Merge pull request 'feat: editable event attendees with contact picker' (!29) from feat/attendee-editing into release/v2.8.0

Reviewed-on: #29

.planning/ROADMAP.md

@@ -236,22 +236,34 @@ pass on the existing controls; new toggles ride in with their own features.
 9. **Reminders — defaults + delivery reliability** *(shipped v2.6.0)* — global
    default reminder **+ per-calendar override**, bundled with battery-exemption
    hardening. Full sketch in "Reminders — defaults & delivery reliability" below.
-10. **The `.ics` engine — export + import** *(in progress → v2.7)* — one
+10. **The `.ics` engine — export + import** *(shipped v2.7.0, 2026-06-18)* — one
     hand-rolled serializer/parser (zero deps, stays on `kotlinx-datetime`),
-    four surfaces: single-event share + whole-calendar backup (export),
+    four surfaces all shipped: single-event share + whole-calendar backup
-    open-`.ics`→form + whole-calendar restore (import). Closes the
+    (export), open-`.ics`→form + whole-calendar bulk import (import). Closed the
-    device-local-calendar data-loss gap (#10/#11 merged here). Built as **two
+    device-local-calendar data-loss gap (#10/#11 merged here). Built as two
-    sequential branches in one release**: `feat/ics-export` (write side +
+    sequential branches: `feat/ics-export` (write side + UID-on-create precursor)
-    UID-on-create precursor) then `feat/ics-import` (parser, restore, dedup).
+    then `feat/ics-import` (parser, restore, dedup by UID). Import is
-    Import is liberal-in/strict-out: skip-and-report foreign `VTIMEZONE` /
+    liberal-in/strict-out: skip-and-report foreign `VTIMEZONE` / `RECURRENCE-ID`
-    `RECURRENCE-ID` it can't model. Timezone rule: all-day `VALUE=DATE`,
+    / guest lists it can't model. Plans:
-    non-recurring timed UTC `Z`, recurring timed `TZID`-labelled from the stored
+    `docs/superpowers/plans/2026-06-18-05-ics-export.md` + `…-06-ics-import.md`.
-    `EVENT_TIMEZONE` (no `VTIMEZONE` blocks; resolved against the OS tz DB on
+11. **Snooze / dismiss notification actions** *(merged into release/v2.8.0)* —
-    import). Plan: `docs/superpowers/plans/2026-06-18-05-ics-export.md`.
+    followed the `.ics` work; inherits v2.6's deferred exact-alarm/WorkManager
-11. **Snooze / dismiss notification actions** *(next, after v2.7)* — follows the
+    decision (snooze must re-fire an alarm).
-    `.ics` work; inherits v2.6's deferred exact-alarm/WorkManager decision (snooze
+
-    must re-fire an alarm).
+**Tier 5 — close the read/write gap on the event model** *(opened 2026-06-22)*
-12. Drag & drop rescheduling in day/week — big-ticket, own slice (recurring drops reuse the scope dialog)
+12. **Attendee editing** *(next — promoted from the gated "Locations & People"
+    bucket, owner says high-importance 2026-06-22)* — attendees are already
+    *read* (queried, mapped, shown on the detail screen since v0.6) but the
+    event form can't *write* them, the last big read-only gap in the event
+    model. Add an attendees section to `EventEditScreen` / `EventForm`: add by
+    typed email (contact-picker entry can follow later), edit/remove rows, set
+    role (required / optional) — writing `CalendarContract.Attendees` rows on
+    insert + dirty-checked update, mirroring the reminders-diff pattern.
+    **Caveat to resolve first:** writing `Attendees` rows triggers sync-adapter
+    *invitation* behavior that differs by backend (Google auto-emails invites;
+    DAVx5/CalDAV writes the `ATTENDEE` property and lets the server decide) —
+    decide and document what Calendula promises before building. Full sketch in
+    "Attendee editing" under Locations & People below.
 
 **Gated — explicit go/no-go before any work (mostly INTERNET-permission calls)**
 - Remote calendar create/edit (re-implements DAVx5; INTERNET + credential storage)
@@ -263,11 +275,13 @@ pass on the existing controls; new toggles ride in with their own features.
   2026-06-17; cheap but low value, pick up only if asked
 
 **Unranked / fill-in** — pinch-to-zoom time scale, tablet/foldable layouts,
-full-text search, ICS file import. Pulled in opportunistically, not sequenced.
+full-text search. Pulled in opportunistically, not sequenced.
 
-Debatable calls worth a second look: whether **local-calendar backup (#10)**
+Tier 4 is now fully shipped (#9 reminders defaults v2.6.0, #10 `.ics`
-should lead Tier 4 outright (it's a silent data-loss risk, not a feature);
+export/import v2.7.0, #11 snooze/dismiss in release/v2.8.0; drag-drop rejected).
-whether drag-drop (#12) jumps ahead given its daily-driver impact.
+**Next committed work is Tier 5 #12 — attendee editing** (the last read-only gap
+in the event model). After it: the theme-group ideas and Tier 2/3 leftovers
+(quick-settings tile, now-line, week numbers in month, full-text search).
 
 ## Navigation & views
 
@@ -288,8 +302,6 @@ whether drag-drop (#12) jumps ahead given its daily-driver impact.
 
 ## Event editing & creation
 
-- Drag & drop rescheduling in day/week (recurring drops reuse the scope
-  dialog) — big-ticket, own slice
 - Duplicate event (detail action → prefilled create form)
 - **Per-event color** (`Events.EVENT_COLOR`, OptionCard picker in the form)
   *(next)* — chosen to follow the in-progress tap-to-create + calendar
@@ -319,13 +331,11 @@ whether drag-drop (#12) jumps ahead given its daily-driver impact.
   go/no-go gate as the OSM/INTERNET item below.
 - Move event to another calendar (copy+delete model with a consequences
   warning — deferred from v2.0; `CALENDAR_ID` is sync-adapter-owned) *(was v3.0)*
-- **Local-calendar backup / export** *(Tier 4 #10)* — device-only
+- ~~**Local-calendar backup / export** *(Tier 4 #10)*~~ **shipped v2.7.0** —
-  (`ACCOUNT_TYPE_LOCAL`) calendars are first-class in Calendula but have **no
+  device-only (`ACCOUNT_TYPE_LOCAL`) calendars had no sync and therefore no
-  sync and therefore no backup**: a lost/wiped phone destroys them permanently.
+  backup. Settings → Calendars → Export writes every event to a user-chosen
-  Whole-calendar `.ics` (VCALENDAR) export to a user-chosen file (SAF), plus
+  `.ics` file (SAF); restore is the bulk-import path (pick a calendar, dedup by
-  restore-on-import that recreates events into a chosen local calendar. Reuses
+  UID). Closed the silent data-loss gap.
-  the .ics serializer from the single-event share work; the restore path reuses
-  the import parser. A data-integrity obligation, not a feature.
 
 ## Reminders — defaults & delivery reliability *(implemented 2026-06-17, `feat/default-reminders` — pending on-device review)*
 
@@ -419,9 +429,11 @@ it directly undermines the feature's premise, so it rides in here.
 
