastlane deploy \
             aab:"$AAB" \

CHANGELOG.md

@@ -7,6 +7,86 @@ All notable changes to this project are documented here. The format follows
 
 ## [Unreleased]
 
+### Added
+- A reminder can count from the task's start as well as from its due date, and
+  tasks with only a start date get reminders too. Default reminders can mix
+  both, e.g. a day before the start and an hour before the due date; each
+  applies to tasks that have its date (#72).
+- An all-day task's reminders can each have their own time, so one task can
+  remind you at 09:00 and again at 17:00 (#78).
+- Other apps can read the tasks kept in Agendula's own database through an
+  OpenTasks-compatible provider, once you grant them permission. Apps that
+  already support OpenTasks or tasks.org need only a small change to support
+  Agendula too (#43).
+- With a second permission, other apps can also add, edit, complete and delete
+  those tasks, including their reminders and tags. They can tick off a single
+  occurrence of a recurring task. Task lists stay read-only for them (#63).
+
+### Changed
+- A new task no longer takes a default reminder whose time has already
+  passed, so a start of "today" does not ring the moment the task is saved.
+- All-day default reminders are whole days; one set in hours rounds to the
+  nearest day.
+- Switching a task between timed and all-day converts its reminders right
+  away in the editor, so what you see is what gets saved.
+- The editor shows the default reminders a new task, or a newly added date,
+  will get, before you save. Removing them leaves the task without a reminder
+  instead of falling back to the default.
+- Reminders now sync. A reminder set on a task is uploaded as a standard alarm
+  (`VALARM`), so it also notifies in macOS and iOS Reminders, Thunderbird,
+  tasks.org and jtx Board, and alarms set in those apps now fire in Agendula
+  instead of the default reminder. Removing a task's alarm in another app
+  turns it off here too, rather than falling back to the default (#52).
+- A new task with a date, or one that gets a new date, takes the default
+  reminder for that date as its own, so it travels with the task to the server.
+  Changing the default later no longer changes those tasks; tasks that rely on
+  the default today are left as they are.
+- On upgrade, reminders on open, synced tasks that so far stayed on this
+  device are uploaded once.
+- Alarms imported from an `.ics` file become reminders on the task.
+- Screens now open and close the way they do in Calendula: they slide in, and
+  a back swipe previews the screen behind before closing (#66).
+- Settings now use Calendula's names and layout. Reminders is now
+  Notifications, Task form is now New task form, and export and import moved
+  out of Storage into a new Backup & restore section (#66).
+
+## [1.1.0] - 2026-10-10
+
+### Added
+- Four new home-screen widgets: Today, Up next, Lists and Week.
+- A widget can show tasks from several lists at once, optionally grouped by
+  list.
+- A setting under Settings → Task form pre-fills a new task's start with today.
+- An offline version of Agendula with no sync and no network access at all,
+  published as a separate APK on Codeberg (#39).
+- Tags. Add them while editing a task, see them on the task and in lists,
+  browse them from the home screen and filter any list by them. They are saved
+  as `CATEGORIES`, so they sync with Nextcloud Tasks, tasks.org and DAVx⁵ (#35).
+- Filters. Save your own view of the open tasks by due date (overdue, today,
+  upcoming, no date, in any combination), lists, tags and minimum priority.
+  They live on the home screen and can be shown in the Tasks widget, so today
+  and overdue tasks can now share one widget (#47).
+
+### Changed
+- The Tasks widget has agenda-style rows, an optional row colour and an "All
+  caught up" state. Ticking a task in any widget shows it as done for a moment
+  before it disappears.
+- The "At a glance" widget is gone; the Tasks and Today widgets cover what it
+  showed.
+- Synced lists can be renamed and deleted, not only device-only ones. A
+  read-only share shows the edit button greyed out and explains why on tap.
+- The sort button in task lists now opens "Sort and filter", which can also
+  filter by tag.
+- While editing a task, its title moves into the top bar once you scroll past
+  it.
+
+### Fixed
+- The list editor's Where and smart-lists rows no longer have double padding.
+- A field you tap now scrolls fully above the keyboard, and the "add subtask"
+  row in task lists no longer ends up hidden behind it.
+- All-day tasks west of UTC no longer show up a day early in Overdue, Today
+  and Upcoming.
+
 ## [1.0.0] - 2026-09-21
 
 ### Added

CONTRIBUTING.md

@@ -28,9 +28,9 @@ layer.
 ## Build, test, lint
 
 ```sh
-./gradlew :app:assembleDebug        # build the debug APK
-./gradlew :app:testDebugUnitTest    # JVM unit tests (JUnit5 + Truth + Turbine)
-./gradlew lintDebug                 # Android lint (CI runs this on every PR)
+./gradlew :app:assembleDebug            # build the debug APKs (full + offline)
+./gradlew :app:testFullDebugUnitTest    # JVM unit tests (JUnit5 + Truth + Turbine)
+./gradlew lintFullDebug lintOfflineDebug  # Android lint (CI runs this on every PR)
 ```
 
 CI (`.forgejo/workflows/ci.yaml`, on Codeberg) runs a reproducible-release invariant check,

README.md

@@ -15,6 +15,10 @@ required.</p>
 </p>
 
 <p>
+<a href="https://f-droid.org/packages/de.jeanlucmakiola.agendula/"><img src="https://fdroid.gitlab.io/artwork/badge/get-it-on.png" alt="Get it on F-Droid" height="56"></a>
+&nbsp;
+<a href="https://play.google.com/store/apps/details?id=de.jeanlucmakiola.agendula"><img src="https://play.google.com/intl/en_us/badges/static/images/badges/en_badge_web_generic.png" alt="Get it on Google Play" height="56"></a>
+&nbsp;
 <a href="https://apps.obtainium.imranr.dev/redirect?r=obtainium://add/https://codeberg.org/jlmakiola/agendula"><img src="https://github.com/ImranR98/Obtainium/blob/main/assets/graphics/badge_obtainium.png?raw=true" alt="Get it on Obtainium" height="56"></a>
 &nbsp;
 <a href="https://ko-fi.com/jeanlucmakiola"><img src="https://storage.ko-fi.com/cdn/brandasset/v2/support_me_on_kofi_badge_beige.png" alt="Support me on Ko-fi" height="56"></a>
@@ -50,7 +54,8 @@ many small *florets* — so the two apps are florets of one bloom.)
   this and the following ones, or the whole series.
 - **Reminders** that fire at the exact time: several per task, separate defaults
   for timed and all-day tasks (globally and per list), Done and Snooze right on
-  the notification, and they survive reboots.
+  the notification, and they survive reboots. They sync as standard `VALARM`s,
+  so they also ring in other CalDAV clients, and theirs ring here.
 - **iCalendar import and export** — open an `.ics` or a zip of them, or write any
   list out as standard `.ics` files.
 - A **home-screen widget**, launcher shortcuts, a Quick Settings tile, and
@@ -76,6 +81,16 @@ back to a full comparison where it does not. Everything the store does not model
 is kept verbatim and sent back unchanged, so passing your tasks through Agendula
 does not quietly lose fields another client wrote.
 
+### Tested With
+
+The following CalDAV Services have been Tested
+
+
+
+| Service | Version | Date | Status | User |
+|---|---|---|---|---|
+| **Nextcloud** | 25.0.0 | Oct 9th 2026 | ✅ | [@jlmakiola](https://codeberg.org/jlmakiola) [@Schanbro](https://codeberg.org/Schanbro)
+
 ## Where your tasks live
 
 |  | Where | Sync | Needs |
@@ -87,6 +102,10 @@ Agendula's own store is an ordinary app database, so it **coexists with
 OpenTasks rather than replacing it**. If you already sync through a provider,
 Agendula can work on top of it exactly as before.
 
+Other apps can read and write the tasks in Agendula's own store through an
+OpenTasks-compatible provider, once you grant them permission. See
+[docs/CONTENT_PROVIDER.md](docs/CONTENT_PROVIDER.md).
+
 Switching between the two moves nothing — each store keeps its own tasks — so
 **Settings → Storage** asks before it switches, and offers to **copy** a
 provider's tasks into Agendula's own store when you want to move over. The copy
@@ -97,10 +116,20 @@ proprietary, and open standards — CalDAV and iCalendar — are the lane.
 
 ## Install
 
-### F-Droid repository
+### F-Droid (recommended)
 
-Every release is built, signed and published to a self-hosted F-Droid
-repository. Add it once and your F-Droid client handles updates from then on:
+Agendula is in the official [F-Droid](https://f-droid.org) repository. Search
+for Agendula in any F-Droid client, or
+[install it from f-droid.org](https://f-droid.org/packages/de.jeanlucmakiola.agendula/).
+
+F-Droid builds from source on its own schedule, so a new version usually shows
+up there a few days after release.
+
+### Self-hosted F-Droid repo (fastest updates)
+
+The release pipeline builds, signs and publishes every release to a
+self-hosted F-Droid repository, so new versions land there first. Add it once
+and your F-Droid client handles updates from then on:
 
 1. In your F-Droid client, open *Settings → Repositories → Add* (or open the
    link below on your phone):
@@ -119,9 +148,30 @@ APK and a `.sha256` checksum attached — the same APK the F-Droid repository
 serves. For automatic updates from there, use
 **[Obtainium](https://github.com/ImranR98/Obtainium)** and
 **[add Agendula in one tap](https://apps.obtainium.imranr.dev/redirect?r=obtainium://add/https://codeberg.org/jlmakiola/agendula)**.
+Each release carries two APKs (see [Offline version](#offline-version)), so set
+*Filter APKs by regular expression* to `^agendula_v` to always get the regular
+app.
 Betas of upcoming versions are published there too, as pre-releases; to test
 them, switch on *Include prereleases* for Agendula in Obtainium.
 
