feat(data): unarchive() primitive on ConversationRepository (#96)

app/src/main/java/de/pyryco/mobile/data/repository/ConversationRepository.kt

@@ -30,6 +30,8 @@ interface ConversationRepository {
 
     suspend fun archive(conversationId: String)
 
+    suspend fun unarchive(conversationId: String)
+
     suspend fun rename(
         conversationId: String,
         name: String,

app/src/main/java/de/pyryco/mobile/data/repository/FakeConversationRepository.kt

@@ -132,6 +132,16 @@ class FakeConversationRepository(
         }
     }
 
+    override suspend fun unarchive(conversationId: String) {
+        state.update { records ->
+            val record = records[conversationId] ?: throw unknown(conversationId)
+            records + (
+                conversationId to
+                    record.copy(conversation = record.conversation.copy(archived = false))
+            )
+        }
+    }
+
     override suspend fun rename(
         conversationId: String,
         name: String,

app/src/test/java/de/pyryco/mobile/data/repository/FakeConversationRepositoryTest.kt

@@ -285,6 +285,67 @@ class FakeConversationRepositoryTest {
             )
         }
 
+    @Test
+    fun unarchive_movesConversation_from_Archived_to_Discussions_andRetainsInStore() =
+        runBlocking {
+            val repo = FakeConversationRepository()
+            val archivedId = "seed-discussion-archived"
+
+            assertTrue(
+                "seeded archived discussion must appear in Archived before unarchive",
+                repo.observeConversations(ConversationFilter.Archived).first().any { it.id == archivedId },
+            )
+            assertTrue(
+                "seeded archived discussion must not appear in Discussions before unarchive",
+                repo.observeConversations(ConversationFilter.Discussions).first().none { it.id == archivedId },
+            )
+
+            repo.unarchive(archivedId)
+
+            assertTrue(
+                "unarchived conversation must leave Archived",
+                repo.observeConversations(ConversationFilter.Archived).first().none { it.id == archivedId },
+            )
+            assertTrue(
+                "unarchived discussion must appear in Discussions",
+                repo.observeConversations(ConversationFilter.Discussions).first().any { it.id == archivedId },
+            )
+            assertTrue(
+                "unarchived discussion must not appear in Channels",
+                repo.observeConversations(ConversationFilter.Channels).first().none { it.id == archivedId },
+            )
+            assertTrue(
+                "unarchived conversation must be retained in All",
+                repo.observeConversations(ConversationFilter.All).first().any { it.id == archivedId },
+            )
+        }
+
+    @Test
+    fun unarchive_onUnknownId_throws() {
+        val repo = FakeConversationRepository()
+        try {
+            runBlocking { repo.unarchive("nope") }
+            assertTrue("expected IllegalArgumentException", false)
+        } catch (_: IllegalArgumentException) {
+            // expected
+        }
+    }
+
+    @Test
+    fun unarchive_isIdempotent() =
+        runBlocking {
+            val repo = FakeConversationRepository()
+            val archivedId = "seed-discussion-archived"
+            repo.unarchive(archivedId)
+            repo.unarchive(archivedId)
+            val discussions = repo.observeConversations(ConversationFilter.Discussions).first()
+            assertEquals(
+                "unarchived conversation must appear exactly once after two unarchive() calls",
+                1,
+                discussions.count { it.id == archivedId },
+            )
+        }
+
     @Test
     fun rename_updates_name_and_reEmits() =
         runBlocking {

app/src/test/java/de/pyryco/mobile/ui/conversations/list/ChannelListViewModelTest.kt

@@ -363,6 +363,8 @@ class ChannelListViewModelTest {
 
             override suspend fun archive(conversationId: String): Unit = TODO("not used")
 
+            override suspend fun unarchive(conversationId: String): Unit = TODO("not used")
+
             override suspend fun rename(
                 conversationId: String,
                 name: String,
@@ -403,6 +405,8 @@ class ChannelListViewModelTest {
 
             override suspend fun archive(conversationId: String): Unit = TODO("not used")
 
+            override suspend fun unarchive(conversationId: String): Unit = TODO("not used")
+
             override suspend fun rename(
                 conversationId: String,
                 name: String,

app/src/test/java/de/pyryco/mobile/ui/conversations/list/DiscussionListViewModelTest.kt

@@ -70,6 +70,8 @@ class DiscussionListViewModelTest {
 
                     override suspend fun archive(conversationId: String): Unit = TODO("not used")
 
