build,docs: add on-device release verification gate

Adds a mandatory pre-tag step to the release process: build the R8-shrunk
release candidate and smoke-test it on a real device, including a first-run /
permission-not-granted state. The v2.7.0 launch crash (calendar observer
registered before the permission gate) reached users because it only manifests
in the minified release build on a device without the permission already
granted — the debug build and an already-permissioned phone both hid it.

- New `releaseTest` build type: same R8 shrinking + obfuscation as `release`,
  but debug-signed with a `.releasetest` applicationId suffix so it installs
  alongside the production and debug apps. Never published; CI only ever builds
  the real `release` variant from the tag.
- scripts/verify-release.sh: builds + installs `releaseTest` and resets it to a
  first-run state, with an on-device checklist.
- docs/RELEASING.md: formalize the release/vX.Y.Z branch flow and the on-device
  verification gate before tagging.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/build.gradle.kts

@@ -61,6 +61,21 @@ android {
             applicationIdSuffix = ".debug"
             isMinifyEnabled = false
         }
+        // A locally-installable twin of `release`: same R8 shrinking + obfuscation
+        // and resource shrinking, but debug-signed and given its own applicationId
+        // suffix so it installs alongside both the production app (signed with the
+        // real key) and the debug build. Used to smoke-test a release candidate on
+        // a real device before tagging — R8-only breakage and first-run/permission
+        // states don't surface in the unminified debug build, nor on a device that
+        // already holds the permission. Never published. See docs/RELEASING.md.
+        create("releaseTest") {
+            initWith(getByName("release"))
+            applicationIdSuffix = ".releasetest"
+            signingConfig = signingConfigs.getByName("debug")
+            isMinifyEnabled = true
+            isShrinkResources = true
+            matchingFallbacks += "release"
+        }
     }
 
     compileOptions {

docs/RELEASING.md

@@ -22,20 +22,44 @@ Published version codes so far: `v0.1.0`→100 … `v1.0.0`→10000 … `v2.0.0`
 
 ## Cutting a release
 
-1. Move the `## [Unreleased]` section of `CHANGELOG.md` under a new
+1. **Assemble the release branch.** Create `release/vX.Y.Z` and merge the
+   feature/fix branches that make up this release into it. This branch is the
+   release candidate — everything below happens on it, before it reaches `main`.
+2. Move the `## [Unreleased]` section of `CHANGELOG.md` under a new
    `## [X.Y.Z] — <date>` heading (Keep a Changelog format). The text between
    that heading and the next `## [` becomes both the Gitea release notes and
    the F-Droid per-version changelog.
-2. Optionally bump the committed `versionCode`/`versionName` in
-   `app/build.gradle.kts` to match the new version (keeps local builds tidy).
-3. Commit, then tag and push:
+3. Bump the committed `versionCode`/`versionName` in `app/build.gradle.kts` to
+   match the new version (keeps local builds tidy; CI overwrites from the tag).
+4. **Verify the release build on a real device** — the mandatory gate. The
+   shipped APK is R8-shrunk/obfuscated, and bugs that only appear there, or
+   only on first run, never show up in the debug build or on a device that
+   already granted the calendar permission (this is how the v2.7.0 launch
+   crash slipped through). Run:
+   ```bash
+   scripts/verify-release.sh
+   ```
+   It builds the `releaseTest` variant (same R8 config as `release`, debug-signed
+   with a `.releasetest` suffix so it installs alongside the real app) and resets
+   it to a first-run state. Then, on the device:
+   - launch from a **clean / permission-not-granted** state — the permission
+     screen must appear, no crash;
+   - grant access — the calendar must load;
+   - add both home-screen **widgets** and confirm they render;
+   - exercise this release's headline changes.
+
+   Only proceed once all of that passes on-device.
+5. Merge `release/vX.Y.Z` into `main`, then tag and push:
    ```bash
    git tag vX.Y.Z
    git push origin vX.Y.Z
    ```
-4. The push triggers the release workflow. **Hold UI releases for on-device
+6. The push triggers the release workflow. **Hold UI releases for on-device
    review and explicit go-ahead before tagging.**
 
+> The `releaseTest` build type exists only for step 4 — it is never published.
+> The pipeline always builds and signs the real `release` variant from the tag.
+
 ## What the pipeline does
 
 `release.yaml` has three jobs:

scripts/verify-release.sh

@@ -0,0 +1,42 @@
+#!/usr/bin/env bash
+#
+# Build the release-candidate APK and install it on a connected device for the
+# mandatory pre-tag on-device check (see docs/RELEASING.md).
+#
+# It builds the `releaseTest` variant: the same R8 shrinking + obfuscation and
+# resource shrinking as the published `release` build, but debug-signed and
+# with a `.releasetest` applicationId suffix so it installs alongside the
+# production and debug apps. This is what surfaces release-only breakage (R8
+# stripping) and first-run states (permission not yet granted) that the
+# unminified debug build — or a device that already holds the permission —
+# silently hides.
+#
+# Usage: scripts/verify-release.sh
+set -euo pipefail
+
+cd "$(dirname "$0")/.."
+
+PKG="de.jeanlucmakiola.calendula.releasetest"
+APK="app/build/outputs/apk/releaseTest/app-releaseTest.apk"
+
+echo "==> Building release-candidate APK (releaseTest, R8 minified)…"
+./gradlew :app:assembleReleaseTest
+
+echo "==> Installing $PKG …"
+adb install -r "$APK"
+
+echo "==> Resetting to a first-run state (revoking calendar permission)…"
+# The release build crashed at launch precisely because this state was never
+# tested. Force it so the permission gate / onboarding is exercised every time.
+adb shell pm revoke "$PKG" android.permission.READ_CALENDAR  2>/dev/null || true
+adb shell pm revoke "$PKG" android.permission.WRITE_CALENDAR 2>/dev/null || true
+
+echo
+echo "Installed and reset. Now verify ON THE DEVICE before tagging:"
+echo "  1. Launch from a clean state — the permission screen must appear (no crash)."
+echo "  2. Grant calendar access — the calendar must load with events."
+echo "  3. Add both home-screen widgets and confirm they render (not a spinner)."
+echo "  4. Exercise the release's headline changes end to end."
+echo
+echo "Watch for crashes with:  adb logcat -b crash"
+echo "Only tag the release once all of the above pass on a real device."