+### Google Play
+
+Agendula is on
+[Google Play](https://play.google.com/store/apps/details?id=de.jeanlucmakiola.agendula).
+
+Play builds are signed with Google's key rather than mine, so switching between
+Play and any other channel means uninstalling first. Tasks kept only in
+Agendula's own database go with it, so sync them to a CalDAV account first.
+
+### Offline version
+
+Each Codeberg release also carries `agendula-offline_v<version>.apk`: Agendula
+without CalDAV sync and **without the network permission**, so it cannot
+connect to anything. It installs alongside the regular app rather than replacing
+it; move tasks between the two with Settings → Backup & restore → Export / Import. In
+Obtainium, pick it with *Filter APKs by regular expression* set to
+`^agendula-offline_v`.
+
 ### Build from source
 
 ```sh
@@ -136,8 +186,9 @@ JDK 17 and the Android SDK are all it needs; see
 ## Translations
 
 Translations are managed on a self-hosted **Weblate**, and partial ones are
-fine — an untranslated string simply falls back to English. Agendula ships in
-English, German and Brazilian Portuguese so far.
+fine — an untranslated string simply falls back to English.
+
+<a href="https://weblate.dev.jeanlucmakiola.de/engage/agendula/"><img src="https://weblate.dev.jeanlucmakiola.de/widget/agendula/multi-auto.svg" alt="Translation status" width="600"></a>
 
 **→ [Help translate Agendula](https://weblate.dev.jeanlucmakiola.de/engage/agendula/)**
 

app/build.gradle.kts

@@ -1,3 +1,4 @@
+import com.android.build.api.artifact.SingleArtifact
 import java.util.Properties
 import java.io.FileInputStream
 
@@ -32,8 +33,8 @@ android {
         // (1.0.x: 1.0.0 -> 10000; from 1.1.0: 1.1.0-beta.1 -> 1010001,
         // 1.1.0 -> 1010099), and CI fails if the committed one doesn't match.
         // See docs/RELEASING.md.
-        versionCode = 10000
-        versionName = "1.0.0"
+        versionCode = 1020001
+        versionName = "1.2.0-beta.1"
 
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
 
@@ -46,6 +47,20 @@ android {
         resValue("string", "sync_authority", "de.jeanlucmakiola.agendula.sync")
     }
 
+    // `offline` (#39): no sync code, network libraries or network permission.
+    flavorDimensions += "network"
+    productFlavors {
+        create("full") {
+            dimension = "network"
+            buildConfigField("boolean", "SYNC_ENABLED", "true")
+        }
+        create("offline") {
+            dimension = "network"
+            applicationIdSuffix = ".offline"
+            buildConfigField("boolean", "SYNC_ENABLED", "false")
+        }
+    }
+
     signingConfigs {
         if (keystorePropertiesFile.exists()) {
             create("release") {
@@ -208,26 +223,26 @@ dependencies {
     // @HiltWorker plumbing.
     implementation(libs.androidx.work.runtime.ktx)
     // Custom Tabs: the Nextcloud login flow hands the browser an approval page.
-    implementation(libs.androidx.browser)
+    "fullImplementation"(libs.androidx.browser)
     implementation(libs.androidx.hilt.work)
     ksp(libs.androidx.hilt.compiler)
 
     // Push sync: a UnifiedPush distributor delivers the server's WebDAV-Push messages.
-    implementation(libs.unifiedpush.connector)
+    "fullImplementation"(libs.unifiedpush.connector)
 
     // RFC 5545 recurrence expansion, in-process; see the catalog for the pin.
     implementation(libs.dmfs.lib.recur)
 
     // Vendored dav4jvm — the CalDAV protocol layer. See dav/PROVENANCE.md.
-    implementation(project(":dav"))
+    "fullImplementation"(project(":dav"))
     // Discovery, auth and Nextcloud Login Flow v2.
-    implementation(project(":caldav"))
+    "fullImplementation"(project(":caldav"))
     // :dav gets org.xmlpull.v1 from the Android framework at runtime and declares
     // xpp3 compileOnly, which is not transitive. Unit tests run on a plain JVM
     // with no framework, and android.jar's stub factory returns null under
     // isReturnDefaultValues — so anything touching XmlUtils would NPE without a
     // real implementation here.
-    testImplementation(libs.xpp3)
+    "testFullImplementation"(libs.xpp3)
 
     implementation(libs.androidx.room.runtime)
     implementation(libs.androidx.room.ktx)
@@ -246,6 +261,7 @@ dependencies {
     implementation(libs.floret.core.crash)
     implementation(libs.floret.identity)
     implementation(libs.floret.components)
+    implementation(libs.floret.glance)
 
     debugImplementation(libs.androidx.ui.tooling)
     debugImplementation(libs.androidx.ui.test.manifest)
@@ -265,3 +281,34 @@ dependencies {
     androidTestImplementation(platform(libs.androidx.compose.bom))
     androidTestImplementation(libs.androidx.ui.test.junit4)
 }
+
+/** Fails the build if the offline flavor's merged manifest asks for the network. */
+abstract class VerifyNoNetworkPermissions : DefaultTask() {
+    @get:InputFile
+    @get:PathSensitive(PathSensitivity.NONE)
+    abstract val manifest: RegularFileProperty
+
+    @TaskAction
+    fun verify() {
+        val text = manifest.get().asFile.readText()
+        val found = listOf("INTERNET", "ACCESS_NETWORK_STATE", "ACCESS_WIFI_STATE", "CHANGE_NETWORK_STATE")
+            .filter { "\"android.permission.$it\"" in text }
+        if (found.isNotEmpty()) {
+            throw GradleException(
+                "The offline flavor's merged manifest declares ${found.joinToString()}. " +
+                    "Remove it in app/src/offline/AndroidManifest.xml with tools:node=\"remove\".",
+            )
+        }
+    }
+}
+
+androidComponents {
+    onVariants(selector().withFlavor("network" to "offline")) { variant ->
+        val name = variant.name.replaceFirstChar { it.uppercase() }
+        val verify = tasks.register<VerifyNoNetworkPermissions>("verify${name}Manifest") {
+            manifest.set(variant.artifacts.get(SingleArtifact.MERGED_MANIFEST))
+        }
+        tasks.matching { it.name in setOf("package$name", "package${name}Bundle", "check") }
+            .configureEach { dependsOn(verify) }
+    }
+}

app/schemas/de.jeanlucmakiola.agendula.data.tasks.room.TasksDatabase/2.json

@@ -0,0 +1,529 @@
+{
+  "formatVersion": 1,
+  "database": {
+    "version": 2,
+    "identityHash": "14b159c51416ba27653f6320ac7f6f03",
+    "entities": [
+      {
+        "tableName": "accounts",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`id` INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, `display_name` TEXT NOT NULL, `principal_url` TEXT, `home_set_url` TEXT, `username` TEXT, `last_sync_at` INTEGER, `last_sync_error` TEXT)",
+        "fields": [
+          {
+            "fieldPath": "id",
+            "columnName": "id",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "displayName",
+            "columnName": "display_name",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "principalUrl",
+            "columnName": "principal_url",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "homeSetUrl",
+            "columnName": "home_set_url",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "username",
+            "columnName": "username",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "lastSyncAt",
+            "columnName": "last_sync_at",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "lastSyncError",
+            "columnName": "last_sync_error",
+            "affinity": "TEXT"
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": true,
+          "columnNames": [
+            "id"
+          ]
+        }
+      },
+      {
+        "tableName": "task_lists",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`id` INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, `name` TEXT NOT NULL, `color` INTEGER NOT NULL, `account_id` INTEGER, `is_visible` INTEGER NOT NULL DEFAULT 1, `is_synced` INTEGER NOT NULL DEFAULT 1, `owner` TEXT, `is_read_only` INTEGER NOT NULL DEFAULT 0, `sort_order` INTEGER NOT NULL DEFAULT 0, `href` TEXT, `ctag` TEXT, `sync_token` TEXT, `is_dirty` INTEGER NOT NULL DEFAULT 0, FOREIGN KEY(`account_id`) REFERENCES `accounts`(`id`) ON UPDATE NO ACTION ON DELETE SET NULL )",
+        "fields": [
+          {
+            "fieldPath": "id",
+            "columnName": "id",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "name",
+            "columnName": "name",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "color",
+            "columnName": "color",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "accountId",
+            "columnName": "account_id",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "isVisible",
+            "columnName": "is_visible",
+            "affinity": "INTEGER",
+            "notNull": true,
+            "defaultValue": "1"
+          },
+          {
+            "fieldPath": "isSynced",
+            "columnName": "is_synced",
+            "affinity": "INTEGER",
+            "notNull": true,
+            "defaultValue": "1"
+          },
+          {
+            "fieldPath": "owner",
+            "columnName": "owner",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "isReadOnly",
+            "columnName": "is_read_only",
+            "affinity": "INTEGER",
+            "notNull": true,
+            "defaultValue": "0"
+          },
+          {
+            "fieldPath": "sortOrder",
+            "columnName": "sort_order",
+            "affinity": "INTEGER",
+            "notNull": true,
+            "defaultValue": "0"
+          },
+          {
+            "fieldPath": "href",
+            "columnName": "href",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "ctag",
+            "columnName": "ctag",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "syncToken",
+            "columnName": "sync_token",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "isDirty",
+            "columnName": "is_dirty",
+            "affinity": "INTEGER",
+            "notNull": true,
+            "defaultValue": "0"
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": true,
+          "columnNames": [
+            "id"
+          ]
+        },
+        "indices": [
+          {
+            "name": "index_task_lists_account_id",
+            "unique": false,
+            "columnNames": [
+              "account_id"
+            ],
+            "orders": [],
+            "createSql": "CREATE INDEX IF NOT EXISTS `index_task_lists_account_id` ON `${TABLE_NAME}` (`account_id`)"
+          }
+        ],
+        "foreignKeys": [
+          {
+            "table": "accounts",
+            "onDelete": "SET NULL",
+            "onUpdate": "NO ACTION",
+            "columns": [
+              "account_id"
+            ],
+            "referencedColumns": [
+              "id"
+            ]
+          }
+        ]
+      },
+      {
+        "tableName": "tasks",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`id` INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, `list_id` INTEGER NOT NULL, `uid` TEXT NOT NULL, `href` TEXT, `etag` TEXT, `title` TEXT, `description` TEXT, `location` TEXT, `url` TEXT, `color` INTEGER, `categories` TEXT NOT NULL DEFAULT '', `status` INTEGER NOT NULL DEFAULT 0, `percent_complete` INTEGER, `completed_at` INTEGER, `priority` INTEGER NOT NULL DEFAULT 0, `classification` INTEGER, `dtstart` INTEGER, `due` INTEGER, `duration` TEXT, `is_all_day` INTEGER NOT NULL DEFAULT 0, `timezone` TEXT, `rrule` TEXT, `rdate` TEXT, `exdate` TEXT, `recurrence_id` INTEGER, `master_id` INTEGER, `parent_id` INTEGER, `sort_order` INTEGER NOT NULL DEFAULT 0, `created_at` INTEGER, `last_modified` INTEGER, `sequence` INTEGER NOT NULL DEFAULT 0, `is_dirty` INTEGER NOT NULL DEFAULT 0, `is_deleted` INTEGER NOT NULL DEFAULT 0, `unknown_properties` TEXT, FOREIGN KEY(`list_id`) REFERENCES `task_lists`(`id`) ON UPDATE NO ACTION ON DELETE CASCADE , FOREIGN KEY(`master_id`) REFERENCES `tasks`(`id`) ON UPDATE NO ACTION ON DELETE CASCADE , FOREIGN KEY(`parent_id`) REFERENCES `tasks`(`id`) ON UPDATE NO ACTION ON DELETE SET NULL )",
+        "fields": [
+          {
+            "fieldPath": "id",
+            "columnName": "id",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "listId",
+            "columnName": "list_id",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "uid",
+            "columnName": "uid",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "href",
+            "columnName": "href",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "etag",
+            "columnName": "etag",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "title",
+            "columnName": "title",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "description",
+            "columnName": "description",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "location",
+            "columnName": "location",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "url",
+            "columnName": "url",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "color",
+            "columnName": "color",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "categories",
+            "columnName": "categories",
+            "affinity": "TEXT",
+            "notNull": true,
+            "defaultValue": "''"
+          },
+          {
+            "fieldPath": "status",
+            "columnName": "status",
+            "affinity": "INTEGER",
+            "notNull": true,
+            "defaultValue": "0"
+          },
+          {
+            "fieldPath": "percentComplete",
+            "columnName": "percent_complete",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "completedAt",
+            "columnName": "completed_at",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "priority",
+            "columnName": "priority",
+            "affinity": "INTEGER",
+            "notNull": true,
+            "defaultValue": "0"
+          },
+          {
+            "fieldPath": "classification",
+            "columnName": "classification",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "dtstart",
+            "columnName": "dtstart",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "due",
+            "columnName": "due",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "duration",
+            "columnName": "duration",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "isAllDay",
+            "columnName": "is_all_day",
+            "affinity": "INTEGER",
+            "notNull": true,
+            "defaultValue": "0"
+          },
+          {
+            "fieldPath": "timezone",
+            "columnName": "timezone",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "rrule",
+            "columnName": "rrule",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "rdate",
+            "columnName": "rdate",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "exdate",
+            "columnName": "exdate",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "recurrenceId",
+            "columnName": "recurrence_id",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "masterId",
+            "columnName": "master_id",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "parentId",
+            "columnName": "parent_id",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "sortOrder",
+            "columnName": "sort_order",
+            "affinity": "INTEGER",
+            "notNull": true,
+            "defaultValue": "0"
+          },
+          {
+            "fieldPath": "createdAt",
+            "columnName": "created_at",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "lastModified",
+            "columnName": "last_modified",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "sequence",
+            "columnName": "sequence",
+            "affinity": "INTEGER",
+            "notNull": true,
+            "defaultValue": "0"
+          },
+          {
+            "fieldPath": "isDirty",
+            "columnName": "is_dirty",
+            "affinity": "INTEGER",
+            "notNull": true,
+            "defaultValue": "0"
+          },
+          {
+            "fieldPath": "isDeleted",
+            "columnName": "is_deleted",
+            "affinity": "INTEGER",
+            "notNull": true,
+            "defaultValue": "0"
+          },
+          {
+            "fieldPath": "unknownProperties",
+            "columnName": "unknown_properties",
+            "affinity": "TEXT"
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": true,
+          "columnNames": [
+            "id"
+          ]
+        },
+        "indices": [
+          {
+            "name": "index_tasks_list_id_is_deleted",
+            "unique": false,
+            "columnNames": [
+              "list_id",
+              "is_deleted"
+            ],
+            "orders": [],
+            "createSql": "CREATE INDEX IF NOT EXISTS `index_tasks_list_id_is_deleted` ON `${TABLE_NAME}` (`list_id`, `is_deleted`)"
+          },
+          {
+            "name": "index_tasks_parent_id",
+            "unique": false,
+            "columnNames": [
+              "parent_id"
+            ],
+            "orders": [],
+            "createSql": "CREATE INDEX IF NOT EXISTS `index_tasks_parent_id` ON `${TABLE_NAME}` (`parent_id`)"
+          },
+          {
+            "name": "index_tasks_master_id_recurrence_id",
+            "unique": false,
+            "columnNames": [
+              "master_id",
+              "recurrence_id"
+            ],
+            "orders": [],
+            "createSql": "CREATE INDEX IF NOT EXISTS `index_tasks_master_id_recurrence_id` ON `${TABLE_NAME}` (`master_id`, `recurrence_id`)"
+          },
+          {
+            "name": "index_tasks_is_dirty",
+            "unique": false,
+            "columnNames": [
+              "is_dirty"
+            ],
+            "orders": [],
+            "createSql": "CREATE INDEX IF NOT EXISTS `index_tasks_is_dirty` ON `${TABLE_NAME}` (`is_dirty`)"
+          },
+          {
+            "name": "index_tasks_list_id_uid_recurrence_id",
+            "unique": true,
+            "columnNames": [
+              "list_id",
+              "uid",
+              "recurrence_id"
+            ],
+            "orders": [],
+            "createSql": "CREATE UNIQUE INDEX IF NOT EXISTS `index_tasks_list_id_uid_recurrence_id` ON `${TABLE_NAME}` (`list_id`, `uid`, `recurrence_id`)"
+          }
+        ],
+        "foreignKeys": [
+          {
+            "table": "task_lists",
+            "onDelete": "CASCADE",
+            "onUpdate": "NO ACTION",
+            "columns": [
+              "list_id"
+            ],
+            "referencedColumns": [
+              "id"
+            ]
+          },
+          {
+            "table": "tasks",
+            "onDelete": "CASCADE",
+            "onUpdate": "NO ACTION",
+            "columns": [
+              "master_id"
+            ],
+            "referencedColumns": [
+              "id"
+            ]
+          },
+          {
+            "table": "tasks",
+            "onDelete": "SET NULL",
+            "onUpdate": "NO ACTION",
+            "columns": [
+              "parent_id"
+            ],
+            "referencedColumns": [
+              "id"
+            ]
+          }
+        ]
+      },
+      {
+        "tableName": "task_alarms",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`id` INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, `task_id` INTEGER NOT NULL, `minutes_before` INTEGER NOT NULL, `reference` TEXT NOT NULL DEFAULT 'DUE', `message` TEXT, FOREIGN KEY(`task_id`) REFERENCES `tasks`(`id`) ON UPDATE NO ACTION ON DELETE CASCADE )",
+        "fields": [
+          {
+            "fieldPath": "id",
+            "columnName": "id",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "taskId",
+            "columnName": "task_id",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "minutesBefore",
+            "columnName": "minutes_before",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "reference",
+            "columnName": "reference",
+            "affinity": "TEXT",
+            "notNull": true,
+            "defaultValue": "'DUE'"
+          },
+          {
+            "fieldPath": "message",
+            "columnName": "message",
+            "affinity": "TEXT"
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": true,
+          "columnNames": [
+            "id"
+          ]
+        },
+        "indices": [
+          {
+            "name": "index_task_alarms_task_id",
+            "unique": false,
+            "columnNames": [
+              "task_id"
+            ],
+            "orders": [],
+            "createSql": "CREATE INDEX IF NOT EXISTS `index_task_alarms_task_id` ON `${TABLE_NAME}` (`task_id`)"
+          }
+        ],
+        "foreignKeys": [
+          {
+            "table": "tasks",
+            "onDelete": "CASCADE",
+            "onUpdate": "NO ACTION",
+            "columns": [
+              "task_id"
+            ],
+            "referencedColumns": [
+              "id"
+            ]
+          }
+        ]
+      }
+    ],
+    "setupQueries": [
+      "CREATE TABLE IF NOT EXISTS room_master_table (id INTEGER PRIMARY KEY,identity_hash TEXT)",
+      "INSERT OR REPLACE INTO room_master_table (id,identity_hash) VALUES(42, '14b159c51416ba27653f6320ac7f6f03')"
+    ]
+  }
+}

app/schemas/de.jeanlucmakiola.agendula.data.tasks.room.TasksDatabase/3.json

@@ -0,0 +1,548 @@
+{
+  "formatVersion": 1,
+  "database": {
+    "version": 3,
+    "identityHash": "725292b38bce25ce9032c4650573ae85",
+    "entities": [
+      {
+        "tableName": "accounts",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`id` INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, `display_name` TEXT NOT NULL, `principal_url` TEXT, `home_set_url` TEXT, `username` TEXT, `last_sync_at` INTEGER, `last_sync_error` TEXT)",
+        "fields": [
+          {
+            "fieldPath": "id",
+            "columnName": "id",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "displayName",
+            "columnName": "display_name",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "principalUrl",
+            "columnName": "principal_url",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "homeSetUrl",
+            "columnName": "home_set_url",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "username",
+            "columnName": "username",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "lastSyncAt",
+            "columnName": "last_sync_at",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "lastSyncError",
+            "columnName": "last_sync_error",
+            "affinity": "TEXT"
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": true,
+          "columnNames": [
+            "id"
+          ]
+        }
+      },
+      {
+        "tableName": "task_lists",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`id` INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, `name` TEXT NOT NULL, `color` INTEGER NOT NULL, `account_id` INTEGER, `is_visible` INTEGER NOT NULL DEFAULT 1, `is_synced` INTEGER NOT NULL DEFAULT 1, `owner` TEXT, `is_read_only` INTEGER NOT NULL DEFAULT 0, `sort_order` INTEGER NOT NULL DEFAULT 0, `href` TEXT, `ctag` TEXT, `sync_token` TEXT, `is_dirty` INTEGER NOT NULL DEFAULT 0, FOREIGN KEY(`account_id`) REFERENCES `accounts`(`id`) ON UPDATE NO ACTION ON DELETE SET NULL )",
+        "fields": [
+          {
+            "fieldPath": "id",
+            "columnName": "id",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "name",
+            "columnName": "name",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "color",
+            "columnName": "color",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "accountId",
+            "columnName": "account_id",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "isVisible",
+            "columnName": "is_visible",
+            "affinity": "INTEGER",
+            "notNull": true,
+            "defaultValue": "1"
+          },
+          {
+            "fieldPath": "isSynced",
+            "columnName": "is_synced",
+            "affinity": "INTEGER",
+            "notNull": true,
+            "defaultValue": "1"
+          },
+          {
+            "fieldPath": "owner",
+            "columnName": "owner",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "isReadOnly",
+            "columnName": "is_read_only",
+            "affinity": "INTEGER",
+            "notNull": true,
+            "defaultValue": "0"
+          },
+          {
+            "fieldPath": "sortOrder",
+            "columnName": "sort_order",
+            "affinity": "INTEGER",
+            "notNull": true,
+            "defaultValue": "0"
+          },
+          {
+            "fieldPath": "href",
+            "columnName": "href",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "ctag",
+            "columnName": "ctag",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "syncToken",
+            "columnName": "sync_token",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "isDirty",
+            "columnName": "is_dirty",
+            "affinity": "INTEGER",
+            "notNull": true,
+            "defaultValue": "0"
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": true,
+          "columnNames": [
+            "id"
+          ]
+        },
+        "indices": [
+          {
+            "name": "index_task_lists_account_id",
+            "unique": false,
+            "columnNames": [
+              "account_id"
+            ],
+            "orders": [],
+            "createSql": "CREATE INDEX IF NOT EXISTS `index_task_lists_account_id` ON `${TABLE_NAME}` (`account_id`)"
+          }
+        ],
+        "foreignKeys": [
+          {
+            "table": "accounts",
+            "onDelete": "SET NULL",
+            "onUpdate": "NO ACTION",
+            "columns": [
+              "account_id"
+            ],
+            "referencedColumns": [
+              "id"
+            ]
+          }
+        ]
+      },
+      {
+        "tableName": "tasks",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`id` INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, `list_id` INTEGER NOT NULL, `uid` TEXT NOT NULL, `href` TEXT, `etag` TEXT, `title` TEXT, `description` TEXT, `location` TEXT, `url` TEXT, `color` INTEGER, `categories` TEXT NOT NULL DEFAULT '', `status` INTEGER NOT NULL DEFAULT 0, `percent_complete` INTEGER, `completed_at` INTEGER, `priority` INTEGER NOT NULL DEFAULT 0, `classification` INTEGER, `dtstart` INTEGER, `due` INTEGER, `duration` TEXT, `is_all_day` INTEGER NOT NULL DEFAULT 0, `timezone` TEXT, `rrule` TEXT, `rdate` TEXT, `exdate` TEXT, `recurrence_id` INTEGER, `master_id` INTEGER, `parent_id` INTEGER, `sort_order` INTEGER NOT NULL DEFAULT 0, `created_at` INTEGER, `last_modified` INTEGER, `sequence` INTEGER NOT NULL DEFAULT 0, `is_dirty` INTEGER NOT NULL DEFAULT 0, `is_deleted` INTEGER NOT NULL DEFAULT 0, `unknown_properties` TEXT, `reminders_off` INTEGER NOT NULL DEFAULT 0, FOREIGN KEY(`list_id`) REFERENCES `task_lists`(`id`) ON UPDATE NO ACTION ON DELETE CASCADE , FOREIGN KEY(`master_id`) REFERENCES `tasks`(`id`) ON UPDATE NO ACTION ON DELETE CASCADE , FOREIGN KEY(`parent_id`) REFERENCES `tasks`(`id`) ON UPDATE NO ACTION ON DELETE SET NULL )",
+        "fields": [
+          {
+            "fieldPath": "id",
+            "columnName": "id",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "listId",
+            "columnName": "list_id",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "uid",
+            "columnName": "uid",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "href",
+            "columnName": "href",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "etag",
+            "columnName": "etag",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "title",
+            "columnName": "title",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "description",
+            "columnName": "description",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "location",
+            "columnName": "location",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "url",
+            "columnName": "url",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "color",
+            "columnName": "color",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "categories",
+            "columnName": "categories",
+            "affinity": "TEXT",
+            "notNull": true,
+            "defaultValue": "''"
+          },
+          {
+            "fieldPath": "status",
+            "columnName": "status",
+            "affinity": "INTEGER",
+            "notNull": true,
+            "defaultValue": "0"
+          },
+          {
+            "fieldPath": "percentComplete",
+            "columnName": "percent_complete",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "completedAt",
+            "columnName": "completed_at",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "priority",
+            "columnName": "priority",
+            "affinity": "INTEGER",
+            "notNull": true,
+            "defaultValue": "0"
+          },
+          {
+            "fieldPath": "classification",
+            "columnName": "classification",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "dtstart",
+            "columnName": "dtstart",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "due",
+            "columnName": "due",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "duration",
+            "columnName": "duration",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "isAllDay",
+            "columnName": "is_all_day",
+            "affinity": "INTEGER",
+            "notNull": true,
+            "defaultValue": "0"
+          },
+          {
+            "fieldPath": "timezone",
+            "columnName": "timezone",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "rrule",
+            "columnName": "rrule",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "rdate",
+            "columnName": "rdate",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "exdate",
+            "columnName": "exdate",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "recurrenceId",
+            "columnName": "recurrence_id",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "masterId",
+            "columnName": "master_id",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "parentId",
+            "columnName": "parent_id",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "sortOrder",
+            "columnName": "sort_order",
+            "affinity": "INTEGER",
+            "notNull": true,
+            "defaultValue": "0"
+          },
+          {
+            "fieldPath": "createdAt",
+            "columnName": "created_at",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "lastModified",
+            "columnName": "last_modified",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "sequence",
+            "columnName": "sequence",
+            "affinity": "INTEGER",
+            "notNull": true,
+            "defaultValue": "0"
+          },
+          {
+            "fieldPath": "isDirty",
+            "columnName": "is_dirty",
+            "affinity": "INTEGER",
+            "notNull": true,
+            "defaultValue": "0"
+          },
+          {
+            "fieldPath": "isDeleted",
+            "columnName": "is_deleted",
+            "affinity": "INTEGER",
+            "notNull": true,
+            "defaultValue": "0"
+          },
+          {
+            "fieldPath": "unknownProperties",
+            "columnName": "unknown_properties",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "remindersOff",
+            "columnName": "reminders_off",
+            "affinity": "INTEGER",
+            "notNull": true,
+            "defaultValue": "0"
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": true,
+          "columnNames": [
+            "id"
+          ]
+        },
+        "indices": [
+          {
+            "name": "index_tasks_list_id_is_deleted",
+            "unique": false,
+            "columnNames": [
+              "list_id",
+              "is_deleted"
+            ],
+            "orders": [],
+            "createSql": "CREATE INDEX IF NOT EXISTS `index_tasks_list_id_is_deleted` ON `${TABLE_NAME}` (`list_id`, `is_deleted`)"
+          },
+          {
+            "name": "index_tasks_parent_id",
+            "unique": false,
+            "columnNames": [
+              "parent_id"
+            ],
+            "orders": [],
+            "createSql": "CREATE INDEX IF NOT EXISTS `index_tasks_parent_id` ON `${TABLE_NAME}` (`parent_id`)"
+          },
+          {
+            "name": "index_tasks_master_id_recurrence_id",
+            "unique": false,
+            "columnNames": [
+              "master_id",
+              "recurrence_id"
+            ],
+            "orders": [],
+            "createSql": "CREATE INDEX IF NOT EXISTS `index_tasks_master_id_recurrence_id` ON `${TABLE_NAME}` (`master_id`, `recurrence_id`)"
+          },
+          {
+            "name": "index_tasks_is_dirty",
+            "unique": false,
+            "columnNames": [
+              "is_dirty"
+            ],
+            "orders": [],
+            "createSql": "CREATE INDEX IF NOT EXISTS `index_tasks_is_dirty` ON `${TABLE_NAME}` (`is_dirty`)"
+          },
+          {
+            "name": "index_tasks_list_id_uid_recurrence_id",
+            "unique": true,
+            "columnNames": [
+              "list_id",
+              "uid",
+              "recurrence_id"
+            ],
+            "orders": [],
+            "createSql": "CREATE UNIQUE INDEX IF NOT EXISTS `index_tasks_list_id_uid_recurrence_id` ON `${TABLE_NAME}` (`list_id`, `uid`, `recurrence_id`)"
+          }
+        ],
+        "foreignKeys": [
+          {
+            "table": "task_lists",
+            "onDelete": "CASCADE",
+            "onUpdate": "NO ACTION",
+            "columns": [
+              "list_id"
+            ],
+            "referencedColumns": [
+              "id"
+            ]
+          },
+          {
+            "table": "tasks",
+            "onDelete": "CASCADE",
+            "onUpdate": "NO ACTION",
+            "columns": [
+              "master_id"
+            ],
+            "referencedColumns": [
+              "id"
+            ]
+          },
+          {
+            "table": "tasks",
+            "onDelete": "SET NULL",
+            "onUpdate": "NO ACTION",
+            "columns": [
+              "parent_id"
+            ],
+            "referencedColumns": [
+              "id"
+            ]
+          }
+        ]
+      },
+      {
+        "tableName": "task_alarms",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`id` INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, `task_id` INTEGER NOT NULL, `minutes_before` INTEGER NOT NULL, `reference` TEXT NOT NULL DEFAULT 'DUE', `message` TEXT, `uid` TEXT NOT NULL DEFAULT '', `raw` TEXT, FOREIGN KEY(`task_id`) REFERENCES `tasks`(`id`) ON UPDATE NO ACTION ON DELETE CASCADE )",
+        "fields": [
+          {
+            "fieldPath": "id",
+            "columnName": "id",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "taskId",
+            "columnName": "task_id",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "minutesBefore",
+            "columnName": "minutes_before",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "reference",
+            "columnName": "reference",
+            "affinity": "TEXT",
+            "notNull": true,
+            "defaultValue": "'DUE'"
+          },
+          {
+            "fieldPath": "message",
+            "columnName": "message",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "uid",
+            "columnName": "uid",
+            "affinity": "TEXT",
+            "notNull": true,
+            "defaultValue": "''"
+          },
+          {
+            "fieldPath": "raw",
+            "columnName": "raw",
+            "affinity": "TEXT"
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": true,
+          "columnNames": [
+            "id"
+          ]
+        },
+        "indices": [
+          {
+            "name": "index_task_alarms_task_id",
+            "unique": false,
+            "columnNames": [
+              "task_id"
+            ],
+            "orders": [],
+            "createSql": "CREATE INDEX IF NOT EXISTS `index_task_alarms_task_id` ON `${TABLE_NAME}` (`task_id`)"
+          }
+        ],
+        "foreignKeys": [
+          {
+            "table": "tasks",
+            "onDelete": "CASCADE",
+            "onUpdate": "NO ACTION",
+            "columns": [
+              "task_id"
+            ],
+            "referencedColumns": [
+              "id"
+            ]
+          }
+        ]
+      }
+    ],
+    "setupQueries": [
+      "CREATE TABLE IF NOT EXISTS room_master_table (id INTEGER PRIMARY KEY,identity_hash TEXT)",
+      "INSERT OR REPLACE INTO room_master_table (id,identity_hash) VALUES(42, '725292b38bce25ce9032c4650573ae85')"
+    ]
+  }
+}

app/src/androidTest/java/de/jeanlucmakiola/agendula/data/tasks/legacy/OneShotImportTest.kt

@@ -212,6 +212,15 @@ class OneShotImportTest {
         assertThat(db.alarms().all().map { it.message }).doesNotContain("Errands")
     }
 
+    @Test
+    fun importsCategoryPropertiesAsTags() {
+        importer.importFrom(fixture())
+        val tasks = taskRows()
+
+        assertThat(tasks.getValue("Buy milk").categories).containsExactly("Errands")
+        assertThat(tasks.getValue("Ship the release").categories).isEmpty()
+    }
+
     // --- running it -----------------------------------------------------------
 
     @Test

app/src/androidTest/java/de/jeanlucmakiola/agendula/data/tasks/provider/AgendulaTaskProviderTest.kt

@@ -0,0 +1,157 @@
+package de.jeanlucmakiola.agendula.data.tasks.provider
+
+import android.content.ContentProviderOperation
+import android.content.ContentValues
+import android.content.Context
+import android.content.pm.PermissionInfo
+import android.os.Build
+import android.os.ParcelFileDescriptor
+import androidx.core.net.toUri
+import androidx.test.core.app.ApplicationProvider
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import androidx.test.platform.app.InstrumentationRegistry
+import com.google.common.truth.Truth.assertThat
+import org.junit.Assert.assertThrows
+import org.junit.Assume.assumeTrue
+import org.junit.Test
+import org.junit.runner.RunWith
+
+/** The provider as another app meets it: manifest, permission, URIs. */
+@RunWith(AndroidJUnit4::class)
+class AgendulaTaskProviderTest {
+
+    private val context = ApplicationProvider.getApplicationContext<Context>()
+    private val authority = "${context.packageName}.tasks"
+    private val readPermission = "${context.packageName}.permission.READ_TASKS"
+    private val writePermission = "${context.packageName}.permission.WRITE_TASKS"
+    private val resolver = context.contentResolver
+
+    private fun uri(path: String) = "content://$authority/$path".toUri()
+
+    @Test
+    fun isExportedUnderItsPermissions() {
+        val info = requireNotNull(context.packageManager.resolveContentProvider(authority, 0))
+
+        assertThat(info.name).isEqualTo(AgendulaTaskProvider::class.java.name)
+        assertThat(info.exported).isTrue()
+        assertThat(info.readPermission).isEqualTo(readPermission)
+        assertThat(info.writePermission).isEqualTo(writePermission)
+    }
+
+    @Test
+    fun bothPermissionsAreDangerous() {