 ## Sharing & interop
 
-- Share event as .ics + open/receive .ics into a prefilled create form
+- ~~Share event as .ics + open/receive .ics into a prefilled create form~~
-  (front-runs the import below)
+  **shipped v2.7.0** — single-event share from detail; opening an `.ics` with one
-- ICS file import (drag-and-drop) *(was v3.0, optional)*
+  event prefills the create form, many events opens a bulk import (dedup by UID)
+- ~~ICS file import~~ **shipped v2.7.0** — covered by the open/receive `.ics`
+  flow above (single → form, many → bulk import)
 
 ## Platform & launchers
 
@@ -455,9 +467,57 @@ in detail yet:
   trade-off is an explicit go/no-go decision before any work starts.
 - **Inline contact suggestions** while typing (needs READ_CONTACTS) — only
   if the picker proves clunky.
-- **Attendee editing / invites from contacts** — own milestone; writing
+- **Attendee editing** *(promoted out of this gated bucket 2026-06-22 — now
-  `Attendees` rows touches sync-adapter invitation behavior (Google vs
+  Tier 5 #12, high-importance; the no-permission typed-email path is not an
-  DAVx5 differ).
+  INTERNET/contacts call)*. See the "Attendee editing" sketch below.
+
+### Attendee editing *(Tier 5 #12, opened 2026-06-22)*
+
+The last read-only gap in the event model: attendees are read & shown on the
+detail screen (since v0.6) but the form can't write them. Make guests editable.
+
+- **Read side already done:** `Attendee` domain model + status/relationship/type
+  enums, `queryAttendees` + `EventDetailMapper.toAttendee` (with tests), and the
+  attendees `DetailCard` + `AttendeeRow` in `EventDetailScreen`. Nothing to add
+  there.
+- **Write side — SHIPPED (`feat/attendee-editing`, commit b0f34ff, 2026-06-22):**
+  `attendees` on `EventForm`; a Guests section in `EventEditScreen` rendered as an
+  inline grouped list — each guest a tonal card (avatar, name/email, tappable
+  Required/Optional role chip, remove), the trailing card an inline email field
+  (type → Done commits). Persisted by `reconcileAttendees` diffing the provider's
+  `CalendarContract.Attendees` rows on insert + dirty-checked update (new guests =
+  `RELATIONSHIP_ATTENDEE` / `STATUS_INVITED`; kept rows keep their status, only the
+  required/optional type updates; organizer/resource/no-email rows untouched).
+  Reminders restyled to the same grouped-list pattern in passing. Needs only the
+  existing `WRITE_CALENDAR` — no new permission.
+- **Name on manual add — SHIPPED via a contact picker** (2026-06-22). The inline
+  field is email-only (the quick path); the add row also has a **"from contacts"
+  button**: `ACTION_PICK` on `ContactsContract.CommonDataKinds.Email.CONTENT_URI` →
+  the system Contacts app returns a URI to the picked email row, queried for
+  `Email.ADDRESS` **and** the contact `DISPLAY_NAME`, so a picked guest gets both
+  email and name in one tap. The result Intent grants temporary read access, so
+  **no `READ_CONTACTS` permission** — one-shot and user-driven, same no-permission
+  mechanism as the location address picker above. Self/organizer rows stay
+  non-editable.
+- **Invitation behavior — DECIDED 2026-06-22: record-only, all writable
+  calendars.** Calendula has no INTERNET and never sends an invitation itself; it
+  only writes `Attendees` rows. Whether a guest is notified is decided downstream:
+  local calendars notify no one (no sync); CalDAV/DAVx5 PUTs the `ATTENDEE` lines
+  and the *server* decides iMIP delivery; Google's sync adapter pushes the change
+  and Google decides (third-party attendee writes are historically unreliable
+  there). Editing is allowed on **any writable calendar** — not gated to local.
+  - **Honest, backend-aware copy is mandatory** (this is the whole point of the
+    decision): on a synced calendar show "Calendula doesn't send invitations —
+    your calendar account may email guests when it syncs"; on a local calendar
+    show "Stored on this device. No one is notified."
+  - Calendula must **not fabricate an ORGANIZER** or otherwise fake scheduling
+    state to coax a send — it writes the guest list faithfully and leaves
+    scheduling entirely to the backend.
+  - The optional "send an .ics invite via your email app" delegate (`ACTION_SEND`,
+    still no INTERNET) was considered and **deferred** — revisit only if users ask
+    to notify guests explicitly.
+- **Out of scope (for now):** RSVP/your-own-response editing, free/busy lookups,
+  resource booking — all carry server round-trips or richer sync semantics.
 
 ## Consciously rejected
 
@@ -465,3 +525,5 @@ in detail yet:
 - Natural-language quick entry (high effort, locale-fragile; the prefilled
   form already covers fast entry)
 - Quick-add sheet (the prefilled full form already covers it — cut in v2.0)
+- Drag & drop rescheduling in day/week — **rejected** (owner decision,
+  reaffirmed 2026-06-22): not wanted. Rescheduling stays via the edit form.

.planning/STATE.md

@@ -1,17 +1,27 @@
 # Calendula — Current State
 
-*Last updated: 2026-06-17*
+*Last updated: 2026-06-22*
 
 ## Status
 
-**Milestone:** 2 (write support) **complete** — v2.0.0 shipped 2026-06-11;
+**Milestone:** 2 (write support) **complete** — v2.0.0 shipped 2026-06-11.
-v2.1.0 (month event grid, drawer view tabs, cursor fix) shipped 2026-06-15.
+**Phase:** post-2.x theme-based backlog work (organised in `ROADMAP.md`).
-**Phase:** post-2.1 backlog work. v2.2.0 (tap-to-create in day/week + local
+**Latest released tag: v2.7.5.** The whole Tier 4 (reliability/data-safety/
-calendar management) and v2.3.0 (Material 3 grouped-list redesign of Settings,
+interop) arc is now done or in flight:
-the calendar manager and the navigation drawer) both shipped 2026-06-16;
+- v2.4.0 per-event colors (2026-06-17)
-v2.4.0 (per-event colors) and v2.5.0 (jump-to-date, Agenda view, home-screen
+- v2.5.0 jump-to-date, Agenda view, agenda + month home-screen widgets, "New
-agenda + month widgets, and a "New event" launcher shortcut) shipped
+  event" launcher shortcut (2026-06-17)
-2026-06-17. The backlog is now organised by theme in `ROADMAP.md`.
+- v2.6.0 default reminders (global + per-calendar override, all-day default,
+  battery-exemption row) + system per-app language (2026-06-18)
+- v2.7.0 **`.ics` engine** — single-event share, local-calendar backup export,
+  open/receive `.ics` (single → form, many → bulk import, dedup by UID)
+  (2026-06-18)
+- v2.7.1–v2.7.5 — crash-reporting + F-Droid reproducible-build hardening + fixes
+
+**Next release `release/v2.8.0` (integration branch, not yet cut to main):**
+holds crash reports via the public Codeberg tracker (MR !27) + reminder
+snooze/dismiss notification actions (MR !28). Version bump to 2.8.0 happens at
+release-cut.
 
 ## Progress
 
@@ -120,11 +130,48 @@ agenda + month widgets, and a "New event" launcher shortcut) shipped
   sync" warning on the picker and in Settings. Color writes flow through
   insert / dirty-checked update / occurrence-exception; mapper + form tests.
 