+                    override suspend fun unarchive(conversationId: String): Unit = TODO("not used")
+
                     override suspend fun rename(
                         conversationId: String,
                         name: String,
@@ -356,6 +358,8 @@ class DiscussionListViewModelTest {
 
             override suspend fun archive(conversationId: String): Unit = TODO("not used")
 
+            override suspend fun unarchive(conversationId: String): Unit = TODO("not used")
+
             override suspend fun rename(
                 conversationId: String,
                 name: String,
@@ -389,6 +393,8 @@ class DiscussionListViewModelTest {
 
             override suspend fun archive(conversationId: String): Unit = TODO("not used")
 
+            override suspend fun unarchive(conversationId: String): Unit = TODO("not used")
+
             override suspend fun rename(
                 conversationId: String,
                 name: String,
@@ -441,6 +447,8 @@ class DiscussionListViewModelTest {
 
         override suspend fun archive(conversationId: String): Unit = TODO("not used")
 
+        override suspend fun unarchive(conversationId: String): Unit = TODO("not used")
+
         override suspend fun rename(
             conversationId: String,
             name: String,

docs/knowledge/INDEX.md

@@ -10,7 +10,7 @@ One-line pointers to evergreen docs. Per-ticket implementation notes live under
 - [Scanner Denied screen](features/scanner-denied-screen.md) — stateless camera-permission-denied surface locked to Figma node `32:2` (#61); `Surface` + `Column` with a 120dp Compose-`Canvas` camera-with-strike illustration (rounded-rect body + viewfinder-bridge `Path` + stroked outer-lens circle + filled inner-lens dot + `colorScheme.error` diagonal `drawLine`), `headlineSmall` headline, `bodyMedium` explainer (`widthIn` 300dp), bottom-pinned `fillMaxWidth` filled `Button` + `TextButton` via a `Spacer(weight=1f)`. Two caller-owned lambdas; no NavHost wiring yet (Phase 4 adds the `TopAppBar` and routes from the CameraX permission flow). Instrumented Compose tests since #101 — three-method `ScannerDeniedScreenTest` at `app/src/androidTest/.../onboarding/ScannerDeniedScreenTest.kt` asserts the `"Camera permission required"` heading (exact match) plus `hasClickAction()` on `"Open settings"` and `"Paste code instead"`; structure only, the two lambdas are passed as `{}` no-ops and callback wiring isn't asserted.
 - [Scanner Connecting screen](features/scanner-connecting-screen.md) — stateless in-flight-pairing surface locked to Figma node `32:20` (#62); `Surface` + `Column(Arrangement.Center)` of a 48dp indeterminate `CircularProgressIndicator` (zero theming args — M3 defaults bind `colorScheme.primary` arc + `colorScheme.surfaceVariant` track) → `bodyLarge` headline ("Connecting to your pyrycode server…") on `colorScheme.onSurface` → `bodyMedium` server address on `colorScheme.onSurfaceVariant` with `fontFamily = FontFamily.Monospace` as a top-level `Text` parameter (family-only override of the named role). Single `serverAddress: String` parameter, no callbacks; no NavHost wiring yet (Phase 4 owns the handshake state machine). Instrumented Compose tests since #101 — two-method `ScannerConnectingScreenTest` at `app/src/androidTest/.../onboarding/ScannerConnectingScreenTest.kt` asserts `hasText("Connecting to your pyrycode server", substring = true)` (substring deliberately avoids the U+2026 ellipsis) and exact match on the `"home.lan:7117"` literal passed as `serverAddress`. The project's first instrumented test for a no-callback screen — the pattern degenerates cleanly to two render assertions with no counters or event lists.