+        listOf(readPermission, writePermission).forEach { permission ->
+            val info = context.packageManager.getPermissionInfo(permission, 0)
+
+            assertThat(info.protection).isEqualTo(PermissionInfo.PROTECTION_DANGEROUS)
+            assertThat(info.loadLabel(context.packageManager).toString()).isNotEmpty()
+            assertThat(info.loadDescription(context.packageManager)?.toString()).isNotEmpty()
+        }
+    }
+
+    @Test
+    fun anAppWithoutThePermissionIsDenied() {
+        assumeTrue(Build.VERSION.SDK_INT >= Build.VERSION_CODES.S)
+        // The shell is another uid that was never granted it.
+        val output = shell("content query --uri content://$authority/tasks")
+
+        assertThat(output).contains("Permission Denial")
+    }
+
+    @Test
+    fun anAppWithoutTheWritePermissionCannotWrite() {
+        assumeTrue(Build.VERSION.SDK_INT >= Build.VERSION_CODES.S)
+
+        val output = shell("content insert --uri content://$authority/tasks --bind title:s:x --bind list_id:i:1")
+
+        assertThat(output).contains("Permission Denial")
+        assertThat(output).contains(writePermission)
+    }
+
+    @Test
+    fun reportsOpenTasksMimeTypes() {
+        ProviderTable.entries.forEach { table ->
+            assertThat(resolver.getType(uri(table.path))).isEqualTo(table.mimeType(single = false))
+            assertThat(resolver.getType(uri("${table.path}/3"))).isEqualTo(table.mimeType(single = true))
+        }
+    }
+
+    @Test
+    fun everyTableAnswersWithItsColumns() {
+        ProviderTable.entries.forEach { table ->
+            resolver.query(uri(table.path), null, null, null, null)!!.use {
+                assertThat(it.columnNames.toList()).containsExactlyElementsIn(table.columns.map { c -> c.first }).inOrder()
+            }
+        }
+    }
+
+    @Test
+    fun aCursorWatchesTheUriItWasQueriedFor() {
+        val tasks = uri("tasks")
+
+        resolver.query(tasks, null, null, null, null)!!.use { assertThat(it.notificationUri).isEqualTo(tasks) }
+    }
+
+    @Test
+    fun aRowUriReadsOnlyThatRow() {
+        // Ids start at 1, so 0 names nothing whatever the store holds.
+        resolver.query(uri("tasks/0"), null, null, null, null)!!.use { assertThat(it.count).isEqualTo(0) }
+        resolver.query(uri("tasks/0"), null, "1 = 1 OR 1 = 1", null, null)!!.use { assertThat(it.count).isEqualTo(0) }
+    }
+
+    @Test
+    fun anUnknownUriIsRejected() {
+        assertThrows(IllegalArgumentException::class.java) { resolver.query(uri("events"), null, null, null, null) }
+        // ContentResolver.getType swallows the provider's exception and answers null.
+        assertThat(runCatching { resolver.getType(uri("tasks/abc")) }.getOrNull()).isNull()
+    }
+
+    @Test
+    fun listsAreReadOnly() {
+        val values = ContentValues().apply { put("list_name", "x") }
+
+        assertThrows(UnsupportedOperationException::class.java) { resolver.insert(uri("tasklists"), values) }
+        assertThrows(UnsupportedOperationException::class.java) { resolver.update(uri("tasklists/1"), values, null, null) }
+        assertThrows(UnsupportedOperationException::class.java) { resolver.delete(uri("tasklists/1"), null, null) }
+    }
+
+    @Test
+    fun aRowUriTakesNoInsert() {
+        assertThrows(IllegalArgumentException::class.java) {
+            resolver.insert(uri("tasks/1"), ContentValues().apply { put("title", "x") })
+        }
+    }
+
+    @Test
+    fun aBadWriteReachesTheClientAsIllegalArgument() {
+        // No list has this id, so nothing in the app's real store is touched.
+        val values = ContentValues().apply {
+            put("list_id", Long.MAX_VALUE)
+            put("title", "x")
+        }
+
+        assertThrows(IllegalArgumentException::class.java) { resolver.insert(uri("tasks"), values) }
+    }
+
+    @Test
+    fun aFailingBatchWritesNothing() {
+        val missingList = Long.MAX_VALUE
+        val operations = arrayListOf(
+            ContentProviderOperation.newInsert(uri("tasks")).withValue("list_id", missingList).withValue("title", "a").build(),
+        )
+
+        assertThrows(IllegalArgumentException::class.java) { resolver.applyBatch(authority, operations) }
+        resolver.query(uri("tasks"), arrayOf("_id"), "list_id = ?", arrayOf(missingList.toString()), null)!!
+            .use { assertThat(it.count).isEqualTo(0) }
+    }
+
+    /** stdout and stderr of [command]; the denial lands on stderr. */
+    private fun shell(command: String): String {
+        val (stdout, stdin, stderr) = InstrumentationRegistry.getInstrumentation().uiAutomation
+            .executeShellCommandRwe(command)
+        stdin.close()
+        return listOf(stdout, stderr).joinToString("\n") { pfd ->
+            ParcelFileDescriptor.AutoCloseInputStream(pfd).bufferedReader().use { it.readText() }
+        }
+    }
+}

app/src/androidTest/java/de/jeanlucmakiola/agendula/data/tasks/provider/ProviderSnapshotSourceTest.kt

@@ -0,0 +1,214 @@
+package de.jeanlucmakiola.agendula.data.tasks.provider
+
+import android.content.Context
+import android.database.ContentObserver
+import android.database.Cursor
+import android.net.Uri
+import androidx.room.Room
+import androidx.test.core.app.ApplicationProvider
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.google.common.truth.Truth.assertThat
+import de.jeanlucmakiola.agendula.data.tasks.ProviderEnvironment
+import de.jeanlucmakiola.agendula.data.tasks.ProviderResolver
+import de.jeanlucmakiola.agendula.data.tasks.StorageMode
+import de.jeanlucmakiola.agendula.data.tasks.TasksContract
+import de.jeanlucmakiola.agendula.data.tasks.TasksContract.Instances
+import de.jeanlucmakiola.agendula.data.tasks.TasksContract.Lists
+import de.jeanlucmakiola.agendula.data.tasks.TasksContract.Tasks
+import de.jeanlucmakiola.agendula.data.tasks.room.TaskAlarmEntity
+import de.jeanlucmakiola.agendula.data.tasks.room.TaskEntity
+import de.jeanlucmakiola.agendula.data.tasks.room.TaskListEntity
+import de.jeanlucmakiola.agendula.data.tasks.room.TasksDatabase
+import org.junit.After
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import java.util.concurrent.LinkedBlockingQueue
+import java.util.concurrent.TimeUnit
+import kotlin.time.Clock
+import kotlin.time.Duration.Companion.days
+import kotlin.time.Duration.Companion.minutes
+import kotlin.time.Instant
+
+/** The snapshot follows the Room store, the storage mode and the clock, and says when it moved. */
+@RunWith(AndroidJUnit4::class)
+class ProviderSnapshotSourceTest {
+
+    private val context = ApplicationProvider.getApplicationContext<Context>()
+    private lateinit var db: TasksDatabase
+    private lateinit var resolver: ProviderResolver
+    private lateinit var source: ProviderSnapshotSource
+    private val clock = MutableClock(Instant.parse("2026-10-10T08:00:00Z"))
+    private val changes = LinkedBlockingQueue<Uri>()
+    private val observer = object : ContentObserver(null) {
+        override fun onChange(selfChange: Boolean, uri: Uri?) {
+            changes += uri ?: Uri.EMPTY
+        }
+    }
+    private var listId = 0L
+
+    @Before
+    fun setUp() {
+        db = Room.inMemoryDatabaseBuilder(context, TasksDatabase::class.java).allowMainThreadQueries().build()
+        resolver = ProviderResolver(NoProviderInstalled)
+        source = ProviderSnapshotSource(context, db, resolver, awaitStartup = {}, clock = clock)
+        listId = db.taskLists().insert(TaskListEntity(name = "Home", color = 0xFF112233.toInt()))
+        context.contentResolver.registerContentObserver(TasksContract.authorityUri(source.authority), true, observer)
+    }
+
+    @After
+    fun tearDown() {
+        context.contentResolver.unregisterContentObserver(observer)
+        db.close()
+    }
+
+    private fun query(table: ProviderTable, selection: String? = null, args: Array<String>? = null): Cursor =
+        source.query(table, null, selection, args, null)
+
+    private fun titles(): List<String?> = query(ProviderTable.TASKS).use { cursor ->
+        val index = cursor.getColumnIndexOrThrow(Tasks.TITLE)
+        buildList { while (cursor.moveToNext()) add(cursor.getString(index)) }
+    }
+
+    private fun insert(title: String, due: Instant? = null, rrule: String? = null): Long =
+        db.tasks().insert(TaskEntity(listId = listId, uid = title, title = title, due = due, rrule = rrule, timezone = "UTC"))
+
+    /** Waits for the coalesced notification, then drains any stragglers. */
+    private fun awaitChange() {
+        assertThat(changes.poll(5, TimeUnit.SECONDS)).isNotNull()
+        Thread.sleep(700)
+        changes.clear()
+    }
+
+    private fun assertNoChange() {
+        assertThat(changes.poll(1500, TimeUnit.MILLISECONDS)).isNull()
+    }
+
+    @Test
+    fun servesTheOwnStore() {
+        val id = insert("Milk")
+        db.alarms().insert(TaskAlarmEntity(taskId = id, minutesBefore = 10))
+
+        assertThat(titles()).containsExactly("Milk")
+        query(ProviderTable.LISTS).use {
+            it.moveToFirst()
+            assertThat(it.getString(it.getColumnIndexOrThrow(Lists.NAME))).isEqualTo("Home")
+        }
+        query(ProviderTable.INSTANCES).use { assertThat(it.count).isEqualTo(1) }
+        query(ProviderTable.PROPERTIES).use { assertThat(it.count).isEqualTo(1) }
+    }
+
+    @Test
+    fun aDeletedTaskIsNotPublished() {
+        val id = insert("Gone")
+        insert("Kept")
+        db.tasks().markDeleted(id, clock.now())
+
+        assertThat(titles()).containsExactly("Kept")
+    }
+
+    @Test
+    fun aWriteNotifiesObserversAndIsServedNext() {
+        source.start()
+        assertThat(titles()).isEmpty()
+
+        insert("Later")
+
+        awaitChange()
+        assertThat(titles()).containsExactly("Later")
+    }
+
+    @Test
+    fun aBurstOfWritesNotifiesOnce() {
+        source.start()
+        titles()
+
+        repeat(5) { insert("t$it") }
+
+        assertThat(changes.poll(5, TimeUnit.SECONDS)).isNotNull()
+        assertNoChange()
+    }
+
+    @Test
+    fun externalModeServesNothing() {
+        insert("Mine")
+        resolver.storageMode = StorageMode.EXTERNAL
+
+        ProviderTable.entries.forEach { table -> query(table).use { assertThat(it.count).isEqualTo(0) } }
+    }
+
+    @Test
+    fun switchingModeNotifiesAndRebuilds() {
+        source.start()
+        insert("Mine")
+        assertThat(titles()).containsExactly("Mine")
+        changes.clear()
+
+        resolver.storageMode = StorageMode.EXTERNAL
+        awaitChange()
+        assertThat(titles()).isEmpty()
+
+        resolver.storageMode = StorageMode.OWN
+        awaitChange()
+        assertThat(titles()).containsExactly("Mine")
+    }
+
+    @Test
+    fun writesInExternalModeDoNotNotify() {
+        resolver.storageMode = StorageMode.EXTERNAL
+        source.start()
+        titles()
+
+        insert("Hidden")
+
+        assertNoChange()
+    }
+
+    @Test
+    fun aClientSelectionNarrowsTheRows() {
+        insert("a")
+        insert("b")
+
+        query(ProviderTable.TASKS, "${Tasks.TITLE} = ?", arrayOf("b")).use { assertThat(it.count).isEqualTo(1) }
+    }
+
+    @Test
+    fun anHourOldSnapshotIsRebuiltAgainstTheClock() {
+        source.start()
+        insert("Daily", due = Instant.parse("2026-10-10T09:00:00Z"), rrule = "FREQ=DAILY;COUNT=3")
+        awaitChange()
+        assertThat(currentOriginalTime()).isEqualTo(Instant.parse("2026-10-10T09:00:00Z").toEpochMilliseconds())
+
+        clock.current += 1.days
+
+        assertThat(currentOriginalTime()).isEqualTo(Instant.parse("2026-10-11T09:00:00Z").toEpochMilliseconds())
+        awaitChange()
+    }
+
+    @Test
+    fun aFreshSnapshotIsReused() {
+        insert("a")
+        titles()
+
+        clock.current += 30.minutes
+
+        query(ProviderTable.INSTANCES).use { assertThat(it.count).isEqualTo(1) }
+        assertNoChange()
+    }
+
+    private fun currentOriginalTime(): Long =
+        query(ProviderTable.INSTANCES, "${Instances.DISTANCE_FROM_CURRENT} = 0").use {
+            assertThat(it.moveToFirst()).isTrue()
+            it.getLong(it.getColumnIndexOrThrow(Instances.INSTANCE_ORIGINAL_TIME))
+        }
+}
+
+private class MutableClock(var current: Instant) : Clock {
+    override fun now(): Instant = current
+}
+
+private object NoProviderInstalled : ProviderEnvironment {
+    override fun packageDeclaring(authority: String): String? = null
+    override fun isGranted(permission: String): Boolean = false
+    override fun appLabel(packageName: String): String? = null
+}

app/src/androidTest/java/de/jeanlucmakiola/agendula/data/tasks/provider/ProviderWriterTest.kt

@@ -0,0 +1,811 @@
+package de.jeanlucmakiola.agendula.data.tasks.provider
+
+import android.content.Context
+import androidx.room.Room
+import androidx.test.core.app.ApplicationProvider
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.google.common.truth.Truth.assertThat
+import de.jeanlucmakiola.agendula.data.tasks.ProviderEnvironment
+import de.jeanlucmakiola.agendula.data.tasks.ProviderResolver
+import de.jeanlucmakiola.agendula.data.tasks.StorageMode
+import de.jeanlucmakiola.agendula.data.tasks.TasksContract
+import de.jeanlucmakiola.agendula.data.tasks.TasksContract.Alarm
+import de.jeanlucmakiola.agendula.data.tasks.TasksContract.Category
+import de.jeanlucmakiola.agendula.data.tasks.TasksContract.Instances
+import de.jeanlucmakiola.agendula.data.tasks.TasksContract.Properties
+import de.jeanlucmakiola.agendula.data.tasks.TasksContract.Tasks
+import de.jeanlucmakiola.agendula.data.tasks.room.AccountEntity
+import de.jeanlucmakiola.agendula.data.tasks.room.AlarmReference
+import de.jeanlucmakiola.agendula.data.tasks.room.RoomTasksDataSource
+import de.jeanlucmakiola.agendula.data.tasks.room.TaskAlarmEntity
+import de.jeanlucmakiola.agendula.data.tasks.room.TaskEntity
+import de.jeanlucmakiola.agendula.data.tasks.room.TaskListEntity
+import de.jeanlucmakiola.agendula.data.tasks.room.TasksDatabase
+import de.jeanlucmakiola.agendula.domain.TaskStatus
+import org.junit.After
+import org.junit.Assert.assertThrows
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import kotlin.time.Clock
+import kotlin.time.Duration.Companion.days
+import kotlin.time.Duration.Companion.hours
+import kotlin.time.Duration.Companion.milliseconds
+import kotlinx.coroutines.awaitCancellation
+import kotlin.time.Instant
+
+/** Writes from another app, applied to the own store through the published tables. */
+@RunWith(AndroidJUnit4::class)
+class ProviderWriterTest {
+
+    private val context = ApplicationProvider.getApplicationContext<Context>()
+    private lateinit var db: TasksDatabase
+    private lateinit var resolver: ProviderResolver
+    private lateinit var source: ProviderSnapshotSource
+    private lateinit var writer: ProviderWriter
+    private var afterWrites = 0
+    private var home = 0L
+
+    /** Truncated to the store's granularity, and on the hour so occurrences land on round times. */
+    private val today = Instant.fromEpochMilliseconds(Clock.System.now().toEpochMilliseconds() / 3_600_000 * 3_600_000)
+
+    @Before
+    fun setUp() {
+        db = Room.inMemoryDatabaseBuilder(context, TasksDatabase::class.java).allowMainThreadQueries().build()
+        resolver = ProviderResolver(NoProvider)
+        source = ProviderSnapshotSource(context, db, resolver, awaitStartup = {})
+        writer = ProviderWriter(db, RoomTasksDataSource(db), source, resolver, afterWrite = { afterWrites++ })
+        home = db.taskLists().insert(TaskListEntity(name = "Home", color = 0))
+    }
+
+    @After
+    fun tearDown() = db.close()
+
+    private fun task(id: Long) = db.tasks().entity(id)
+
+    private fun insert(vararg values: Pair<String, Any?>): Long =
+        writer.insert(ProviderTable.TASKS, mapOf(Tasks.LIST_ID to home, *values))
+
+    private fun byId(table: ProviderTable, id: Long) = "${table.idColumn} = $id"
+
+    private fun synced(readOnly: Boolean = false): Long {
+        val account = db.accounts().insert(AccountEntity(displayName = "me", username = "me"))
+        return db.taskLists().insert(
+            TaskListEntity(name = "Work", color = 0, accountId = account, href = "https://s/w/", isReadOnly = readOnly),
+        )
+    }
+
+    private fun dailySeries(title: String = "Daily"): Long = db.tasks().insert(
+        TaskEntity(listId = home, uid = title, title = title, dtstart = today - 1.days, due = today - 1.days + 1.hours,
+            rrule = "FREQ=DAILY;COUNT=5", timezone = "UTC"),
+    )
+
+    /** Each instance of [taskId]'s series by its original time, with its task row and status. */
+    private fun instances(): List<Triple<Long, Long, Int>> =
+        source.rows(
+            ProviderTable.INSTANCES,
+            listOf(Instances.INSTANCE_ORIGINAL_TIME, Instances.TASK_ID, Tasks.STATUS),
+            null,
+            null,
+        ).map { (original, taskId, status) -> Triple(original as Long, taskId as Long, (status as Long).toInt()) }
+
+    private fun instanceId(original: Instant): Long =
+        source.rows(
+            ProviderTable.INSTANCES,
+            listOf(Tasks.ID),
+            "${Instances.INSTANCE_ORIGINAL_TIME} = ?",
+            arrayOf(original.toEpochMilliseconds().toString()),
+        ).single().single() as Long
+
+    // --- inserts ----------------------------------------------------------------
+
+    @Test
+    fun anInsertedTaskIsPublishedAndOwedASync() {
+        val id = insert(Tasks.TITLE to "Milk", Tasks.PRIORITY to 1)
+
+        val stored = task(id)!!
+        assertThat(stored.title).isEqualTo("Milk")
+        assertThat(stored.priority).isEqualTo(1)
+        assertThat(stored.isDirty).isTrue()
+        assertThat(source.rows(ProviderTable.TASKS, listOf(Tasks.TITLE), byId(ProviderTable.TASKS, id), null))
+            .containsExactly(listOf("Milk"))
+        assertThat(afterWrites).isEqualTo(1)
+    }
+
+    @Test
+    fun anInsertNeedsAListThatExistsAndIsWritable() {
+        assertThrows(IllegalArgumentException::class.java) { writer.insert(ProviderTable.TASKS, mapOf(Tasks.TITLE to "x")) }
+        assertThrows(IllegalArgumentException::class.java) { insert(Tasks.LIST_ID to 999L) }
+        val readOnly = synced(readOnly = true)
+        assertThrows(UnsupportedOperationException::class.java) { insert(Tasks.LIST_ID to readOnly) }
+        assertThat(db.tasks().live()).isEmpty()
+    }
+
+    @Test
+    fun anOccurrenceCannotBeInsertedAsATask() {
+        val series = dailySeries()
+
+        assertThrows(IllegalArgumentException::class.java) {
+            insert(Tasks.ORIGINAL_INSTANCE_ID to series, Tasks.ORIGINAL_INSTANCE_TIME to today.toEpochMilliseconds())
+        }
+    }
+
+    @Test
+    fun aDuplicateUidIsRejected() {
+        insert(Tasks.UID to "same")
+
+        assertThrows(IllegalArgumentException::class.java) { insert(Tasks.UID to "same") }
+    }
+
+    @Test
+    fun listsAndInstancesTakeNoInserts() {
+        assertThrows(UnsupportedOperationException::class.java) {
+            writer.insert(ProviderTable.LISTS, mapOf(TasksContract.Lists.NAME to "New"))
+        }
+        assertThrows(UnsupportedOperationException::class.java) { writer.insert(ProviderTable.INSTANCES, emptyMap()) }
+        assertThrows(UnsupportedOperationException::class.java) {
+            writer.update(ProviderTable.LISTS, mapOf(TasksContract.Lists.NAME to "x"), null, null)
+        }
+        assertThrows(UnsupportedOperationException::class.java) { writer.delete(ProviderTable.LISTS, null, null) }
+    }
+
+    @Test
+    fun anUnknownColumnIsRejected() {
+        assertThrows(IllegalArgumentException::class.java) { insert("etag" to "x") }
+    }
+
+    @Test
+    fun nothingIsWrittenInExternalMode() {
+        val id = insert(Tasks.TITLE to "Mine")
+        resolver.storageMode = StorageMode.EXTERNAL
+
+        assertThrows(IllegalStateException::class.java) { insert() }
+        assertThrows(IllegalStateException::class.java) {
+            writer.update(ProviderTable.TASKS, mapOf(Tasks.TITLE to "x"), null, null)
+        }
+        assertThat(task(id)!!.title).isEqualTo("Mine")
+    }
+
+    // --- updates ----------------------------------------------------------------
+
+    @Test
+    fun anUpdateChangesTheRowsItsSelectionMatches() {
+        val a = insert(Tasks.TITLE to "a")
+        val b = insert(Tasks.TITLE to "b")
+
+        val count = writer.update(ProviderTable.TASKS, mapOf(Tasks.STATUS to 2), "${Tasks.TITLE} = ?", arrayOf("b"))
+
+        assertThat(count).isEqualTo(1)
+        assertThat(task(a)!!.status).isEqualTo(TaskStatus.NEEDS_ACTION)
+        assertThat(task(b)!!.status).isEqualTo(TaskStatus.COMPLETED)
+        assertThat(task(b)!!.completedAt).isNotNull()
+    }
+
+    @Test
+    fun anUpdateMatchingNothingChangesNothing() {
+        insert(Tasks.TITLE to "a")
+
+        assertThat(writer.update(ProviderTable.TASKS, mapOf(Tasks.TITLE to "x"), "${Tasks.TITLE} = 'zzz'", null)).isEqualTo(0)
+    }
+
+    @Test
+    fun aTaskInAReadOnlyListCannotChange() {
+        val readOnly = synced(readOnly = true)
+        val id = db.tasks().insert(TaskEntity(listId = readOnly, uid = "r", title = "theirs"))
+
+        assertThrows(UnsupportedOperationException::class.java) {
+            writer.update(ProviderTable.TASKS, mapOf(Tasks.TITLE to "mine"), byId(ProviderTable.TASKS, id), null)
+        }
+        assertThrows(UnsupportedOperationException::class.java) {
+            writer.delete(ProviderTable.TASKS, byId(ProviderTable.TASKS, id), null)
+        }
+        assertThat(task(id)!!.title).isEqualTo("theirs")
+    }
+
+    @Test
+    fun aTaskMovesBetweenLists() {
+        val work = synced()
+        val id = insert(Tasks.TITLE to "t")
+
+        writer.update(ProviderTable.TASKS, mapOf(Tasks.LIST_ID to work), byId(ProviderTable.TASKS, id), null)
+
+        assertThat(db.tasks().live().single { it.title == "t" }.listId).isEqualTo(work)
+    }
+
+    @Test
+    fun aParentMustBeInTheSameListAndNotADescendant() {
+        val work = synced()
+        val parent = insert(Tasks.TITLE to "parent")
+        val child = insert(Tasks.TITLE to "child", Tasks.PARENT_ID to parent)
+        val elsewhere = insert(Tasks.LIST_ID to work, Tasks.TITLE to "elsewhere")
+
+        assertThat(task(child)!!.parentId).isEqualTo(parent)
+        assertThrows(IllegalArgumentException::class.java) {
+            writer.update(ProviderTable.TASKS, mapOf(Tasks.PARENT_ID to elsewhere), byId(ProviderTable.TASKS, child), null)
+        }
+        assertThrows(IllegalArgumentException::class.java) {
+            writer.update(ProviderTable.TASKS, mapOf(Tasks.PARENT_ID to child), byId(ProviderTable.TASKS, parent), null)
+        }
+        assertThrows(IllegalArgumentException::class.java) { insert(Tasks.PARENT_ID to 999L) }
+    }
+
+    @Test
+    fun movingASeriesDropsTheOverridesItNoLongerGenerates() {
+        val series = dailySeries()
+        writer.update(ProviderTable.INSTANCES, mapOf(Tasks.STATUS to 2), byId(ProviderTable.INSTANCES, instanceId(today)), null)
+        assertThat(db.tasks().overrides(series)).hasSize(1)
+
+        writer.update(
+            ProviderTable.TASKS,
+            mapOf(Tasks.DTSTART to (today + 2.hours).toEpochMilliseconds(), Tasks.DUE to (today + 3.hours).toEpochMilliseconds()),
+            byId(ProviderTable.TASKS, series),
+            null,
+        )
+
+        assertThat(db.tasks().overrides(series)).isEmpty()
+    }
+
+    @Test
+    fun aClientCannotTouchSyncState() {
+        val work = synced()
+        val id = db.tasks().insert(
+            TaskEntity(listId = work, uid = "s", title = "t", href = "/s.ics", etag = "e", sequence = 2, unknownProperties = "X-A:1"),
+        )
+
+        writer.update(ProviderTable.TASKS, mapOf(Tasks.TITLE to "new", "_sync_id" to "x", "sync1" to "y"), byId(ProviderTable.TASKS, id), null)
+
+        val stored = task(id)!!
+        assertThat(stored.title).isEqualTo("new")
+        assertThat(stored.href).isEqualTo("/s.ics")
+        assertThat(stored.etag).isEqualTo("e")
+        assertThat(stored.sequence).isEqualTo(2)
+        assertThat(stored.unknownProperties).isEqualTo("X-A:1")
+        assertThat(stored.isDirty).isTrue()
+    }
+
+    // --- instances --------------------------------------------------------------
+
+    @Test
+    fun completingAnOccurrenceTicksOffOnlyThatOne() {
+        val series = dailySeries()
+
+        val count = writer.update(ProviderTable.INSTANCES, mapOf(Tasks.STATUS to 2), byId(ProviderTable.INSTANCES, instanceId(today)), null)
+
+        assertThat(count).isEqualTo(1)
+        assertThat(task(series)!!.status).isEqualTo(TaskStatus.NEEDS_ACTION)
+        val override = db.tasks().overrides(series).single()
+        assertThat(override.recurrenceId).isEqualTo(today)
+        assertThat(override.status).isEqualTo(TaskStatus.COMPLETED)
+        val statuses = instances().associate { it.first to it.third }
+        assertThat(statuses[today.toEpochMilliseconds()]).isEqualTo(TasksContract.STATUS_COMPLETED)
+        assertThat(statuses.filterKeys { it != today.toEpochMilliseconds() }.values.toSet())
+            .containsExactly(TasksContract.STATUS_NEEDS_ACTION)
+    }
+
+    @Test
+    fun anOccurrenceCanBeCancelledAndReopened() {
+        val series = dailySeries()
+
+        writer.update(ProviderTable.INSTANCES, mapOf(Tasks.STATUS to 3), byId(ProviderTable.INSTANCES, instanceId(today)), null)
+        assertThat(db.tasks().overrides(series).single().status).isEqualTo(TaskStatus.CANCELLED)
+
+        writer.update(ProviderTable.INSTANCES, mapOf(Tasks.PERCENT_COMPLETE to 0), byId(ProviderTable.INSTANCES, instanceId(today)), null)
+        assertThat(db.tasks().overrides(series).single().status).isEqualTo(TaskStatus.NEEDS_ACTION)
+    }
+
+    @Test
+    fun contentWrittenToAnOccurrenceEditsTheSeries() {
+        val series = dailySeries()
+
+        writer.update(ProviderTable.INSTANCES, mapOf(Tasks.TITLE to "Renamed"), byId(ProviderTable.INSTANCES, instanceId(today)), null)
+
+        assertThat(task(series)!!.title).isEqualTo("Renamed")
+        assertThat(db.tasks().overrides(series)).isEmpty()
+    }
+
+    @Test
+    fun anOccurrenceCannotBeMoved() {
+        dailySeries()
+
+        assertThrows(IllegalArgumentException::class.java) {
+            writer.update(ProviderTable.INSTANCES, mapOf(Tasks.DUE to 0L), byId(ProviderTable.INSTANCES, instanceId(today)), null)
+        }
+    }
+
+    @Test
+    fun anOccurrenceHasNoPartialProgress() {
+        dailySeries()
+
+        assertThrows(IllegalArgumentException::class.java) {
+            writer.update(ProviderTable.INSTANCES, mapOf(Tasks.PERCENT_COMPLETE to 50), byId(ProviderTable.INSTANCES, instanceId(today)), null)
+        }
+    }
+
+    @Test
+    fun aPlainTaskInstanceWritesTheTask() {
+        val id = insert(Tasks.TITLE to "t", Tasks.DUE to today.toEpochMilliseconds())
+        val instance = source.rows(ProviderTable.INSTANCES, listOf(Tasks.ID), "${Instances.TASK_ID} = $id", null).single().single() as Long
+
+        writer.update(ProviderTable.INSTANCES, mapOf(Tasks.PERCENT_COMPLETE to 50, Tasks.DUE to (today + 1.days).toEpochMilliseconds()), byId(ProviderTable.INSTANCES, instance), null)
+
+        assertThat(task(id)!!.status).isEqualTo(TaskStatus.IN_PROCESS)
+        assertThat(task(id)!!.due).isEqualTo(today + 1.days)
+    }
+
+    @Test
+    fun deletingAnOccurrenceExceptsIt() {
+        val series = dailySeries()
+
+        assertThat(writer.delete(ProviderTable.INSTANCES, byId(ProviderTable.INSTANCES, instanceId(today)), null)).isEqualTo(1)
+
+        assertThat(task(series)!!.exdate).isNotNull()
+        assertThat(instances().map { it.first }).doesNotContain(today.toEpochMilliseconds())
+        assertThat(instances()).hasSize(4)
+    }
+
+    @Test
+    fun deletingAModifiedOccurrenceExceptsItToo() {
+        val series = dailySeries()
+        writer.update(ProviderTable.INSTANCES, mapOf(Tasks.STATUS to 2), byId(ProviderTable.INSTANCES, instanceId(today)), null)
+
+        writer.delete(ProviderTable.INSTANCES, byId(ProviderTable.INSTANCES, instanceId(today)), null)
+
+        assertThat(db.tasks().overrides(series)).isEmpty()
+        assertThat(instances().map { it.first }).doesNotContain(today.toEpochMilliseconds())
+    }
+
+    // --- deletes ----------------------------------------------------------------
+
+    @Test
+    fun aParentGoesWithItsSubtasks() {
+        val parent = insert(Tasks.TITLE to "parent")
+        val child = insert(Tasks.TITLE to "child", Tasks.PARENT_ID to parent)
+        val grandchild = insert(Tasks.TITLE to "grandchild", Tasks.PARENT_ID to child)
+        val other = insert(Tasks.TITLE to "other")
+
+        assertThat(writer.delete(ProviderTable.TASKS, byId(ProviderTable.TASKS, parent), null)).isEqualTo(1)
+
+        assertThat(task(parent)).isNull()
+        assertThat(task(child)).isNull()
+        assertThat(task(grandchild)).isNull()
+        assertThat(task(other)).isNotNull()
+    }
+
+    @Test
+    fun aSyncedTaskLeavesATombstone() {
+        val work = synced()
+        val id = insert(Tasks.LIST_ID to work, Tasks.TITLE to "t")
+
+        writer.delete(ProviderTable.TASKS, byId(ProviderTable.TASKS, id), null)
+
+        assertThat(task(id)!!.isDeleted).isTrue()
+        assertThat(source.rows(ProviderTable.TASKS, listOf(Tasks.ID), null, null)).isEmpty()
+        assertThat(writer.update(ProviderTable.TASKS, mapOf(Tasks.TITLE to "x"), byId(ProviderTable.TASKS, id), null)).isEqualTo(0)
+    }
+
+    @Test
+    fun deletingAnOverrideThroughTasksExceptsTheOccurrence() {
+        val series = dailySeries()
+        writer.update(ProviderTable.INSTANCES, mapOf(Tasks.STATUS to 2), byId(ProviderTable.INSTANCES, instanceId(today)), null)
+        val override = db.tasks().overrides(series).single().id
+
+        writer.delete(ProviderTable.TASKS, byId(ProviderTable.TASKS, override), null)
+
+        assertThat(task(series)).isNotNull()
+        assertThat(task(series)!!.exdate).isNotNull()
+        assertThat(instances()).hasSize(4)
+    }
+
+    // --- properties -------------------------------------------------------------
+
+    @Test
+    fun anAlarmCanBeAddedChangedAndRemoved() {
+        val id = insert(Tasks.TITLE to "t", Tasks.DUE to (today + 1.days).toEpochMilliseconds())
+        db.tasks().update(task(id)!!.copy(isDirty = false))
+
+        val propertyId = writer.insert(
+            ProviderTable.PROPERTIES,
+            mapOf(Properties.TASK_ID to id, Properties.MIMETYPE to Alarm.MIMETYPE, Alarm.MINUTES_BEFORE to "15", Alarm.REFERENCE to "1"),
+        )
+        val alarm = db.alarms().forTask(id).single()
+        assertThat(alarm.minutesBefore).isEqualTo(15)
+        assertThat(alarm.reference).isEqualTo(AlarmReference.DUE)
+        assertThat(task(id)!!.isDirty).isTrue()
+        assertThat(propertyId).isEqualTo(ProviderIds.alarm(alarm.id))
+
+        writer.update(ProviderTable.PROPERTIES, mapOf(Alarm.MINUTES_BEFORE to 60, Alarm.REFERENCE to 2), byId(ProviderTable.PROPERTIES, propertyId), null)
+        assertThat(db.alarms().forTask(id).single().minutesBefore).isEqualTo(60)
+        assertThat(db.alarms().forTask(id).single().reference).isEqualTo(AlarmReference.START)
+
+        writer.delete(ProviderTable.PROPERTIES, "${Properties.MIMETYPE} = ?", arrayOf(Alarm.MIMETYPE))
+        assertThat(db.alarms().forTask(id)).isEmpty()
+    }
+
+    @Test
+    fun tagsCanBeAddedRenamedAndRemoved() {
+        val id = insert(Tasks.TITLE to "t")
+
+        val propertyId = writer.insert(
+            ProviderTable.PROPERTIES,
+            mapOf(Properties.TASK_ID to id, Properties.MIMETYPE to Category.MIMETYPE, Category.NAME to " errand "),
+        )
+        assertThat(task(id)!!.categories).containsExactly("errand")
+
+        writer.update(ProviderTable.PROPERTIES, mapOf(Category.NAME to "shopping"), byId(ProviderTable.PROPERTIES, propertyId), null)
+        assertThat(task(id)!!.categories).containsExactly("shopping")
+
+        writer.insert(ProviderTable.PROPERTIES, mapOf(Properties.TASK_ID to id, Properties.MIMETYPE to Category.MIMETYPE, Category.NAME to "shopping"))
+        assertThat(task(id)!!.categories).containsExactly("shopping")
+
+        writer.delete(ProviderTable.PROPERTIES, "${Category.NAME} = ?", arrayOf("shopping"))
+        assertThat(task(id)!!.categories).isEmpty()
+    }
+
+    @Test
+    fun aPropertyCannotChangeItsKindOrTask() {
+        val id = insert(Tasks.TITLE to "t")
+        val other = insert(Tasks.TITLE to "o")
+        db.alarms().insert(TaskAlarmEntity(taskId = id, minutesBefore = 5))
+        val propertyId = source.rows(ProviderTable.PROPERTIES, listOf(Properties.PROPERTY_ID), null, null).single().single() as Long
+
+        assertThrows(IllegalArgumentException::class.java) {
+            writer.update(ProviderTable.PROPERTIES, mapOf(Properties.MIMETYPE to Category.MIMETYPE), byId(ProviderTable.PROPERTIES, propertyId), null)
+        }
+        assertThrows(IllegalArgumentException::class.java) {
+            writer.update(ProviderTable.PROPERTIES, mapOf(Properties.TASK_ID to other), byId(ProviderTable.PROPERTIES, propertyId), null)
+        }
+    }
+
+    @Test
+    fun onlyAlarmsAndTagsCanBeWritten() {
+        val id = insert(Tasks.TITLE to "t")
+
+        assertThrows(IllegalArgumentException::class.java) {
+            writer.insert(ProviderTable.PROPERTIES, mapOf(Properties.TASK_ID to id, Properties.MIMETYPE to "vnd.android.cursor.item/comment"))
+        }
+        assertThrows(IllegalArgumentException::class.java) {
+            writer.insert(ProviderTable.PROPERTIES, mapOf(Properties.TASK_ID to id, Properties.MIMETYPE to Alarm.MIMETYPE))
+        }
+    }
+
+    // --- batches ----------------------------------------------------------------
+
+    @Test
+    fun aBatchIsAllOrNothing() {
+        assertThrows(IllegalArgumentException::class.java) {
+            writer.batch {
+                insert(Tasks.TITLE to "first")
+                insert(Tasks.TITLE to "second")
+                insert(Tasks.LIST_ID to 999L)
+            }
+        }
+
+        assertThat(db.tasks().live()).isEmpty()
+        assertThat(source.rows(ProviderTable.TASKS, listOf(Tasks.ID), null, null)).isEmpty()
+    }
+
+    @Test
+    fun aBatchSeesItsOwnWritesAndReArmsRemindersOnce() {
+        writer.batch {
+            insert(Tasks.TITLE to "first")
+            writer.update(ProviderTable.TASKS, mapOf(Tasks.STATUS to 2), "${Tasks.TITLE} = ?", arrayOf("first"))
+        }
+
+        assertThat(db.tasks().live().single().status).isEqualTo(TaskStatus.COMPLETED)
+        assertThat(afterWrites).isEqualTo(1)
+    }
+
+    // --- review regressions -----------------------------------------------------
+
+    @Test
+    fun aBatchDeletingTwoPropertiesDeletesThoseTwo() {
+        val a = insert(Tasks.TITLE to "a")
+        val b = insert(Tasks.TITLE to "b")
+        listOf(5, 10).forEach { db.alarms().insert(TaskAlarmEntity(taskId = a, minutesBefore = it)) }
+        db.alarms().insert(TaskAlarmEntity(taskId = b, minutesBefore = 15))
+        val ids = source.rows(ProviderTable.PROPERTIES, listOf(Properties.PROPERTY_ID), "${Properties.TASK_ID} = $a", null)
+            .map { it.single() as Long }
+
+        writer.batch { ids.forEach { writer.delete(ProviderTable.PROPERTIES, byId(ProviderTable.PROPERTIES, it), null) } }
+
+        assertThat(db.alarms().forTask(a)).isEmpty()
+        assertThat(db.alarms().forTask(b).map { it.minutesBefore }).containsExactly(15)
+    }
+
+    @Test
+    fun aBatchDeletingTwoOccurrencesDeletesThoseTwo() {
+        dailySeries()
+        val first = instanceId(today)
+        val second = instanceId(today + 1.days)
+
+        writer.batch {
+            writer.delete(ProviderTable.INSTANCES, byId(ProviderTable.INSTANCES, first), null)
+            writer.delete(ProviderTable.INSTANCES, byId(ProviderTable.INSTANCES, second), null)
+        }
+
+        assertThat(instances().map { it.first }).containsExactly(
+            (today - 1.days).toEpochMilliseconds(),
+            (today + 2.days).toEpochMilliseconds(),
+            (today + 3.days).toEpochMilliseconds(),
+        )
+    }
+
+    @Test
+    fun anInstanceIdOutlivesAnotherOccurrencesDeletion() {
+        dailySeries()
+        val later = instanceId(today + 2.days)
+
+        writer.delete(ProviderTable.INSTANCES, byId(ProviderTable.INSTANCES, instanceId(today)), null)
+
+        assertThat(instanceId(today + 2.days)).isEqualTo(later)
+        assertThat(writer.update(ProviderTable.INSTANCES, mapOf(Tasks.STATUS to 2), byId(ProviderTable.INSTANCES, later), null))
+            .isEqualTo(1)
+        assertThat(instances().single { it.third == TasksContract.STATUS_COMPLETED }.first)
+            .isEqualTo((today + 2.days).toEpochMilliseconds())
+    }
+
+    @Test
+    fun aRecurringSubtaskOutsideTheWindowGoesWithItsParent() {
+        val parent = insert(Tasks.TITLE to "parent")
+        val longAgo = today - 1000.days
+        val subtask = db.tasks().insert(
+            TaskEntity(listId = home, uid = "old", title = "old", dtstart = longAgo, rrule = "FREQ=DAILY;COUNT=2",
+                timezone = "UTC", parentId = parent),
+        )
+
+        writer.delete(ProviderTable.TASKS, byId(ProviderTable.TASKS, parent), null)
+
+        assertThat(task(subtask)).isNull()
+    }
+
+    @Test
+    fun anOverriddenRecurringSubtaskGoesWholeWithItsParent() {
+        val parent = insert(Tasks.TITLE to "parent")
+        val subtask = dailySeries("sub")
+        db.tasks().update(task(subtask)!!.copy(parentId = parent))
+        writer.update(ProviderTable.INSTANCES, mapOf(Tasks.STATUS to 2), byId(ProviderTable.INSTANCES, instanceId(today)), null)
+
+        writer.delete(ProviderTable.TASKS, byId(ProviderTable.TASKS, parent), null)
+
+        assertThat(task(subtask)).isNull()
+        assertThat(db.tasks().live()).isEmpty()
+    }
+
+    @Test
+    fun aModifiedOccurrenceCanBeWrittenBackAsRead() {
+        val series = dailySeries()
+        writer.update(ProviderTable.INSTANCES, mapOf(Tasks.STATUS to 2), byId(ProviderTable.INSTANCES, instanceId(today)), null)
+        val override = db.tasks().overrides(series).single().id
+        val row = readRow(ProviderTable.TASKS, override)
+
+        writer.update(ProviderTable.TASKS, row + (Tasks.TITLE to "Renamed"), byId(ProviderTable.TASKS, override), null)
+
+        assertThat(task(override)!!.title).isEqualTo("Renamed")
+    }
+
+    @Test
+    fun anInstanceCanBeWrittenBackAsReadToCompleteIt() {
+        val series = dailySeries()
+        val instance = instanceId(today)
+        val row = readRow(ProviderTable.INSTANCES, instance)
+
+        writer.update(ProviderTable.INSTANCES, row + (Tasks.STATUS to 2), byId(ProviderTable.INSTANCES, instance), null)
+
+        assertThat(db.tasks().overrides(series).single().status).isEqualTo(TaskStatus.COMPLETED)
+        assertThat(task(series)!!.dtstart).isEqualTo(today - 1.days)
+    }
+
+    @Test
+    fun movingASubtreeMovesItsSubtasks() {
+        val work = synced()
+        val parent = insert(Tasks.TITLE to "parent")
+        val child = insert(Tasks.TITLE to "child", Tasks.PARENT_ID to parent)
+        val grandchild = insert(Tasks.TITLE to "grandchild", Tasks.PARENT_ID to child)
+
+        writer.update(ProviderTable.TASKS, mapOf(Tasks.LIST_ID to work), byId(ProviderTable.TASKS, parent), null)
+