+- [x] v2.5 (shipped 2026-06-17) — Agenda view (4th top-level view),
+  jump-to-date drawer date picker, two home-screen widgets (scrolling
+  "Upcoming" agenda + month grid), and a "New event" launcher long-press
+  shortcut
+
+- [x] v2.6 (shipped 2026-06-18) — default reminders: global timed default +
+  separate all-day default + per-calendar override (timed), applied on create
+  with dirty-flag handling; three pickers + override list in Settings →
+  Notifications; battery-optimisation exemption row (status + system deep-link,
+  no new permission). Plus system per-app language (Android 13+) and an
+  immediate-effect fix for the in-app language picker
+
+- [x] v2.7 (shipped 2026-06-18) — the `.ics` engine: share a single event as
+  `.ics` from the detail screen; back up local calendars (Settings → Calendars
+  → Export) to a SAF file; open/receive an `.ics` — one event prefills the
+  create form, many events open a bulk import into a chosen calendar (dedup by
+  UID, skip-and-report unrepresentable VTIMEZONE / RECURRENCE-ID / guests).
+  Hand-rolled serializer/parser, zero deps. Plus all-day single-day UTC fix and
+  a widget R8 keep-rule crash fix
+
+- [x] v2.7.1–v2.7.5 (2026-06-21) — launch crash fix (listener before grant),
+  user-controlled crash reporting, widget loading-spinner R8 keep rule, and
+  F-Droid reproducible-build cleanups for the official repo
+
+- [~] release/v2.8.0 (not yet cut) — crash reports via the public Codeberg
+  tracker (MR !27) + reminder snooze/dismiss notification actions (MR !28,
+  snooze self-schedules an exact alarm; primary delivery stays provider-broadcast)
+
 ## Next
 
-1. Monitor the F-Droid build/publish for the v2.4.0 tag
+1. Cut **v2.8.0** from `release/v2.8.0` (bump versionName → tag via the
-2. Decide the "Locations & People" and "remote calendar create/edit"
+   merge-driven pipeline) once on-device review signs off
-   go/no-go calls (both hinge on the INTERNET permission) — see `ROADMAP.md`
+2. **Attendee editing** — the committed next feature (Tier 5 #12, high-
-3. **Duplicate event** and **jump-to-date** are the cheap follow-ups; then
+   importance, opened 2026-06-22). Attendees are already read & shown on the
-   agenda view (strategic, backs a future widget). Full ranked sequence in
+   detail screen since v0.6; the gap is the write side — make guests editable
-   `ROADMAP.md` → "Near-term sequence".
+   in `EventEditScreen` / `EventForm` (add by typed email, role, remove),
+   persisted by diffing `CalendarContract.Attendees`. No new permission for the
+   typed-email path. **Invitation behavior DECIDED 2026-06-22: record-only on all
+   writable calendars** — Calendula never sends (no INTERNET); honest backend-aware
+   copy ("your account may email guests when it syncs" on synced calendars, "no one
+   is notified" on local). Full sketch in `ROADMAP.md` → "Attendee editing".
+3. Then: the two INTERNET go/no-go calls (OSM autocomplete, remote calendar
+   create/edit) and Tier 2/3 leftovers (quick-settings tile, now-line, week
+   numbers in month, full-text search, accessibility pass). Drag-and-drop
+   rescheduling is **rejected**.

app/src/main/java/de/jeanlucmakiola/calendula/data/calendar/CalendarDataSource.kt

@@ -17,6 +17,7 @@ import androidx.core.content.ContextCompat
 import dagger.hilt.android.qualifiers.ApplicationContext
 import de.jeanlucmakiola.calendula.domain.Attendee
 import de.jeanlucmakiola.calendula.domain.CalendarSource
+import de.jeanlucmakiola.calendula.domain.EventAttendee
 import de.jeanlucmakiola.calendula.domain.EventColorOption
 import de.jeanlucmakiola.calendula.domain.EventDetail
 import de.jeanlucmakiola.calendula.domain.EventForm
@@ -536,6 +537,10 @@ class AndroidCalendarDataSource @Inject constructor(
                     Log.w(TAG, "Failed to attach reminder ($minutes min) to event $eventId")
                 }
             }
+        // Guests are best-effort like reminders: a row that fails to attach is
+        // logged, not surfaced as a failed create. Calendula never sends an
+        // invitation — it only writes the rows; the backend decides delivery.
+        insertAttendees(eventId, form.attendees)
         return eventId
     }
 
@@ -565,6 +570,12 @@ class AndroidCalendarDataSource @Inject constructor(
         if (updated.reminders.toSet() != original.reminders.toSet()) {
             reconcileReminders(eventId, encodedReminders(updated, allDayReminderTimeMinutes))
         }
+        // Same untouched-set guard for guests: only reconcile when the form's
+        // attendees actually changed, so unrelated edits never disturb the
+        // organizer/resource rows the form doesn't model.
+        if (updated.attendees.toSet() != original.attendees.toSet()) {
+            reconcileAttendees(eventId, updated.attendees)
+        }
     }
 
     override fun updateOccurrence(
@@ -587,6 +598,7 @@ class AndroidCalendarDataSource @Inject constructor(
         // Whether the provider copied the parent's reminder rows is its
         // business — reconciling against the actual rows handles both ways.
         reconcileReminders(exceptionId, encodedReminders(form, allDayReminderTimeMinutes))
+        reconcileAttendees(exceptionId, form.attendees)
         return exceptionId
     }
 
@@ -720,6 +732,135 @@ class AndroidCalendarDataSource @Inject constructor(
         }
     }
 
+    /** Normalised key an attendee is matched/deduped on (case-insensitive email). */
+    private fun EventAttendee.key(): String = email.trim().lowercase()
+
+    /** Distinct guests by email; blanks dropped (we key and write on the address). */
+    private fun List<EventAttendee>.distinctByEmail(): List<EventAttendee> {
+        val seen = HashSet<String>()
+        return filter { it.email.isNotBlank() && seen.add(it.key()) }
+    }
+
+    private fun attendeeValues(eventId: Long, attendee: EventAttendee): ContentValues =
+        ContentValues().apply {
+            put(CalendarContract.Attendees.EVENT_ID, eventId)
+            put(CalendarContract.Attendees.ATTENDEE_EMAIL, attendee.email.trim())
+            attendee.name.trim().takeIf { it.isNotEmpty() }
+                ?.let { put(CalendarContract.Attendees.ATTENDEE_NAME, it) }
+            // A plain guest — never the organizer (we don't fabricate scheduling
+            // identity; the backend owns that). Invited = awaiting their reply.
+            put(
+                CalendarContract.Attendees.ATTENDEE_RELATIONSHIP,
+                CalendarContract.Attendees.RELATIONSHIP_ATTENDEE,
+            )
+            put(CalendarContract.Attendees.ATTENDEE_TYPE, attendee.providerType())
+            put(
+                CalendarContract.Attendees.ATTENDEE_STATUS,
+                CalendarContract.Attendees.ATTENDEE_STATUS_INVITED,
+            )
+        }
+
+    private fun EventAttendee.providerType(): Int = if (optional) {
+        CalendarContract.Attendees.TYPE_OPTIONAL
+    } else {
+        CalendarContract.Attendees.TYPE_REQUIRED
+    }
+
+    /** Best-effort attendee inserts (like reminders); emails are never logged. */
+    private fun insertAttendees(eventId: Long, attendees: List<EventAttendee>) {
+        attendees.distinctByEmail().forEach { attendee ->
+            if (resolver.insert(
+                    CalendarContract.Attendees.CONTENT_URI,
+                    attendeeValues(eventId, attendee),
+                ) == null
+            ) {
+                Log.w(TAG, "Failed to attach a guest to event $eventId")
+            }
+        }
+    }
+
+    private data class AttendeeRow(
+        val id: Long,
+        val email: String,
+        val relationship: Int,
+        val type: Int,
+    ) {
+        val key: String get() = email.trim().lowercase()
+    }
+
+    private fun queryAttendeeRows(eventId: Long): List<AttendeeRow> = resolver.query(
+        CalendarContract.Attendees.CONTENT_URI,
+        arrayOf(
+            CalendarContract.Attendees._ID,
+            CalendarContract.Attendees.ATTENDEE_EMAIL,
+            CalendarContract.Attendees.ATTENDEE_RELATIONSHIP,
+            CalendarContract.Attendees.ATTENDEE_TYPE,
+        ),
+        CalendarContract.Attendees.EVENT_ID + " = ?",
+        arrayOf(eventId.toString()),
+        null,
+    )?.use { c ->
+        buildList {
+            while (c.moveToNext()) {
+                add(
+                    AttendeeRow(
+                        id = c.getLong(0),
+                        email = c.getString(1).orEmpty(),
+                        relationship = c.getInt(2),
+                        type = c.getInt(3),
+                    ),
+                )
+            }
+        }
+    } ?: emptyList()
+
+    /**
+     * Make the event's *editable* guest rows match [attendees]. Only rows we
+     * own — has an email, not the organizer, not a resource — are reconciled;
+     * everything else the backend put there is left untouched. Matched rows keep
+     * their response status (only the required/optional type is updated if it
+     * changed); dropped rows are deleted; new guests inserted. Calendula sends
+     * nothing — the backend decides if anyone is notified on sync.
+     */
+    private fun reconcileAttendees(eventId: Long, attendees: List<EventAttendee>) {
+        val target = attendees.distinctByEmail()
+        val targetByKey = target.associateBy { it.key() }
+        val editable = queryAttendeeRows(eventId).filter {
+            it.email.isNotBlank() &&
+                it.relationship != CalendarContract.Attendees.RELATIONSHIP_ORGANIZER &&
+                it.type != CalendarContract.Attendees.TYPE_RESOURCE
+        }
+        val editableKeys = editable.map { it.key }.toSet()
+        editable.forEach { row ->
+            val want = targetByKey[row.key]
+            if (want == null) {
+                resolver.delete(
+                    CalendarContract.Attendees.CONTENT_URI,
+                    CalendarContract.Attendees._ID + " = ?",
+                    arrayOf(row.id.toString()),
+                )
+            } else if (row.type != want.providerType()) {
+                resolver.update(
+                    CalendarContract.Attendees.CONTENT_URI,
+                    ContentValues().apply {
+                        put(CalendarContract.Attendees.ATTENDEE_TYPE, want.providerType())
+                    },
+                    CalendarContract.Attendees._ID + " = ?",
+                    arrayOf(row.id.toString()),
+                )
+            }
+        }
+        target.filterNot { it.key() in editableKeys }.forEach { attendee ->
+            if (resolver.insert(
+                    CalendarContract.Attendees.CONTENT_URI,
+                    attendeeValues(eventId, attendee),
+                ) == null
+            ) {
+                Log.w(TAG, "Failed to attach a guest to event $eventId")
+            }
+        }
+    }
+
     private fun Map<String, Any?>.toContentValues(): ContentValues =
         ContentValues().also { cv ->
             forEach { (column, value) ->