 - [Data model](features/data-model.md) — `Conversation` / `Session` / `Message` schema in `data/model/`; shared shape across mobile, Discord, and pyrycode CLI consumers. Sentinel `DefaultScratchCwd` co-lives in `Conversation.kt` as the single-source-of-truth marker for unbound-workspace conversations. `Conversation.isSleeping: Boolean = false` (#20) is derived in Phase 1 and wire-parsed in Phase 4. `Conversation.archived: Boolean = false` (#93) is the authoritative archive bit — flipped by `archive(id)`, parsed from the wire in Phase 4.
-- [Conversation repository](features/conversation-repository.md) — `ConversationRepository` interface + `ConversationFilter` (`All` / `Channels` / `Discussions` / `Archived` since #93), `ThreadItem` (`MessageItem` / `SessionBoundary`), `BoundaryReason`; data-layer seam every UI tier binds to. Phase 1 binding is the in-memory `FakeConversationRepository`; the `observeConversations` projection also stamps the derived `Conversation.isSleeping` flag (#20). Filter matrix (#93): `All` returns everything including archived; `Channels` / `Discussions` carry an explicit `!archived` clause; `Archived` returns archived rows regardless of `isPromoted`. `archive(id)` since #93 flips the flag instead of removing the entry — the conversation stays observable through `Archived` (and `All`).
+- [Conversation repository](features/conversation-repository.md) — `ConversationRepository` interface + `ConversationFilter` (`All` / `Channels` / `Discussions` / `Archived` since #93), `ThreadItem` (`MessageItem` / `SessionBoundary`), `BoundaryReason`; data-layer seam every UI tier binds to. Phase 1 binding is the in-memory `FakeConversationRepository`; the `observeConversations` projection also stamps the derived `Conversation.isSleeping` flag (#20). Filter matrix (#93): `All` returns everything including archived; `Channels` / `Discussions` carry an explicit `!archived` clause; `Archived` returns archived rows regardless of `isPromoted`. `archive(id)` since #93 flips the flag instead of removing the entry; `unarchive(id)` since #96 is the symmetric inverse (silent-idempotent flag flip back to `false`, same `unknown(id)` throw on missing).
 - [Dependency injection](features/dependency-injection.md) — Koin scaffold; single `appModule` at `di/AppModule.kt`, `startKoin` owned by `PyryApp.onCreate`. Downstream tickets append `single`/`viewModel` lines.
 - [App preferences](features/app-preferences.md) — `AppPreferences` wrapper over a shared `DataStore<Preferences>` (file `app_prefs`); typed `Flow<T>` reads + `suspend` setters for non-secret app state. Keys: `pairedServerExists` (#11/#12/#13), `themeMode: Flow<ThemeMode>` (#86 — `stringPreferencesKey("theme_mode")` holding the enum's `.name`; `entries.firstOrNull { it.name == stored } ?: SYSTEM` fallback for both absent + unparseable; consumed reactively at `MainActivity`'s `setContent` root to resolve `PyrycodeMobileTheme(darkTheme = …)` and inside `composable(Routes.SETTINGS)` to drive the Theme row subtitle).
 - [ConversationRow](features/conversation-row.md) — stateless M3 `ListItem`-based row consuming `Conversation` + `Message?`; auto-name fallback branched on `isPromoted`, whitespace-normalized 2-line preview, kotlinx-datetime relative-time bucketing (`just now` / `Nm ago` / `Nh ago` / `Yesterday` / `Nd ago` / abbreviated date). Headline is a `Row` with two natural-width decorations: workspace label (#19, trailing) and sleeping-session dot (#20, leading — 8.dp `Box` filled with `colorScheme.outline`, gated on `Conversation.isSleeping`). Optional `onLongClick: (() -> Unit)? = null` (#25) switches the modifier chain from `Modifier.clickable` to `Modifier.combinedClickable` so callers can attach long-press affordances without fanning a screen-specific concept into the shared primitive. Since #68 the `ListItem` carries a `leadingContent = { ConversationAvatar(conversation) }` slot. Shared between the #46 channel list and the discussions drilldown.