+        assertThat(listOf(parent, child, grandchild).map { task(it)!!.listId }).containsExactly(work, work, work)
+        assertThat(task(child)!!.parentId).isEqualTo(parent)
+        assertThat(task(grandchild)!!.parentId).isEqualTo(child)
+    }
+
+    @Test
+    fun aMoveOntoATakenUidIsRejected() {
+        val work = synced()
+        insert(Tasks.LIST_ID to work, Tasks.UID to "same")
+        val id = insert(Tasks.UID to "same")
+
+        assertThrows(IllegalArgumentException::class.java) {
+            writer.update(ProviderTable.TASKS, mapOf(Tasks.LIST_ID to work), byId(ProviderTable.TASKS, id), null)
+        }
+        assertThat(task(id)!!.listId).isEqualTo(home)
+    }
+
+    @Test
+    fun contentOnAModifiedOccurrenceStillEditsTheSeries() {
+        val series = dailySeries()
+        writer.update(ProviderTable.INSTANCES, mapOf(Tasks.STATUS to 2), byId(ProviderTable.INSTANCES, instanceId(today)), null)
+        val override = db.tasks().overrides(series).single().id
+
+        writer.update(ProviderTable.INSTANCES, mapOf(Tasks.TITLE to "Renamed"), byId(ProviderTable.INSTANCES, instanceId(today)), null)
+
+        assertThat(task(series)!!.title).isEqualTo("Renamed")
+        assertThat(task(override)!!.title).isEqualTo("Renamed")
+        assertThat(task(override)!!.status).isEqualTo(TaskStatus.COMPLETED)
+    }
+
+    @Test
+    fun aWriteThatChangesNothingOwesNoSync() {
+        val id = insert(Tasks.TITLE to "t")
+        db.tasks().update(task(id)!!.copy(isDirty = false))
+        val modified = task(id)!!.lastModified
+
+        writer.update(ProviderTable.TASKS, readRow(ProviderTable.TASKS, id), byId(ProviderTable.TASKS, id), null)
+        writer.update(ProviderTable.TASKS, emptyMap(), byId(ProviderTable.TASKS, id), null)
+
+        assertThat(task(id)!!.isDirty).isFalse()
+        assertThat(task(id)!!.lastModified).isEqualTo(modified)
+    }
+
+    @Test
+    fun reopeningAnOpenOccurrenceForksNothing() {
+        val series = dailySeries()
+
+        writer.update(ProviderTable.INSTANCES, mapOf(Tasks.STATUS to 0), byId(ProviderTable.INSTANCES, instanceId(today)), null)
+
+        assertThat(db.tasks().overrides(series)).isEmpty()
+    }
+
+    @Test
+    fun aWriteBeforeStartupSettlesIsRefused() {
+        val stuck = ProviderSnapshotSource(context, db, resolver, awaitStartup = { awaitCancellation() }, startupWait = 50.milliseconds)
+        val early = ProviderWriter(db, RoomTasksDataSource(db), stuck, resolver, afterWrite = {})
+
+        assertThrows(IllegalStateException::class.java) { early.insert(ProviderTable.TASKS, mapOf(Tasks.LIST_ID to home)) }
+        assertThat(db.tasks().live()).isEmpty()
+    }
+
+    @Test
+    fun aSingleRowWriteNeedsNoSnapshot() {
+        val id = insert(Tasks.TITLE to "t")
+        val unknown = 987_654L
+
+        assertThat(writer.update(ProviderTable.TASKS, mapOf(Tasks.TITLE to "x"), byId(ProviderTable.TASKS, unknown), null)).isEqualTo(0)
+        assertThat(writer.update(ProviderTable.TASKS, mapOf(Tasks.TITLE to "x"), byId(ProviderTable.TASKS, id), null)).isEqualTo(1)
+        assertThat(writer.update(ProviderTable.INSTANCES, mapOf(Tasks.TITLE to "x"), byId(ProviderTable.INSTANCES, unknown), null)).isEqualTo(0)
+        assertThat(writer.delete(ProviderTable.PROPERTIES, byId(ProviderTable.PROPERTIES, unknown), null)).isEqualTo(0)
+    }
+
+    // --- second review regressions -----------------------------------------------
+
+    @Test
+    fun tickingOffAModifiedOccurrenceAsReadLeavesTheSeriesAlone() {
+        val series = dailySeries("Standup")
+        // Reopening forks an override, which then gets its own title as the app's "this occurrence" edit would.
+        store().setCompletedInstance(series, today, false)
+        val override = db.tasks().overrides(series).single()
+        db.tasks().update(override.copy(title = "Standup (moved room)"))
+        val row = readRow(ProviderTable.INSTANCES, instanceId(today))
+
+        writer.update(ProviderTable.INSTANCES, row + (Tasks.STATUS to 2), byId(ProviderTable.INSTANCES, instanceId(today)), null)
+
+        assertThat(task(series)!!.title).isEqualTo("Standup")
+        assertThat(task(override.id)!!.title).isEqualTo("Standup (moved room)")
+        assertThat(task(override.id)!!.status).isEqualTo(TaskStatus.COMPLETED)
+    }
+
+    @Test
+    fun anInstanceWrittenBackWithOnlyProgressChangedIsCompleted() {
+        val series = dailySeries()
+        val row = readRow(ProviderTable.INSTANCES, instanceId(today))
+
+        writer.update(ProviderTable.INSTANCES, row + (Tasks.PERCENT_COMPLETE to 100), byId(ProviderTable.INSTANCES, instanceId(today)), null)
+
+        assertThat(db.tasks().overrides(series).single().status).isEqualTo(TaskStatus.COMPLETED)
+    }
+
+    @Test
+    fun aBadZoneOnAnInstanceReportsTheZone() {
+        dailySeries()
+        val instance = instanceId(today)
+
+        val error = assertThrows(IllegalArgumentException::class.java) {
+            writer.update(ProviderTable.INSTANCES, mapOf(Tasks.TZ to "Europe/Berln"), byId(ProviderTable.INSTANCES, instance), null)
+        }
+
+        assertThat(error).hasMessageThat().contains("Unknown time zone")
+    }
+
+    @Test
+    fun anInProcessSeriesCanBeWrittenBackAsRead() {
+        val series = dailySeries()
+        db.tasks().update(task(series)!!.copy(status = TaskStatus.IN_PROCESS, percentComplete = 50))
+        val row = readRow(ProviderTable.INSTANCES, instanceId(today))
+
+        writer.update(ProviderTable.INSTANCES, row + (Tasks.TITLE to "Renamed"), byId(ProviderTable.INSTANCES, instanceId(today)), null)
+
+        assertThat(task(series)!!.title).isEqualTo("Renamed")
+        assertThat(task(series)!!.status).isEqualTo(TaskStatus.IN_PROCESS)
+        assertThat(db.tasks().overrides(series)).isEmpty()
+    }
+
+    @Test
+    fun aFloatingSeriesCanBeWrittenBackAsRead() {
+        val series = db.tasks().insert(
+            TaskEntity(listId = home, uid = "f", title = "Floating", due = today, rrule = "FREQ=DAILY;COUNT=3", timezone = null),
+        )
+        val row = readRow(ProviderTable.INSTANCES, instanceId(today))
+
+        writer.update(ProviderTable.INSTANCES, row + (Tasks.STATUS to 2), byId(ProviderTable.INSTANCES, instanceId(today)), null)
+        writer.update(ProviderTable.TASKS, mapOf(Tasks.TITLE to "Still floating"), byId(ProviderTable.TASKS, series), null)
+
+        assertThat(db.tasks().overrides(series).single().status).isEqualTo(TaskStatus.COMPLETED)
+        assertThat(task(series)!!.timezone).isNull()
+    }
+
+    @Test
+    fun aParentLoopDeletesInsteadOfRecursingForever() {
+        val a = insert(Tasks.TITLE to "a")
+        val b = insert(Tasks.TITLE to "b", Tasks.PARENT_ID to a)
+        db.tasks().update(task(a)!!.copy(parentId = b))
+
+        writer.delete(ProviderTable.TASKS, byId(ProviderTable.TASKS, a), null)
+
+        assertThat(task(a)).isNull()
+        assertThat(task(b)).isNull()
+    }
+
+    @Test
+    fun aBulkMoveWorksWhicheverOrderTheRowsComeIn() {
+        val work = synced()
+        // The subtask gets the lower id, so it comes first unless the writer reorders.
+        val child = insert(Tasks.TITLE to "child")
+        val parent = insert(Tasks.TITLE to "parent")
+        db.tasks().update(task(child)!!.copy(parentId = parent))
+
+        val count = writer.update(ProviderTable.TASKS, mapOf(Tasks.LIST_ID to work), "${Tasks.LIST_ID} = ?", arrayOf(home.toString()))
+
+        assertThat(count).isEqualTo(2)
+        assertThat(task(child)!!.listId).isEqualTo(work)
+        assertThat(task(parent)!!.listId).isEqualTo(work)
+        assertThat(task(child)!!.parentId).isEqualTo(parent)
+    }
+
+    @Test
+    fun aRowSelectedWithAnArgumentIsWritten() {
+        val a = insert(Tasks.TITLE to "a")
+        val b = insert(Tasks.TITLE to "b")
+
+        assertThat(writer.update(ProviderTable.TASKS, mapOf(Tasks.TITLE to "x"), "${Tasks.ID}=?", arrayOf(b.toString()))).isEqualTo(1)
+        assertThat(writer.update(ProviderTable.TASKS, mapOf(Tasks.TITLE to "x"), "${Tasks.ID} = ?", arrayOf("987654"))).isEqualTo(0)
+
+        assertThat(task(a)!!.title).isEqualTo("a")
+        assertThat(task(b)!!.title).isEqualTo("x")
+    }
+
+    @Test
+    fun garbageExceptionDatesAreRejected() {
+        val series = dailySeries()
+
+        assertThrows(IllegalArgumentException::class.java) {
+            writer.update(ProviderTable.TASKS, mapOf(Tasks.EXDATE to "tomorrow"), byId(ProviderTable.TASKS, series), null)
+        }
+        assertThat(task(series)!!.exdate).isNull()
+    }
+
+    private fun store() = RoomTasksDataSource(db)
+
+    /** Every column of one published row, as a client that read it would write it back. */
+    private fun readRow(table: ProviderTable, id: Long): Map<String, Any?> {
+        val columns = table.columns.map { it.first }
+        val row = source.rows(table, columns, byId(table, id), null).single()
+        return columns.zip(row).toMap() - table.idColumn
+    }
+
+}
+
+private object NoProvider : ProviderEnvironment {
+    override fun packageDeclaring(authority: String): String? = null
+    override fun isGranted(permission: String): Boolean = false
+    override fun appLabel(packageName: String): String? = null
+}

app/src/androidTest/java/de/jeanlucmakiola/agendula/data/tasks/provider/SnapshotDatabaseTest.kt

@@ -0,0 +1,141 @@
+package de.jeanlucmakiola.agendula.data.tasks.provider
+
+import android.database.Cursor
+import android.os.Build
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.google.common.truth.Truth.assertThat
+import de.jeanlucmakiola.agendula.data.tasks.TasksContract.Lists
+import de.jeanlucmakiola.agendula.data.tasks.TasksContract.Tasks
+import org.junit.Assert.assertThrows
+import org.junit.Assume.assumeTrue
+import org.junit.Test
+import org.junit.runner.RunWith
+
+/** The SQL a client sends runs against the snapshot as it would against OpenTasks. */
+@RunWith(AndroidJUnit4::class)
+class SnapshotDatabaseTest {
+
+    private val db = SnapshotDatabase()
+
+    private fun task(id: Long, title: String?, due: Long? = null): ProviderRow =
+        mapOf(Tasks.ID to id, Tasks.LIST_ID to 1L, Tasks.TITLE to title, Tasks.DUE to due, Tasks.PRIORITY to 0)
+
+    private fun load(vararg tasks: ProviderRow, lists: List<ProviderRow> = emptyList()) = db.load(
+        ProviderSnapshot(
+            ProviderTable.entries.associateWith {
+                when (it) {
+                    ProviderTable.TASKS -> tasks.toList()
+                    ProviderTable.LISTS -> lists
+                    else -> emptyList()
+                }
+            },
+        ),
+    )
+
+    private fun Cursor.strings(column: String): List<String?> = use {
+        val index = getColumnIndexOrThrow(column)
+        buildList { while (moveToNext()) add(if (isNull(index)) null else getString(index)) }
+    }
+
+    @Test
+    fun aNullProjectionReturnsEveryColumnInTableOrder() {
+        load(task(1, "a"))
+
+        db.query(ProviderTable.TASKS, null, null, null, null).use {
+            assertThat(it.columnNames.toList()).containsExactlyElementsIn(ProviderTable.TASKS.columns.map { c -> c.first })
+                .inOrder()
+            assertThat(it.count).isEqualTo(1)
+        }
+    }
+
+    @Test
+    fun selectionArgumentsAndSortOrderApply() {
+        load(task(1, "b", due = 30), task(2, "a", due = 10), task(3, "c", due = 20), task(4, "skip", due = 5))
+
+        val titles = db.query(ProviderTable.TASKS, arrayOf(Tasks.TITLE), "${Tasks.TITLE} != ?", arrayOf("skip"), "${Tasks.DUE} ASC")
+            .strings(Tasks.TITLE)
+
+        assertThat(titles).containsExactly("a", "c", "b").inOrder()
+    }
+
+    @Test
+    fun typesSurviveTheCopy() {
+        load(task(1, null, due = 1_700_000_000_000))
+
+        db.query(ProviderTable.TASKS, arrayOf(Tasks.TITLE, Tasks.DUE, Tasks.PRIORITY), null, null, null).use {
+            it.moveToFirst()
+            assertThat(it.isNull(0)).isTrue()
+            assertThat(it.getType(1)).isEqualTo(Cursor.FIELD_TYPE_INTEGER)
+            assertThat(it.getLong(1)).isEqualTo(1_700_000_000_000)
+            assertThat(it.getInt(2)).isEqualTo(0)
+        }
+    }
+
+    @Test
+    fun anUnsupportedColumnReadsAsNull() {
+        load(task(1, "a"))
+
+        assertThat(db.query(ProviderTable.TASKS, arrayOf("_sync_id"), null, null, null).strings("_sync_id"))
+            .containsExactly(null)
+    }
+
+    @Test
+    fun anUnknownProjectionColumnIsRejected() {
+        load(task(1, "a"))
+
+        assertThrows(IllegalArgumentException::class.java) {
+            db.query(ProviderTable.TASKS, arrayOf("no_such_column"), null, null, null)
+        }
+    }
+
+    @Test
+    fun anUnknownSelectionColumnIsRejected() {
+        assumeTrue(Build.VERSION.SDK_INT >= Build.VERSION_CODES.R)
+        load(task(1, "a"))
+
+        assertThrows(IllegalArgumentException::class.java) {
+            db.query(ProviderTable.TASKS, null, "sqlite_master.name IS NOT NULL", null, null)
+        }
+    }
+
+    @Test
+    fun aSelectionCannotBreakOutOfItsWhereClause() {
+        load(task(1, "a"))
+
+        assertThrows(IllegalArgumentException::class.java) {
+            db.query(ProviderTable.TASKS, null, "1) UNION SELECT name FROM sqlite_master --", null, null)
+        }
+    }
+
+    @Test
+    fun eachTableAnswersOnlyForItsOwnRows() {
+        load(task(1, "a"), lists = listOf(mapOf(Lists.ID to 7L, Lists.NAME to "Home")))
+
+        assertThat(db.query(ProviderTable.LISTS, arrayOf(Lists.NAME), null, null, null).strings(Lists.NAME))
+            .containsExactly("Home")
+        db.query(ProviderTable.INSTANCES, null, null, null, null).use { assertThat(it.count).isEqualTo(0) }
+    }
+
+    @Test
+    fun aReloadReplacesTheRowsButNotAnOpenCursor() {
+        load(task(1, "old"))
+        val before = db.query(ProviderTable.TASKS, arrayOf(Tasks.TITLE), null, null, null)
+
+        load(task(2, "new"))
+
+        assertThat(before.strings(Tasks.TITLE)).containsExactly("old")
+        assertThat(db.query(ProviderTable.TASKS, arrayOf(Tasks.TITLE), null, null, null).strings(Tasks.TITLE))
+            .containsExactly("new")
+    }
+
+    @Test
+    fun anEmptySnapshotEmptiesEveryTable() {
+        load(task(1, "a"))
+
+        db.load(ProviderSnapshot.EMPTY)
+
+        ProviderTable.entries.forEach { table ->
+            db.query(table, null, null, null, null).use { assertThat(it.count).isEqualTo(0) }
+        }
+    }
+}

app/src/androidTest/java/de/jeanlucmakiola/agendula/data/tasks/room/RoomTasksDataSourceTest.kt

@@ -5,7 +5,7 @@ import androidx.test.core.app.ApplicationProvider
 import androidx.test.ext.junit.runners.AndroidJUnit4
 import com.google.common.truth.Truth.assertThat
 import de.jeanlucmakiola.agendula.data.tasks.TaskQuery
-import de.jeanlucmakiola.agendula.data.tasks.TaskReminder
+import de.jeanlucmakiola.agendula.domain.TaskReminder
 import de.jeanlucmakiola.agendula.domain.TaskForm
 import de.jeanlucmakiola.agendula.domain.TaskStatus
 import org.junit.After
@@ -366,41 +366,23 @@ class RoomTasksDataSourceTest {
     @Test
     fun alarmsRoundTripAndReplaceRatherThanAccumulate() {
         val id = source.insertTask(form(due = now + 1.days))
+        val start = TaskReminder(minutesBefore = 10, fromStart = true)
 
         // The whole reminder, not just the minute count: collapsing it to a bare
-        // Int is what fired an imported START-referenced alarm off DUE, and an
-        // alarm this seam sets from the UI is always due-referenced.
-        source.setAlarm(id, 30)
-        assertThat(source.alarms()[id]).isEqualTo(TaskReminder(minutesBefore = 30))
-
-        source.setAlarm(id, 60)
-        assertThat(db.alarms().forTask(id)).hasSize(1)
-        assertThat(source.alarms()[id]).isEqualTo(TaskReminder(minutesBefore = 60))
-
-        source.setAlarm(id, null)
-        assertThat(source.alarms()).doesNotContainKey(id)
-    }
-
-    @Test
-    fun settingTheEditableReminderLeavesTheOthersAlone() {
-        val id = source.insertTask(form(due = now + 1.days))
-        val start = TaskReminder(minutesBefore = 10, fromStart = true)
-        source.setReminders(id, listOf(start, TaskReminder(30), TaskReminder(120)))
-
-        source.setAlarm(id, 45)
-        assertThat(source.reminders()[id]).containsExactly(start, TaskReminder(30), TaskReminder(45)).inOrder()
-        assertThat(source.alarms()[id]).isEqualTo(TaskReminder(45))
-
-        source.setAlarm(id, null)
+        // Int is what fired an imported START-referenced alarm off DUE.
+        source.setReminders(id, listOf(start, TaskReminder(30)))
         assertThat(source.reminders()[id]).containsExactly(start, TaskReminder(30)).inOrder()
-        assertThat(source.alarms()[id]).isEqualTo(TaskReminder(30))
+
+        source.setReminders(id, listOf(TaskReminder(60)))
+        assertThat(db.alarms().forTask(id)).hasSize(1)
+        assertThat(source.reminders()[id]).containsExactly(TaskReminder(60))
     }
 
     @Test
     fun forkingAnOccurrenceCarriesTheReminderOntoIt() {
         val id = source.insertTask(form(due = now + 1.days))
         makeRecurring(id, now)
-        source.setAlarm(id, 30)
+        source.setReminders(id, listOf(TaskReminder(30)))
         val target = source.tasks(TaskQuery(listId = listId))
             .filter { it.taskId == id }
             .first { it.distanceFromCurrent == 1 }
@@ -411,6 +393,134 @@ class RoomTasksDataSourceTest {
         assertThat(db.alarms().forTask(override.id).single().minutesBefore).isEqualTo(30)
     }
 
+    @Test
+    fun aSaveKeepsTheIdentityOfAReminderItDidNotChange() {
+        val id = source.insertTask(form(due = now + 1.days), listOf(TaskReminder(15)))
+        val original = db.alarms().forTask(id).single()
+        db.alarms().update(original.copy(raw = "BEGIN:VALARM\r\nX-VENDOR:keep\r\nEND:VALARM\r\n"))
+
+        source.updateTask(id, form(title = "renamed", due = now + 2.days), reminders = listOf(TaskReminder(15), TaskReminder(60)))
+
+        val rows = db.alarms().forTask(id)
+        val kept = rows.single { it.minutesBefore == 15 }
+        // Same row, same identity on the server, same original text.
+        assertThat(kept.id).isEqualTo(original.id)
+        assertThat(kept.uid).isEqualTo(original.uid)
+        assertThat(kept.raw).contains("X-VENDOR:keep")
+        assertThat(rows.single { it.minutesBefore == 60 }.uid).isNotEqualTo(original.uid)
+    }
+
+    @Test
+    fun aSaveWritesBeforeStartAndBeforeDueRemindersAlike() {
+        val id = source.insertTask(form(due = now + 1.days))
+        source.setReminders(id, listOf(TaskReminder(10, fromStart = true), TaskReminder(30)))
+
+        source.updateTask(id, form(due = now + 1.days), reminders = listOf(TaskReminder(5, fromStart = true), TaskReminder(45)))
+
+        assertThat(source.reminders()[id]).containsExactly(TaskReminder(5, fromStart = true), TaskReminder(45))
+    }
+
+    @Test
+    fun aReminderForOneOccurrenceLeavesTheSeriesUntouched() {
+        val work = syncedList()
+        val id = source.insertTask(form(due = now + 1.days).copy(listId = work), listOf(TaskReminder(30)))
+        makeRecurring(id, now)
+        db.tasks().update(db.tasks().entity(id)!!.copy(isDirty = false))
+        val target = source.tasks(TaskQuery(listId = work))
+            .filter { it.taskId == id }
+            .first { it.distanceFromCurrent == 1 }
+
+        source.updateInstance(id, target.occurrenceStart!!, form(title = "moved").copy(listId = work), listOf(TaskReminder(60)))
+
+        // ⚠️ The master is never written, not even briefly: a sync landing in
+        // between would upload the occurrence's reminder for the whole series.
+        assertThat(db.alarms().forTask(id).map { it.minutesBefore }).containsExactly(30)
+        assertThat(db.tasks().entity(id)!!.isDirty).isFalse()
+        val override = db.tasks().override(id, target.occurrenceStart)!!
+        assertThat(db.alarms().forTask(override.id).map { it.minutesBefore }).containsExactly(60)
+    }
+
+    @Test
+    fun splittingASeriesGivesTheNewSeriesItsOwnReminderIdentities() {
+        val id = source.insertTask(form(due = now + 1.days), listOf(TaskReminder(30)))
+        makeRecurring(id, now - 14.days)
+        val master = db.alarms().forTask(id).single()
+        val target = source.tasks(TaskQuery(listId = listId))
+            .filter { it.taskId == id }
+            .first { it.distanceFromCurrent == 1 }
+
+        val created = source.splitSeries(id, target.occurrenceStart!!, form(title = "later"), listOf(TaskReminder(30)))
+
+        assertThat(created).isNotEqualTo(id)
+        val copy = db.alarms().forTask(created).single()
+        assertThat(copy.minutesBefore).isEqualTo(30)
+        // A different UID on the server, so the alarm must not share one either.
+        assertThat(copy.uid).isNotEqualTo(master.uid)
+        assertThat(db.alarms().forTask(id).single().uid).isEqualTo(master.uid)
+    }
+
+    @Test
+    fun changingOnlyTheRemindersOwesTheServerAPut() {
+        val work = syncedList()
+        val id = source.insertTask(form(due = now + 1.days).copy(listId = work))
+        db.tasks().update(db.tasks().entity(id)!!.copy(isDirty = false))
+
+        source.setReminders(id, listOf(TaskReminder(15)))
+        assertThat(db.tasks().entity(id)!!.isDirty).isTrue()
+
+        db.tasks().update(db.tasks().entity(id)!!.copy(isDirty = false))
+        source.setReminders(id, listOf(TaskReminder(15)))
+        // Nothing changed, so nothing is owed.
+        assertThat(db.tasks().entity(id)!!.isDirty).isFalse()
+    }
+
+    @Test
+    fun aSeriesReminderEditReachesTheOccurrencesThatStillHadTheOldOne() {
+        val id = source.insertTask(form(due = now + 1.days), listOf(TaskReminder(15)))
+        makeRecurring(id, now)
+        val occurrences = source.tasks(TaskQuery(listId = listId)).filter { it.taskId == id }
+        val completed = occurrences.first { it.distanceFromCurrent == 1 }.occurrenceStart!!
+        val own = occurrences.first { it.distanceFromCurrent == 2 }.occurrenceStart!!
+        source.setCompletedInstance(id, completed, true)
+        source.updateInstance(id, own, form(title = "own"), listOf(TaskReminder(5)))
+
+        // Same times and rule, so the series is not reshaped — that drops its overrides.
+        val first = occurrences.first()
+        val unchanged = form().copy(start = first.start, due = first.due, rrule = "FREQ=WEEKLY")
+        source.updateSeries(id, first.occurrenceStart!!, unchanged, listOf(TaskReminder(60)))
+
+        fun leads(anchor: Instant) = db.alarms().forTask(db.tasks().override(id, anchor)!!.id).map { it.minutesBefore }
+        assertThat(db.alarms().forTask(id).map { it.minutesBefore }).containsExactly(60)
+        // A snapshot of the series' reminder follows it…
+        assertThat(leads(completed)).containsExactly(60)
+        // …one set for that occurrence alone does not.
+        assertThat(leads(own)).containsExactly(5)
+    }
+
+    @Test
+    fun aTaskWhoseAlarmsWereTurnedOffElsewhereReportsNone() {
+        val id = source.insertTask(form(due = now + 1.days))
+        db.alarms().setRemindersOff(id, true)
+
+        assertThat(source.reminders()[id]).isEmpty()
+        assertThat(source.reminders()).containsKey(id)
+
+        // A reminder of its own again: the flag goes.
+        source.setReminders(id, listOf(TaskReminder(15)))
+        assertThat(db.tasks().entity(id)!!.remindersOff).isFalse()
+    }
+
+    @Test
+    fun settingRemindersOwesTheServerAPut() {
+        val work = syncedList()
+        val id = source.insertTask(form(due = now + 1.days).copy(listId = work))
+        db.tasks().update(db.tasks().entity(id)!!.copy(isDirty = false))
+
+        source.setReminders(id, listOf(TaskReminder(30)))
+
+        assertThat(db.tasks().entity(id)!!.isDirty).isTrue()
+    }
+
     @Test
     fun deletingATaskInALocalListRemovesItOutright() {
         val id = source.insertTask(form())
@@ -439,7 +549,7 @@ class RoomTasksDataSourceTest {
     fun aForkedOccurrenceCarriesTheSeriesReminder() {
         val id = source.insertTask(form())
         makeRecurring(id, now)
-        source.setAlarm(id, minutesBeforeDue = 30)
+        source.setReminders(id, listOf(TaskReminder(30)))
         val target = source.tasks(TaskQuery(listId = listId))
             .filter { it.taskId == id }
             .first { it.distanceFromCurrent == 1 }
@@ -447,7 +557,7 @@ class RoomTasksDataSourceTest {
         source.updateInstance(id, target.occurrenceStart!!, form(title = "moved"))
 
         // The fork copies the master's properties, which is what carries the
-        // reminder across — the repository is what puts the series' own back.
+        // reminder across.
         val override = db.tasks().override(id, target.occurrenceStart)!!
         assertThat(db.alarms().forTask(override.id).single().minutesBefore).isEqualTo(30)
     }
@@ -539,4 +649,47 @@ class RoomTasksDataSourceTest {
 
         assertThat(thrown).isNotNull()
     }
+
+    @Test
+    fun subtaskIdsNameRowsNotOccurrences() {
+        val parent = source.insertTask(form("parent"))
+        val longAgo = now - 1000.days
+        val outOfWindow = db.tasks().insert(
+            TaskEntity(listId = listId, uid = "old", title = "old", dtstart = longAgo, rrule = "FREQ=DAILY;COUNT=2", parentId = parent),
+        )
+        val series = db.tasks().insert(
+            TaskEntity(listId = listId, uid = "s", title = "s", dtstart = now, rrule = "FREQ=DAILY;COUNT=3", parentId = parent),
+        )
+        source.setCompletedInstance(series, now, true)
+        val plain = source.insertTask(form("plain").copy(parentId = parent))
+
+        assertThat(source.subtaskIds(parent)).containsExactly(outOfWindow, series, plain)
+    }
+
+    @Test
+    fun deletingASubtreeEndsOnAParentLoop() {
+        val a = source.insertTask(form("a"))
+        val b = source.insertTask(form("b").copy(parentId = a))
+        val c = source.insertTask(form("c").copy(parentId = b))
+        db.tasks().update(db.tasks().entity(a)!!.copy(parentId = c))
+
+        source.deleteWithSubtasks(a)
+
+        assertThat(listOf(a, b, c).mapNotNull { db.tasks().entity(it) }).isEmpty()
+    }
+
+    @Test
+    fun deletingFollowingFromTheFirstOccurrenceTakesTheWholeSubtree() {
+        val start = now
+        val series = db.tasks().insert(
+            TaskEntity(listId = listId, uid = "s", title = "s", dtstart = start, rrule = "FREQ=DAILY;COUNT=3"),
+        )
+        val child = source.insertTask(form("child").copy(parentId = series))
+        val grandchild = source.insertTask(form("grandchild").copy(parentId = child))
+
+        source.deleteFollowing(series, start)
+
+        assertThat(listOf(series, child, grandchild).mapNotNull { db.tasks().entity(it) }).isEmpty()
+    }
 }
+

app/src/androidTest/java/de/jeanlucmakiola/agendula/data/tasks/room/TasksDatabaseMigrationTest.kt

@@ -8,27 +8,7 @@ import org.junit.Rule
 import org.junit.Test
 import org.junit.runner.RunWith
 
-/**
- * The migration harness, proven against the committed schema in `app/schemas/`.
- *
- * There is one schema version today, so all there is to assert is that the helper
- * can build v1 from the exported JSON, seed it, and validate it back — i.e. the
- * export, the assets wiring and the identity hash all line up. That is the point:
- * the first real migration only has to add its own case.
- *
- * **Adding a v1 → v2 case.** When sync adds columns, bump [TasksDatabase]'s
- * `version`, let KSP export `2.json`, declare the `Migration(1, 2)` next to the
- * database, and add a test here shaped like this:
- *
- * ```
- * helper.createDatabase(TEST_DB, 1).use { db ->
- *     db.execSQL("INSERT INTO task_lists (name, color) VALUES ('Groceries', 0)")
- * }
- * helper.runMigrationsAndValidate(TEST_DB, 2, true, MIGRATION_1_2).use { db ->
- *     // read the seeded rows back — validation proves the shape, not the data
- * }
- * ```
- */
+/** Migrations, proven against the committed schemas in `app/schemas/`. */
 @RunWith(AndroidJUnit4::class)
 class TasksDatabaseMigrationTest {
 
@@ -62,6 +42,111 @@ class TasksDatabaseMigrationTest {
         }
     }
 
+    @Test
+    fun liftsCategoriesOutOfTheResidueWithoutDirtyingTheTask() {
+        helper.createDatabase(TEST_DB, 1).use { db ->
+            db.execSQL("INSERT INTO task_lists (id, name, color) VALUES (1, 'Work', 0)")
+            db.execSQL(
+                "INSERT INTO tasks (id, list_id, uid, title, unknown_properties) VALUES (?, 1, ?, ?, ?)",
+                arrayOf<Any?>(1, "uid-1", "Claimed", "X-FOO:bar\r\nCATEGORIES:Work,Home\r\n"),
+            )
+            db.execSQL(
+                "INSERT INTO tasks (id, list_id, uid, title, unknown_properties) VALUES (?, 1, ?, ?, ?)",
+                arrayOf<Any?>(2, "uid-2", "Split", "CATEGORIES:a\r\nCATEGORIES:b\r\n"),
+            )
+            db.execSQL("INSERT INTO tasks (id, list_id, uid, title) VALUES (3, 1, 'uid-3', 'Untagged')")
+        }
+
+        helper.runMigrationsAndValidate(TEST_DB, 2, true, TasksDatabase.MIGRATION_1_2).use { db ->
+            db.query("SELECT categories, unknown_properties, is_dirty FROM tasks ORDER BY id").use { c ->
+                c.moveToNext()
+                assertThat(c.getString(0)).isEqualTo("Work,Home")
+                assertThat(c.getString(1)).doesNotContain("CATEGORIES")
+                assertThat(c.getString(1)).contains("X-FOO:bar")
+                assertThat(c.getInt(2)).isEqualTo(0)
+
+                c.moveToNext()
+                assertThat(c.getString(0)).isEqualTo("a,b")
+                assertThat(c.getString(1)).isEqualTo("CATEGORIES:a\r\nCATEGORIES:b\r\n")
+
+                c.moveToNext()
+                assertThat(c.getString(0)).isEmpty()
+            }
+        }
+    }
+
+    @Test
+    fun liftsClaimableAlarmsAndPushesRemindersThatNeverLeftTheDevice() {
+        val future = System.currentTimeMillis() + 7L * 24 * 60 * 60 * 1000
+        val past = System.currentTimeMillis() - 7L * 24 * 60 * 60 * 1000
+        val claimable = "X-FOO:bar\r\nBEGIN:VALARM\r\nACTION:DISPLAY\r\nX-WR-ALARMUID:srv\r\n" +
+            "TRIGGER;RELATED=END:-PT15M\r\nEND:VALARM\r\n"
+        val appleDefault = "BEGIN:VALARM\r\nACTION:DISPLAY\r\nX-APPLE-DEFAULT-ALARM:TRUE\r\n" +
+            "TRIGGER;RELATED=END:-PT30M\r\nEND:VALARM\r\n"
+        helper.createDatabase(TEST_DB, 2).use { db ->
+            db.execSQL("INSERT INTO accounts (id, display_name) VALUES (1, 'me')")
+            db.execSQL("INSERT INTO task_lists (id, name, color, account_id) VALUES (1, 'Synced', 0, 1)")
+            db.execSQL("INSERT INTO task_lists (id, name, color) VALUES (2, 'Local', 0)")
+            db.execSQL("INSERT INTO task_lists (id, name, color, account_id, is_read_only) VALUES (3, 'Shared', 0, 1, 1)")
+            fun task(id: Int, list: Int, due: Long, residue: String? = null) = db.execSQL(
+                "INSERT INTO tasks (id, list_id, uid, title, due, unknown_properties) VALUES (?, ?, ?, ?, ?, ?)",
+                arrayOf<Any?>(id, list, "uid-$id", "Task $id", due, residue),
+            )
+            fun alarm(task: Int, minutes: Int) =
+                db.execSQL("INSERT INTO task_alarms (task_id, minutes_before) VALUES (?, ?)", arrayOf<Any?>(task, minutes))
+            // A server alarm, and the same lead copied locally by a fork.
+            task(1, 1, future, claimable)
+            alarm(1, 15)
+            // Set in Agendula, never uploaded — still to fire, already past, device-only.
+            task(2, 1, future)
+            alarm(2, 30)
+            task(3, 1, past)
+            alarm(3, 30)
+            task(4, 2, future)
+            alarm(4, 30)
+            // Somebody else's default alarm: not ours to claim.
+            task(5, 1, future, appleDefault)
+            // A read-only share: dirty would freeze it, never sent and never refreshed.
+            task(6, 3, future)
+            alarm(6, 30)
+        }
+
+        helper.runMigrationsAndValidate(TEST_DB, 3, true, TasksDatabase.MIGRATION_2_3).use { db ->
+            db.query("SELECT task_id, minutes_before, uid, raw FROM task_alarms ORDER BY task_id").use { c ->
+                val rows = buildList { while (c.moveToNext()) add(listOf(c.getLong(0), c.getInt(1), c.getString(2), c.getString(3))) }
+                // One for task 1: the lifted copy won and the local duplicate went.
+                assertThat(rows.map { it[0] }).containsExactly(1L, 2L, 3L, 4L, 6L).inOrder()
+                assertThat(rows[0][2]).isEqualTo("srv")
+                assertThat(rows[0][3] as String).contains("TRIGGER;RELATED=END:-PT15M")
+                // Every pre-existing row got an identity of its own, shaped as a UUID.
+                assertThat(rows.drop(1).map { it[2] as String }.toSet()).hasSize(4)
+                rows.drop(1).forEach {
+                    assertThat(it[2] as String).matches("[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}")
+                }
+                assertThat(rows.drop(1).all { (it[2] as String).isNotEmpty() && it[3] == null }).isTrue()
+            }
+            db.query("SELECT id, unknown_properties, is_dirty, last_modified, reminders_off FROM tasks ORDER BY id").use { c ->
+                c.moveToNext()
+                assertThat(c.getString(1)).isEqualTo("X-FOO:bar\r\n")
+                assertThat(c.getInt(2)).isEqualTo(0)
+                assertThat(c.getInt(4)).isEqualTo(0)
+                c.moveToNext()
+                assertThat(c.getInt(2)).isEqualTo(1)
+                // The body changes, so its modification stamp does too.
+                assertThat(c.isNull(3)).isFalse()
+                c.moveToNext()
+                assertThat(c.getInt(2)).isEqualTo(0)
+                c.moveToNext()
+                assertThat(c.getInt(2)).isEqualTo(0)
+                c.moveToNext()
+                assertThat(c.getString(1)).contains("X-APPLE-DEFAULT-ALARM:TRUE")
+                assertThat(c.getInt(2)).isEqualTo(0)
+                c.moveToNext()
+                assertThat(c.getInt(2)).isEqualTo(0)
+            }
+        }
+    }
+
     private companion object {
         const val TEST_DB = "migration-test.db"
     }

app/src/androidTest/java/de/jeanlucmakiola/agendula/data/tasks/transfer/ExternalImportTest.kt

@@ -11,7 +11,7 @@ import com.google.common.truth.Truth.assertThat
 import de.jeanlucmakiola.agendula.data.tasks.ProviderEnvironment
 import de.jeanlucmakiola.agendula.data.tasks.ProviderResolver
 import de.jeanlucmakiola.agendula.data.tasks.TaskQuery
-import de.jeanlucmakiola.agendula.data.tasks.TaskReminder
+import de.jeanlucmakiola.agendula.domain.TaskReminder
 import de.jeanlucmakiola.agendula.data.tasks.TasksDataSource
 import de.jeanlucmakiola.agendula.data.tasks.room.AlarmReference
 import de.jeanlucmakiola.agendula.data.tasks.room.TasksDatabase
@@ -107,6 +107,17 @@ class ExternalImportTest {
         assertThat(importer.hasRun.first()).isTrue()
     }
 
+    @Test
+    fun copiesTagsCleanedUp() = runBlocking {
+        source.lists = listOf(list(7, "Errands"))
+        source.tasks = mapOf(7L to listOf(task(100, "Milk", tags = listOf("Shop", " Shop ", "", "Home"))))
+
+        importer.run()
+
+        assertThat(db.tasks().tasks(listId = null, includeCompleted = true).single().task.categories)
+            .containsExactly("Shop", "Home").inOrder()
+    }
+
     /** Every list arrives device-only: the account belongs to the sync app. */
     @Test
     fun importedListsAreDeviceOnly() = runBlocking {
@@ -241,6 +252,7 @@ class ExternalImportTest {
         title: String,
         uid: String? = "uid-$id",
         parentId: Long? = null,
+        tags: List<String> = emptyList(),
     ) = ExportTask(
         taskId = id,
         uid = uid,
@@ -260,6 +272,7 @@ class ExternalImportTest {
         rrule = null,
         rdate = null,
         parentId = parentId,
+        tags = tags,
     )
 
     private companion object {
@@ -281,23 +294,25 @@ private class FakeExternalStore : TasksDataSource {
         return tasks[listId].orEmpty()
     }
 
-    override fun alarms(): Map<Long, TaskReminder> = alarms
+    override fun reminders(): Map<Long, List<TaskReminder>> = alarms.mapValues { listOf(it.value) }
 
     override fun tasks(query: TaskQuery): List<Task> = unused()
     override fun task(taskId: Long): Task? = unused()
     override fun subtasks(parentTaskId: Long): List<Task> = unused()
-    override fun insertTask(form: TaskForm): Long = unused()
-    override fun updateTask(taskId: Long, form: TaskForm) = unused()
-    override fun updateInstance(taskId: Long, occurrenceStart: Instant, form: TaskForm) = unused()
-    override fun setAlarm(taskId: Long, minutesBeforeDue: Int?) = unused()
+    override fun insertTask(form: TaskForm, reminders: List<TaskReminder>?): Long = unused()
+    override fun updateTask(taskId: Long, form: TaskForm, reminders: List<TaskReminder>?) = unused()
+    override fun updateInstance(taskId: Long, occurrenceStart: Instant, form: TaskForm, reminders: List<TaskReminder>?) =
+        unused()
     override fun setReminders(taskId: Long, reminders: List<TaskReminder>) = unused()
     override fun setCompleted(taskId: Long, completed: Boolean) = unused()
     override fun setCompletedInstance(taskId: Long, occurrenceStart: Instant, completed: Boolean) = unused()
     override fun deleteTask(taskId: Long) = unused()
     override fun setCancelled(taskId: Long, cancelled: Boolean) = unused()
     override fun setCancelledInstance(taskId: Long, occurrenceStart: Instant, cancelled: Boolean) = unused()
-    override fun updateSeries(seriesId: Long, occurrenceStart: Instant, form: TaskForm) = unused()
-    override fun splitSeries(seriesId: Long, occurrenceStart: Instant, form: TaskForm): Long = unused()
+    override fun updateSeries(seriesId: Long, occurrenceStart: Instant, form: TaskForm, reminders: List<TaskReminder>?) =
+        unused()
+    override fun splitSeries(seriesId: Long, occurrenceStart: Instant, form: TaskForm, reminders: List<TaskReminder>?): Long =
+        unused()
     override fun deleteOccurrence(seriesId: Long, occurrenceStart: Instant) = unused()
     override fun deleteFollowing(seriesId: Long, occurrenceStart: Instant) = unused()
     override fun createLocalList(name: String, color: Int): Long = unused()

app/src/full/AndroidManifest.xml

@@ -0,0 +1,88 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- CalDAV sync and UnifiedPush; everything here needs the network. -->
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+
+    <!-- CalDAV sync. ACCESS_NETWORK_STATE is merged in by work-runtime anyway,
+         but it shows in F-Droid's permission diff, so declare it deliberately
+         rather than letting it appear from nowhere.
+
+         READ_SYNC_SETTINGS / WRITE_SYNC_SETTINGS are what the ContentResolver
+         sync APIs need. No FOREGROUND_SERVICE: sync is a plain worker, and the
+         dataSync FGS type would bring the Android 15 six-hours-per-24 budget
+         (whose failure mode is a fatal RemoteServiceException) and a Play
+         requirement for a video demo.
+
+         Two more permissions appear in the merged manifest without being
+         declared here, and both come from work-runtime: WAKE_LOCK, and
+         FOREGROUND_SERVICE. The latter is not us taking the FGS route — below
+         API 31 WorkManager implements expedited work with a foreground service,