app/src/main/java/de/jeanlucmakiola/calendula/domain/EventForm.kt

@@ -41,6 +41,27 @@ data class EventForm(
      */
     val colorKey: String? = null,
     val color: Int? = null,
+    /**
+     * Guests the user has added/kept on the event. Calendula only writes these
+     * `Attendees` rows — it has no INTERNET and never sends an invitation
+     * itself; whether a guest is notified is decided downstream by the
+     * calendar's backend (local: no one; CalDAV/Google: the server/account).
+     * Read-only rows the form doesn't model (the organizer, resources) are
+     * preserved by the data layer, not carried here.
+     */
+    val attendees: List<EventAttendee> = emptyList(),
+)
+
+/**
+ * One editable guest: the user controls the [email] (the identity we dedup and
+ * write on), an optional display [name], and whether they're [optional] rather
+ * than required. Response status and the organizer/resource distinction are not
+ * user-editable, so they aren't modelled here.
+ */
+data class EventAttendee(
+    val email: String,
+    val name: String = "",
+    val optional: Boolean = false,
 )
 
 /**
@@ -55,6 +76,7 @@ enum class EventFormField {
     Availability,
     Visibility,
     Color,
+    Attendees,
 }
 
 enum class EventFormProblem {
@@ -108,6 +130,24 @@ fun EventDetail.toEditForm(beginMillis: Long, endMillis: Long, zone: TimeZone):
         // calendar's colour.
         colorKey = eventColorKey,
         color = eventColor,
+        // Only editable guests ride in the form: drop the organizer and
+        // resource rows (not user-editable) and any without an email (we key
+        // edits and dedup on the address). The data layer preserves the rows we
+        // don't carry here, so they're never clobbered on save.
+        attendees = attendees
+            .filter {
+                it.relationship != AttendeeRelationship.Organizer &&
+                    it.type != AttendeeType.Resource
+            }
+            .mapNotNull { a ->
+                a.email?.takeIf { it.isNotBlank() }?.let { email ->
+                    EventAttendee(
+                        email = email,
+                        name = a.name,
+                        optional = a.type == AttendeeType.Optional,
+                    )
+                }
+            },
     )
 }
 
@@ -117,9 +157,10 @@ fun EventDetail.toEditForm(beginMillis: Long, endMillis: Long, zone: TimeZone):
  * while the form was open. The raw row times ride along because
  * [toEditForm] derives the form's times from the *tapped occurrence*, so
  * re-deriving with the same occurrence would mask an externally moved
- * event. Not covered (the form can't write them, and the dirty-checked
+ * event. Guests are covered (the form writes editable attendees), so an
- * write can't clobber them): attendees, status, the user's own response,
+ * external attendee change now also trips the conflict check. Still not
- * reminder methods, and a recurring event's duration.
+ * covered: status, the user's own response, reminder methods, the
+ * organizer/resource rows, and a recurring event's duration.
  */
 data class EditSnapshot(
     val form: EventForm,
@@ -148,6 +189,7 @@ fun EventForm.populatedFields(): Set<EventFormField> = buildSet {
     if (availability != Availability.Busy) add(EventFormField.Availability)
     if (accessLevel != AccessLevel.Default) add(EventFormField.Visibility)
     if (colorKey != null || color != null) add(EventFormField.Color)
+    if (attendees.isNotEmpty()) add(EventFormField.Attendees)
 }
 
 fun EventForm.problems(): Set<EventFormProblem> = buildSet {

app/src/main/java/de/jeanlucmakiola/calendula/ui/common/InlineTextField.kt

@@ -4,6 +4,7 @@ import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.text.BasicTextField
+import androidx.compose.foundation.text.KeyboardActions
 import androidx.compose.foundation.text.KeyboardOptions
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
@@ -12,6 +13,7 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.SolidColor
 import androidx.compose.ui.graphics.isSpecified
 import androidx.compose.ui.text.TextStyle
+import androidx.compose.ui.text.input.ImeAction
 import androidx.compose.ui.text.input.KeyboardCapitalization
 import androidx.compose.ui.text.input.KeyboardType
 import androidx.compose.ui.unit.dp
@@ -36,6 +38,9 @@ fun InlineTextField(
     minLines: Int = 1,
     keyboardType: KeyboardType = KeyboardType.Text,
     capitalization: KeyboardCapitalization = KeyboardCapitalization.None,
+    imeAction: ImeAction = ImeAction.Default,
+    /** Invoked when the IME action key (e.g. Done) is pressed. */
+    onImeAction: (() -> Unit)? = null,
 ) {
     val resolvedStyle = textStyle.copy(
         color = if (textStyle.color.isSpecified) {
@@ -53,7 +58,11 @@ fun InlineTextField(
         keyboardOptions = KeyboardOptions(
             keyboardType = keyboardType,
             capitalization = capitalization,
+            imeAction = imeAction,
         ),
+        keyboardActions = onImeAction?.let { action ->
+            KeyboardActions(onAny = { action() })
+        } ?: KeyboardActions.Default,
         cursorBrush = SolidColor(MaterialTheme.colorScheme.primary),
         decorationBox = { innerTextField ->
             Box {