docs/knowledge/codebase/96.md

@@ -0,0 +1,40 @@
+# #96 — `unarchive()` primitive on `ConversationRepository` + Fake impl
+
+Adds the trivial inverse of `archive()` introduced in #93: a one-shot mutator that clears `Conversation.archived`, so an archived row leaves `ConversationFilter.Archived` and reappears in the matching live tier (`Discussions` for unpromoted; `Channels` for the hypothetical archived-promoted case). Data-layer-only — the UI restore action (#94) consumes this primitive in a follow-up.
+
+## Summary
+
+- `ConversationRepository` gains `suspend fun unarchive(conversationId: String)`, slotted directly under `archive()` (line 32) so the inverse pairing is visually obvious. Signature mirrors `archive()` exactly: raw `String` id, `suspend`, `Unit`, no extra parameters.
+- `FakeConversationRepository.unarchive(conversationId)` is a 6-line `state.update { ... }` that copies the existing record with `conversation.copy(archived = false)`. Unknown id throws via the same `unknown(id)` helper as `archive()`. Idempotent by construction — the second call produces an `equals`-identical map and `MutableStateFlow.update` does not re-emit. No precondition check on the current `archived` value (the issue body delegated this choice to the architect; chosen to match `archive()`'s established silent-idempotent shape and stay symmetric with the eventual REST `DELETE`-style remote impl).
+- Three new `unarchive_*` tests in `FakeConversationRepositoryTest` mirroring the existing `archive_*` cluster — round-trip from `Archived` → `Discussions` (using the existing `seed-discussion-archived` seed, no `repo.archive()` setup needed), unknown-id-throws, and idempotence-after-double-call.
+- Two existing test files (`ChannelListViewModelTest`, `DiscussionListViewModelTest`) gained `override suspend fun unarchive(conversationId: String): Unit = TODO("not used")` arms on five inline `ConversationRepository` stubs so they keep compiling against the widened interface. No production-VM consumer in this slice.
+
+## Files touched
+
+- `app/src/main/java/de/pyryco/mobile/data/repository/ConversationRepository.kt:32` — new `unarchive` interface method, two lines below `archive`.
+- `app/src/main/java/de/pyryco/mobile/data/repository/FakeConversationRepository.kt:135-143` — new `unarchive` impl, structurally identical to the `archive` block above it.
+- `app/src/test/java/de/pyryco/mobile/data/repository/FakeConversationRepositoryTest.kt:288-348` — `unarchive_movesConversation_from_Archived_to_Discussions_andRetainsInStore` (the AC test), `unarchive_onUnknownId_throws`, `unarchive_isIdempotent`.
+- `app/src/test/java/de/pyryco/mobile/ui/conversations/list/ChannelListViewModelTest.kt:366,408` — `unarchive` stub override on both inline fake repositories.
+- `app/src/test/java/de/pyryco/mobile/ui/conversations/list/DiscussionListViewModelTest.kt:73,361,396,450` — `unarchive` stub override on all four inline fake repositories.
+
+## Patterns established
+
+None new — this slice deliberately reuses every pattern #93 set:
+
+- **Inverse mutators sit immediately next to their forward counterpart in the interface and the impl.** Two-line gap, identical signature shape, identical impl scaffold (`state.update { records -> val record = records[id] ?: throw unknown(id); records + (id to record.copy(...)) }`). When the next paired-inverse mutator lands (e.g. an `unsleep` for the sleeping-session bit, if ever), follow this physical-adjacency rule rather than alphabetising or grouping by lifecycle stage.
+- **Reuse the existing `unknown(id)` helper rather than open-coding the error message.** Three call sites today (`archive`, `unarchive`, `rename`); the helper exists at `FakeConversationRepository.kt:217`. New mutators that need an unknown-id branch should reuse it; do not introduce a parallel error-formatting helper.
+
+## Lessons learned
+
+- **Widening the `ConversationRepository` interface forces edits to every test file with an inline anonymous-object stub, even if no production VM consumes the new method.** Five `override suspend fun unarchive(conversationId: String): Unit = TODO("not used")` arms across two test files were the bulk of the file count for an XS slice. The reason these stubs aren't shared (as a `BaseFakeConversationRepository` or test-only abstract class) is that each one is scoped to a specific test method and stubs only what that test needs — extracting a shared base would mean every test paying for every method's `TODO`, which isn't a net win at the current ~7 mutator surface. Worth revisiting if the interface grows past ~12 methods or if a test starts needing two stubs that differ on only one method's body.
+- **The `archive()` idempotency property generalises cleanly to its inverse.** `archive_isIdempotent` (#93) passed because `MutableStateFlow.update` deduplicates on value equality and `data class` `.copy(archived = true)` on an already-`true` field produces an `equals`-identical record. The same logic applies in reverse: `unarchive_isIdempotent` passes for free because `.copy(archived = false)` on an already-`false` record is also `equals`-identical. This isn't a coincidence — it's the load-bearing property of the `state.update`-with-`data-class-copy` pattern that the file standardised on. Any future paired-inverse mutator using the same shape gets free idempotency on both sides.
+
+## Links
+
+- Issue: https://github.com/pyrycode/pyrycode-mobile/issues/96
+- Spec: `docs/specs/architecture/96-unarchive-primitive.md`
+- Foundation: #93 ([`./93.md`](./93.md)) — introduced the `archived` flag, `ConversationFilter.Archived`, and the flag-based `archive()` this primitive inverts.
+- Split from: #77 (Archived Discussions UI epic).
+- Downstream: #94 — Archived Discussions UI restore action consumes this primitive.
+- Feature docs touched: [ConversationRepository](../features/conversation-repository.md).
+- Prior shape it builds on: #3 ([`./3.md`](./3.md)) — interface; #4 ([`./4.md`](./4.md)) — `state.update { ... }` mutator pattern + `unknown(id)` helper.