+         and minSdk is 29, so it is load-bearing for the "Sync now" button.
+         Removing it with tools:node="remove" would break expedited work on
+         exactly the older devices that need it most. Noted because it shows in
+         F-Droid's permission diff and would otherwise look unexplained. -->
+    <uses-permission android:name="android.permission.INTERNET" />
+    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
+    <uses-permission android:name="android.permission.READ_SYNC_SETTINGS" />
+    <uses-permission android:name="android.permission.WRITE_SYNC_SETTINGS" />
+
+    <queries>
+        <!-- Custom Tabs provider detection. Without this entry it silently finds
+             nothing on API 30+, and the Nextcloud login flow falls back to an
+             external browser for no visible reason. -->
+        <intent>
+            <action android:name="android.support.customtabs.action.CustomTabsService" />
+        </intent>
+    </queries>
+
+    <application android:networkSecurityConfig="@xml/network_security_config">
+
+        <!-- Sync plumbing. The stub provider exists only to give the sync
+             adapter an authority to register against: Agendula publishes no real
+             ContentProvider since :provider was deleted, and without an authority
+             ContentService.hasAuthorityAccess() makes every ContentResolver sync
+             call a silent no-op at targetSdk >= 34. -->
+        <provider
+            android:name=".data.sync.SyncStubProvider"
+            android:authorities="${applicationId}.sync"
+            android:exported="false"
+            android:syncable="true" />
+
+        <!-- Exported and guarded by ACCOUNT_MANAGER. Note that
+             android.permission.ACCOUNT_AUTHENTICATOR does not exist. -->
+        <service
+            android:name=".data.sync.AuthenticatorService"
+            android:exported="true"
+            android:permission="android.permission.ACCOUNT_MANAGER">
+            <intent-filter>
+                <action android:name="android.accounts.AccountAuthenticator" />
+            </intent-filter>
+            <meta-data
+                android:name="android.accounts.AccountAuthenticator"
+                android:resource="@xml/authenticator" />
+        </service>
+
+        <service
+            android:name=".data.sync.SyncAdapterService"
+            android:exported="true"
+            android:permission="android.permission.BIND_SYNC_ADAPTER">
+            <intent-filter>
+                <action android:name="android.content.SyncAdapter" />
+            </intent-filter>
+            <meta-data
+                android:name="android.content.SyncAdapter"
+                android:resource="@xml/sync_adapter" />
+        </service>
+
+        <!-- UnifiedPush: the connector binds this to deliver endpoints and
+             WebDAV-Push messages. Not exported; the connector's own receiver is
+             what distributors talk to. -->
+        <service
+            android:name=".data.sync.push.AgendulaPushService"
+            android:exported="false">
+            <intent-filter>
+                <action android:name="org.unifiedpush.android.connector.PUSH_EVENT" />
+            </intent-filter>
+        </service>
+    </application>
+
+</manifest>

app/src/full/java/de/jeanlucmakiola/agendula/data/di/SyncModule.kt

@@ -0,0 +1,131 @@
+package de.jeanlucmakiola.agendula.data.di
+
+import android.content.Context
+import androidx.datastore.core.DataStore
+import androidx.datastore.preferences.core.Preferences
+import androidx.datastore.preferences.preferencesDataStore
+import dagger.Binds
+import dagger.Module
+import dagger.Provides
+import dagger.hilt.InstallIn
+import dagger.hilt.android.qualifiers.ApplicationContext
+import dagger.hilt.components.SingletonComponent
+import dagger.multibindings.IntoSet
+import de.jeanlucmakiola.agendula.data.sync.AccountCreator
+import de.jeanlucmakiola.agendula.data.sync.AccountRepository
+import de.jeanlucmakiola.agendula.data.sync.CalDavGateway
+import de.jeanlucmakiola.agendula.data.sync.LoginFlowRecord
+import de.jeanlucmakiola.agendula.data.sync.OkHttpCalDavGateway
+import de.jeanlucmakiola.agendula.data.sync.PendingLoginFlowStore
+import de.jeanlucmakiola.agendula.data.sync.RemoteListRepository
+import de.jeanlucmakiola.agendula.data.sync.RemoteLists
+import de.jeanlucmakiola.agendula.data.sync.SyncNoticeNotifier
+import de.jeanlucmakiola.agendula.data.sync.SyncOnEdit
+import de.jeanlucmakiola.agendula.data.sync.SyncRequests
+import de.jeanlucmakiola.agendula.data.sync.SyncTrigger
+import de.jeanlucmakiola.agendula.data.sync.push.PushRegistrar
+import de.jeanlucmakiola.agendula.data.tasks.room.LocalWriteListener
+import javax.inject.Provider
+import javax.inject.Singleton
+
+/** See [CredentialsDataStore] for why this is a separate file. */
+private val Context.credentialsDataStore: DataStore<Preferences> by preferencesDataStore(
+    name = CREDENTIALS_DATASTORE,
+    corruptionHandler = replaceCorrupted(),
+)
+
+/** See [SyncStateDataStore] for why this is a separate file. */
+private val Context.syncStateDataStore: DataStore<Preferences> by preferencesDataStore(
+    name = SYNC_STATE_DATASTORE,
+    corruptionHandler = replaceCorrupted(),
+)
+
+/**
+ * Named here and in `backup_rules.xml` / `data_extraction_rules.xml`, which
+ * exclude `datastore/$CREDENTIALS_DATASTORE.preferences_pb` by this name.
+ */
+const val CREDENTIALS_DATASTORE = "agendula_credentials"
+
+/**
+ * Named here and in `backup_rules.xml` / `data_extraction_rules.xml`, which
+ * exclude `datastore/$SYNC_STATE_DATASTORE.preferences_pb` by this name.
+ */
+const val SYNC_STATE_DATASTORE = "agendula_sync_state"
+
+/** CalDAV sync: the `full` flavor's side of the seams `main` declares. */
+@Module
+@InstallIn(SingletonComponent::class)
+abstract class SyncBindModule {
+
+    @Binds
+    @Singleton
+    abstract fun bindCalDavGateway(impl: OkHttpCalDavGateway): CalDavGateway
+
+    @Binds
+    @Singleton
+    abstract fun bindAccountCreator(impl: AccountRepository): AccountCreator
+
+    @Binds
+    @Singleton
+    abstract fun bindLoginFlowRecord(impl: PendingLoginFlowStore): LoginFlowRecord
+
+    @Binds
+    @Singleton
+    abstract fun bindLocalWriteListener(impl: SyncOnEdit): LocalWriteListener
+
+    @Binds
+    @Singleton
+    abstract fun bindRemoteLists(impl: RemoteListRepository): RemoteLists
+
+    @Binds
+    @Singleton
+    abstract fun bindSyncRequests(impl: SyncTrigger): SyncRequests
+
+    @Binds
+    @IntoSet
+    abstract fun bindSyncNoticeChannel(impl: SyncNoticeNotifier): ChannelRefresher
+}
+
+@Module
+@InstallIn(SingletonComponent::class)
+object SyncProvideModule {
+
+    @Provides
+    @Singleton
+    @CredentialsDataStore
+    fun provideCredentialsDataStore(@ApplicationContext context: Context): DataStore<Preferences> =
+        context.credentialsDataStore
+
+    @Provides
+    @Singleton
+    @SyncStateDataStore
+    fun provideSyncStateDataStore(@ApplicationContext context: Context): DataStore<Preferences> =
+        context.syncStateDataStore
+
+    /**
+     * Sync hard on app open: the periodic worker's interval is a floor, and in
+     * the `rare` and `restricted` App Standby buckets it may not have run at
+     * all. `KEEP` makes rescheduling idempotent, so this also repairs a schedule
+     * lost to "clear app data" or to a restore.
+     */
+    @Provides
+    @IntoSet
+    fun syncOnOpenHook(
+        accounts: Provider<AccountRepository>,
+        syncTrigger: Provider<SyncTrigger>,
+        pendingLoginFlows: Provider<PendingLoginFlowStore>,
+        push: Provider<PushRegistrar>,
+    ): LaunchHook = LaunchHook {
+        runCatching {
+            accounts.get().rescheduleAll()
+            accounts.get().syncable().forEach { syncTrigger.get().enqueue(it.displayName) }
+            // A login flow the previous process died in the middle of.
+            // Its password, if the user approved, exists nowhere else.
+            pendingLoginFlows.get().reclaim()
+        }
+        // Last and on its own: it waits on the network, and must not hold up
+        // the reclaim above. Re-registering on open is what the connector
+        // recommends.
+        runCatching { push.get().updateAll() }
+    }
+}

app/src/full/java/de/jeanlucmakiola/agendula/data/di/SyncQualifiers.kt

@@ -0,0 +1,34 @@
+package de.jeanlucmakiola.agendula.data.di
+
+import javax.inject.Qualifier
+
+/**
+ * Marks the DataStore holding **only** the Keystore-encrypted app passwords.
+ *
+ * A separate file from `agendula_prefs` on purpose: Auto Backup includes
+ * `datastore/`, and a restored ciphertext is permanently undecryptable because
+ * Keystore keys are non-exportable. Its own file is what lets the backup rules
+ * exclude the credentials and nothing else — excluding the whole database or
+ * all of DataStore would trade a latent bug for a live one.
+ */
+@Qualifier
+@Retention(AnnotationRetention.BINARY)
+annotation class CredentialsDataStore
+
+/**
+ * Marks the DataStore holding per-device **sync bookkeeping** — the quarantine
+ * counters and the full-reconciliation clock.
+ *
+ * Its own file for the same reason the credentials have one: Auto Backup
+ * includes `datastore/`, and every value in here is a statement about *this*
+ * device's conversation with a server. Restored onto a new install they are all
+ * lies, and two of them are dangerous — a restored "reconciled recently" makes
+ * the engine trust a sync token for another day, which is precisely the silently
+ * pruned change log the full path exists to catch, and a restored quarantine
+ * count silently skips resources that were never tried here.
+ *
+ * Not user data, so nothing is lost by excluding it.
+ */
+@Qualifier
+@Retention(AnnotationRetention.BINARY)
+annotation class SyncStateDataStore

app/src/full/java/de/jeanlucmakiola/agendula/data/sync/CollectionSyncer.kt

@@ -1,8 +1,10 @@
 package de.jeanlucmakiola.agendula.data.sync
 
+import de.jeanlucmakiola.agendula.data.tasks.ical.AlarmCodec
 import de.jeanlucmakiola.agendula.data.tasks.ical.CalendarResource
 import de.jeanlucmakiola.agendula.data.tasks.ical.ResourceValidator
 import de.jeanlucmakiola.agendula.data.tasks.ical.VTodoMapper
+import de.jeanlucmakiola.agendula.data.tasks.room.TaskAlarmEntity
 import de.jeanlucmakiola.agendula.data.tasks.room.TaskEntity
 import de.jeanlucmakiola.agendula.data.tasks.room.TaskListEntity
 import at.bitfire.dav4jvm.exception.UnauthorizedException
@@ -422,8 +424,9 @@ class CollectionSyncer(
 
         /** Null when the resource was rejected before it left the device. */
         private fun serialize(local: LocalResource): String? {
+            val alarms = store.alarmsFor(local.live.map { it.id })
             val todos = local.live.map { row ->
-                VTodoMapper.write(row, parentUidOf(row), now())
+                VTodoMapper.write(row, parentUidOf(row), now(), alarms[row.id].orEmpty())
             }
             val calendar = CalendarResource.build(todos)
 
@@ -778,14 +781,17 @@ class CollectionSyncer(
             val losing = existing.values.firstOrNull { it.isDirty }
 
             val master = mapped.firstOrNull { it.entity.recurrenceId == null } ?: mapped.first()
-            val masterRow = upsert(master.entity, existing[master.entity.recurrenceId], null, href, eTag)
+            val masterRow = upsert(master, existing[master.entity.recurrenceId], null, href, eTag)
             val masterId = masterRow.id
             parents[uid] = master.parentUid
 
             val written = mutableListOf(masterRow)
             mapped.filter { it !== master }.forEach { override ->
+                // ⚠️ An override's alarms are its own: RFC 5545 has an override
+                // replace the component, so one the server sends without a
+                // VALARM has none, whatever its master carries.
                 written += upsert(
-                    override.entity, existing[override.entity.recurrenceId], masterId, href, eTag,
+                    override, existing[override.entity.recurrenceId], masterId, href, eTag,
                 )
             }
             val kept = written.map { it.recurrenceId }.toSet()
@@ -832,12 +838,13 @@ class CollectionSyncer(
 
         /** @return the row as it now stands, so the caller can index it. */
         private fun upsert(
-            incoming: TaskEntity,
+            mapped: VTodoMapper.Mapped,
             existing: TaskEntity?,
             masterId: Long?,
             href: String,
             eTag: String?,
         ): TaskEntity {
+            val incoming = mapped.entity
             // Local-only columns the server has no opinion about. Taking the
             // mapper's defaults here would silently reset the user's ordering and
             // per-task colour on every download.
@@ -854,12 +861,42 @@ class CollectionSyncer(
                 // set uploads what was just downloaded.
                 isDirty = false,
                 isDeleted = false,
+                // The store's to change, from what the alarms do.
+                remindersOff = existing?.remindersOff ?: false,
             )
-            return if (existing == null) {
-                row.copy(id = store.insert(row))
-            } else {
-                store.update(row)
-                row
+            // The server's alarms replace ours, as every other field does: a
+            // dirty row is never downloaded except to discard its edit.
+            val alarms = existing?.let { keepLocalPrecision(mapped.alarms, it, row) } ?: mapped.alarms
+            return row.copy(id = store.upsertWithAlarms(row, alarms))
+        }
+
+        /**
+         * [incoming] with each alarm we uploaded ourselves put back to the lead
+         * we hold for it.
+         *
+         * ⚠️ The wire is coarser than the row: a lead past the end of its
+         * anchor is clamped, and a before-start reminder on a task without a
+         * start goes out before-due. Taking the round trip at its word would
+         * quietly turn a before-start reminder into a before-due one the first
+         * time the task is downloaded again.
+         * An alarm that comes back as exactly what we would have sent has not
+         * been changed, so the row's own lead stands.
+         */
+        private fun keepLocalPrecision(
+            incoming: List<TaskAlarmEntity>,
+            existing: TaskEntity,
+            task: TaskEntity,
+        ): List<TaskAlarmEntity> {
+            val local = store.alarmsFor(listOf(existing.id))[existing.id].orEmpty()
+            if (local.isEmpty()) return incoming
+            return incoming.map { alarm ->
+                val mine = local.firstOrNull { it.uid == alarm.uid } ?: return@map alarm
+                val sent = AlarmCodec.wireLead(mine, task)
+                if (sent == AlarmCodec.Lead(alarm.minutesBefore, alarm.reference)) {
+                    alarm.copy(minutesBefore = mine.minutesBefore, reference = mine.reference)
+                } else {
+                    alarm
+                }
             }
         }
 

app/src/full/java/de/jeanlucmakiola/agendula/data/sync/RemoteListRepository.kt

@@ -1,6 +1,7 @@
 package de.jeanlucmakiola.agendula.data.sync
 
 import de.jeanlucmakiola.agendula.data.di.IoDispatcher
+import de.jeanlucmakiola.agendula.data.sync.RemoteLists.Outcome
 import de.jeanlucmakiola.agendula.data.sync.push.PushStore
 import de.jeanlucmakiola.agendula.data.tasks.ProviderResolver
 import de.jeanlucmakiola.agendula.data.tasks.StorageMode
@@ -53,38 +54,7 @@ class RemoteListRepository @Inject constructor(
     private val resolver: ProviderResolver,
     private val push: PushStore,
     @IoDispatcher private val io: CoroutineDispatcher,
-) {
-
-    /** Why a collection write did not happen, in a form the UI can translate. */
-    sealed interface Outcome {
-        data object Done : Outcome
-
-        /** The server said no, and will say no again. */
-        data class Refused(val code: Int) : Outcome
-
-        /** The server could not be reached. Worth another try. */
-        data object Unreachable : Outcome
-
-        /** This account cannot make collections at all — iCloud, Posteo, Google. */
-        data object Unsupported : Outcome
-
-        /** Ours is a read-only share; the write belongs to whoever owns it. */
-        data object ReadOnly : Outcome
-
-        /** The account is gone, stopped, or has no credential we can decrypt. */
-        data object NoAccount : Outcome
-
-        /**
-         * The server answered something this call cannot make sense of.
-         *
-         * ⚠️ Not [Unreachable]. `CollectionOutcome` is one type across create,
-         * update and delete, so each of them has branches the other's method
-         * can return and its own cannot — and mapping those to [Unreachable]
-         * told someone sitting on wifi that they were offline. Unreachable is a
-         * claim about the network, and this is not one.
-         */
-        data object Unexpected : Outcome
-    }
+) : RemoteLists {
 
     /**
      * The accounts a new list may be created on, freshest answer first.
@@ -95,7 +65,7 @@ class RemoteListRepository @Inject constructor(
      * able to say so, and the only moment that costs nothing is while the user
      * is looking at the picker.
      */
-    suspend fun creatableAccounts(): List<AccountEntity> = withContext(io) {
+    override suspend fun creatableAccounts(): List<AccountEntity> = withContext(io) {
         // ⚠️ Empty in External mode, whatever the accounts table holds. The
         // lists on screen then come from a third-party provider, so a row
         // inserted into ours would exist, sync, and be visible to nobody.
@@ -120,7 +90,7 @@ class RemoteListRepository @Inject constructor(
      *
      * @return the new list's local id, or why there is none.
      */
-    suspend fun create(
+    override suspend fun create(
         accountId: Long,
         name: String,
         color: Int,
@@ -189,7 +159,7 @@ class RemoteListRepository @Inject constructor(
      * a row that has already been renamed locally by then reads as a rename that
      * worked and then quietly reverted on the next sync.
      */
-    suspend fun rename(listId: Long, name: String, color: Int): Outcome = withContext(io) {
+    override suspend fun rename(listId: Long, name: String, color: Int): Outcome = withContext(io) {
         val list = database.taskLists().entity(listId) ?: return@withContext Outcome.NoAccount
         if (list.isReadOnly) return@withContext Outcome.ReadOnly
         val url = list.href?.toHttpUrlOrNull() ?: return@withContext Outcome.NoAccount
@@ -227,7 +197,7 @@ class RemoteListRepository @Inject constructor(
      * grades 404 and 410 that way — because otherwise a collection someone
      * removed from another client leaves a row here that nothing can get rid of.
      */
-    suspend fun delete(listId: Long): Outcome = withContext(io) {
+    override suspend fun delete(listId: Long): Outcome = withContext(io) {
         val list = database.taskLists().entity(listId) ?: return@withContext Outcome.Done
         if (list.isReadOnly) return@withContext Outcome.ReadOnly
         val url = list.href?.toHttpUrlOrNull() ?: return@withContext Outcome.NoAccount

app/src/full/java/de/jeanlucmakiola/agendula/data/sync/SyncNoticeNotifier.kt

@@ -14,6 +14,7 @@ import androidx.core.app.NotificationManagerCompat
 import androidx.core.content.ContextCompat
 import dagger.hilt.android.qualifiers.ApplicationContext
 import de.jeanlucmakiola.agendula.MainActivity
+import de.jeanlucmakiola.agendula.data.di.ChannelRefresher
 import de.jeanlucmakiola.agendula.R
 import javax.inject.Inject
 import javax.inject.Singleton
@@ -33,7 +34,7 @@ import javax.inject.Singleton
 @Singleton
 class SyncNoticeNotifier @Inject constructor(
     @ApplicationContext private val context: Context,
-) {
+) : ChannelRefresher {
 
     fun canPost(): Boolean {
         val granted = Build.VERSION.SDK_INT < Build.VERSION_CODES.TIRAMISU ||
@@ -123,7 +124,7 @@ class SyncNoticeNotifier @Inject constructor(
      * extra names the account for routing to Settings → Accounts → it.
      */
     private fun signInIntent(accountId: Long): Intent =
-        MainActivity.openIntent(context).putExtra(EXTRA_SIGN_IN_ACCOUNT_ID, accountId)
+        MainActivity.openIntent(context).putExtra(MainActivity.EXTRA_SIGN_IN_ACCOUNT_ID, accountId)
 
     private fun ensureSignInChannel() {
         if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) return
@@ -170,16 +171,13 @@ class SyncNoticeNotifier @Inject constructor(
     }
 
     /** Re-create the channel, if it exists, in the current language. */
-    fun refreshChannel() {
+    override fun refreshChannel() {
         if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) return
         val manager = context.getSystemService(NotificationManager::class.java)
         if (manager.getNotificationChannel(CHANNEL_ID) != null) ensureChannel()
     }
 
     companion object {
-        /** The account a sign-in notification is about, on the intent it opens. */
-        const val EXTRA_SIGN_IN_ACCOUNT_ID = "de.jeanlucmakiola.agendula.extra.SIGN_IN_ACCOUNT_ID"
-
         private const val CHANNEL_ID = "sync_notices"
         private const val NOTIFICATION_ID = 2
         private const val SIGN_IN_CHANNEL_ID = "account_sign_in"

app/src/full/java/de/jeanlucmakiola/agendula/data/sync/SyncStore.kt

@@ -1,5 +1,6 @@
 package de.jeanlucmakiola.agendula.data.sync
 
+import de.jeanlucmakiola.agendula.data.tasks.room.TaskAlarmEntity
 import de.jeanlucmakiola.agendula.data.tasks.room.TaskEntity
 import de.jeanlucmakiola.agendula.data.tasks.room.TasksDatabase
 import javax.inject.Inject
@@ -11,17 +12,33 @@ import javax.inject.Inject
  * discovery: the reconciliation above this interface is where local edits are
  * discarded, tombstones swept and conflicts resolved, and every one of those is
  * a decision that should be provable without a device. Room's test double is
- * Robolectric plus an in-memory database; this is eight methods.
+ * Robolectric plus an in-memory database; this is a dozen methods.
  */
 interface SyncStore {
 
     /** Every row in a list, **tombstones included**. */
     fun rowsIn(listId: Long): List<TaskEntity>
 
-    fun insert(row: TaskEntity): Long
-
     fun update(row: TaskEntity)
 
+    /** The reminders of [taskIds] — one resource's rows — by task id, for the body that uploads them. */
+    fun alarmsFor(taskIds: List<Long>): Map<Long, List<TaskAlarmEntity>>
+
+    /**
+     * Writes a downloaded row — inserted when its id is 0 — and makes its
+     * reminders exactly [alarms], in one transaction.
+     *
+     * ⚠️ One transaction, not an [update] and a second call. The row lands clean
+     * with the server's ETag, so if the process died between the two, nothing
+     * would ever download it again and the reminders would stay stale for good.
+     *
+     * A row that is gone by the time it is written — deleted on the device
+     * while the sync ran — stays gone, reminders and all.
+     *
+     * @return the row's id.
+     */
+    fun upsertWithAlarms(row: TaskEntity, alarms: List<TaskAlarmEntity>): Long
+
     fun deleteAll(taskIds: List<Long>)
 
     /**
@@ -56,12 +73,26 @@ class RoomSyncStore @Inject constructor(
 
     override fun rowsIn(listId: Long) = database.tasks().allIn(listId)
 
-    override fun insert(row: TaskEntity) = database.tasks().insert(row)
-
     override fun update(row: TaskEntity) {
         database.tasks().update(row)
     }
 
+    override fun alarmsFor(taskIds: List<Long>) =
+        if (taskIds.isEmpty()) emptyMap() else database.alarms().forTasks(taskIds).groupBy { it.taskId }
+
+    override fun upsertWithAlarms(row: TaskEntity, alarms: List<TaskAlarmEntity>): Long =
+        database.runInTransaction<Long> {
+            if (row.id == 0L) {
+                database.tasks().insert(row).also { database.alarms().replaceFromServer(it, alarms) }
+            } else {
+                // ⚠️ Zero rows means the row was deleted under us. Its alarms
+                // would then name a task that does not exist, and the foreign
+                // key would fail the whole transaction.
+                if (database.tasks().update(row) > 0) database.alarms().replaceFromServer(row.id, alarms)
+                row.id
+            }
+        }
+
     override fun deleteAll(taskIds: List<Long>) {
         if (taskIds.isNotEmpty()) database.tasks().deleteAll(taskIds)
     }

app/src/full/java/de/jeanlucmakiola/agendula/data/sync/SyncTrigger.kt

@@ -35,7 +35,11 @@ import kotlin.time.Duration.Companion.seconds
 @Singleton
 class SyncTrigger @Inject constructor(
     @ApplicationContext private val context: Context,
-) {
+) : SyncRequests {
+
+    override fun syncNow(accountName: String) {
+        enqueue(accountName)
+    }
 
     /**
      * Starts a sync now.

app/src/full/java/de/jeanlucmakiola/agendula/ui/accounts/AccountDetailScreen.kt

@@ -70,6 +70,7 @@ internal fun AccountDetailScreen(
     onSignInAgain: (AccountEntity) -> Unit,
     onOpenStorage: () -> Unit,
     viewModel: AccountsViewModel,
+    visible: Boolean,
 ) {
     val accounts by viewModel.accounts.collectAsStateWithLifecycle()
     val usable by viewModel.accountsUsable.collectAsStateWithLifecycle()
@@ -90,7 +91,7 @@ internal fun AccountDetailScreen(
     // shown on the accounts list rather than here.
     var confirming by remember { mutableStateOf(false) }
 
-    CollapsingScaffold(title = identity.title, onBack = onBack) {
+    CollapsingScaffold(title = identity.title, onBack = onBack, predictiveBack = true, visible = visible) {
         AccountHero(identity)
         Spacer(Modifier.height(24.dp))
 

app/src/full/java/de/jeanlucmakiola/agendula/ui/accounts/AccountsScreen.kt

@@ -48,6 +48,7 @@ internal fun AccountsScreen(
     onOpenStorage: () -> Unit,
     onBack: () -> Unit,
     viewModel: AccountsViewModel,
+    visible: Boolean,
 ) {
     val accounts by viewModel.accounts.collectAsStateWithLifecycle()
     val usable by viewModel.accountsUsable.collectAsStateWithLifecycle()
@@ -60,6 +61,8 @@ internal fun AccountsScreen(
     CollapsingScaffold(
         title = stringResource(R.string.settings_section_accounts),
         onBack = onBack,
+        predictiveBack = true,
+        visible = visible,
     ) {
         val loaded = accounts ?: return@CollapsingScaffold
 

app/src/full/java/de/jeanlucmakiola/agendula/ui/onboarding/AccountStep.kt

@@ -0,0 +1,35 @@
+package de.jeanlucmakiola.agendula.ui.onboarding
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.getValue
+import androidx.hilt.lifecycle.viewmodel.compose.hiltViewModel
+import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import de.jeanlucmakiola.agendula.ui.accounts.add.ADD_ACCOUNT_STEPS
+import de.jeanlucmakiola.agendula.ui.accounts.add.AddAccountScreen
+import de.jeanlucmakiola.agendula.ui.accounts.add.AddAccountViewModel
+
+/** The inline wizard's shortest length, before a provider is picked. */
+internal const val ACCOUNT_STEP_SLOTS = ADD_ACCOUNT_STEPS
+
+/** [OnboardingStep.Account]: the add-account wizard, given the whole screen. */
+@Composable
+internal fun AccountStep(state: OnboardingUiState, viewModel: OnboardingViewModel) {
+    // The same instance the wizard resolves for itself, so its length can be
+    // read here without keeping a second copy of its state.
+    val account: AddAccountViewModel = hiltViewModel()
+    val accountState by account.state.collectAsStateWithLifecycle()
+    // ⚠️ The wizard grows a step for a provider that needs an app password
+    // minted first, and the outer bar has to grow with it — otherwise first
+    // run counts one flow while the screen inside it counts another.
+    LaunchedEffect(accountState.totalSteps) {
+        viewModel.onAccountStepsChanged(accountState.totalSteps)
+    }
+    AddAccountScreen(
+        onDone = { viewModel.onAccountFinished(added = true) },
+        onBack = { viewModel.onAccountFinished(added = false) },
+        stepOffset = state.position - 1,
+        totalSteps = state.total,
+        viewModel = account,
+    )
+}

app/src/full/java/de/jeanlucmakiola/agendula/ui/settings/AccountSections.kt

@@ -0,0 +1,81 @@
+package de.jeanlucmakiola.agendula.ui.settings
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.saveable.rememberSaveable
+import androidx.compose.runtime.setValue
+import androidx.hilt.lifecycle.viewmodel.compose.hiltViewModel
+import de.jeanlucmakiola.agendula.data.tasks.room.AccountEntity
+import de.jeanlucmakiola.agendula.ui.accounts.AccountDetailScreen
+import de.jeanlucmakiola.agendula.ui.accounts.AccountsScreen
+import de.jeanlucmakiola.agendula.ui.accounts.AccountsViewModel
+import de.jeanlucmakiola.agendula.ui.accounts.add.AddAccountScreen
+import de.jeanlucmakiola.agendula.ui.accounts.add.AddAccountViewModel
+
+/** Settings → Accounts and the screens under it, layered over the hub. */
+@Composable
+internal fun AccountSections(
+    section: SettingsSection?,
+    initialAccountId: Long?,
+    onSection: (SettingsSection?) -> Unit,
+) {
+    // Hoisted so the add flow can refresh the list it returns to.
+    val accountsViewModel: AccountsViewModel = hiltViewModel()
+    // Shared with the add flow's own lookup, so "sign in again" can prefill it.
+    val addAccountViewModel: AddAccountViewModel = hiltViewModel()
+    val signInAgain: (AccountEntity) -> Unit = { account ->
+        addAccountViewModel.startReauthentication(account.id, account.principalUrl, account.username)
+        onSection(SettingsSection.AddAccount)
+    }
+    // Which account the detail screen is showing; the section alone cannot say.
+    var openAccount by rememberSaveable(initialAccountId) { mutableStateOf(initialAccountId) }
+
+    // Accounts stays composed under Add account, for the same reason Backup
+    // stays composed under export and import: the deeper screen slides over it.
+    val accountsOpen = section == SettingsSection.Accounts ||
+        section?.parent == SettingsSection.Accounts
+    SlideInSection(visible = accountsOpen) {
+        AccountsScreen(
+            onAddAccount = {
+                // A sign-in abandoned half-way must not turn this into one.
+                if (addAccountViewModel.state.value.reauthenticating) addAccountViewModel.onStartOver()
+                onSection(SettingsSection.AddAccount)
+            },
+            onSignInAgain = signInAgain,
+            onOpenAccount = {
+                openAccount = it
+                onSection(SettingsSection.Account)
+            },
+            onOpenStorage = { onSection(SettingsSection.Storage) },
+            onBack = { onSection(null) },
+            viewModel = accountsViewModel,
+            visible = accountsOpen,
+        )
+    }
+    val accountOpen = section == SettingsSection.Account
+    SlideInSection(visible = accountOpen) {
+        openAccount?.let { id ->
+            AccountDetailScreen(
+                accountId = id,
+                onBack = { onSection(SettingsSection.Accounts) },
+                onRemoved = { onSection(SettingsSection.Accounts) },
+                onSignInAgain = signInAgain,
+                onOpenStorage = { onSection(SettingsSection.Storage) },
+                viewModel = accountsViewModel,
+                visible = accountOpen,
+            )
+        }
+    }
+    SlideInSection(visible = section == SettingsSection.AddAccount) {
+        AddAccountScreen(
+            // The list stays composed underneath, so nothing re-runs its
+            // init and OnResume never fires on a section change. It no longer
+            // needs to: the accounts come from an observed query, so a new
+            // account — and every later sync — arrives on its own.
+            onDone = { onSection(SettingsSection.Accounts) },
+            onBack = { onSection(SettingsSection.Accounts) },
+            viewModel = addAccountViewModel,
+        )
+    }
+}

app/src/main/AndroidManifest.xml

@@ -9,35 +9,25 @@
          selected External mode. Both are dangerous-level.
 
          StorageMode.OWN needs nothing here: it is a Room database in our own data
-         directory. Agendula publishes no ContentProvider and declares no
-         permissions of its own. -->
+         directory. -->
     <uses-permission android:name="org.dmfs.permission.READ_TASKS" />
     <uses-permission android:name="org.dmfs.permission.WRITE_TASKS" />
     <uses-permission android:name="org.tasks.permission.READ_TASKS" />
     <uses-permission android:name="org.tasks.permission.WRITE_TASKS" />
 
-    <!-- CalDAV sync. ACCESS_NETWORK_STATE is merged in by work-runtime anyway,
-         but it shows in F-Droid's permission diff, so declare it deliberately
-         rather than letting it appear from nowhere.
-
-         READ_SYNC_SETTINGS / WRITE_SYNC_SETTINGS are what the ContentResolver
-         sync APIs need. No FOREGROUND_SERVICE: sync is a plain worker, and the
-         dataSync FGS type would bring the Android 15 six-hours-per-24 budget
-         (whose failure mode is a fatal RemoteServiceException) and a Play
-         requirement for a video demo.
-
-         Two more permissions appear in the merged manifest without being
-         declared here, and both come from work-runtime: WAKE_LOCK, and
-         FOREGROUND_SERVICE. The latter is not us taking the FGS route — below
-         API 31 WorkManager implements expedited work with a foreground service,
-         and minSdk is 29, so it is load-bearing for the "Sync now" button.
-         Removing it with tools:node="remove" would break expedited work on
-         exactly the older devices that need it most. Noted because it shows in
-         F-Droid's permission diff and would otherwise look unexplained. -->
-    <uses-permission android:name="android.permission.INTERNET" />
-    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
-    <uses-permission android:name="android.permission.READ_SYNC_SETTINGS" />
-    <uses-permission android:name="android.permission.WRITE_SYNC_SETTINGS" />
+    <!-- What another app requests to read or write the own store through
+         AgendulaTaskProvider. Dangerous, like OpenTasks' own: the user grants
+         them per app. Suffixed per build, so debug and release can coexist. -->
+    <permission
+        android:name="${applicationId}.permission.READ_TASKS"
+        android:description="@string/permission_read_tasks_description"
+        android:label="@string/permission_read_tasks_label"
+        android:protectionLevel="dangerous" />
+    <permission
+        android:name="${applicationId}.permission.WRITE_TASKS"
+        android:description="@string/permission_write_tasks_description"
+        android:label="@string/permission_write_tasks_label"
+        android:protectionLevel="dangerous" />
 
     <uses-permission android:name="android.permission.POST_NOTIFICATIONS" />
     <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
@@ -55,23 +45,17 @@
             <action android:name="android.intent.action.MAIN" />
             <category android:name="android.intent.category.LAUNCHER" />
         </intent>
-        <!-- Custom Tabs provider detection. Without this entry it silently finds
-             nothing on API 30+, and the Nextcloud login flow falls back to an
-             external browser for no visible reason. -->
-        <intent>
-            <action android:name="android.support.customtabs.action.CustomTabsService" />
-        </intent>
     </queries>
 
     <application
         android:name=".AgendulaApp"
         android:allowBackup="true"
+        android:enableOnBackInvokedCallback="true"
         android:dataExtractionRules="@xml/data_extraction_rules"
         android:fullBackupContent="@xml/backup_rules"
         android:icon="@mipmap/ic_launcher"
         android:label="@string/app_name"
         android:localeConfig="@xml/locales_config"
-        android:networkSecurityConfig="@xml/network_security_config"
         android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
         android:theme="@style/Theme.Agendula"
@@ -185,6 +169,58 @@
                 android:resource="@xml/appwidget_info_tasks" />
         </receiver>
 
+        <!-- "Today" home-screen widget (Glance): a progress ring for today's tasks. -->
+        <receiver
+            android:name=".widget.TodayWidgetReceiver"
+            android:label="@string/widget_today_label"
+            android:exported="true">
+            <intent-filter>
+                <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
+            </intent-filter>
+            <meta-data
+                android:name="android.appwidget.provider"
+                android:resource="@xml/appwidget_info_today" />
+        </receiver>
+
+        <!-- "Up next" home-screen widget (Glance): the single nearest due task. -->
+        <receiver
+            android:name=".widget.UpNextWidgetReceiver"
+            android:label="@string/widget_up_next_label"
+            android:exported="true">
+            <intent-filter>
+                <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
+            </intent-filter>
+            <meta-data
+                android:name="android.appwidget.provider"
+                android:resource="@xml/appwidget_info_up_next" />
+        </receiver>
+
+        <!-- "Lists" home-screen widget (Glance): one shortcut tile per list. -->
+        <receiver
+            android:name=".widget.ListsWidgetReceiver"
+            android:label="@string/widget_lists_label"
+            android:exported="true">
+            <intent-filter>
+                <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
+            </intent-filter>
+            <meta-data
+                android:name="android.appwidget.provider"
+                android:resource="@xml/appwidget_info_lists" />
+        </receiver>
+
+        <!-- "Week" home-screen widget (Glance): a seven-day strip of task counts. -->
+        <receiver
+            android:name=".widget.WeekWidgetReceiver"
+            android:label="@string/widget_week_label"
+            android:exported="true">
+            <intent-filter>
+                <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
+            </intent-filter>
+            <meta-data
+                android:name="android.appwidget.provider"
+                android:resource="@xml/appwidget_info_week" />
+        </receiver>
+
         <!-- Per-widget list picker, launched by the host on placement / reconfigure. -->
         <activity
             android:name=".widget.TaskWidgetConfigActivity"
@@ -211,53 +247,15 @@
             </intent-filter>
         </receiver>
 
-        <!-- Sync plumbing. The stub provider exists only to give the sync
-             adapter an authority to register against: Agendula publishes no real
-             ContentProvider since :provider was deleted, and without an authority
-             ContentService.hasAuthorityAccess() makes every ContentResolver sync
-             call a silent no-op at targetSdk >= 34. -->
+        <!-- The own store under the OpenTasks contract. Empty, and refusing
+             writes, while External mode is active. -->
         <provider
-            android:name=".data.sync.SyncStubProvider"
-            android:authorities="${applicationId}.sync"