app/src/main/java/de/jeanlucmakiola/calendula/ui/detail/EventDetailScreen.kt

@@ -590,10 +590,22 @@ private fun AttendeeRow(attendee: Attendee) {
         verticalAlignment = Alignment.CenterVertically,
     ) {
         Column(modifier = Modifier.weight(1f)) {
+            val hasName = attendee.name.isNotBlank()
             Text(
-                text = attendee.name.ifBlank { attendee.email.orEmpty() },
+                text = if (hasName) attendee.name else attendee.email.orEmpty(),
                 style = MaterialTheme.typography.bodyMedium,
             )
+            // Email as supporting text — only when the name is the headline, so we
+            // don't repeat it on rows that already fall back to the email above.
+            if (hasName) {
+                attendee.email?.takeIf { it.isNotBlank() }?.let { email ->
+                    Text(
+                        text = email,
+                        style = MaterialTheme.typography.bodySmall,
+                        color = MaterialTheme.colorScheme.onSurfaceVariant,
+                    )
+                }
+            }
             attendeeRoleLabel(attendee)?.let { roleRes ->
                 Text(
                     text = stringResource(roleRes),

app/src/main/java/de/jeanlucmakiola/calendula/ui/edit/EventEditScreen.kt

@@ -1,7 +1,13 @@
 package de.jeanlucmakiola.calendula.ui.edit
 
 import android.Manifest
+import android.app.Activity
+import android.content.Context
+import android.content.Intent
 import android.content.pm.PackageManager
+import android.net.Uri
+import android.provider.ContactsContract
+import android.util.Patterns
 import androidx.activity.compose.BackHandler
 import androidx.activity.compose.rememberLauncherForActivityResult
 import androidx.activity.result.contract.ActivityResultContracts
@@ -30,7 +36,6 @@ import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.shape.CircleShape
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.foundation.text.BasicTextField
-import androidx.compose.foundation.text.KeyboardOptions
 import androidx.compose.foundation.verticalScroll
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.automirrored.filled.Notes
@@ -38,10 +43,14 @@ import androidx.compose.material.icons.filled.Add
 import androidx.compose.material.icons.filled.ArrowDropDown
 import androidx.compose.material.icons.filled.CalendarMonth
 import androidx.compose.material.icons.filled.Close
+import androidx.compose.material.icons.filled.Contacts
 import androidx.compose.material.icons.filled.EventAvailable
 import androidx.compose.material.icons.filled.Lock
 import androidx.compose.material.icons.filled.Notifications
 import androidx.compose.material.icons.filled.Palette
+import androidx.compose.material.icons.filled.People
+import androidx.compose.material.icons.filled.Person
+import androidx.compose.material.icons.filled.PersonAdd
 import androidx.compose.material.icons.filled.Place
 import androidx.compose.material.icons.filled.Public
 import androidx.compose.material.icons.filled.Repeat
@@ -49,11 +58,11 @@ import androidx.compose.material.icons.filled.Schedule
 import androidx.compose.material.icons.filled.Tune
 import androidx.compose.material.icons.filled.VisibilityOff
 import androidx.compose.material3.AlertDialog
-import androidx.compose.material3.AssistChip
 import androidx.compose.material3.Button
 import androidx.compose.material3.DropdownMenu
 import androidx.compose.material3.DropdownMenuItem
 import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.FilterChip
 import androidx.compose.material3.ExperimentalMaterial3ExpressiveApi
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
@@ -82,13 +91,17 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.graphics.SolidColor
 import androidx.compose.ui.graphics.isSpecified
+import androidx.compose.ui.graphics.Shape
 import androidx.compose.ui.graphics.vector.ImageVector
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.text.AnnotatedString
 import androidx.compose.ui.text.TextStyle
 import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.text.style.TextOverflow
+import androidx.compose.ui.text.input.ImeAction
 import androidx.compose.ui.text.input.KeyboardType
+import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.dp
 import androidx.core.content.ContextCompat
 import androidx.hilt.navigation.compose.hiltViewModel
@@ -97,6 +110,7 @@ import de.jeanlucmakiola.calendula.R
 import de.jeanlucmakiola.calendula.domain.AccessLevel
 import de.jeanlucmakiola.calendula.domain.Availability
 import de.jeanlucmakiola.calendula.domain.CalendarSource
+import de.jeanlucmakiola.calendula.domain.EventAttendee
 import de.jeanlucmakiola.calendula.domain.EventColorOption
 import de.jeanlucmakiola.calendula.domain.EventForm
 import de.jeanlucmakiola.calendula.domain.EventFormField
@@ -115,6 +129,8 @@ import de.jeanlucmakiola.calendula.ui.common.DialogUnitDropdown
 import de.jeanlucmakiola.calendula.ui.common.MILLIS_PER_DAY
 import de.jeanlucmakiola.calendula.ui.common.InlineTextField
 import de.jeanlucmakiola.calendula.ui.common.OptionCard
+import de.jeanlucmakiola.calendula.ui.common.Position
+import de.jeanlucmakiola.calendula.ui.common.positionOf
 import de.jeanlucmakiola.calendula.ui.common.REMINDER_PRESETS
 import de.jeanlucmakiola.calendula.ui.common.ReminderUnit
 import de.jeanlucmakiola.calendula.ui.common.TimePickerAlert
@@ -429,6 +445,22 @@ private fun EventEditContent(
     var showColorPicker by rememberSaveable { mutableStateOf(false) }
     var showFieldPicker by rememberSaveable { mutableStateOf(false) }
 
+    // Pick a guest from contacts: a one-shot system picker returning the chosen
+    // email row (email + display name). No READ_CONTACTS — the result Intent
+    // grants temporary read access, so Calendula stays no-network/no-permission.
+    val context = LocalContext.current
+    val pickContact = rememberLauncherForActivityResult(
+        ActivityResultContracts.StartActivityForResult(),
+    ) { result ->
+        if (result.resultCode == Activity.RESULT_OK) {
+            result.data?.data?.let { uri ->
+                readContactEmail(context, uri)?.let { (email, name) ->
+                    viewModel.addAttendee(email, name)
+                }
+            }
+        }
+    }
+
     val selectedCalendar = state.calendars.firstOrNull { it.id == form.calendarId }
     // The accent ties the form to the detail screen's design language: the
     // bar under the title takes the target calendar's colour.
@@ -587,33 +619,24 @@ private fun EventEditContent(
 
         OptionalFormSection(visible = EventFormField.Reminders in state.visibleFields) {
             Spacer(Modifier.height(gap))
-            // Reminders stack one per row (remove on the right edge); the
+            // A grouped list like guests: each reminder is its own tonal card
-            // add chip closes the card at the bottom. The card icon centres
+            // with connected corners, the last row being "Add reminder".
-            // on the first row, whatever that is.
+            val reminders = form.reminders
-            EditCard(
+            val rows = reminders.size + 1
-                icon = Icons.Default.Notifications,
+            reminders.forEachIndexed { index, minutes ->
-                iconContentDescription = stringResource(R.string.event_detail_reminders),
+                GroupedItemCard(
-                header = {
+                    position = positionOf(index, rows),
-                    when (val first = form.reminders.firstOrNull()) {
+                    icon = Icons.Default.Notifications,
-                        null -> AddReminderChip(onClick = { showReminderPicker = true })
+                    title = reminderLabel(minutes),
-                        else -> ReminderRow(
+                    removeContentDescription = stringResource(R.string.event_edit_remove_reminder),
-                            label = reminderLabel(first),
+                    onRemove = { viewModel.removeReminder(minutes) },
-                            onRemove = { viewModel.removeReminder(first) },
+                )
-                        )
-                    }
-                },
-            ) {
-                form.reminders.drop(1).forEach { minutes ->
-                    ReminderRow(
-                        label = reminderLabel(minutes),
-                        onRemove = { viewModel.removeReminder(minutes) },
-                    )
-                }
-                if (form.reminders.isNotEmpty()) {
-                    Spacer(Modifier.height(4.dp))
-                    AddReminderChip(onClick = { showReminderPicker = true })
-                }
             }
+            AddActionCard(
+                label = stringResource(R.string.event_edit_add_reminder),
+                position = positionOf(reminders.size, rows),
+                onClick = { showReminderPicker = true },
+            )
         }
 
         OptionalFormSection(visible = EventFormField.Recurrence in state.visibleFields) {
@@ -776,6 +799,52 @@ private fun EventEditContent(
             }
         }
 
+        OptionalFormSection(visible = EventFormField.Attendees in state.visibleFields) {
+            Spacer(Modifier.height(gap))
+            // Guests are an inline grouped list: each is a tonal card with a
+            // role toggle + remove, and the trailing card is an inline email
+            // field — type an address, press Done, it commits. Below sits an
+            // honest note — Calendula never sends invitations, so whether a
+            // guest is notified is the calendar backend's call.
+            val guests = form.attendees
+            val rows = guests.size + 1
+            guests.forEachIndexed { index, attendee ->
+                GuestCard(
+                    attendee = attendee,
+                    position = positionOf(index, rows),
+                    onToggleOptional = { viewModel.setAttendeeOptional(attendee, it) },
+                    onRemove = { viewModel.removeAttendee(attendee) },
+                )
+            }
+            AddGuestInlineCard(
+                position = positionOf(guests.size, rows),
+                onAdd = { viewModel.addAttendee(it) },
+                onPickContact = {
+                    runCatching {
+                        pickContact.launch(
+                            Intent(
+                                Intent.ACTION_PICK,
+                                ContactsContract.CommonDataKinds.Email.CONTENT_URI,
+                            ),
+                        )
+                    }
+                },
+            )
+            Spacer(Modifier.height(8.dp))
+            Text(
+                text = stringResource(
+                    if (isLocalCalendar) {
+                        R.string.event_edit_attendees_note_local
+                    } else {
+                        R.string.event_edit_attendees_note_synced
+                    },
+                ),
+                style = MaterialTheme.typography.bodySmall,
+                color = MaterialTheme.colorScheme.onSurfaceVariant,
+                modifier = Modifier.padding(horizontal = 4.dp),
+            )
+        }
+
         OptionalFormSection(visible = state.hiddenFields.isNotEmpty()) {
             Spacer(Modifier.height(20.dp))
             TextButton(
@@ -840,6 +909,7 @@ private fun EventEditContent(
         )
     }
 
+
     if (showRecurrencePicker) {
         RecurrencePickerDialog(
             current = form.rrule,
@@ -1262,45 +1332,253 @@ private fun recurrenceUnitLabel(freq: RecurrenceFreq): Int = when (freq) {
     RecurrenceFreq.Yearly -> R.string.recurrence_unit_years
 }
 
-/** One chosen reminder: humanised lead time, remove pinned to the right edge. */
+/** Corner shape for a card at [position] in a grouped run (mirrors GroupedRow). */
-@Composable
+private fun groupedShape(position: Position, full: Dp = 20.dp, small: Dp = 6.dp): Shape =
-private fun ReminderRow(label: String, onRemove: () -> Unit) {
+    when (position) {
-    Row(
+        Position.Alone -> RoundedCornerShape(full)
-        verticalAlignment = Alignment.CenterVertically,
+        Position.Top -> RoundedCornerShape(
-        modifier = Modifier.fillMaxWidth(),
+            topStart = full, topEnd = full, bottomStart = small, bottomEnd = small,
-    ) {
-        Text(
-            text = label,
-            style = MaterialTheme.typography.titleMedium,
-            modifier = Modifier.weight(1f),
         )
-        IconButton(onClick = onRemove, modifier = Modifier.size(32.dp)) {
+        Position.Middle -> RoundedCornerShape(small)
+        Position.Bottom -> RoundedCornerShape(
+            topStart = small, topEnd = small, bottomStart = full, bottomEnd = full,
+        )
+    }
+
+/** The 2dp gap that visually separates grouped cards (none after the last). */
+private fun groupedGap(position: Position): Modifier = when (position) {
+    Position.Top, Position.Middle -> Modifier.padding(bottom = 2.dp)
+    Position.Bottom, Position.Alone -> Modifier
+}
+
+/**
+ * One entry in a grouped form list (a guest, a reminder): a leading [icon],
+ * a [title] with optional [supporting] line, and a remove button — all on a
+ * tonal card whose corners come from its [position] in the run.
+ */
+@Composable
+private fun GroupedItemCard(
+    position: Position,
+    icon: ImageVector,
+    title: String,
+    removeContentDescription: String,
+    onRemove: () -> Unit,
+    supporting: String? = null,
+    titleMaxLines: Int = Int.MAX_VALUE,
+    trailing: @Composable (() -> Unit)? = null,
+) {
+    Surface(
+        color = MaterialTheme.colorScheme.surfaceContainerHigh,
+        shape = groupedShape(position),
+        modifier = Modifier
+            .fillMaxWidth()
+            .then(groupedGap(position)),
+    ) {
+        Row(
+            verticalAlignment = Alignment.CenterVertically,
+            modifier = Modifier.padding(start = 16.dp, end = 8.dp, top = 8.dp, bottom = 8.dp),
+        ) {
             Icon(
-                imageVector = Icons.Default.Close,
+                imageVector = icon,
-                contentDescription = stringResource(R.string.event_edit_remove_reminder),
+                contentDescription = null,
-                modifier = Modifier.size(18.dp),
+                tint = MaterialTheme.colorScheme.onSurfaceVariant,
+                modifier = Modifier.size(24.dp),
+            )
+            Spacer(Modifier.width(16.dp))
+            Column(modifier = Modifier.weight(1f)) {
+                Text(
+                    text = title,
+                    style = MaterialTheme.typography.titleMedium,
+                    maxLines = titleMaxLines,
+                    overflow = TextOverflow.Ellipsis,
+                )
+                if (supporting != null) {
+                    Text(
+                        text = supporting,
+                        style = MaterialTheme.typography.bodySmall,
+                        color = MaterialTheme.colorScheme.onSurfaceVariant,
+                    )
+                }
+            }
+            if (trailing != null) {
+                Spacer(Modifier.width(8.dp))
+                trailing()
+            }
+            IconButton(onClick = onRemove, modifier = Modifier.size(40.dp)) {
+                Icon(
+                    imageVector = Icons.Default.Close,
+                    contentDescription = removeContentDescription,
+                    tint = MaterialTheme.colorScheme.onSurfaceVariant,
+                    modifier = Modifier.size(20.dp),
+                )
+            }
+        }
+    }
+}
+
+/**
+ * One guest as a grouped-list card: avatar glyph, name/email, a tappable
+ * Required/Optional role chip, and remove. The email shows as the supporting
+ * line when a name is present, otherwise as the title.
+ */
+@Composable
+private fun GuestCard(
+    attendee: EventAttendee,
+    position: Position,
+    onToggleOptional: (Boolean) -> Unit,
+    onRemove: () -> Unit,
+) {
+    val hasName = attendee.name.isNotBlank()
+    GroupedItemCard(
+        position = position,
+        icon = Icons.Default.Person,
+        title = if (hasName) attendee.name else attendee.email,
+        supporting = attendee.email.takeIf { hasName },
+        titleMaxLines = 1,
+        removeContentDescription = stringResource(R.string.event_edit_remove_guest),
+        onRemove = onRemove,
+        trailing = {
+            FilterChip(
+                selected = attendee.optional,
+                onClick = { onToggleOptional(!attendee.optional) },
+                label = {
+                    Text(
+                        stringResource(
+                            if (attendee.optional) {
+                                R.string.event_edit_attendee_optional
+                            } else {
+                                R.string.event_edit_attendee_required
+                            },
+                        ),
+                    )
+                },
+            )
+        },
+    )
+}
+
+/** The trailing "Add …" action card of a grouped form list (opens a picker). */
+@Composable
+private fun AddActionCard(label: String, position: Position, onClick: () -> Unit) {
+    Surface(
+        onClick = onClick,
+        color = MaterialTheme.colorScheme.surfaceContainerHigh,
+        shape = groupedShape(position),
+        modifier = Modifier
+            .fillMaxWidth()
+            .then(groupedGap(position)),
+    ) {
+        Row(
+            verticalAlignment = Alignment.CenterVertically,
+            modifier = Modifier.padding(horizontal = 16.dp, vertical = 14.dp),
+        ) {
+            Icon(
+                imageVector = Icons.Default.Add,
+                contentDescription = null,
+                tint = MaterialTheme.colorScheme.primary,
+                modifier = Modifier.size(24.dp),
+            )
+            Spacer(Modifier.width(16.dp))
+            Text(
+                text = label,
+                style = MaterialTheme.typography.titleMedium,
+                color = MaterialTheme.colorScheme.primary,
             )
         }
     }
 }
 