-            android:exported="false"
-            android:syncable="true" />
-
-        <!-- Exported and guarded by ACCOUNT_MANAGER. Note that
-             android.permission.ACCOUNT_AUTHENTICATOR does not exist. -->
-        <service
-            android:name=".data.sync.AuthenticatorService"
+            android:name=".data.tasks.provider.AgendulaTaskProvider"
+            android:authorities="${applicationId}.tasks"
             android:exported="true"
-            android:permission="android.permission.ACCOUNT_MANAGER">
-            <intent-filter>
-                <action android:name="android.accounts.AccountAuthenticator" />
-            </intent-filter>
-            <meta-data
-                android:name="android.accounts.AccountAuthenticator"
-                android:resource="@xml/authenticator" />
-        </service>
-
-        <service
-            android:name=".data.sync.SyncAdapterService"
-            android:exported="true"
-            android:permission="android.permission.BIND_SYNC_ADAPTER">
-            <intent-filter>
-                <action android:name="android.content.SyncAdapter" />
-            </intent-filter>
-            <meta-data
-                android:name="android.content.SyncAdapter"
-                android:resource="@xml/sync_adapter" />
-        </service>
-
-        <!-- UnifiedPush: the connector binds this to deliver endpoints and
-             WebDAV-Push messages. Not exported; the connector's own receiver is
-             what distributors talk to. -->
-        <service
-            android:name=".data.sync.push.AgendulaPushService"
-            android:exported="false">
-            <intent-filter>
-                <action android:name="org.unifiedpush.android.connector.PUSH_EVENT" />
-            </intent-filter>
-        </service>
+            android:readPermission="${applicationId}.permission.READ_TASKS"
+            android:writePermission="${applicationId}.permission.WRITE_TASKS"
+            tools:ignore="SystemPermissionTypo" />
 
         <!-- WorkManager's on-demand initialisation. Removing the default
              initializer is what lets AgendulaApp supply a HiltWorkerFactory, so

app/src/main/java/de/jeanlucmakiola/agendula/AgendulaApp.kt

@@ -10,12 +10,13 @@ import dagger.hilt.android.EntryPointAccessors
 import dagger.hilt.android.HiltAndroidApp
 import dagger.hilt.components.SingletonComponent
 import de.jeanlucmakiola.agendula.data.di.ApplicationScope
+import de.jeanlucmakiola.agendula.data.di.ChannelRefresher
 import de.jeanlucmakiola.agendula.data.reminders.ReminderMaintenanceWorker
 import de.jeanlucmakiola.agendula.data.reminders.ReminderScheduler
 import de.jeanlucmakiola.agendula.data.reminders.TaskNotifier
-import de.jeanlucmakiola.agendula.data.sync.SyncNoticeNotifier
 import de.jeanlucmakiola.agendula.data.tasks.ProviderResolver
 import de.jeanlucmakiola.agendula.data.tasks.StartupGate
+import de.jeanlucmakiola.agendula.data.tasks.provider.ProviderSnapshotSource
 import de.jeanlucmakiola.agendula.data.tasks.room.DatabaseCheckpoint
 import de.jeanlucmakiola.agendula.widget.TaskWidgetUpdater
 import de.jeanlucmakiola.floret.crash.CrashConfig
@@ -87,6 +88,7 @@ class AgendulaApp : Application(), Configuration.Provider {
                 scheduler.sync()
             }
             runCatching { entryPoint.taskWidgetUpdater().start() }
+            runCatching { entryPoint.providerSnapshotSource().start() }
             runCatching { ReminderMaintenanceWorker.schedule(this@AgendulaApp) }
         }
     }
@@ -105,7 +107,7 @@ class AgendulaApp : Application(), Configuration.Provider {
         val entryPoint = EntryPointAccessors.fromApplication(this, AppEntryPoint::class.java)
         runCatching {
             entryPoint.taskNotifier().refreshChannel()
-            entryPoint.syncNoticeNotifier().refreshChannel()
+            entryPoint.channelRefreshers().forEach { it.refreshChannel() }
         }
     }
 
@@ -120,7 +122,8 @@ class AgendulaApp : Application(), Configuration.Provider {
         fun applicationScope(): CoroutineScope
         fun databaseCheckpoint(): DatabaseCheckpoint
         fun taskNotifier(): TaskNotifier
-        fun syncNoticeNotifier(): SyncNoticeNotifier
+        fun channelRefreshers(): Set<@JvmSuppressWildcards ChannelRefresher>
         fun taskWidgetUpdater(): TaskWidgetUpdater
+        fun providerSnapshotSource(): ProviderSnapshotSource
     }
 }

app/src/main/java/de/jeanlucmakiola/agendula/MainActivity.kt

@@ -25,7 +25,6 @@ import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import androidx.lifecycle.lifecycleScope
 import dagger.hilt.android.AndroidEntryPoint
 import de.jeanlucmakiola.agendula.data.di.LaunchHook
-import de.jeanlucmakiola.agendula.data.sync.SyncNoticeNotifier
 import de.jeanlucmakiola.agendula.domain.SmartList
 import de.jeanlucmakiola.agendula.ui.imports.importIntentUri
 import de.jeanlucmakiola.agendula.ui.navigation.AppShortcuts
@@ -33,10 +32,6 @@ import de.jeanlucmakiola.agendula.data.prefs.ThemeMode
 import de.jeanlucmakiola.agendula.ui.RootScreen
 import de.jeanlucmakiola.agendula.ui.crash.CrashReportActivity
 import de.jeanlucmakiola.agendula.ui.navigation.NavRequest
-import de.jeanlucmakiola.agendula.data.sync.AccountRepository
-import de.jeanlucmakiola.agendula.data.sync.PendingLoginFlowStore
-import de.jeanlucmakiola.agendula.data.sync.SyncTrigger
-import de.jeanlucmakiola.agendula.data.sync.push.PushRegistrar
 import de.jeanlucmakiola.agendula.ui.settings.SettingsViewModel
 import de.jeanlucmakiola.agendula.ui.theme.AgendulaTheme
 import de.jeanlucmakiola.floret.crash.CrashReportDialog
@@ -55,14 +50,6 @@ class MainActivity : ComponentActivity() {
 
     @Inject lateinit var launchHooks: Set<@JvmSuppressWildcards LaunchHook>
 
-    @Inject lateinit var accounts: AccountRepository
-
-    @Inject lateinit var syncTrigger: SyncTrigger
-
-    @Inject lateinit var pendingLoginFlows: PendingLoginFlowStore
-
-    @Inject lateinit var push: PushRegistrar
-
     // A captured crash report awaiting the user's decision, surfaced as a dialog
     // over the app on the next launch (the single-crash path). A startup
     // crash-loop is handled out of band, before setContent — see below.
@@ -94,34 +81,9 @@ class MainActivity : ComponentActivity() {
         // Surface a single captured crash as a dialog on the next launch.
         if (CrashReporter.shouldPrompt(this)) pendingCrashReport = CrashReporter.pendingReport(this)
 
-        // Sync hard on app open: the periodic worker's interval is a floor, and
-        // in the `rare` and `restricted` App Standby buckets it may not have run
-        // at all. `KEEP` makes rescheduling idempotent, so this also repairs a
-        // schedule lost to "clear app data" or to a restore.
-        //
-        // ⚠️ Only on a genuine open. This activity declares no `configChanges`,
-        // so onCreate runs again on every rotation, theme switch, locale change
-        // and font-scale change — each of which would otherwise start a fresh
-        // network sync the moment the previous one finished.
+        // Each hook on its own, so one waiting on the network holds up no other.
         if (savedInstanceState == null) {
-            lifecycleScope.launch {
-                runCatching {
-                    accounts.rescheduleAll()
-                    accounts.syncable().forEach { syncTrigger.enqueue(it.displayName) }
-                    // A login flow the previous process died in the middle of.
-                    // Its password, if the user approved, exists nowhere else.
-                    pendingLoginFlows.reclaim()
-                }
-                // Last and on its own: it waits on the network, and must not
-                // hold up the reclaim above. Re-registering on open is what
-                // the connector recommends.
-                runCatching { push.updateAll() }
-            }
-        }
-
-        // Variant hooks: the demo seeder in debug builds, nothing in release.
-        if (savedInstanceState == null) {
-            lifecycleScope.launch { launchHooks.forEach { runCatching { it.onLaunch(intent) } } }
+            launchHooks.forEach { hook -> lifecycleScope.launch { runCatching { hook.onLaunch(intent) } } }
         }
         setContent {
             val settingsViewModel: SettingsViewModel = hiltViewModel()
@@ -180,12 +142,18 @@ class MainActivity : ComponentActivity() {
         const val EXTRA_TASK_ID = "de.jeanlucmakiola.agendula.extra.TASK_ID"
         const val EXTRA_OCCURRENCE_START = "de.jeanlucmakiola.agendula.extra.OCCURRENCE_START"
         private const val EXTRA_OPEN_ACCOUNTS = "de.jeanlucmakiola.agendula.extra.OPEN_ACCOUNTS"
+
+        /** The account a sign-in notification is about, on the intent it opens. */
+        const val EXTRA_SIGN_IN_ACCOUNT_ID = "de.jeanlucmakiola.agendula.extra.SIGN_IN_ACCOUNT_ID"
         const val ACTION_NEW_TASK = "de.jeanlucmakiola.agendula.action.NEW_TASK"
         const val ACTION_TODAY = "de.jeanlucmakiola.agendula.action.TODAY"
         private const val ACTION_OPEN_SMART = "de.jeanlucmakiola.agendula.action.OPEN_SMART"
         private const val ACTION_OPEN_LIST = "de.jeanlucmakiola.agendula.action.OPEN_LIST"
+        private const val ACTION_OPEN_FILTER = "de.jeanlucmakiola.agendula.action.OPEN_FILTER"
+        private const val EXTRA_FILTER_ID = "de.jeanlucmakiola.agendula.extra.FILTER_ID"
         private const val EXTRA_SMART_LIST = "de.jeanlucmakiola.agendula.extra.SMART_LIST"
         private const val EXTRA_LIST_ID = "de.jeanlucmakiola.agendula.extra.LIST_ID"
+        private const val EXTRA_PRESET_LIST_ID = "de.jeanlucmakiola.agendula.extra.PRESET_LIST_ID"
         private const val SHARED_TITLE_LIMIT = 500
         private const val NO_OCCURRENCE = -1L
 
@@ -206,9 +174,14 @@ class MainActivity : ComponentActivity() {
                 .putExtra(EXTRA_OPEN_ACCOUNTS, true)
                 .addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
 
-        /** The launcher shortcut's and Quick Settings tile's "New task". */
-        fun newTaskIntent(context: Context): Intent =
-            Intent(ACTION_NEW_TASK, null, context, MainActivity::class.java)
+        /**
+         * The launcher shortcut's, Quick Settings tile's and a widget's "New
+         * task". [listId] preset the list when it names exactly one; the data
+         * URI keeps each widget's PendingIntent apart from the others.
+         */
+        fun newTaskIntent(context: Context, listId: Long? = null): Intent =
+            Intent(ACTION_NEW_TASK, listId?.let { "agendula://newtask/$it".toUri() }, context, MainActivity::class.java)
+                .putExtra(EXTRA_PRESET_LIST_ID, listId ?: -1L)
                 .addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
 
         fun todayIntent(context: Context): Intent =
@@ -227,19 +200,31 @@ class MainActivity : ComponentActivity() {
                 .putExtra(EXTRA_LIST_ID, listId)
                 .addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
 
+        /** Opens one saved filter. */
+        fun filterIntent(context: Context, filterId: Long): Intent =
+            Intent(ACTION_OPEN_FILTER, "agendula://filter/$filterId".toUri(), context, MainActivity::class.java)
+                .putExtra(EXTRA_FILTER_ID, filterId)
+                .addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
+
         internal fun navRequestOf(intent: Intent?): NavRequest? {
             if (intent == null) return null
-            intent.getLongExtra(SyncNoticeNotifier.EXTRA_SIGN_IN_ACCOUNT_ID, -1L).takeIf { it > 0L }
-                ?.let { return NavRequest.OpenAccount(it) }
-            if (intent.getBooleanExtra(EXTRA_OPEN_ACCOUNTS, false)) return NavRequest.OpenAccounts
+            if (BuildConfig.SYNC_ENABLED) {
+                intent.getLongExtra(EXTRA_SIGN_IN_ACCOUNT_ID, -1L).takeIf { it > 0L }
+                    ?.let { return NavRequest.OpenAccount(it) }
+                if (intent.getBooleanExtra(EXTRA_OPEN_ACCOUNTS, false)) return NavRequest.OpenAccounts
+            }
             when (intent.action) {
-                ACTION_NEW_TASK -> return NavRequest.NewTask()
+                ACTION_NEW_TASK -> return NavRequest.NewTask(
+                    listId = intent.getLongExtra(EXTRA_PRESET_LIST_ID, -1L).takeIf { it > 0L },
+                )
                 ACTION_TODAY -> return NavRequest.OpenSmart(SmartList.TODAY)
                 ACTION_OPEN_SMART -> intent.getStringExtra(EXTRA_SMART_LIST)
                     ?.let { name -> SmartList.entries.firstOrNull { it.name == name } }
                     ?.let { return NavRequest.OpenSmart(it) }
                 ACTION_OPEN_LIST -> intent.getLongExtra(EXTRA_LIST_ID, -1L).takeIf { it > 0L }
                     ?.let { return NavRequest.OpenList(it) }
+                ACTION_OPEN_FILTER -> intent.getLongExtra(EXTRA_FILTER_ID, -1L).takeIf { it > 0L }
+                    ?.let { return NavRequest.OpenFilter(it) }
             }
             importIntentUri(intent)?.let { return NavRequest.Import(it) }
             if (intent.action == Intent.ACTION_SEND && intent.type?.startsWith("text/plain") == true) {

app/src/main/java/de/jeanlucmakiola/agendula/data/di/ChannelRefresher.kt

@@ -0,0 +1,22 @@
+package de.jeanlucmakiola.agendula.data.di
+
+import dagger.Module
+import dagger.hilt.InstallIn
+import dagger.hilt.components.SingletonComponent
+import dagger.multibindings.Multibinds
+
+/**
+ * A notification channel a build variant adds, re-created in the current
+ * language on start and on a configuration change. The `full` flavor
+ * contributes the sync notices; `offline` has none.
+ */
+fun interface ChannelRefresher {
+    fun refreshChannel()
+}
+
+@Module
+@InstallIn(SingletonComponent::class)
+abstract class ChannelRefresherModule {
+    @Multibinds
+    abstract fun channelRefreshers(): Set<ChannelRefresher>
+}

app/src/main/java/de/jeanlucmakiola/agendula/data/di/DataModule.kt

@@ -12,13 +12,6 @@ import dagger.Provides
 import dagger.hilt.InstallIn
 import dagger.hilt.android.qualifiers.ApplicationContext
 import dagger.hilt.components.SingletonComponent
-import de.jeanlucmakiola.agendula.data.sync.AccountCreator
-import de.jeanlucmakiola.agendula.data.sync.AccountRepository
-import de.jeanlucmakiola.agendula.data.sync.CalDavGateway
-import de.jeanlucmakiola.agendula.data.sync.LoginFlowRecord
-import de.jeanlucmakiola.agendula.data.sync.PendingLoginFlowStore
-import de.jeanlucmakiola.agendula.data.sync.SyncOnEdit
-import de.jeanlucmakiola.agendula.data.sync.OkHttpCalDavGateway
 import de.jeanlucmakiola.agendula.data.tasks.AndroidProviderEnvironment
 import de.jeanlucmakiola.agendula.data.tasks.AndroidTasksDataSource
 import de.jeanlucmakiola.agendula.data.tasks.ModeRoutingTasksDataSource
@@ -27,7 +20,6 @@ import de.jeanlucmakiola.agendula.data.tasks.ProviderResolver
 import de.jeanlucmakiola.agendula.data.tasks.TasksDataSource
 import de.jeanlucmakiola.agendula.data.tasks.TasksRepository
 import de.jeanlucmakiola.agendula.data.tasks.TasksRepositoryImpl
-import de.jeanlucmakiola.agendula.data.tasks.room.LocalWriteListener
 import de.jeanlucmakiola.agendula.data.tasks.room.RoomTasksDataSource
 import de.jeanlucmakiola.agendula.data.tasks.room.TasksDatabase
 import androidx.datastore.core.handlers.ReplaceFileCorruptionHandler
@@ -51,37 +43,13 @@ import javax.inject.Singleton
  * reconciled", and the credential store to accounts that ask to be signed in
  * again — all states the app already knows how to be in, unlike a launch loop.
  */
-private fun replaceCorrupted() = ReplaceFileCorruptionHandler { emptyPreferences() }
+internal fun replaceCorrupted() = ReplaceFileCorruptionHandler { emptyPreferences() }
 
 private val Context.agendulaDataStore: DataStore<Preferences> by preferencesDataStore(
     name = "agendula_prefs",
     corruptionHandler = replaceCorrupted(),
 )
 
-/** See [CredentialsDataStore] for why this is a separate file. */
-private val Context.credentialsDataStore: DataStore<Preferences> by preferencesDataStore(
-    name = CREDENTIALS_DATASTORE,
-    corruptionHandler = replaceCorrupted(),
-)
-
-/** See [SyncStateDataStore] for why this is a separate file. */
-private val Context.syncStateDataStore: DataStore<Preferences> by preferencesDataStore(
-    name = SYNC_STATE_DATASTORE,
-    corruptionHandler = replaceCorrupted(),
-)
-
-/**
- * Named here and in `backup_rules.xml` / `data_extraction_rules.xml`, which
- * exclude `datastore/$CREDENTIALS_DATASTORE.preferences_pb` by this name.
- */
-const val CREDENTIALS_DATASTORE = "agendula_credentials"
-
-/**
- * Named here and in `backup_rules.xml` / `data_extraction_rules.xml`, which
- * exclude `datastore/$SYNC_STATE_DATASTORE.preferences_pb` by this name.
- */
-const val SYNC_STATE_DATASTORE = "agendula_sync_state"
-
 @Module
 @InstallIn(SingletonComponent::class)
 abstract class DataBindModule {
@@ -94,22 +62,6 @@ abstract class DataBindModule {
     @Singleton
     abstract fun bindProviderEnvironment(impl: AndroidProviderEnvironment): ProviderEnvironment
 
-    @Binds
-    @Singleton
-    abstract fun bindCalDavGateway(impl: OkHttpCalDavGateway): CalDavGateway
-
-    @Binds
-    @Singleton
-    abstract fun bindAccountCreator(impl: AccountRepository): AccountCreator
-
-    @Binds
-    @Singleton
-    abstract fun bindLoginFlowRecord(impl: PendingLoginFlowStore): LoginFlowRecord
-
-    @Binds
-    @Singleton
-    abstract fun bindLocalWriteListener(impl: SyncOnEdit): LocalWriteListener
-
     // Deliberately unqualified-free of the routing above: this is the external
     // store itself, for the one caller that has to read it while another store is
     // the active one.
@@ -128,18 +80,6 @@ object DataProvideModule {
     fun provideDataStore(@ApplicationContext context: Context): DataStore<Preferences> =
         context.agendulaDataStore
 
-    @Provides
-    @Singleton
-    @CredentialsDataStore
-    fun provideCredentialsDataStore(@ApplicationContext context: Context): DataStore<Preferences> =
-        context.credentialsDataStore
-
-    @Provides
-    @Singleton
-    @SyncStateDataStore
-    fun provideSyncStateDataStore(@ApplicationContext context: Context): DataStore<Preferences> =
-        context.syncStateDataStore
-
     @Provides
     @Singleton
     fun provideTasksDatabase(@ApplicationContext context: Context): TasksDatabase =
@@ -149,6 +89,7 @@ object DataProvideModule {
             // backed-up `.db` does not. The backup rules carry all three files and
             // the app checkpoints on ON_STOP.
             .setJournalMode(RoomDatabase.JournalMode.WRITE_AHEAD_LOGGING)
+            .addMigrations(TasksDatabase.MIGRATION_1_2, TasksDatabase.MIGRATION_2_3)
             .build()
 
     /**

app/src/main/java/de/jeanlucmakiola/agendula/data/di/LaunchHook.kt

@@ -7,9 +7,8 @@ import dagger.hilt.components.SingletonComponent
 import dagger.multibindings.Multibinds
 
 /**
- * Something a build variant wants to run when the app is launched with [Intent].
- * Release builds contribute none; the debug source set adds the demo seeder, so
- * that class never ships.
+ * Something a build variant runs on a genuine app open (not on a configuration
+ * change): sync in the `full` flavor, the demo seeder in debug builds.
  */
 fun interface LaunchHook {
     suspend fun onLaunch(intent: Intent)

app/src/main/java/de/jeanlucmakiola/agendula/data/di/Qualifiers.kt

@@ -17,37 +17,6 @@ annotation class IoDispatcher
 @Retention(AnnotationRetention.BINARY)
 annotation class ApplicationScope
 
-/**
- * Marks the DataStore holding **only** the Keystore-encrypted app passwords.
- *
- * A separate file from `agendula_prefs` on purpose: Auto Backup includes
- * `datastore/`, and a restored ciphertext is permanently undecryptable because
- * Keystore keys are non-exportable. Its own file is what lets the backup rules
- * exclude the credentials and nothing else — excluding the whole database or
- * all of DataStore would trade a latent bug for a live one.
- */
-@Qualifier
-@Retention(AnnotationRetention.BINARY)
-annotation class CredentialsDataStore
-
-/**
- * Marks the DataStore holding per-device **sync bookkeeping** — the quarantine
- * counters and the full-reconciliation clock.
- *
- * Its own file for the same reason the credentials have one: Auto Backup
- * includes `datastore/`, and every value in here is a statement about *this*
- * device's conversation with a server. Restored onto a new install they are all
- * lies, and two of them are dangerous — a restored "reconciled recently" makes
- * the engine trust a sync token for another day, which is precisely the silently
- * pruned change log the full path exists to catch, and a restored quarantine
- * count silently skips resources that were never tried here.
- *
- * Not user data, so nothing is lost by excluding it.
- */
-@Qualifier
-@Retention(AnnotationRetention.BINARY)
-annotation class SyncStateDataStore
-
 /**
  * Marks the **external** provider's [de.jeanlucmakiola.agendula.data.tasks
  * .TasksDataSource] — the OpenTasks/tasks.org path specifically, rather than

app/src/main/java/de/jeanlucmakiola/agendula/data/prefs/SavedFilterCodec.kt

@@ -0,0 +1,83 @@
+package de.jeanlucmakiola.agendula.data.prefs
+
+import de.jeanlucmakiola.agendula.domain.DueWindow
+import de.jeanlucmakiola.agendula.domain.Priority
+import de.jeanlucmakiola.agendula.domain.SavedFilter
+import de.jeanlucmakiola.agendula.domain.TagMatch
+import java.net.URLDecoder
+import java.net.URLEncoder
+
+/**
+ * Stored form of the saved filters: one line per filter,
+ * `id|name|due|lists|tags|match|priority`, with name and tags URL-encoded and
+ * list ids qualified by the store they belong to (`OWN:3`), since each store
+ * numbers its lists on its own. Fixed once released — don't change without a
+ * data migration.
+ */
+internal object SavedFilterCodec {
+
+    /** The filters in [raw], with only the list ids of [mode]'s store. */
+    fun decode(raw: String?, mode: String): List<SavedFilter> =
+        lines(raw).mapNotNull { runCatching { decodeLine(it, mode) }.getOrNull() }
+
+    /** [raw] with [filter] replacing the line of the same id, or appended. */
+    fun upsert(raw: String?, filter: SavedFilter, mode: String): String {
+        val existing = lines(raw)
+        val index = existing.indexOfFirst { idOf(it) == filter.id }
+        // Keep the lists another store contributed, so switching stores and back
+        // doesn't widen a filter that was edited in between, unless "any list"
+        // was chosen here, which drops them on purpose.
+        val foreign = if (filter.anyList) {
+            emptyList()
+        } else {
+            existing.getOrNull(index)?.let(::fields)?.getOrNull(3)
+                ?.let(::splitList)?.filterNot { it.startsWith("$mode:") }.orEmpty()
+        }
+        val line = encodeLine(filter, mode, foreign)
+        val updated = if (index >= 0) existing.toMutableList().also { it[index] = line } else existing + line
+        return updated.joinToString("\n")
+    }
+
+    fun remove(raw: String?, id: Long): String = lines(raw).filterNot { idOf(it) == id }.joinToString("\n")
+
+    private fun lines(raw: String?): List<String> = raw.orEmpty().split('\n').filter { it.isNotBlank() }
+
+    private fun fields(line: String): List<String> = line.split('|')
+
+    private fun idOf(line: String): Long? = fields(line).firstOrNull()?.toLongOrNull()
+
+    private fun splitList(value: String): List<String> = value.split(',').filter { it.isNotEmpty() }
+
+    private fun encodeLine(filter: SavedFilter, mode: String, foreignLists: List<String>): String =
+        listOf(
+            filter.id.toString(),
+            encode(filter.name),
+            filter.due.sorted().joinToString(",") { it.name },
+            (filter.listIds.sorted().map { "$mode:$it" } + foreignLists).joinToString(","),
+            filter.tags.sorted().joinToString(",") { encode(it) },
+            filter.tagMatch.name,
+            filter.minPriority.name,
+        ).joinToString("|")
+
+    private fun decodeLine(line: String, mode: String): SavedFilter? {
+        val f = fields(line)
+        if (f.size < 7) return null
+        val id = f[0].toLongOrNull() ?: return null
+        val lists = splitList(f[3])
+        val here = lists.filter { it.startsWith("$mode:") }.mapNotNull { it.removePrefix("$mode:").toLongOrNull() }.toSet()
+        return SavedFilter(
+            id = id,
+            name = decode(f[1]),
+            due = splitList(f[2]).mapNotNull { runCatching { DueWindow.valueOf(it) }.getOrNull() }.toSet(),
+            listIds = here,
+            listsElsewhere = lists.any { !it.startsWith("$mode:") },
+            tags = splitList(f[4]).map(::decode).toSet(),
+            tagMatch = runCatching { TagMatch.valueOf(f[5]) }.getOrDefault(TagMatch.ANY),
+            minPriority = runCatching { Priority.valueOf(f[6]) }.getOrDefault(Priority.NONE),
+        )
+    }
+
+    private fun encode(value: String): String = URLEncoder.encode(value, Charsets.UTF_8.name())
+
+    private fun decode(value: String): String = URLDecoder.decode(value, Charsets.UTF_8.name())
+}

app/src/main/java/de/jeanlucmakiola/agendula/data/prefs/SettingsPrefs.kt

@@ -10,16 +10,22 @@ import androidx.datastore.preferences.core.stringPreferencesKey
 import androidx.datastore.preferences.core.stringSetPreferencesKey
 import de.jeanlucmakiola.agendula.data.tasks.ProviderResolver
 import de.jeanlucmakiola.agendula.data.tasks.StorageMode
+import de.jeanlucmakiola.agendula.domain.SavedFilter
 import de.jeanlucmakiola.agendula.domain.Task
 import de.jeanlucmakiola.agendula.domain.TaskFilter
 import de.jeanlucmakiola.agendula.domain.TaskFormField
+import de.jeanlucmakiola.agendula.domain.TaskReminder
+import de.jeanlucmakiola.agendula.domain.asTaskReminder
+import de.jeanlucmakiola.agendula.domain.asReminderLead
 import de.jeanlucmakiola.agendula.domain.TaskSortOrder
+import de.jeanlucmakiola.floret.reminders.ReminderLead
 import de.jeanlucmakiola.floret.reminders.ReminderOverride
 import de.jeanlucmakiola.floret.reminders.ReminderOverrideCodec
 import de.jeanlucmakiola.floret.reminders.applyReminderOverride
 import de.jeanlucmakiola.floret.reminders.normalizeReminders
 import de.jeanlucmakiola.floret.reminders.reminderLeadsFor
 import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.distinctUntilChanged
 import java.time.DayOfWeek
 import kotlinx.coroutines.flow.map
 import javax.inject.Inject
@@ -55,10 +61,10 @@ data class Settings(
     val dynamicColor: Boolean = true,
     /** The list a new task defaults to; `null` = first available. */
     val defaultListId: Long? = null,
-    /** Default reminders, as minutes before due (0 = at due time); empty = none. */
-    val defaultReminderMinutes: List<Int> = listOf(0),
-    /** Default reminders for all-day tasks, as days-scale minutes before [allDayReminderMinuteOfDay]. */
-    val defaultAllDayReminderMinutes: List<Int> = listOf(0),
+    /** Default reminders (0 before due = at due time); empty = none. */
+    val defaultReminders: List<ReminderLead> = listOf(ReminderLead(0)),
+    /** Default reminders for all-day tasks, in whole days, rung at [allDayReminderMinuteOfDay]. */
+    val defaultAllDayReminders: List<ReminderLead> = listOf(ReminderLead(0)),
     /** Local time (minutes from midnight) an all-day task's reminder counts back from. */
     val allDayReminderMinuteOfDay: Int = DEFAULT_ALL_DAY_REMINDER_MINUTE,
     /** Master switch for due reminders; off clears every scheduled alarm. */
@@ -72,13 +78,13 @@ data class Settings(
      */
     val bottomAddBar: Boolean = false,
     /**
-     * Per-list overrides of [defaultReminderMinutes]: a list present in the map
+     * Per-list overrides of [defaultReminders]: a list present in the map
      * overrides the global default (an empty list = no reminder); absent =
      * inherit.
      */
-    val perListReminderOverride: Map<Long, List<Int>> = emptyMap(),
-    /** Per-list overrides of [defaultAllDayReminderMinutes], same shape as [perListReminderOverride]. */
-    val perListAllDayReminderOverride: Map<Long, List<Int>> = emptyMap(),
+    val perListReminderOverride: Map<Long, List<ReminderLead>> = emptyMap(),
+    /** Per-list overrides of [defaultAllDayReminders], same shape as [perListReminderOverride]. */
+    val perListAllDayReminderOverride: Map<Long, List<ReminderLead>> = emptyMap(),
     /** Optional edit-form fields shown by default; the rest sit behind "More fields". */
     val defaultEditFields: Set<TaskFormField> = emptySet(),
     val sortOrder: TaskSortOrder = TaskSortOrder.DUE,
@@ -95,6 +101,8 @@ data class Settings(
     val pushEnabled: Boolean = true,
     /** Lists of the current store whose tasks the smart lists (and their counts) leave out. */
     val hiddenFromSmartLists: Set<Long> = emptySet(),
+    /** Pre-fill a new task's start with today's date. */
+    val defaultStartToday: Boolean = false,
 ) {
     /** [tasks] as [filter] shows them: a smart list drops the lists kept out of it. */
     fun visibleIn(filter: TaskFilter, tasks: List<Task>): List<Task> =
@@ -105,12 +113,16 @@ data class Settings(
         }
 
     /** The lead times for a task in [listId]: its override if set, else the global default. */
-    fun reminderLeadsFor(listId: Long): List<Int> =
-        perListReminderOverride.reminderLeadsFor(listId, defaultReminderMinutes)
+    fun reminderLeadsFor(listId: Long): List<ReminderLead> =
+        perListReminderOverride.reminderLeadsFor(listId, defaultReminders)
 
     /** The lead times for an all-day task in [listId]. */
-    fun allDayReminderLeadsFor(listId: Long): List<Int> =
-        perListAllDayReminderOverride.reminderLeadsFor(listId, defaultAllDayReminderMinutes)
+    fun allDayReminderLeadsFor(listId: Long): List<ReminderLead> =
+        perListAllDayReminderOverride.reminderLeadsFor(listId, defaultAllDayReminders)
+
+    /** The default reminders a task in [listId] takes — the one rule for which default applies. */
+    fun defaultRemindersFor(listId: Long, allDay: Boolean): List<TaskReminder> =
+        (if (allDay) allDayReminderLeadsFor(listId) else reminderLeadsFor(listId)).map { it.asTaskReminder() }
 }
 
 /** App preferences, backed by DataStore. Mirrors Calendula's prefs shape. */
@@ -126,16 +138,18 @@ class SettingsPrefs @Inject constructor(
             dynamicColor = p[DYNAMIC_COLOR] ?: true,
             defaultListId = p[DEFAULT_LIST_ID]?.takeIf { it > 0 },
             // The single lead of earlier versions carries over until a list is saved.
-            defaultReminderMinutes = p[DEFAULT_REMINDERS]?.let(::parseMinutes)
-                ?: listOf(p[REMINDER_LEAD] ?: 0),
-            defaultAllDayReminderMinutes = p[DEFAULT_ALL_DAY_REMINDERS]?.let(::parseMinutes) ?: listOf(0),
+            defaultReminders = p[DEFAULT_REMINDERS]?.let(::parseLeads)
+                ?: listOf(ReminderLead(p[REMINDER_LEAD] ?: 0)),
+            defaultAllDayReminders = p[DEFAULT_ALL_DAY_REMINDERS]?.let(::parseLeads)?.inWholeDays()
+                ?: listOf(ReminderLead(0)),
             allDayReminderMinuteOfDay = p[ALL_DAY_REMINDER_MINUTE]?.takeIf { it in 0 until 24 * 60 }
                 ?: DEFAULT_ALL_DAY_REMINDER_MINUTE,
             remindersEnabled = p[REMINDERS_ENABLED] ?: true,
             showAddSubtaskRow = p[SHOW_ADD_SUBTASK_ROW] ?: true,
             bottomAddBar = p[BOTTOM_ADD_BAR] ?: false,
-            perListReminderOverride = reminderCodec.parse(p[LIST_REMINDER_OVERRIDE]),
-            perListAllDayReminderOverride = reminderCodec.parse(p[LIST_ALL_DAY_REMINDER_OVERRIDE]),
+            perListReminderOverride = reminderCodec.parseLeads(p[LIST_REMINDER_OVERRIDE]),
+            perListAllDayReminderOverride = reminderCodec.parseLeads(p[LIST_ALL_DAY_REMINDER_OVERRIDE])
+                .mapValues { it.value.inWholeDays() },
             defaultEditFields = p[DEFAULT_EDIT_FIELDS].orEmpty()
                 .mapNotNull { name -> runCatching { TaskFormField.valueOf(name) }.getOrNull() }
                 .toSet(),
@@ -153,6 +167,7 @@ class SettingsPrefs @Inject constructor(
                     .mapNotNull { entry -> entry.substringAfter("$mode:", "").toLongOrNull() }
                     .toSet()
             },
+            defaultStartToday = p[DEFAULT_START_TODAY] ?: false,
         )
     }
 
@@ -166,6 +181,8 @@ class SettingsPrefs @Inject constructor(
 
     suspend fun setAutofocusTitle(enabled: Boolean) = dataStore.edit { it[AUTOFOCUS_TITLE] = enabled }
 
+    suspend fun setDefaultStartToday(enabled: Boolean) = dataStore.edit { it[DEFAULT_START_TODAY] = enabled }
+
     suspend fun setTimeFormat(pref: TimeFormatPref) = dataStore.edit { it[TIME_FORMAT] = pref.name }
 
     suspend fun setWeekStart(day: DayOfWeek?) = dataStore.edit {
@@ -178,12 +195,12 @@ class SettingsPrefs @Inject constructor(
         if (id == null) it.remove(DEFAULT_LIST_ID) else it[DEFAULT_LIST_ID] = id
     }
 
-    suspend fun setDefaultReminderMinutes(minutes: List<Int>) = dataStore.edit {
-        it[DEFAULT_REMINDERS] = minutes.normalizeReminders().joinToString(",")
+    suspend fun setDefaultReminders(leads: List<ReminderLead>) = dataStore.edit {
+        it[DEFAULT_REMINDERS] = leads.normalizeReminders().joinToString(",") { lead -> lead.toToken() }
     }
 
-    suspend fun setDefaultAllDayReminderMinutes(minutes: List<Int>) = dataStore.edit {
-        it[DEFAULT_ALL_DAY_REMINDERS] = minutes.normalizeReminders().joinToString(",")
+    suspend fun setDefaultAllDayReminders(leads: List<ReminderLead>) = dataStore.edit {
+        it[DEFAULT_ALL_DAY_REMINDERS] = leads.normalizeReminders().joinToString(",") { lead -> lead.toToken() }
     }
 
     suspend fun setAllDayReminderMinuteOfDay(minuteOfDay: Int) =
@@ -236,16 +253,16 @@ class SettingsPrefs @Inject constructor(
 
     /** Set (or clear, via [ReminderOverride.Inherit]) a list's reminder override. */
     suspend fun setListReminderOverride(listId: Long, override: ReminderOverride) = dataStore.edit { p ->
-        val current = reminderCodec.parse(p[LIST_REMINDER_OVERRIDE]).toMutableMap()
+        val current = reminderCodec.parseLeads(p[LIST_REMINDER_OVERRIDE]).toMutableMap()
         current.applyReminderOverride(listId, override)
-        p[LIST_REMINDER_OVERRIDE] = reminderCodec.serialize(current)
+        p[LIST_REMINDER_OVERRIDE] = reminderCodec.serializeLeads(current)
     }
 
     /** Set (or clear) a list's all-day reminder override. */
     suspend fun setListAllDayReminderOverride(listId: Long, override: ReminderOverride) = dataStore.edit { p ->
-        val current = reminderCodec.parse(p[LIST_ALL_DAY_REMINDER_OVERRIDE]).toMutableMap()
+        val current = reminderCodec.parseLeads(p[LIST_ALL_DAY_REMINDER_OVERRIDE]).toMutableMap()
         current.applyReminderOverride(listId, override)
-        p[LIST_ALL_DAY_REMINDER_OVERRIDE] = reminderCodec.serialize(current)
+        p[LIST_ALL_DAY_REMINDER_OVERRIDE] = reminderCodec.serializeLeads(current)
     }
 
     suspend fun setHiddenFromSmartLists(listId: Long, hidden: Boolean) = dataStore.edit { p ->
@@ -254,6 +271,34 @@ class SettingsPrefs @Inject constructor(
         p[SMART_LIST_HIDDEN] = if (hidden) current + entry else current - entry
     }
 
+    /** The saved filters, oldest first, with the list ids of the current store. */
+    val savedFilters: Flow<List<SavedFilter>> =
+        dataStore.data.map { p -> p[SAVED_FILTERS] to p[STORAGE_MODE] }
+            .distinctUntilChanged()
+            .map { (raw, mode) -> SavedFilterCodec.decode(raw, (storedMode(mode) ?: resolver.autoMode()).name) }
+            .distinctUntilChanged()
+
+    /** One saved filter; `null` while it doesn't exist. */
+    fun savedFilter(id: Long): Flow<SavedFilter?> =
+        savedFilters.map { all -> all.firstOrNull { it.id == id } }.distinctUntilChanged()
+
+    /** Store [filter]; an id of 0 makes a new one. Returns the filter's id. */
+    suspend fun saveFilter(filter: SavedFilter): Long {
+        var id = filter.id
+        dataStore.edit { p ->
+            if (id <= 0) {
+                id = p[SAVED_FILTER_NEXT_ID] ?: 1L
+                p[SAVED_FILTER_NEXT_ID] = id + 1
+            }
+            p[SAVED_FILTERS] = SavedFilterCodec.upsert(p[SAVED_FILTERS], filter.copy(id = id), modeOf(p).name)
+        }
+        return id
+    }
+
+    suspend fun deleteFilter(id: Long) = dataStore.edit { p ->
+        p[SAVED_FILTERS] = SavedFilterCodec.remove(p[SAVED_FILTERS], id)
+    }
+
     suspend fun setDefaultEditFields(fields: Set<TaskFormField>) = dataStore.edit {
         it[DEFAULT_EDIT_FIELDS] = fields.mapTo(mutableSetOf()) { field -> field.name }
     }
@@ -282,6 +327,9 @@ class SettingsPrefs @Inject constructor(
         val SYNC_INTERVAL = intPreferencesKey("sync_interval_minutes")
         val PUSH_ENABLED = booleanPreferencesKey("push_enabled")
         val SMART_LIST_HIDDEN = stringSetPreferencesKey("smart_list_hidden")
+        val DEFAULT_START_TODAY = booleanPreferencesKey("default_start_today")
+        val SAVED_FILTERS = stringPreferencesKey("saved_filters")
+        val SAVED_FILTER_NEXT_ID = longPreferencesKey("saved_filter_next_id")
     }
 }
 
@@ -292,6 +340,13 @@ class SettingsPrefs @Inject constructor(
  */
 private val reminderCodec = ReminderOverrideCodec.DEFAULT
 
-/** `5,30` → [5, 30]; an empty string is an explicit "no reminder". */
-private fun parseMinutes(stored: String): List<Int> =
-    stored.split(',').mapNotNull { it.trim().toIntOrNull()?.takeIf { m -> m >= 0 } }.normalizeReminders()
+/** `s5,30` → [5 before start, 30 before due]; an empty string is an explicit "no reminder". */
+private fun parseLeads(stored: String): List<ReminderLead> =
+    stored.split(',').mapNotNull { ReminderLead.parse(it)?.takeIf { lead -> lead.minutes >= 0 } }.normalizeReminders()
+
+/**
+ * All-day defaults as whole days. Before 1.2 an all-day default could be hours
+ * before the all-day time; a lead that is not whole days now names a time of day.
+ */
+private fun List<ReminderLead>.inWholeDays(): List<ReminderLead> =
+    map { it.asTaskReminder().inWholeDays().asReminderLead() }.normalizeReminders()

app/src/main/java/de/jeanlucmakiola/agendula/data/reminders/ReminderPlanner.kt

@@ -1,8 +1,9 @@
 package de.jeanlucmakiola.agendula.data.reminders
 
 import de.jeanlucmakiola.agendula.data.prefs.Settings
-import de.jeanlucmakiola.agendula.data.tasks.TaskReminder
+import de.jeanlucmakiola.agendula.domain.AllDayReminder
 import de.jeanlucmakiola.agendula.domain.Task
+import de.jeanlucmakiola.agendula.domain.TaskReminder
 import de.jeanlucmakiola.agendula.domain.calendarDate
 import java.time.LocalTime
 import java.time.ZoneId
@@ -36,31 +37,53 @@ internal object ReminderPlanner {
         // One reminder per *occurrence* and lead: a recurring series yields a row
         // per occurrence, all sharing a taskId, so this is a Set rather than a
         // taskId-keyed Map.
-        .filter { !it.isClosed && it.due != null }
+        .filter { !it.isClosed && (it.due != null || it.start != null) }
         .flatMap { task ->
-            // Reminders set on the task itself win — every one of them, not just
-            // the one the editor shows; otherwise the task's list may override the
-            // global lead, or opt out entirely (override = null). All-day tasks
-            // have their own day-scale defaults.
-            val reminders = perTask[task.taskId].orEmpty().ifEmpty {
-                val leads = if (task.isAllDay) settings.allDayReminderLeadsFor(task.listId)
-                else settings.reminderLeadsFor(task.listId)
-                leads.map { TaskReminder(it) }
-            }
-            reminders.map { reminder ->
-                // A stored reminder says what it counts back from. Ours are always
-                // before due, but an imported dmfs alarm or another client's can be
-                // before *start*.
-                val anchor = if (reminder.fromStart) task.start ?: task.due!! else task.due!!
+            // Reminders set on the task itself win — every one of them;
+            // otherwise the task's list may override the global lead, or opt
+            // out entirely (override = null). All-day tasks have their own
+            // day-scale defaults.
+            //
+            // ⚠️ Present-but-empty is "none", not "the default": the store's
+            // answer for a task whose alarms another client turned off. A
+            // default here would keep ringing for what the user switched off.
+            // A default counts only from a date the task has; its own reminders
+            // stand in each date for the other when the task lacks it.
+            val own = perTask[task.taskId]
+            val reminders = own ?: settings.defaultRemindersFor(task.listId, task.isAllDay)
+                .filter { (if (it.fromStart) task.start else task.due) != null }
+            val created = task.created?.toEpochMilliseconds()
+            reminders.mapNotNull { reminder ->
+                val anchor = if (reminder.fromStart) task.start ?: task.due!! else task.due ?: task.start!!
+                val trigger = triggerAt(
+                    anchor,
+                    task.isAllDay,
+                    reminder.minutesBefore,
+                    settings.allDayReminderMinuteOfDay,
+                    zone,
+                )
+                // A default never rings for a moment before the task existed:
+                // that is a task saved after its default had passed, not a
+                // reminder missed while the device was off.
+                if (own == null && created != null && trigger < created) return@mapNotNull null
+                // Dismissed on another client already: firing it here within
+                // the missed-reminder grace would ring for something done with.
+                //
+                // ⚠️ An all-day reminder without a time of its own is compared
+                // from the start of its day, not from this device's time of
+                // day: other clients ring it at midnight, or at their own hour,
+                // so a dismissal at 07:00 must still silence the 09:00 this
+                // device would ring it at.
+                val earliest = if (task.isAllDay && reminder.allDay.minuteOfDay == null) {
+                    triggerAt(anchor, true, reminder.minutesBefore, 0, zone)
+                } else {
+                    trigger
+                }
+                val acknowledged = reminder.acknowledgedAt?.let { earliest <= it.toEpochMilliseconds() } == true
+                if (acknowledged) return@mapNotNull null
                 ScheduledReminder(
                     taskId = task.taskId,
-                    triggerAt = triggerAt(
-                        anchor,
-                        task.isAllDay,
-                        reminder.minutesBefore,
-                        settings.allDayReminderMinuteOfDay,
-                        zone,
-                    ),
+                    triggerAt = trigger,
                     occurrenceStart = task.occurrenceStart?.toEpochMilliseconds() ?: ScheduledReminder.NO_OCCURRENCE,
                 )
             }
@@ -80,8 +103,9 @@ internal object ReminderPlanner {
      *
      * ⚠️ An all-day anchor is UTC midnight of its date (see `AllDayTime.kt`), a
      * storage convention and not a moment — firing off it rang at 02:00 in
-     * Berlin and the evening before in New York. It is read as its calendar date
-     * at [allDayMinuteOfDay] local time instead, and the lead counts back from that.
+     * Berlin and the evening before in New York. It is read as its calendar
+     * date instead, and the lead as [TaskReminder.allDay]: whole days ring at
+     * [allDayMinuteOfDay] local time, anything else at the time it names.
      */
     fun triggerAt(
         anchor: Instant,
@@ -90,12 +114,11 @@ internal object ReminderPlanner {
         allDayMinuteOfDay: Int,
         zone: ZoneId,
     ): Long {
-        val base = if (allDay) {
-            val time = LocalTime.of(allDayMinuteOfDay / 60 % 24, allDayMinuteOfDay % 60)
-            anchor.calendarDate(allDay = true).atTime(time).atZone(zone).toInstant().toEpochMilli()
-        } else {
-            anchor.toEpochMilliseconds()
-        }
-        return base - leadMinutes.coerceAtLeast(0) * 60_000L
+        if (!allDay) return anchor.toEpochMilliseconds() - leadMinutes.coerceAtLeast(0) * 60_000L
+        val (days, minuteOfDay) = AllDayReminder.of(leadMinutes)
+        val minute = minuteOfDay ?: allDayMinuteOfDay
+        val time = LocalTime.of(minute / 60 % 24, minute % 60)
+        return anchor.calendarDate(allDay = true).minusDays(days.toLong())
+            .atTime(time).atZone(zone).toInstant().toEpochMilli()
     }
 }

app/src/main/java/de/jeanlucmakiola/agendula/data/sync/RemoteLists.kt

@@ -0,0 +1,52 @@
+package de.jeanlucmakiola.agendula.data.sync
+
+import de.jeanlucmakiola.agendula.data.tasks.room.AccountEntity
+
+/**
+ * Task lists that live on a server: making, renaming, recolouring and deleting
+ * them. The `full` flavor talks CalDAV; the `offline` one has no accounts, so
+ * every list is device-only and none of this is ever reached with a real one.
+ */
+interface RemoteLists {
+
+    /** Why a collection write did not happen, in a form the UI can translate. */
+    sealed interface Outcome {
+        data object Done : Outcome
+
+        /** The server said no, and will say no again. */
+        data class Refused(val code: Int) : Outcome
+
+        /** The server could not be reached. Worth another try. */
+        data object Unreachable : Outcome
+
+        /** This account cannot make collections at all — iCloud, Posteo, Google. */
+        data object Unsupported : Outcome
+
+        /** Ours is a read-only share; the write belongs to whoever owns it. */
+        data object ReadOnly : Outcome
+
+        /** The account is gone, stopped, or has no credential we can decrypt. */
+        data object NoAccount : Outcome
+
+        /**
+         * The server answered something this call cannot make sense of.
+         *
+         * ⚠️ Not [Unreachable]. `CollectionOutcome` is one type across create,
+         * update and delete, so each of them has branches the other's method
+         * can return and its own cannot — and mapping those to [Unreachable]
+         * told someone sitting on wifi that they were offline. Unreachable is a
+         * claim about the network, and this is not one.
+         */
+        data object Unexpected : Outcome
+    }
+
+    /** The accounts a new list may be created on. */
+    suspend fun creatableAccounts(): List<AccountEntity>
+
+    /** Makes a collection on [accountId]'s home set and a row pointing at it. */
+    suspend fun create(accountId: Long, name: String, color: Int): Outcome
+
+    suspend fun rename(listId: Long, name: String, color: Int): Outcome
+
+    suspend fun delete(listId: Long): Outcome
+}

app/src/main/java/de/jeanlucmakiola/agendula/data/sync/SyncRequests.kt

@@ -0,0 +1,6 @@
+package de.jeanlucmakiola.agendula.data.sync
+
+/** Asks for an account to be synced now. A no-op in the `offline` flavor. */
+fun interface SyncRequests {
+    fun syncNow(accountName: String)
+}

app/src/main/java/de/jeanlucmakiola/agendula/data/tasks/AndroidTasksDataSource.kt

@@ -1,5 +1,7 @@
 package de.jeanlucmakiola.agendula.data.tasks
 
+import de.jeanlucmakiola.agendula.domain.TaskReminder
+import android.content.ContentProviderOperation
 import android.content.ContentResolver
 import android.content.ContentUris
 import android.content.ContentValues
@@ -19,6 +21,7 @@ import de.jeanlucmakiola.agendula.domain.Task
 import de.jeanlucmakiola.agendula.domain.TaskForm
 import de.jeanlucmakiola.agendula.domain.TaskList
 import de.jeanlucmakiola.agendula.domain.export.ExportTask
+import de.jeanlucmakiola.agendula.domain.normalizeTags
 import de.jeanlucmakiola.agendula.domain.recurrence.ExpansionWindow
 import de.jeanlucmakiola.agendula.domain.recurrence.RecurrenceExpander
 import de.jeanlucmakiola.agendula.domain.recurrence.RecurrenceSpec
@@ -83,6 +86,27 @@ class AndroidTasksDataSource @Inject constructor(
     override fun subtasks(parentTaskId: Long): List<Task> =
         queryInstances("${Tasks.PARENT_ID} = ?", arrayOf(parentTaskId.toString()))
 
+    /**
+     * Read from the `tasks` table, so a recurring subtask with no occurrence in
+     * the window still counts. All columns and a lenient `_deleted`, as in
+     * [exportTasks], since the table's shape varies across providers.
+     */
+    override fun subtaskIds(parentTaskId: Long): List<Long> = resolver.query(
+        TasksContract.tasksUri(authority()),
+        null,
+        "${Tasks.PARENT_ID} = ? AND (${Tasks.DELETED} IS NULL OR ${Tasks.DELETED} = 0)",
+        arrayOf(parentTaskId.toString()),
+        null,
+    )?.use { c ->
+        val r = CursorColumnReader(c)
+        buildList {
+            while (c.moveToNext()) {
+                if (r.getLong(Tasks.ORIGINAL_INSTANCE_ID) != null) continue
+                r.getLong(Tasks.ID)?.takeIf { it != parentTaskId }?.let(::add)
+            }
+        }
+    } ?: emptyList()
+
     private fun queryInstances(selection: String?, args: Array<String>?): List<Task> {
         val uri = TasksContract.instancesUri(authority())
         // projection = null (all columns): the instances view differs across
@@ -90,11 +114,14 @@ class AndroidTasksDataSource @Inject constructor(
         // `is_recurring` / `distance_from_current`). The by-name mapper reads
         // whatever is present and nulls the rest; the repository re-sorts, so we
         // don't depend on a provider sort column either.
-        return resolver.query(uri, null, selection, args, null)
+        val tasks = resolver.query(uri, null, selection, args, null)
             ?.use { c ->
                 val reader = CursorColumnReader(c)
                 buildList { while (c.moveToNext()) add(TaskMapper.task(reader)) }
             } ?: emptyList()
+        if (tasks.isEmpty()) return tasks
+        val tags = categories(tasks.map { it.taskId })
+        return tasks.map { task -> tags[task.taskId]?.let { task.copy(tags = it) } ?: task }
     }
 
     override fun exportTasks(listId: Long): List<ExportTask> {
@@ -102,7 +129,7 @@ class AndroidTasksDataSource @Inject constructor(
         // table's shape varies across provider versions, and the by-name mapper
         // reads what's there.
         val uri = TasksContract.tasksUri(authority())
-        return resolver.query(
+        val tasks = resolver.query(
             uri,
             null,
             // _deleted marks a row awaiting a sync round-trip. It's gone as far as
@@ -115,24 +142,58 @@ class AndroidTasksDataSource @Inject constructor(
             val reader = CursorColumnReader(c)
             buildList { while (c.moveToNext()) add(TaskMapper.exportTask(reader)) }
         } ?: emptyList()
+        if (tasks.isEmpty()) return tasks
+        val tags = categories(tasks.map { it.taskId })
+        return tasks.map { task -> tags[task.taskId]?.let { task.copy(tags = it) } ?: task }
     }
 
     // --- writes ---------------------------------------------------------------
 
-    override fun insertTask(form: TaskForm): Long {
+    override fun insertTask(form: TaskForm, reminders: List<TaskReminder>?): Long {
         val values = TaskWriteMapper.seriesValues(form, ZoneId.systemDefault().id)
-        val uri = resolver.insert(TasksContract.tasksUri(authority()), values.toContentValues())
-            ?: throw TaskWriteFailedException("insert task")
-        return uri.lastPathSegment?.toLongOrNull() ?: throw TaskWriteFailedException("insert task: no id")
+        // One batch, so a refused tag or alarm leaves no task behind for a retry
+        // to duplicate.
+        val authority = authority()
+        val ops = arrayListOf(
+            ContentProviderOperation.newInsert(TasksContract.tasksUri(authority))
+                .withValues(values.toContentValues())
+                .build(),
+        )
+        normalizeTags(form.tags).forEach { tag ->
+            ops += ContentProviderOperation.newInsert(TasksContract.propertiesUri(authority))
+                .withValues(TaskWriteMapper.categoryValues(0, tag).toContentValues().apply { remove(Properties.TASK_ID) })
+                .withValueBackReference(Properties.TASK_ID, 0)
+                .build()
+        }
+        reminders.orEmpty().forEach { reminder ->
+            ops += ContentProviderOperation.newInsert(TasksContract.propertiesUri(authority))
+                .withValues(
+                    TaskWriteMapper.alarmValues(0, reminder.minutesBefore, reminder.fromStart)
+                        .toContentValues().apply { remove(Properties.TASK_ID) },
+                )
+                .withValueBackReference(Properties.TASK_ID, 0)
+                .build()
+        }
+        val results = runCatching { resolver.applyBatch(authority, ops) }
+            .getOrElse { throw TaskWriteFailedException("insert task", it) }
+        return results.firstOrNull()?.uri?.lastPathSegment?.toLongOrNull()
+            ?: throw TaskWriteFailedException("insert task: no id")
     }
 
-    override fun updateTask(taskId: Long, form: TaskForm) {
+    override fun updateTask(taskId: Long, form: TaskForm, reminders: List<TaskReminder>?) {
         val values = TaskWriteMapper.seriesValues(form, ZoneId.systemDefault().id)
         val rows = resolver.update(taskUri(authority(), taskId), values.toContentValues(), null, null)
         if (rows == 0) throw TaskWriteFailedException("update task $taskId")
+        setCategories(taskId, form.tags)
+        writeReminders(taskId, reminders)
     }
 
-    override fun updateSeries(seriesId: Long, occurrenceStart: Instant, form: TaskForm) {
+    private fun writeReminders(taskId: Long, reminders: List<TaskReminder>?) {
+        if (reminders == null) return
+        setReminders(taskId, reminders)
+    }
+
+    override fun updateSeries(seriesId: Long, occurrenceStart: Instant, form: TaskForm, reminders: List<TaskReminder>?) {
         val occurrence = task(seriesId, occurrenceStart)
         val anchors = resolver.query(
             taskUri(authority(), seriesId), arrayOf(Tasks.DTSTART, Tasks.DUE), null, null, null,
@@ -151,6 +212,8 @@ class AndroidTasksDataSource @Inject constructor(
             (Tasks.DUE to shifted(anchors?.second, occurrence?.due, form.due))
         val rows = resolver.update(taskUri(authority(), seriesId), values.toContentValues(), null, null)
         if (rows == 0) throw TaskWriteFailedException("update series $seriesId")
+        setCategories(seriesId, form.tags)
+        writeReminders(seriesId, reminders)
     }
 
     /**
@@ -159,10 +222,10 @@ class AndroidTasksDataSource @Inject constructor(
      * task. Per-occurrence edits past the split point are dropped rather than
      * carried over — the provider offers no way to re-parent an exception.
      */
-    override fun splitSeries(seriesId: Long, occurrenceStart: Instant, form: TaskForm): Long {
+    override fun splitSeries(seriesId: Long, occurrenceStart: Instant, form: TaskForm, reminders: List<TaskReminder>?): Long {
         val spec = seriesSpec(seriesId) ?: throw TaskWriteFailedException("split series $seriesId")
         if (spec.rrule == null || occurrenceStart <= spec.anchor) {
-            updateSeries(seriesId, occurrenceStart, form)
+            updateSeries(seriesId, occurrenceStart, form, reminders)
             return seriesId
         }
         // COUNT counts before EXDATE is applied (RFC 5545 §3.8.5.3).
@@ -172,12 +235,12 @@ class AndroidTasksDataSource @Inject constructor(
         ).size
         endSeriesBefore(seriesId, spec, occurrenceStart)
         val rule = form.rrule?.let { if (it == spec.rrule) TaskFormWriter.remainingCount(it, spent) else it }
-        return insertTask(form.copy(rrule = rule, percentComplete = null))
+        return insertTask(form.copy(rrule = rule, percentComplete = null), reminders)
     }
 
     override fun deleteFollowing(seriesId: Long, occurrenceStart: Instant) {
         val spec = seriesSpec(seriesId) ?: return
-        if (spec.rrule == null || occurrenceStart <= spec.anchor) return deleteTask(seriesId)
+        if (spec.rrule == null || occurrenceStart <= spec.anchor) return deleteWithSubtasks(seriesId)
         endSeriesBefore(seriesId, spec, occurrenceStart)
     }
 
@@ -238,13 +301,49 @@ class AndroidTasksDataSource @Inject constructor(
         resolver.delete(TasksContract.instanceUri(authority(), instanceId), null, null)
     }
 
-    override fun updateInstance(taskId: Long, occurrenceStart: Instant, form: TaskForm) {
+    override fun updateInstance(taskId: Long, occurrenceStart: Instant, form: TaskForm, reminders: List<TaskReminder>?) {
+        if (reminders == null) return writeInstance(taskId, occurrenceStart, form)
+        // ⚠️ Written to the series, and then put back. Forking an occurrence
+        // copies the task's *current* properties onto the new override row, so
+        // setting the alarm beforehand is the only way to carry it across — and
+        // leaving it there would silently give every other occurrence in the
+        // series the reminder the user set on one of them.
+        val seriesReminders = alarmRows(taskId).map { it.second }
+        writeReminders(taskId, reminders)
+        try {
+            writeInstance(taskId, occurrenceStart, form)
+        } finally {
+            setReminders(taskId, seriesReminders)
+        }
+    }
+
+    private fun writeInstance(taskId: Long, occurrenceStart: Instant, form: TaskForm) {
         val instanceId = instanceIdFor(taskId, occurrenceStart)
             ?: throw TaskWriteFailedException("update instance $taskId@$occurrenceStart: no such occurrence")
         val values = TaskWriteMapper.instanceValues(form, ZoneId.systemDefault().id)
         val uri = TasksContract.instanceUri(authority(), instanceId)
-        val rows = resolver.update(uri, values.toContentValues(), null, null)
-        if (rows == 0) throw TaskWriteFailedException("update instance $instanceId")
+        // The fork copies the series' properties onto the override, so the tags
+        // go onto the series first and are put back once the override exists.
+        // Unchanged tags are inherited as they are, and the series is left alone.
+        val seriesTags = categories(listOf(taskId))[taskId].orEmpty()
+        val retag = normalizeTags(form.tags) != seriesTags
+        if (retag) setCategories(taskId, form.tags)
+        var failure: Throwable? = null
+        try {
+            val rows = resolver.update(uri, values.toContentValues(), null, null)
+            if (rows == 0) throw TaskWriteFailedException("update instance $instanceId")
+        } catch (e: Throwable) {
+            failure = e
+            throw e
+        } finally {
+            if (retag) {
+                try {
+                    setCategories(taskId, seriesTags)
+                } catch (e: Throwable) {
+                    failure?.addSuppressed(e) ?: throw e
+                }
+            }
+        }
     }
 
     /**
@@ -271,21 +370,6 @@ class AndroidTasksDataSource @Inject constructor(
         }
     }
 
-    override fun setAlarm(taskId: Long, minutesBeforeDue: Int?) {
-        val uri = TasksContract.propertiesUri(authority())
-        // Replace rather than update: the provider's AlarmHandler re-validates the
-        // whole row on every update, so a partial edit throws. Only the editable
-        // (last before-due) row goes — a start-relative or additional alarm
-        // another client wrote is not ours to drop.
-        alarmRows(taskId).lastOrNull { !it.second.fromStart }?.let { (propertyId, _) ->
-            resolver.delete(uri, "${Properties.PROPERTY_ID} = ?", arrayOf(propertyId.toString()))
-        }
-        if (minutesBeforeDue != null) {
-            resolver.insert(uri, TaskWriteMapper.alarmValues(taskId, minutesBeforeDue).toContentValues())
-                ?: throw TaskWriteFailedException("set alarm for task $taskId")
-        }
-    }
-
     override fun setReminders(taskId: Long, reminders: List<TaskReminder>) {
         val uri = TasksContract.propertiesUri(authority())
         resolver.delete(
@@ -302,9 +386,6 @@ class AndroidTasksDataSource @Inject constructor(
     override fun reminders(): Map<Long, List<TaskReminder>> =
         readAlarms(null).groupBy({ it.first }) { it.third }
 
-    override fun alarms(): Map<Long, TaskReminder> =
-        reminders().mapNotNull { (id, list) -> list.editable()?.let { id to it } }.toMap()
-
     /** `(property_id, reminder)` for [taskId]'s alarm rows, in stored order. */
     private fun alarmRows(taskId: Long): List<Pair<Long, TaskReminder>> =
         readAlarms(taskId).map { it.second to it.third }
@@ -348,6 +429,58 @@ class AndroidTasksDataSource @Inject constructor(
         } ?: emptyList()
     }
 
+    /** Tags by task id for [taskIds], in stored order. */
+    private fun categories(taskIds: Collection<Long>): Map<Long, List<String>> {
+        val rows = taskIds.distinct().chunked(MAX_SQL_ARGS - 1).flatMap { chunk ->
+            val selection = "${Properties.MIMETYPE} = ? AND ${Properties.TASK_ID} IN (${chunk.joinToString(",") { "?" }})"
+            val args = (listOf(TasksContract.Category.MIMETYPE) + chunk.map(Long::toString)).toTypedArray()
+            resolver.query(
+                TasksContract.propertiesUri(authority()),
+                arrayOf(Properties.TASK_ID, TasksContract.Category.NAME),
+                selection,
+                args,
+                Properties.PROPERTY_ID,
+            )?.use { c ->
+                val reader = CursorColumnReader(c)
+                buildList {
+                    while (c.moveToNext()) {
+                        val id = reader.getLong(Properties.TASK_ID) ?: continue
+                        val name = reader.getString(TasksContract.Category.NAME) ?: continue
+                        add(id to name)
+                    }
+                }
+            } ?: emptyList()
+        }
+        return rows.groupBy({ it.first }, { it.second }).mapValues { normalizeTags(it.value) }
+    }
+
+    /**
+     * Replaces [taskId]'s category rows in one batch, so a refused insert cannot
+     * leave half the tags, and leaves them alone when nothing changed so the task
+     * isn't dirtied.
+     */
+    private fun setCategories(taskId: Long, tags: List<String>) {
+        val wanted = normalizeTags(tags)
+        if (categories(listOf(taskId))[taskId].orEmpty() == wanted) return
+        val authority = authority()
+        val uri = TasksContract.propertiesUri(authority)
+        val ops = arrayListOf(
+            ContentProviderOperation.newDelete(uri)
+                .withSelection(
+                    "${Properties.TASK_ID} = ? AND ${Properties.MIMETYPE} = ?",
+                    arrayOf(taskId.toString(), TasksContract.Category.MIMETYPE),
+                )
+                .build(),
+        )
+        wanted.forEach {
+            ops += ContentProviderOperation.newInsert(uri)
+                .withValues(TaskWriteMapper.categoryValues(taskId, it).toContentValues())
+                .build()
+        }
+        runCatching { resolver.applyBatch(authority, ops) }
+            .getOrElse { throw TaskWriteFailedException("set categories for task $taskId", it) }
+    }
+
     override fun setCancelled(taskId: Long, cancelled: Boolean) {
         val rows = resolver.update(taskUri(authority(), taskId), cancelValues(cancelled).toContentValues(), null, null)
         if (rows == 0) throw TaskWriteFailedException("cancel task $taskId")
@@ -460,3 +593,6 @@ class AndroidTasksDataSource @Inject constructor(
         return cv
     }
 }
+
+/** SQLite's default bound-argument limit on older Android releases. */
+private const val MAX_SQL_ARGS = 999

app/src/main/java/de/jeanlucmakiola/agendula/data/tasks/Failures.kt

@@ -5,8 +5,8 @@ class ProviderUnavailableException :
     IllegalStateException("No tasks provider installed")
 
 /** A ContentResolver write returned no URI or affected no rows. */
-class TaskWriteFailedException(operation: String) :
-    RuntimeException("Task write failed: $operation")
+class TaskWriteFailedException(operation: String, cause: Throwable? = null) :
+    RuntimeException("Task write failed: $operation", cause)
 
 /**
  * The task changed (e.g. a DAVx5 sync or another app) since the edit form loaded

app/src/main/java/de/jeanlucmakiola/agendula/data/tasks/ModeRoutingTasksDataSource.kt

@@ -1,5 +1,6 @@
 package de.jeanlucmakiola.agendula.data.tasks
 
+import de.jeanlucmakiola.agendula.domain.TaskReminder
 import de.jeanlucmakiola.agendula.data.tasks.room.RoomTasksDataSource
 import de.jeanlucmakiola.agendula.domain.Task
 import de.jeanlucmakiola.agendula.domain.TaskForm
@@ -34,23 +35,24 @@ class ModeRoutingTasksDataSource(
     override fun tasks(query: TaskQuery): List<Task> = active().tasks(query)
     override fun task(taskId: Long): Task? = active().task(taskId)
     override fun task(taskId: Long, occurrenceStart: Instant?): Task? = active().task(taskId, occurrenceStart)
-    override fun updateSeries(seriesId: Long, occurrenceStart: Instant, form: TaskForm) =
-        active().updateSeries(seriesId, occurrenceStart, form)
-    override fun splitSeries(seriesId: Long, occurrenceStart: Instant, form: TaskForm): Long =
-        active().splitSeries(seriesId, occurrenceStart, form)
+    override fun updateSeries(seriesId: Long, occurrenceStart: Instant, form: TaskForm, reminders: List<TaskReminder>?) =
+        active().updateSeries(seriesId, occurrenceStart, form, reminders)
+    override fun splitSeries(seriesId: Long, occurrenceStart: Instant, form: TaskForm, reminders: List<TaskReminder>?): Long =
+        active().splitSeries(seriesId, occurrenceStart, form, reminders)
     override fun deleteOccurrence(seriesId: Long, occurrenceStart: Instant) =
         active().deleteOccurrence(seriesId, occurrenceStart)
     override fun deleteFollowing(seriesId: Long, occurrenceStart: Instant) =
         active().deleteFollowing(seriesId, occurrenceStart)
     override fun subtasks(parentTaskId: Long): List<Task> = active().subtasks(parentTaskId)
-    override fun insertTask(form: TaskForm): Long = active().insertTask(form)
-    override fun updateTask(taskId: Long, form: TaskForm) = active().updateTask(taskId, form)
+    override fun subtaskIds(parentTaskId: Long): List<Long> = active().subtaskIds(parentTaskId)
+    override fun deleteWithSubtasks(taskId: Long) = active().deleteWithSubtasks(taskId)
+    override fun insertTask(form: TaskForm, reminders: List<TaskReminder>?): Long = active().insertTask(form, reminders)
+    override fun updateTask(taskId: Long, form: TaskForm, reminders: List<TaskReminder>?) =
+        active().updateTask(taskId, form, reminders)
 
-    override fun updateInstance(taskId: Long, occurrenceStart: Instant, form: TaskForm) =
-        active().updateInstance(taskId, occurrenceStart, form)
+    override fun updateInstance(taskId: Long, occurrenceStart: Instant, form: TaskForm, reminders: List<TaskReminder>?) =
+        active().updateInstance(taskId, occurrenceStart, form, reminders)
 
-    override fun setAlarm(taskId: Long, minutesBeforeDue: Int?) = active().setAlarm(taskId, minutesBeforeDue)
-    override fun alarms(): Map<Long, TaskReminder> = active().alarms()
     override fun reminders(): Map<Long, List<TaskReminder>> = active().reminders()
     override fun setReminders(taskId: Long, reminders: List<TaskReminder>) =
         active().setReminders(taskId, reminders)

app/src/main/java/de/jeanlucmakiola/agendula/data/tasks/StoredReminders.kt

@@ -0,0 +1,101 @@
+package de.jeanlucmakiola.agendula.data.tasks
+
+import de.jeanlucmakiola.agendula.data.prefs.Settings
+import de.jeanlucmakiola.agendula.data.reminders.ReminderPlanner
+import de.jeanlucmakiola.agendula.domain.Task
+import de.jeanlucmakiola.agendula.domain.TaskForm
+import de.jeanlucmakiola.agendula.domain.TaskReminder
+import java.time.ZoneId
+import kotlin.time.Instant
+
+internal object StoredReminders {
+
+    /**
+     * The reminders to store for [form], given the task as it was.
+     *
+     * A date the task gets in this write brings the list's or the app's
+     * default for it *as the task's own reminders*. The default is this
+     * device's setting, which nothing else can see; stored on the task, it
+     * travels with it to the server and fires on every client. The cost is
+     * tasks.org's: changing the default later does not reach the tasks that
+     * already have it.
+     *
+     * A task getting its first date takes the defaults only when the form
+     * names no reminder; one that already had a date takes those of the new
+     * date that no reminder of the form counts from. Otherwise the form is
+     * kept, so an edit that clears every reminder means "use the default
+     * here" as before.
+     *
+     * The form's reminders are already of its kind, timed or all-day — see
+     * [switched]. Reminders the editor [chose][TaskForm.remindersChosen] are
+     * kept as they are: it showed these defaults already.
+     */
+    fun of(form: TaskForm, current: Task?, settings: Settings, now: Long, zone: ZoneId): List<TaskReminder> {
+        val wanted = form.reminders.map { it.lead }.distinct()
+        if (form.remindersChosen) return wanted
+        return withDefaults(form, current?.start, current?.due, settings, now, zone)
+    }
+
+    /** [of] for a task whose dates were [start] and [due], whatever the form chose. */
+    fun withDefaults(
+        form: TaskForm,
+        start: Instant?,
+        due: Instant?,
+        settings: Settings,
+        now: Long,
+        zone: ZoneId,
+    ): List<TaskReminder> {
+        val wanted = form.reminders.map { it.lead }.distinct()
+        val had = anchorsOf(start, due)
+        val gained = anchorsOf(form.start, form.due) - had
+        if (gained.isEmpty()) return wanted
+        if (had.isEmpty() || wanted.isEmpty()) return wanted.ifEmpty { defaultsFor(form, settings, now, zone) }
+        val named = wanted.map { it.fromStart }.toSet()
+        return wanted + defaultsFor(form, settings, now, zone).filter { it.fromStart in gained && it.fromStart !in named }
+    }
+
+    /**
+     * [reminders] for [form] once it has switched between timed and all-day.
+     * Reminders that are exactly the old kind's default become the new kind's;
+     * the rest keep what still means something: whole days, rounded to them on
+     * an all-day task.
+     */
+    fun switched(
+        reminders: List<TaskReminder>,
+        form: TaskForm,
+        settings: Settings,
+        now: Long,
+        zone: ZoneId,
+    ): List<TaskReminder> {
+        if (reminders.isEmpty()) return reminders
+        if (reminders.toSet() == settings.defaultRemindersFor(form.listId, !form.isAllDay).toSet()) {
+            return defaultsFor(form, settings, now, zone)
+        }
+        val kept = if (form.isAllDay) {
+            reminders.map { it.inWholeDays() }
+        } else {
+            reminders.filter { it.allDay.minuteOfDay == null }
+        }
+        return kept.distinct().ifEmpty { defaultsFor(form, settings, now, zone) }
+    }
+
+    /** The dates a reminder can count from, as [TaskReminder.fromStart]. */
+    private fun anchorsOf(start: Any?, due: Any?): Set<Boolean> =
+        setOfNotNull(true.takeIf { start != null }, false.takeIf { due != null })
+
+    /**
+     * The defaults [form] takes: those counting from a date it has. A one-off
+     * task leaves out what is already past — a start of "now" would ring at once.
+     */
+    private fun defaultsFor(form: TaskForm, settings: Settings, now: Long, zone: ZoneId): List<TaskReminder> =
+        settings.defaultRemindersFor(form.listId, form.isAllDay).filter { reminder ->
+            val anchor = (if (reminder.fromStart) form.start else form.due) ?: return@filter false
+            form.rrule != null || ReminderPlanner.triggerAt(
+                anchor,
+                form.isAllDay,
+                reminder.minutesBefore,
+                settings.allDayReminderMinuteOfDay,
+                zone,
+            ) >= now
+        }
+}

app/src/main/java/de/jeanlucmakiola/agendula/data/tasks/TaskWriteMapper.kt

@@ -113,6 +113,12 @@ object TaskWriteMapper {
         Alarm.ALARM_TYPE to Alarm.TYPE_MESSAGE,
     )
 
+    fun categoryValues(taskId: Long, name: String): Map<String, Any?> = mapOf(
+        Properties.TASK_ID to taskId,
+        Properties.MIMETYPE to TasksContract.Category.MIMETYPE,
+        TasksContract.Category.NAME to name,
+    )
+
     /** The user-owned columns of a list — what an edit is allowed to change. */
     fun listValues(name: String, color: Int): Map<String, Any?> = mapOf(
         Lists.NAME to name.trim(),

app/src/main/java/de/jeanlucmakiola/agendula/data/tasks/TasksContract.kt

@@ -86,6 +86,12 @@ object TasksContract {
 
         const val UID = "_uid"
         const val DELETED = "_deleted"
+
+        const val HAS_ALARMS = "has_alarms"
+        const val ORIGINAL_INSTANCE_ALLDAY = "original_instance_allday"
+        const val LIST_OWNER = "list_owner"
+        const val LIST_ACCESS_LEVEL = "list_access_level"
+        const val VISIBLE = "visible"
     }
 
     /**
@@ -103,6 +109,7 @@ object TasksContract {
         const val INSTANCE_DUE_SORTING = "instance_due_sorting"
         const val DISTANCE_FROM_CURRENT = "distance_from_current"
         const val IS_RECURRING = "is_recurring"
+        const val INSTANCE_DURATION = "instance_duration"
 
         /**
          * The occurrence's `RECURRENCE-ID` — the time this occurrence was
@@ -118,6 +125,10 @@ object TasksContract {
         const val PROPERTY_ID = "property_id"
         const val TASK_ID = "task_id"
         const val MIMETYPE = "mimetype"
+        const val DATA0 = "data0"
+        const val DATA1 = "data1"
+        const val DATA2 = "data2"
+        const val DATA3 = "data3"
     }
 
     /**
@@ -154,6 +165,21 @@ object TasksContract {
         const val TYPE_MESSAGE = 1
     }
 
+    /**
+     * A category property row — one tag. DAVx5 maps these to and from
+     * `CATEGORIES`. Inserting with only [NAME] is enough: the provider looks the
+     * category up in the task's account, or creates it, and fills in `data0`.
+     */
+    object Category {
+        const val MIMETYPE = "vnd.android.cursor.item/category"
+
+        /** `data1` — the tag as spelled. */
+        const val NAME = "data1"
+
+        /** `data2` — the tag's colour, if any. */
+        const val COLOR = "data2"
+    }
+
     fun propertiesUri(authority: String): Uri = "content://$authority/${Properties.PATH}".toUri()
 
     // --- status values (TaskColumns.STATUS_*) --------------------------------

app/src/main/java/de/jeanlucmakiola/agendula/data/tasks/TasksDataSource.kt

@@ -3,26 +3,9 @@ package de.jeanlucmakiola.agendula.data.tasks
 import de.jeanlucmakiola.agendula.domain.Task
 import de.jeanlucmakiola.agendula.domain.TaskForm
 import de.jeanlucmakiola.agendula.domain.TaskList
+import de.jeanlucmakiola.agendula.domain.TaskReminder
 import kotlin.time.Instant
 
-/**
- * A stored reminder: how long before, and what it counts back from.
- *
- * [fromStart] matters because both stores can hold a `START`-referenced alarm —
- * the dmfs import preserves one, and an external provider's other clients write
- * them — while Agendula's own UI only ever sets a before-due lead. Collapsing it
- * to a number here is what silently fired those reminders off the wrong anchor.
- */
-data class TaskReminder(val minutesBefore: Int, val fromStart: Boolean = false)
-
-/**
- * The one reminder Agendula's single-reminder editor shows and writes: the last
- * before-due one, which is where a write lands, so it stays the same one across
- * saves. Anything else a task carries — a start-relative alarm, or the extra ones
- * another client or the dmfs import brought — is left to ride along.
- */
-fun List<TaskReminder>.editable(): TaskReminder? = lastOrNull { !it.fromStart }
-
 /** What to fetch from the provider. Smart-list date logic is applied above this. */
 data class TaskQuery(
     val listId: Long? = null,
@@ -46,8 +29,38 @@ interface TasksDataSource {
     fun task(taskId: Long, occurrenceStart: Instant?): Task? = task(taskId)
     fun subtasks(parentTaskId: Long): List<Task>
 
-    fun insertTask(form: TaskForm): Long
-    fun updateTask(taskId: Long, form: TaskForm)
+    /**
+     * The task rows directly under [parentTaskId]: one id per subtask, its series
+     * master when it recurs, whether or not any occurrence falls in the window
+     * [subtasks] expands.
+     */
+    fun subtaskIds(parentTaskId: Long): List<Long> =
+        subtasks(parentTaskId).map { it.seriesId ?: it.taskId }.distinct().filter { it != parentTaskId }
+
+    /**
+     * Delete [taskId] and its subtasks, all the way down; left behind they would
+     * hang off a tombstone. Each task once, so a parent loop an import brought in
+     * ends instead of recursing forever.
+     */
+    fun deleteWithSubtasks(taskId: Long) {
+        val seen = HashSet<Long>()
+        fun delete(id: Long) {
+            if (!seen.add(id)) return
+            subtaskIds(id).forEach(::delete)
+            deleteTask(id)
+        }
+        delete(taskId)
+    }
+
+    /**
+     * The write paths take the task's reminders in the same write as the task
+     * itself, so a sync can never upload one without the other.
+     *
+     * Each takes the task's whole set of [reminders], before-start and
+     * before-due alike, and `null` leaves the stored ones alone.
+     */
+    fun insertTask(form: TaskForm, reminders: List<TaskReminder>? = null): Long
+    fun updateTask(taskId: Long, form: TaskForm, reminders: List<TaskReminder>? = null)
 
     /**
      * Update a single occurrence of a recurring task, addressed by the task row and
@@ -60,27 +73,19 @@ interface TasksDataSource {
      * instance row id keeps this seam independent of any one store's row
      * numbering; External mode maps it back to an instance row itself.
      */
-    fun updateInstance(taskId: Long, occurrenceStart: Instant, form: TaskForm)
-    /**
-     * Set (or clear, with `null`) the task's [editable] reminder lead, stored as an
-     * Alarm property row. Every other reminder on the task is left untouched. The
-     * provider never fires it — [de.jeanlucmakiola.agendula.data.reminders
-     * .ReminderScheduler] does — but persisting it here is what syncs the lead and
-     * shares it with other OpenTasks clients.
-     */