+/**
+ * The trailing card of the guests list: an inline email field plus a "from
+ * contacts" button. Type an address and press Done (or tap +) to commit a guest;
+ * or pick from contacts to fill email + name at once. The field clears after,
+ * ready for the next. Matches the form's inline-field input style — no dialog.
+ */
 @Composable
-private fun AddReminderChip(onClick: () -> Unit) {
+private fun AddGuestInlineCard(
-    AssistChip(
+    position: Position,
-        onClick = onClick,
+    onAdd: (String) -> Unit,
-        label = { Text(stringResource(R.string.event_edit_add)) },
+    onPickContact: () -> Unit,
-        leadingIcon = {
+) {
+    var text by rememberSaveable { mutableStateOf("") }
+    val valid = remember(text) { Patterns.EMAIL_ADDRESS.matcher(text.trim()).matches() }
+    fun commit() {
+        if (valid) {
+            onAdd(text.trim())
+            text = ""
+        }
+    }
+    Surface(
+        color = MaterialTheme.colorScheme.surfaceContainerHigh,
+        shape = groupedShape(position),
+        modifier = Modifier
+            .fillMaxWidth()
+            .then(groupedGap(position)),
+    ) {
+        Row(
+            verticalAlignment = Alignment.CenterVertically,
+            modifier = Modifier.padding(start = 16.dp, end = 8.dp, top = 8.dp, bottom = 8.dp),
+        ) {
             Icon(
-                imageVector = Icons.Default.Add,
+                imageVector = Icons.Default.PersonAdd,
                 contentDescription = null,
-                modifier = Modifier.size(16.dp),
+                tint = MaterialTheme.colorScheme.onSurfaceVariant,
+                modifier = Modifier.size(24.dp),
             )
-        },
+            Spacer(Modifier.width(16.dp))
-        border = null,
+            InlineTextField(
-        modifier = Modifier.fillMaxWidth(),
+                value = text,
-    )
+                onValueChange = { text = it },
+                placeholder = stringResource(R.string.event_edit_add_guest_hint),
+                keyboardType = KeyboardType.Email,
+                imeAction = ImeAction.Done,
+                onImeAction = { commit() },
+                modifier = Modifier
+                    .weight(1f)
+                    .padding(vertical = 8.dp),
+            )
+            if (valid) {
+                IconButton(onClick = { commit() }, modifier = Modifier.size(40.dp)) {
+                    Icon(
+                        imageVector = Icons.Default.Add,
+                        contentDescription = stringResource(R.string.event_edit_add_guest),
+                        tint = MaterialTheme.colorScheme.primary,
+                        modifier = Modifier.size(22.dp),
+                    )
+                }
+            }
+            IconButton(onClick = onPickContact, modifier = Modifier.size(40.dp)) {
+                Icon(
+                    imageVector = Icons.Default.Contacts,
+                    contentDescription = stringResource(R.string.event_edit_add_guest_from_contacts),
+                    tint = MaterialTheme.colorScheme.onSurfaceVariant,
+                    modifier = Modifier.size(22.dp),
+                )
+            }
+        }
+    }
 }
 
+/**
+ * Read the email + display name from a contact-pick result URI. No
+ * READ_CONTACTS needed: ACTION_PICK grants this URI temporary read access.
+ */
+private fun readContactEmail(context: Context, uri: Uri): Pair<String, String>? =
+    context.contentResolver.query(
+        uri,
+        arrayOf(
+            ContactsContract.CommonDataKinds.Email.ADDRESS,
+            ContactsContract.Contacts.DISPLAY_NAME,
+        ),
+        null, null, null,
+    )?.use { cursor ->
+        if (!cursor.moveToFirst()) return@use null
+        val email = cursor.getString(0).orEmpty().trim()
+        val name = cursor.getString(1).orEmpty().trim()
+        email.takeIf { it.isNotEmpty() }?.let { it to name }
+    }
+
+
 private fun fieldLabel(field: EventFormField): Int = when (field) {
     EventFormField.Location -> R.string.event_detail_location
     EventFormField.Description -> R.string.event_detail_description
@@ -1309,6 +1587,7 @@ private fun fieldLabel(field: EventFormField): Int = when (field) {
     EventFormField.Availability -> R.string.event_edit_availability
     EventFormField.Visibility -> R.string.event_edit_visibility
     EventFormField.Color -> R.string.event_edit_color
+    EventFormField.Attendees -> R.string.event_edit_attendees
 }
 
 private fun fieldIcon(field: EventFormField): ImageVector = when (field) {
@@ -1319,6 +1598,7 @@ private fun fieldIcon(field: EventFormField): ImageVector = when (field) {
     EventFormField.Availability -> Icons.Default.EventAvailable
     EventFormField.Visibility -> Icons.Default.Lock
     EventFormField.Color -> Icons.Default.Palette
+    EventFormField.Attendees -> Icons.Default.People
 }
 
 /**

app/src/main/java/de/jeanlucmakiola/calendula/ui/edit/EventEditViewModel.kt

@@ -13,6 +13,7 @@ import de.jeanlucmakiola.calendula.domain.AccessLevel
 import de.jeanlucmakiola.calendula.domain.Availability
 import de.jeanlucmakiola.calendula.domain.CalendarSource
 import de.jeanlucmakiola.calendula.domain.EditSnapshot
+import de.jeanlucmakiola.calendula.domain.EventAttendee
 import de.jeanlucmakiola.calendula.domain.EventColorOption
 import de.jeanlucmakiola.calendula.domain.EventForm
 import de.jeanlucmakiola.calendula.domain.EventFormField
@@ -353,6 +354,33 @@ class EventEditViewModel @Inject constructor(
         update { it.copy(reminders = it.reminders - minutes) }
     }
 
+    /**
+     * Add a guest, keyed on a trimmed lower-cased email so re-adding the same
+     * address just refreshes it (no duplicate row). A blank email is ignored —
+     * the email is what we write and dedup on.
+     */
+    fun addAttendee(email: String, name: String = "", optional: Boolean = false) {
+        val trimmed = email.trim()
+        if (trimmed.isEmpty()) return
+        update { form ->
+            val attendee = EventAttendee(email = trimmed, name = name.trim(), optional = optional)
+            val rest = form.attendees.filterNot { it.email.equals(trimmed, ignoreCase = true) }
+            form.copy(attendees = rest + attendee)
+        }
+    }
+
+    fun removeAttendee(attendee: EventAttendee) =
+        update { it.copy(attendees = it.attendees.filterNot { a -> a.email.equals(attendee.email, ignoreCase = true) }) }
+
+    /** Flip a guest between required and optional (the per-row role toggle). */
+    fun setAttendeeOptional(attendee: EventAttendee, optional: Boolean) = update { form ->
+        form.copy(
+            attendees = form.attendees.map { a ->
+                if (a.email.equals(attendee.email, ignoreCase = true)) a.copy(optional = optional) else a
+            },
+        )
+    }
+
     /** Moving the start drags the end along, preserving the duration. */
     fun setStartDate(date: LocalDate) = moveStart { LocalDateTime(date, it.time) }
     fun setStartTime(time: LocalTime) = moveStart { LocalDateTime(it.date, time) }

app/src/main/java/de/jeanlucmakiola/calendula/ui/settings/SettingsScreen.kt

@@ -905,6 +905,7 @@ private fun formFieldLabel(field: EventFormField): Int = when (field) {
     EventFormField.Availability -> R.string.event_edit_availability
     EventFormField.Visibility -> R.string.event_edit_visibility
     EventFormField.Color -> R.string.event_edit_color
+    EventFormField.Attendees -> R.string.event_edit_attendees
 }
 
 @Composable

app/src/main/res/values-de/strings.xml

@@ -77,6 +77,15 @@
     <string name="event_edit_add">Hinzufügen</string>
     <string name="event_edit_add_reminder">Erinnerung hinzufügen</string>
     <string name="event_edit_remove_reminder">Erinnerung entfernen</string>
+    <string name="event_edit_attendees">Gäste</string>
+    <string name="event_edit_add_guest">Gast hinzufügen</string>
+    <string name="event_edit_add_guest_hint">Gast per E-Mail hinzufügen…</string>
+    <string name="event_edit_add_guest_from_contacts">Aus Kontakten hinzufügen</string>
+    <string name="event_edit_remove_guest">Gast entfernen</string>
+    <string name="event_edit_attendee_required">Erforderlich</string>
+    <string name="event_edit_attendee_optional">Optional</string>
+    <string name="event_edit_attendees_note_synced">Calendula versendet keine Einladungen. Dein Kalenderkonto sendet Gästen bei der Synchronisierung unter Umständen eine E-Mail.</string>
+    <string name="event_edit_attendees_note_local">Auf diesem Gerät gespeichert. Niemand wird benachrichtigt.</string>
     <string name="event_edit_reminder_custom">Benutzerdefiniert</string>
     <string name="reminder_unit_minutes">Minuten</string>
     <string name="reminder_unit_hours">Stunden</string>

app/src/main/res/values/strings.xml

@@ -78,6 +78,15 @@
     <string name="event_edit_add">Add</string>
     <string name="event_edit_add_reminder">Add reminder</string>
     <string name="event_edit_remove_reminder">Remove reminder</string>
+    <string name="event_edit_attendees">Guests</string>
+    <string name="event_edit_add_guest">Add guest</string>
+    <string name="event_edit_add_guest_hint">Add a guest by email…</string>
+    <string name="event_edit_add_guest_from_contacts">Add from contacts</string>
+    <string name="event_edit_remove_guest">Remove guest</string>
+    <string name="event_edit_attendee_required">Required</string>
+    <string name="event_edit_attendee_optional">Optional</string>
+    <string name="event_edit_attendees_note_synced">Calendula doesn\'t send invitations. Your calendar account may email guests when it syncs.</string>
+    <string name="event_edit_attendees_note_local">Stored on this device. No one is notified.</string>
     <string name="event_edit_reminder_custom">Custom</string>
     <string name="reminder_unit_minutes">minutes</string>
     <string name="reminder_unit_hours">hours</string>

app/src/test/java/de/jeanlucmakiola/calendula/domain/EventFormTest.kt

@@ -211,12 +211,55 @@ class EventFormTest {
     }
 
     @Test
-    fun `changes the form cannot write do not fake a conflict`() {
+    fun `a reminder-method change the form cannot write does not fake a conflict`() {
+        // The form carries reminder minutes only, not the method — so a method
+        // flip the form can't express must not read as an external change.
+        val loaded = detail(reminders = listOf(Reminder(10, ReminderMethod.Alert)))
+            .toEditSnapshot(0L, 3_600_000L, berlin)
+        val fresh = detail(reminders = listOf(Reminder(10, ReminderMethod.Email)))
+            .toEditSnapshot(0L, 3_600_000L, berlin)
+        assertThat(fresh).isEqualTo(loaded)
+    }
+
+    @Test
+    fun `an external guest change now trips the conflict check`() {
+        // Attendees are writable now, so they ride in the snapshot: adding a
+        // guest externally is a real conflict, not invisible.
         val loaded = detail().toEditSnapshot(0L, 3_600_000L, berlin)
         val fresh = detail(
-            attendees = listOf(Attendee("Ada", "ada@example.org", AttendeeStatus.Accepted)),
+            attendees = listOf(Attendee("Ada", "ada@example.org", AttendeeStatus.NeedsAction)),
         ).toEditSnapshot(0L, 3_600_000L, berlin)
-        assertThat(fresh).isEqualTo(loaded)
+        assertThat(fresh).isNotEqualTo(loaded)
+    }
+
+    @Test
+    fun `toEditForm carries editable guests with name email and optional role`() {
+        val prefilled = detail(
+            attendees = listOf(
+                Attendee("Ada", "ada@example.org", AttendeeStatus.Accepted, type = AttendeeType.Required),
+                Attendee("", "bob@example.org", AttendeeStatus.NeedsAction, type = AttendeeType.Optional),
+            ),
+        ).toEditForm(beginMillis = 0L, endMillis = 3_600_000L, zone = berlin)
+        assertThat(prefilled.attendees).containsExactly(
+            EventAttendee(email = "ada@example.org", name = "Ada", optional = false),
+            EventAttendee(email = "bob@example.org", name = "", optional = true),
+        ).inOrder()
+        assertThat(prefilled.populatedFields()).contains(EventFormField.Attendees)
+    }
+
+    @Test
+    fun `toEditForm drops the organizer, resources and guests without an email`() {
+        val prefilled = detail(
+            attendees = listOf(
+                Attendee("Org", "org@example.org", AttendeeStatus.Accepted, AttendeeRelationship.Organizer),
+                Attendee("Room A", "room@example.org", AttendeeStatus.Accepted, type = AttendeeType.Resource),
+                Attendee("No address", null, AttendeeStatus.NeedsAction),
+                Attendee("Ada", "ada@example.org", AttendeeStatus.NeedsAction),
+            ),
+        ).toEditForm(beginMillis = 0L, endMillis = 3_600_000L, zone = berlin)
+        assertThat(prefilled.attendees).containsExactly(
+            EventAttendee(email = "ada@example.org", name = "Ada", optional = false),
+        )
     }
 
     @Test