-    fun setAlarm(taskId: Long, minutesBeforeDue: Int?)
+    fun updateInstance(taskId: Long, occurrenceStart: Instant, form: TaskForm, reminders: List<TaskReminder>? = null)
 
     /**
      * Edit the whole series [seriesId] through its occurrence at [occurrenceStart]:
      * content from [form], and the series moved by however far that occurrence moved.
      */
-    fun updateSeries(seriesId: Long, occurrenceStart: Instant, form: TaskForm)
+    fun updateSeries(seriesId: Long, occurrenceStart: Instant, form: TaskForm, reminders: List<TaskReminder>? = null)
 
     /**
      * "This and following": end [seriesId] before [occurrenceStart] and continue
      * from there as a new series built from [form]. Returns the new series' id.
      */
-    fun splitSeries(seriesId: Long, occurrenceStart: Instant, form: TaskForm): Long
+    fun splitSeries(seriesId: Long, occurrenceStart: Instant, form: TaskForm, reminders: List<TaskReminder>? = null): Long
 
     /** Delete one generated occurrence of [seriesId] (an `EXDATE`). */
     fun deleteOccurrence(seriesId: Long, occurrenceStart: Instant)
@@ -89,14 +94,15 @@ interface TasksDataSource {
     fun deleteFollowing(seriesId: Long, occurrenceStart: Instant)
 
 
-    /** Replace every reminder on [taskId] with [reminders], in order. */
+    /** Make [taskId]'s reminders exactly [reminders]. A synced task is owed a PUT for it. */
     fun setReminders(taskId: Long, reminders: List<TaskReminder>)
 
-    /** Every task's reminders, by task id, in stored order. One query, for the scheduler. */
-    fun reminders(): Map<Long, List<TaskReminder>> = alarms().mapValues { listOf(it.value) }
-
-    /** Every task's [editable] reminder, by task id. */
-    fun alarms(): Map<Long, TaskReminder>
+    /**
+     * Every task's reminders, by task id, in stored order. One query, for the
+     * scheduler. A task missing from the map takes the default; one present
+     * with an empty list has none (see `TaskEntity.remindersOff`).
+     */
+    fun reminders(): Map<Long, List<TaskReminder>>
 
     /**
      * Every task in [listId] read from the **`tasks` table**, for export. Masters,

app/src/main/java/de/jeanlucmakiola/agendula/data/tasks/TasksRepository.kt

@@ -1,5 +1,7 @@
 package de.jeanlucmakiola.agendula.data.tasks
 
+import de.jeanlucmakiola.agendula.domain.TaskReminder
+import de.jeanlucmakiola.agendula.domain.SavedFilter
 import de.jeanlucmakiola.agendula.domain.Task
 import de.jeanlucmakiola.agendula.domain.TaskDetail
 import de.jeanlucmakiola.agendula.domain.TaskFilter
@@ -13,6 +15,9 @@ import kotlin.time.Instant
 /** Whether Agendula can use the tasks provider right now. Drives onboarding. */
 enum class ProviderStatus { READY, NEEDS_PERMISSION, NO_PROVIDER }
 
+/** Tasks for a filter; [savedFilter] is a saved filter's definition, `null` once it's deleted. */
+data class FilteredTasks(val tasks: List<Task>, val savedFilter: SavedFilter? = null)
+
 /**
  * The single entry point the UI layer uses. Flows re-emit automatically when the
  * provider changes (our writes *and* external sync like DAVx5), via the
@@ -27,7 +32,10 @@ interface TasksRepository {
      */
     fun writableTaskLists(): Flow<List<TaskList>> =
         taskLists().map { lists -> lists.filter { it.acceptsWrites } }
-    fun tasks(filter: TaskFilter): Flow<List<Task>>
+    fun tasks(filter: TaskFilter): Flow<List<Task>> = filteredTasks(filter).map { it.tasks }
+
+    /** [tasks] together with the definition behind a [TaskFilter.Saved]. */
+    fun filteredTasks(filter: TaskFilter): Flow<FilteredTasks>
 
     /**
      * The direct children of [parentId], re-emitting live like the other flows.
@@ -75,13 +83,6 @@ interface TasksRepository {
         scope: RecurringScope = RecurringScope.AllOccurrences,
     )
 
-    /**
-     * The per-task reminder lead in minutes before due, or `null` if the task has
-     * none (in which case the list's / global setting applies). Read when the edit
-     * form loads so saving can't silently drop it.
-     */
-    suspend fun reminderFor(taskId: Long): Int?
-
     /** Every reminder stored on the task, in order — including start-relative ones. */
     suspend fun remindersFor(taskId: Long): List<TaskReminder>
 

app/src/main/java/de/jeanlucmakiola/agendula/data/tasks/TasksRepositoryImpl.kt

@@ -1,7 +1,10 @@
 package de.jeanlucmakiola.agendula.data.tasks
 
+import de.jeanlucmakiola.agendula.domain.TaskReminder
 import de.jeanlucmakiola.agendula.data.di.IoDispatcher
+import de.jeanlucmakiola.agendula.data.prefs.SettingsPrefs
 import de.jeanlucmakiola.floret.time.DayWindow
+import de.jeanlucmakiola.agendula.domain.SavedFilter
 import de.jeanlucmakiola.agendula.domain.SeriesCollapse
 import de.jeanlucmakiola.agendula.domain.Task
 import de.jeanlucmakiola.agendula.domain.TaskDetail
@@ -17,7 +20,11 @@ import kotlinx.coroutines.channels.Channel
 import kotlinx.coroutines.channels.awaitClose
 import kotlinx.coroutines.channels.consumeEach
 import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.flow.callbackFlow
+import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.flow.flatMapLatest
+import kotlinx.coroutines.flow.flowOf
 import kotlinx.coroutines.flow.flowOn
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
@@ -32,12 +39,26 @@ class TasksRepositoryImpl @Inject constructor(
     private val dataSource: TasksDataSource,
     private val providerResolver: ProviderResolver,
     private val startupGate: StartupGate,
+    private val settingsPrefs: SettingsPrefs,
     @IoDispatcher private val io: CoroutineDispatcher,
 ) : TasksRepository {
 
     override fun taskLists(): Flow<List<TaskList>> = observing { dataSource.taskLists() }
 
-    override fun tasks(filter: TaskFilter): Flow<List<Task>> = observing { loadTasks(filter) }
+    @OptIn(ExperimentalCoroutinesApi::class)
+    override fun filteredTasks(filter: TaskFilter): Flow<FilteredTasks> = when (filter) {
+        // A deleted filter shows nothing rather than failing the screen or widget on it.
+        is TaskFilter.Saved -> settingsPrefs.savedFilter(filter.id)
+            .flatMapLatest { saved ->
+                if (saved == null) flowOf(FilteredTasks(emptyList()))
+                else observing {
+                    // A deleted list's id would otherwise leave the filter quietly empty.
+                    val current = saved.withListsIn(dataSource.taskLists().mapTo(HashSet()) { it.id })
+                    FilteredTasks(loadTasks(filter, current), current)
+                }
+            }
+        else -> observing { FilteredTasks(loadTasks(filter)) }
+    }
 
     override fun subtasks(parentId: Long): Flow<List<Task>> = observing {
         SeriesCollapse.visible(dataSource.subtasks(parentId))
@@ -55,7 +76,7 @@ class TasksRepositoryImpl @Inject constructor(
         }
     }
 
-    private fun loadTasks(filter: TaskFilter): List<Task> {
+    private fun loadTasks(filter: TaskFilter, saved: SavedFilter? = null): List<Task> {
         val query = when (filter) {
             is TaskFilter.OfList -> TaskQuery(listId = filter.listId, includeCompleted = true)
             // Read completed tasks too, then let [TaskFiltering.matches] enforce each
@@ -63,6 +84,11 @@ class TasksRepositoryImpl @Inject constructor(
             // parent's subtask-progress reflects ALL its children — completed ones
             // included — even on smart lists that hide completed tasks themselves.
             is TaskFilter.Smart -> TaskQuery(includeCompleted = true)
+            // Same over-read as Smart: TaskQuery.listId only narrows to one list, so
+            // several lists are read in full and membership is filtered in-memory.
+            is TaskFilter.OfLists -> TaskQuery(includeCompleted = true)
+            is TaskFilter.Tagged -> TaskQuery(includeCompleted = true)
+            is TaskFilter.Saved -> TaskQuery(includeCompleted = true)
         }
         val (todayStart, todayEnd) = DayWindow.today(Clock.System.now(), ZoneId.systemDefault())
         val all = SeriesCollapse.visible(dataSource.tasks(query))
@@ -74,7 +100,7 @@ class TasksRepositoryImpl @Inject constructor(
                 (if (t.isCompleted) done + 1 else done) to (total + 1)
             }
         return all
-            .filter { TaskFiltering.matches(it, filter, todayStart, todayEnd) }
+            .filter { TaskFiltering.matches(it, filter, todayStart, todayEnd, saved) }
             .map { task ->
                 progress[task.taskId]?.let { (done, total) ->
                     task.copy(subtaskDone = done, subtaskTotal = total)
@@ -85,11 +111,18 @@ class TasksRepositoryImpl @Inject constructor(
 
     override suspend fun createTask(form: TaskForm): Long =
         withContext(io) {
-            val id = dataSource.insertTask(form)
-            writeReminders(id, form)
-            id
+            dataSource.insertTask(form, storedRemindersFor(form, current = null))
         }
 
+    private suspend fun storedRemindersFor(form: TaskForm, current: Task?): List<TaskReminder> =
+        StoredReminders.of(
+            form,
+            current,
+            settingsPrefs.settings.first(),
+            Clock.System.now().toEpochMilliseconds(),
+            ZoneId.systemDefault(),
+        )
+
     override suspend fun duplicateTask(taskId: Long, occurrenceStart: Instant?): Long =
         withContext(io) {
             val task = checkNotNull(dataSource.task(taskId, occurrenceStart)) { "Task $taskId is gone" }
@@ -97,6 +130,9 @@ class TasksRepositoryImpl @Inject constructor(
         }
 
     private fun copyOf(task: Task, parentId: Long?, depth: Int): Long {
+        // In the same write as the copy: inserted first and given its reminders
+        // after, a sync landing in between uploads the copy without them.
+        val reminders = dataSource.reminders()[task.taskId].orEmpty().map { it.lead }
         val id = dataSource.insertTask(
             TaskForm(
                 title = task.title,
@@ -109,10 +145,10 @@ class TasksRepositoryImpl @Inject constructor(
                 parentId = parentId,
                 location = task.location,
                 url = task.url,
+                tags = task.tags,
             ),
+            reminders,
         )
-        val reminders = dataSource.reminders()[task.taskId].orEmpty()
-        if (reminders.isNotEmpty()) dataSource.setReminders(id, reminders)
         if (depth < MAX_COPY_DEPTH) {
             SeriesCollapse.visible(dataSource.subtasks(task.taskId))
                 .filter { it.taskId != task.taskId && it.status != TaskStatus.CANCELLED }
@@ -121,9 +157,6 @@ class TasksRepositoryImpl @Inject constructor(
         return id
     }
 
-    override suspend fun reminderFor(taskId: Long): Int? =
-        withContext(io) { runCatching { dataSource.alarms()[taskId]?.minutesBefore }.getOrNull() }
-
     override suspend fun remindersFor(taskId: Long): List<TaskReminder> =
         withContext(io) { runCatching { dataSource.reminders()[taskId].orEmpty() }.getOrDefault(emptyList()) }
 
@@ -147,18 +180,17 @@ class TasksRepositoryImpl @Inject constructor(
             val seen = current?.lastModified
             if (seen != null && seen != expectedLastModified) throw TaskConflictException(taskId)
         }
+        val reminders = storedRemindersFor(form, current)
         val seriesId = current?.seriesId
         val occurrence = current?.occurrenceStart
         if (seriesId != null && occurrence != null) {
             when (scope) {
                 RecurringScope.AllOccurrences -> {
-                    writeReminders(seriesId, form)
-                    dataSource.updateSeries(seriesId, occurrence, form)
+                    dataSource.updateSeries(seriesId, occurrence, form, reminders)
                     return@withContext
                 }
                 RecurringScope.ThisAndFollowing -> {
-                    val created = dataSource.splitSeries(seriesId, occurrence, form)
-                    writeReminders(created, form)
+                    dataSource.splitSeries(seriesId, occurrence, form, reminders)
                     return@withContext
                 }
                 RecurringScope.ThisOccurrence -> Unit
@@ -166,31 +198,11 @@ class TasksRepositoryImpl @Inject constructor(
         }
         // A recurring task's start/due are one occurrence's resolved times, so
         // writing them back to the task row would re-anchor the whole series.
-        // Going through the occurrence forks an override instead.
+        // Going through the occurrence forks an override instead, which takes
+        // the reminders on its own row and leaves the series' alone.
         val instance = current?.takeIf { it.isRecurring }?.occurrenceStart
-        if (instance == null) {
-            writeReminders(taskId, form)
-            dataSource.updateTask(taskId, form)
-            return@withContext
-        }
-        // ⚠️ Written to the series, and then put back. Forking an occurrence
-        // copies the task's *current* properties onto the new override row,
-        // so setting the alarm beforehand is the only way to carry it
-        // across — and leaving it there would silently give every other
-        // occurrence in the series the reminder the user set on one of them.
-        val seriesReminders = dataSource.reminders()[taskId].orEmpty()
-        writeReminders(taskId, form)
-        try {
-            dataSource.updateInstance(taskId, instance, form)
-        } finally {
-            dataSource.setReminders(taskId, seriesReminders)
-        }
-    }
-
-    /** The form's before-due reminders; a start-relative one from elsewhere is kept as it was. */
-    private fun writeReminders(taskId: Long, form: TaskForm) {
-        val kept = dataSource.reminders()[taskId].orEmpty().filter { it.fromStart }
-        dataSource.setReminders(taskId, kept + form.reminders.distinct().sorted().map { TaskReminder(it) })
+        if (instance == null) dataSource.updateTask(taskId, form, reminders)
+        else dataSource.updateInstance(taskId, instance, form, reminders)
     }
 
     override suspend fun setCancelled(taskId: Long, occurrenceStart: Instant?, cancelled: Boolean) =
@@ -223,7 +235,7 @@ class TasksRepositoryImpl @Inject constructor(
             val current = dataSource.task(taskId, occurrenceStart)
             val seriesId = current?.seriesId
             val occurrence = current?.occurrenceStart
-            if (seriesId == null || occurrence == null) return@withContext deleteWithSubtasks(taskId)
+            if (seriesId == null || occurrence == null) return@withContext dataSource.deleteWithSubtasks(taskId)
             when (scope) {
                 RecurringScope.ThisOccurrence ->
                     // An override row deletes itself into an EXDATE; a generated
@@ -231,18 +243,10 @@ class TasksRepositoryImpl @Inject constructor(
                     if (current.taskId != seriesId) dataSource.deleteTask(current.taskId)
                     else dataSource.deleteOccurrence(seriesId, occurrence)
                 RecurringScope.ThisAndFollowing -> dataSource.deleteFollowing(seriesId, occurrence)
-                RecurringScope.AllOccurrences -> deleteWithSubtasks(seriesId)
+                RecurringScope.AllOccurrences -> dataSource.deleteWithSubtasks(seriesId)
             }
         }
 
-    /** A parent goes with its subtasks; left behind they would hang off a tombstone. */
-    private fun deleteWithSubtasks(taskId: Long) {
-        dataSource.subtasks(taskId).map { it.taskId }.distinct()
-            .filter { it != taskId }
-            .forEach { dataSource.deleteTask(it) }
-        dataSource.deleteTask(taskId)
-    }
-
     override suspend fun createLocalList(name: String, color: Int): Long =
         withContext(io) { dataSource.createLocalList(name, color) }
 

app/src/main/java/de/jeanlucmakiola/agendula/data/tasks/ical/AlarmCodec.kt

@@ -0,0 +1,228 @@
+package de.jeanlucmakiola.agendula.data.tasks.ical
+
+import de.jeanlucmakiola.agendula.data.reminders.ReminderPlanner
+import de.jeanlucmakiola.agendula.data.tasks.room.AlarmReference
+import de.jeanlucmakiola.agendula.data.tasks.room.TaskAlarmEntity
+import de.jeanlucmakiola.agendula.data.tasks.room.TaskEntity
+import de.jeanlucmakiola.agendula.domain.ical.ICalComponent
+import de.jeanlucmakiola.agendula.domain.ical.ICalParam
+import de.jeanlucmakiola.agendula.domain.ical.ICalParser
+import de.jeanlucmakiola.agendula.domain.ical.ICalProperty
+import de.jeanlucmakiola.agendula.domain.ical.ICalSerializer
+import de.jeanlucmakiola.agendula.domain.ical.ICalValues
+import de.jeanlucmakiola.agendula.domain.DAY_MINUTES
+import de.jeanlucmakiola.agendula.domain.MIN_ALL_DAY_LEAD
+import kotlin.math.roundToLong
+import kotlin.time.Duration.Companion.milliseconds
+import kotlin.time.Duration.Companion.seconds
+import kotlin.time.Instant
+
+/**
+ * `VALARM` ↔ [TaskAlarmEntity].
+ *
+ * ## What is claimed
+ *
+ * Only an alarm Agendula can fire exactly as written becomes a reminder row.
+ * Everything else stays in the task's residue and round-trips untouched — it
+ * still fires in the client that wrote it, just not here:
+ *
+ * - `ACTION` other than `DISPLAY`/`AUDIO`;
+ * - Apple's default alarms (`X-APPLE-DEFAULT-ALARM:TRUE`). They are that Mac's
+ *   preference, not task data: claimed, they would come back to the Mac as an
+ *   explicit alarm without the flag after the first edit here;
+ * - location alarms (`X-APPLE-PROXIMITY`, RFC 9074 `PROXIMITY`, a nested
+ *   component) and Apple's `19760401T005545Z` sentinel trigger they carry;
+ * - repeating alarms (`REPEAT`/`DURATION`) and RFC 9074 snoozes (`RELATED-TO`);
+ * - a trigger *after* its anchor — on an all-day task, after the end of its
+ *   day. The planner coerces a negative lead to 0, so it would fire at the
+ *   wrong time;
+ * - an absolute trigger on a recurring task, or on one with no `DUE` to count
+ *   back from.
+ *
+ * ## What "unchanged" means
+ *
+ * A claimed row keeps the `VALARM` it was read from in [TaskAlarmEntity.raw].
+ * On write, the row is "unchanged" when that original still [resolve]s to the
+ * row's lead against the task *as it is now* — so `-PT15M` and `-P0DT0H15M0S`
+ * are the same, a relative alarm survives a due-date edit, and an absolute one
+ * stops matching once `DUE` moves. An unchanged row is re-emitted verbatim; a
+ * changed one is authored fresh under its existing uid.
+ *
+ * ## Anchors
+ *
+ * `RELATED=END` counts from `DUE`. `RELATED=START` (the default) counts from
+ * `DTSTART` — except when `DTSTART` equals `DUE`, or when there is no
+ * `DTSTART` but there is a `DUE`. Apple writes the latter shape (against §3.8.6.3,
+ * which wants `DTSTART` present).
+ *
+ * ## All-day tasks
+ *
+ * A relative trigger counts from the date's midnight, so the lead is the
+ * reminder as [de.jeanlucmakiola.agendula.domain.TaskReminder.allDay] reads it:
+ * `-P1D` is a day before at this device's all-day time, which this mapper cannot
+ * see, and `PT9H` is 09:00 on the day. An absolute trigger has no zone to read
+ * a time of day in, so it rounds to the nearest whole day.
+ */
+object AlarmCodec {
+
+    /** Apple's placeholder trigger for location alarms. Never a real time. */
+    private const val APPLE_SENTINEL = "19760401T005545Z"
+
+    /** What a `VALARM` means to the scheduler. */
+    data class Lead(val minutesBefore: Int, val reference: AlarmReference)
+
+    /** A `VALARM` as a reminder row — `taskId` is the caller's — or null if it is not ours to claim. */
+    fun fromVAlarm(alarm: ICalComponent, task: TaskEntity): TaskAlarmEntity? {
+        val lead = resolve(alarm, task) ?: return null
+        val raw = ICalSerializer.serialize(alarm)
+        // Too large to keep verbatim means it could not be re-emitted, and an
+        // alarm that is authored fresh on every write loses what made it large.
+        if (raw.toByteArray(Charsets.UTF_8).size > VTodoMapper.MAX_RESIDUE_BYTES) return null
+        val uid = (alarm.property("X-WR-ALARMUID") ?: alarm.property("UID"))?.value?.trim()?.takeIf { it.isNotEmpty() }
+        val base = TaskAlarmEntity(
+            taskId = 0,
+            minutesBefore = lead.minutesBefore,
+            reference = lead.reference,
+            raw = raw,
+        )
+        return if (uid == null) base else base.copy(uid = uid)
+    }
+
+    /** The lead [alarm] stands for on [task], or null when it is not claimable. */
+    fun resolve(alarm: ICalComponent, task: TaskEntity): Lead? {
+        val action = alarm.property("ACTION")?.value?.trim()?.uppercase()
+        if (action != "DISPLAY" && action != "AUDIO") return null
+        if (alarm.property("X-APPLE-DEFAULT-ALARM")?.value?.trim().equals("TRUE", ignoreCase = true)) return null
+        val excluded = listOf("X-APPLE-PROXIMITY", "PROXIMITY", "REPEAT", "DURATION", "RELATED-TO")
+        if (excluded.any { alarm.property(it) != null }) return null
+        if (alarm.components.isNotEmpty()) return null
+
+        val trigger = alarm.properties("TRIGGER").singleOrNull() ?: return null
+        val value = trigger.value.trim()
+        if (value.startsWith(APPLE_SENTINEL)) return null
+
+        val absolute = trigger.param("VALUE").equals("DATE-TIME", ignoreCase = true) ||
+            (!value.startsWith("P", ignoreCase = true) && !value.startsWith("-") && !value.startsWith("+"))
+        return if (absolute) absoluteLead(trigger, task) else relativeLead(trigger, task)
+    }
+
+    private fun relativeLead(trigger: ICalProperty, task: TaskEntity): Lead? {
+        val seconds = ICalValues.parseDuration(trigger.value) ?: return null
+        val reference = when {
+            trigger.param("RELATED").equals("END", ignoreCase = true) ->
+                if (task.due != null) AlarmReference.DUE else return null
+            task.dtstart != null && task.dtstart != task.due -> AlarmReference.START
+            task.due != null -> AlarmReference.DUE
+            else -> return null
+        }
+        val before = -seconds
+        // A lead in seconds is not one the planner can reproduce.
+        if (before % 60 != 0L) return null
+        val minutes = before / 60
+        val latest = if (task.isAllDay) MIN_ALL_DAY_LEAD.toLong() else 0L
+        return minutes.takeIf { it in latest..Int.MAX_VALUE }?.let { Lead(it.toInt(), reference) }
+    }
+
+    private fun absoluteLead(trigger: ICalProperty, task: TaskEntity): Lead? {
+        if (task.rrule != null || task.rdate != null) return null
+        val due = task.due ?: return null
+        val at = (ICalValues.parseTime(trigger) as? ICalValues.TimeValue.Timed)
+            ?.takeIf { it.tzid == null } // §3.8.6.3: an absolute trigger MUST be UTC
+            ?.instant ?: return null
+        val before = (due - at).inWholeSeconds
+        val minutes = if (task.isAllDay) {
+            // An all-day DUE is stored as UTC midnight of its date, which is
+            // the calendar date the trigger counts back from.
+            roundToDays(before)
+        } else {
+            Math.floorDiv(before, 60L)
+        }
+        return minutes.toIntOrNull()?.let { Lead(it, AlarmReference.DUE) }
+    }
+
+    /**
+     * [read] as builds before 1.2 stored it on an all-day task: rounded to whole
+     * days. Such a row keeps the other client's time of day instead of overwriting it.
+     */
+    private fun readAsWholeDays(read: Lead, task: TaskEntity): Lead? =
+        if (task.isAllDay && read.minutesBefore % DAY_MINUTES != 0) {
+            read.copy(minutesBefore = roundToDays(read.minutesBefore * 60L).coerceAtLeast(0).toInt())
+        } else {
+            null
+        }
+
+    /** Nearest whole day, in minutes. */
+    private fun roundToDays(seconds: Long): Long =
+        (seconds / 86_400.0).roundToLong() * DAY_MINUTES
+
+    /** Negative is after the anchor, which is not claimed. */
+    private fun Long.toIntOrNull(): Int? = takeIf { it in 0..Int.MAX_VALUE }?.toInt()
+
+    /**
+     * [row] as a `VALARM` on [task], or null when it cannot be written: its
+     * anchor is missing. That row stays on the device — the planner ignores it
+     * too — because `RELATED=END` without `DUE` is a resource the server
+     * refuses ([VTodoMapper.validate]).
+     *
+     * ⚠️ A row whose anchor the task has lost is written against the other
+     * date, which is what the planner fires it from. Leaving it out would drop
+     * it from every other client, and the next download would then take it off
+     * this device too.
+     *
+     * [now] marks an authored alarm `ACKNOWLEDGED` once it is past even the
+     * planner's missed-reminder grace, so a client that honours RFC 9074 does
+     * not greet it as a missed alarm. Not sooner: the stamp comes back on the
+     * next download and would silence the late reminder this device still owes.
+     */
+    fun toVAlarm(row: TaskAlarmEntity, task: TaskEntity, now: Instant): ICalComponent? {
+        val reference = when {
+            row.reference == AlarmReference.START && task.dtstart == null -> AlarmReference.DUE
+            row.reference == AlarmReference.DUE && task.due == null -> AlarmReference.START
+            else -> row.reference
+        }
+        val lead = Lead(row.minutesBefore, reference)
+        row.raw?.let(::parse)?.let { original ->
+            val read = resolve(original, task)
+            if (read == lead || read != null && readAsWholeDays(read, task) == lead) return original
+        }
+
+        val anchor = when (reference) {
+            AlarmReference.DUE -> task.due
+            AlarmReference.START -> task.dtstart
+        } ?: return null
+        val related = if (reference == AlarmReference.DUE) "END" else "START"
+        val minutes = row.minutesBefore.coerceAtLeast(if (task.isAllDay) MIN_ALL_DAY_LEAD else 0).toLong()
+        val seconds = -minutes * 60
+
+        val properties = mutableListOf(
+            ICalProperty("UID", value = row.uid),
+            ICalProperty("X-WR-ALARMUID", value = row.uid),
+            ICalProperty("ACTION", value = "DISPLAY"),
+            ICalProperty("DESCRIPTION", value = ICalValues.escapeText(row.message ?: "Reminder")),
+            ICalProperty("TRIGGER", listOf(ICalParam("RELATED", related)), ICalValues.formatDuration(seconds)),
+        )
+        val recurring = task.rrule != null || task.rdate != null
+        if (!recurring && anchor + seconds.seconds + ReminderPlanner.MISSED_GRACE_MS.milliseconds < now) {
+            properties += ICalProperty("ACKNOWLEDGED", value = ICalValues.formatDateTime(now, null))
+        }
+        return ICalComponent("VALARM", properties)
+    }
+
+    /**
+     * What [row] reads back as once it has been to the server and back — not
+     * always the row itself, because the wire is coarser: a lead past the end
+     * of its anchor is clamped, and a before-start row on a task without a
+     * start goes out before-due. A download that brings back exactly this has not changed the
+     * reminder, and the row's own lead must be kept rather than taken from it.
+     *
+     * ⚠️ As authored from the row, not re-emitted from [TaskAlarmEntity.raw]:
+     * a row rounded to whole days before 1.2 re-emits a time of day it does
+     * not hold, and would keep its rounded lead against the very alarm that
+     * carries it.
+     */
+    fun wireLead(row: TaskAlarmEntity, task: TaskEntity): Lead? =
+        toVAlarm(row.copy(raw = null), task, Instant.DISTANT_PAST)?.let { resolve(it, task) }
+
+    private fun parse(raw: String): ICalComponent? =
+        runCatching { ICalParser.parse(raw) }.getOrNull()?.takeIf { it.name.equals("VALARM", ignoreCase = true) }
+}

app/src/main/java/de/jeanlucmakiola/agendula/data/tasks/ical/VTodoMapper.kt

@@ -1,5 +1,6 @@
 package de.jeanlucmakiola.agendula.data.tasks.ical
 
+import de.jeanlucmakiola.agendula.data.tasks.room.TaskAlarmEntity
 import de.jeanlucmakiola.agendula.data.tasks.room.TaskEntity
 import de.jeanlucmakiola.agendula.domain.PRIORITY_NONE
 import de.jeanlucmakiola.agendula.domain.TaskStatus
@@ -9,6 +10,7 @@ import de.jeanlucmakiola.agendula.domain.ical.ICalParser
 import de.jeanlucmakiola.agendula.domain.ical.ICalProperty
 import de.jeanlucmakiola.agendula.domain.ical.ICalSerializer
 import de.jeanlucmakiola.agendula.domain.ical.ICalValues
+import de.jeanlucmakiola.agendula.domain.normalizeTags
 import java.time.ZoneId
 import kotlin.time.Clock
 import kotlin.time.Instant
@@ -51,10 +53,11 @@ import kotlin.time.Instant
  *
  * ## Alarms
  *
- * `VALARM`s round-trip in the residue and are never authored here. Local
- * reminders live in `task_alarms` and are never serialised. The two stores are
- * disjoint, so neither can destroy the other. Merging them is a later
- * decision, not a silent one.
+ * A `VALARM` [AlarmCodec] can fire exactly as written is claimed into
+ * [Mapped.alarms] — rows for `task_alarms`, carrying the original verbatim —
+ * and [write] authors the task's rows back. Any other `VALARM` (Apple's default
+ * and location alarms, repeating ones, snoozes) stays in the residue and is
+ * re-emitted untouched after the authored ones.
  */
 object VTodoMapper {
 
@@ -81,6 +84,8 @@ object VTodoMapper {
         // Parameterised copies stay in the residue verbatim; authoring the
         // column beside them would emit the same exclusions twice.
         "RDATE", "EXDATE",
+        // Several lines, or one the column would not re-serialise exactly.
+        "CATEGORIES",
     )
 
     /** What a VTODO yields. Row identity ([TaskEntity.id], `listId`) is the caller's. */
@@ -92,6 +97,8 @@ object VTodoMapper {
         val uidWasMissing: Boolean,
         /** Residue that exceeded [MAX_RESIDUE_BYTES] and had to be dropped. */
         val droppedResidue: Boolean,
+        /** The claimed `VALARM`s, `taskId` unset. Not counted against the residue cap. */
+        val alarms: List<TaskAlarmEntity> = emptyList(),
     )
 
     // ---------------------------------------------------------------- read
@@ -200,6 +207,9 @@ object VTodoMapper {
             CLASS_NAMES.indexOf(classProperty?.value?.trim()?.uppercase()).takeIf { it >= 0 },
         )
 
+        val (categories, categoriesProperty) = readCategories(vtodo)
+        claim(categoriesProperty)
+
         val sequenceProperty = vtodo.property("SEQUENCE")
         val sequence = take(
             sequenceProperty,
@@ -225,6 +235,7 @@ object VTodoMapper {
             title = take(vtodo.property("SUMMARY"), vtodo.property("SUMMARY")?.text()),
             description = take(vtodo.property("DESCRIPTION"), vtodo.property("DESCRIPTION")?.text()),
             location = take(vtodo.property("LOCATION"), vtodo.property("LOCATION")?.text()),
+            categories = categories,
             // URI, not TEXT — escaping it would corrupt a query string.
             url = take(vtodo.property("URL"), vtodo.property("URL")?.value?.trim()),
             status = status,
@@ -256,8 +267,18 @@ object VTodoMapper {
             .filterIndexed { index, _ -> index !in claimed }
             .filterNot { it.name.equals("DTSTAMP", ignoreCase = true) }
 
+        // Claimed against the entity as read, so the anchors are the ones the
+        // rows will be written back against.
+        val alarms = mutableListOf<TaskAlarmEntity>()
+        val residueComponents = vtodo.components.filter { component ->
+            if (!component.name.equals("VALARM", ignoreCase = true)) return@filter true
+            val row = AlarmCodec.fromVAlarm(component, entity) ?: return@filter true
+            alarms += row
+            false
+        }
+
         val residueText = ICalSerializer.serializeProperties(residueProperties) +
-            ICalSerializer.serializeAll(vtodo.components)
+            ICalSerializer.serializeAll(residueComponents)
         val tooLarge = residueText.toByteArray(Charsets.UTF_8).size > MAX_RESIDUE_BYTES
 
         return Mapped(
@@ -267,6 +288,7 @@ object VTodoMapper {
             parentUid = parentUid,
             uidWasMissing = uid.isEmpty(),
             droppedResidue = tooLarge,
+            alarms = alarms,
         )
     }
 
@@ -276,16 +298,19 @@ object VTodoMapper {
      * Serialises [entity] back to a VTODO.
      *
      * [parentUid] is the parent's `UID`, which the entity holds only as a row id.
-     * [now] is the `DTSTAMP`.
+     * [now] is the `DTSTAMP`. [alarms] are the task's reminder rows; one whose
+     * anchor the task no longer has is left out (see [AlarmCodec.toVAlarm]).
      */
     fun write(
         entity: TaskEntity,
         parentUid: String? = null,
         now: Instant = Clock.System.now(),
+        alarms: List<TaskAlarmEntity> = emptyList(),
     ): ICalComponent {
         val residue = parseResidue(entity.unknownProperties)
+        val residueCategories = normalizeTags(residue.properties("CATEGORIES").flatMap(::categoryValues))
         val keptResidue =
-            residue.properties.filterNot { contradictsResidue(it, residue, entity, parentUid) }
+            residue.properties.filterNot { contradictsResidue(it, residue, residueCategories, entity, parentUid) }
         val suppressed = keptResidue
             .map { it.name.uppercase() }
             .filterTo(mutableSetOf()) { it in SUPPRESSED_BY_RESIDUE }
@@ -307,6 +332,7 @@ object VTodoMapper {
         add("DESCRIPTION", entity.description?.let(ICalValues::escapeText))
         add("LOCATION", entity.location?.let(ICalValues::escapeText))
         add("URL", entity.url)
+        add("CATEGORIES", normalizeTags(entity.categories).takeIf { it.isNotEmpty() }?.let(ICalValues::formatTextList))
 
         add("STATUS", entity.status.toICalName())
         add("PERCENT-COMPLETE", entity.percentComplete?.toString())
@@ -340,7 +366,7 @@ object VTodoMapper {
         return ICalComponent(
             name = "VTODO",
             properties = properties + keptResidue,
-            components = residue.components,
+            components = alarms.mapNotNull { AlarmCodec.toVAlarm(it, entity, now) } + residue.components,
         )
     }
 
@@ -386,6 +412,7 @@ object VTodoMapper {
     private fun contradictsResidue(
         property: ICalProperty,
         residue: ICalComponent,
+        residueCategories: List<String>,
         entity: TaskEntity,
         parentUid: String?,
     ): Boolean {
@@ -433,6 +460,7 @@ object VTodoMapper {
             "PRIORITY" -> entity.priority != PRIORITY_NONE
             "PERCENT-COMPLETE" -> entity.percentComplete != null
             "CLASS" -> entity.classification != null
+            "CATEGORIES" -> entity.categories != residueCategories
             // Not SEQUENCE: it is the organiser's counter and never ours to bump,
             // so the column stays at its fallback and the residue always wins.
             else -> false
@@ -475,6 +503,23 @@ object VTodoMapper {
 
     // -------------------------------------------------------------- helpers
 
+    /**
+     * Every `CATEGORIES` copy's values, merged, and the one line to claim — only
+     * when it is the sole, parameterless copy and the column re-serialises it
+     * byte for byte. Anything else is read for display and stays in the residue.
+     */
+    private fun readCategories(vtodo: ICalComponent): Pair<List<String>, ICalProperty?> {
+        val copies = vtodo.properties("CATEGORIES")
+        val values = normalizeTags(copies.flatMap(::categoryValues))
+        val claimable = copies.singleOrNull()?.takeIf {
+            it.params.isEmpty() && values.isNotEmpty() && ICalValues.formatTextList(values) == it.value
+        }
+        return values to claimable
+    }
+
+    private fun categoryValues(property: ICalProperty): List<String> =
+        normalizeTags(ICalValues.parseTextList(property.value))
+
     private val CLASS_NAMES = listOf("PUBLIC", "PRIVATE", "CONFIDENTIAL")
 
     private class TimeRead(

app/src/main/java/de/jeanlucmakiola/agendula/data/tasks/legacy/OneShotImport.kt

@@ -15,6 +15,7 @@ import de.jeanlucmakiola.agendula.data.tasks.room.TaskEntity
 import de.jeanlucmakiola.agendula.data.tasks.room.TaskListEntity
 import de.jeanlucmakiola.agendula.data.tasks.room.TasksDatabase
 import de.jeanlucmakiola.agendula.domain.PRIORITY_NONE
+import de.jeanlucmakiola.agendula.domain.normalizeTags
 import de.jeanlucmakiola.agendula.domain.statusFromInt
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.flow.Flow
@@ -221,12 +222,17 @@ class OneShotImport @Inject constructor(
             }
 
         val alarms = mutableListOf<LegacyAlarm>()
-        db.rawQuery("SELECT task_id, mimetype, data0, data1, data2 FROM Properties", null)
+        val categories = mutableMapOf<Long, MutableList<String>>()
+        db.rawQuery("SELECT task_id, mimetype, data0, data1, data2 FROM Properties ORDER BY property_id", null)
             .use { cursor ->
                 val r = CursorColumnReader(cursor)
                 while (cursor.moveToNext()) {
-                    if (r.getString("mimetype") != ALARM_MIMETYPE) continue
                     val taskId = r.getLong("task_id") ?: continue
+                    if (r.getString("mimetype") == CATEGORY_MIMETYPE) {
+                        r.getString("data1")?.let { categories.getOrPut(taskId, ::mutableListOf) += it }
+                        continue
+                    }
+                    if (r.getString("mimetype") != ALARM_MIMETYPE) continue
                     val minutes = r.getString("data0")?.trim()?.toIntOrNull() ?: continue
                     alarms += LegacyAlarm(
                         taskId = taskId,
@@ -241,7 +247,7 @@ class OneShotImport @Inject constructor(
                 }
             }
 
-        return LegacySnapshot(lists, rows, alarms)
+        return LegacySnapshot(lists, rows, alarms, categories.mapValues { normalizeTags(it.value) })
     }
 
     // --- writing into Room ----------------------------------------------------
@@ -276,7 +282,12 @@ class OneShotImport @Inject constructor(
             // the unique index; a fresh uid costs the row nothing it still has.
             val uid = row.entity.uid.takeIf { seen.add(Triple(listId, it, recurrenceId)) }
                 ?: UUID.randomUUID().toString()
-            val entity = row.entity.copy(listId = listId, uid = uid, recurrenceId = recurrenceId)
+            val entity = row.entity.copy(
+                listId = listId,
+                uid = uid,
+                recurrenceId = recurrenceId,
+                categories = snapshot.categories[row.id].orEmpty(),
+            )
             val newId = taskDao.insert(entity)
             taskIds[row.id] = newId
             inserted += row to entity.copy(id = newId)
@@ -379,6 +390,7 @@ class OneShotImport @Inject constructor(
         const val ARCHIVE_NAME = "tasks.db.imported"
 
         private const val ALARM_MIMETYPE = "vnd.android.cursor.item/alarm"
+        private const val CATEGORY_MIMETYPE = "vnd.android.cursor.item/category"
         private const val REFERENCE_START = "2"
         private val SIDECARS = listOf("-journal", "-wal", "-shm")
         private val IMPORT_DONE = booleanPreferencesKey("legacy_import_done")
@@ -391,6 +403,8 @@ private class LegacySnapshot(
     val lists: List<LegacyList>,
     val tasks: List<LegacyTaskRow>,
     val alarms: List<LegacyAlarm>,
+    /** Tags by legacy task `_id`. */
+    val categories: Map<Long, List<String>>,
 )
 
 private class LegacyList(val id: Long, val entity: TaskListEntity)