refactor: move reply-context logic to commons.model; keep the Compose compiler in commons by measurement

Closes the last two items of documented debt from the commons/commonsUI split.

ParentNote (replyingDirectlyTo, isCommunityDefinition) and ReplyContext are
pure thread logic used by ViewModels, so they move from the misleading
`ui.note` package to `commons.model`, next to ThreadAssembler, together with
their tests and the StubCache fixture that shared the package. No `ui.*`
package is left in commons. The `ui.note` composables in commonsUI gain
explicit imports; consumer imports rewritten.

Whether commons still needs the Compose compiler plugin was an open question;
it is now measured. With compiler reports on the three GUI modules and full,
non-incremental recompiles in both configurations, removing the plugin flips
composable parameters typed with unannotated commons classes (TopFilter,
TorSettings, ProfileBroadcastStatus, ScheduledPost, EmojiPackState, ...) from
runtime-stable to unstable: 20→28 in commonsUI, 33→65 in desktopApp,
90→149 in amethyst. The plugin stays; the numbers are recorded in the build
file, ARCHITECTURE.md and the split plan so the question is not reopened.

Verified: JVM compiles for commons, commonsUI, cli, desktopApp; Android debug
compiles for nappletHost and amethyst; commons/commonsUI/cli/desktopApp JVM
test suites.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N56KzPSYiN5edMRamvKEgD

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/note/NoteCompose.kt

@@ -61,8 +61,10 @@ import com.vitorpamplona.amethyst.commons.icons.symbols.MaterialSymbols
 import com.vitorpamplona.amethyst.commons.model.AddressableNote
 import com.vitorpamplona.amethyst.commons.model.Note
 import com.vitorpamplona.amethyst.commons.model.concord.ConcordChannel
+import com.vitorpamplona.amethyst.commons.model.isCommunityDefinition
 import com.vitorpamplona.amethyst.commons.model.nip28PublicChats.PublicChatChannel
 import com.vitorpamplona.amethyst.commons.model.nip29RelayGroups.RelayGroupChannel
+import com.vitorpamplona.amethyst.commons.model.replyingDirectlyTo
 import com.vitorpamplona.amethyst.commons.model.textNoteModifications
 import com.vitorpamplona.amethyst.commons.resources.Res
 import com.vitorpamplona.amethyst.commons.resources.approve
@@ -78,8 +80,6 @@ import com.vitorpamplona.amethyst.commons.ui.note.QuietMark
 import com.vitorpamplona.amethyst.commons.ui.note.RenderCashuMint
 import com.vitorpamplona.amethyst.commons.ui.note.RenderFedimint
 import com.vitorpamplona.amethyst.commons.ui.note.RenderMintRecommendation
-import com.vitorpamplona.amethyst.commons.ui.note.isCommunityDefinition
-import com.vitorpamplona.amethyst.commons.ui.note.replyingDirectlyTo
 import com.vitorpamplona.amethyst.commons.ui.state.produceCachedStateAsync
 import com.vitorpamplona.amethyst.model.LocalCache
 import com.vitorpamplona.amethyst.service.relayClient.reqCommand.channel.observeChannelPicture

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/note/types/Text.kt

@@ -35,10 +35,10 @@ import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.text.style.TextOverflow
 import com.vitorpamplona.amethyst.commons.model.EmptyTagList
 import com.vitorpamplona.amethyst.commons.model.Note
+import com.vitorpamplona.amethyst.commons.model.replyingDirectlyTo
 import com.vitorpamplona.amethyst.commons.model.toImmutableListOfLists
 import com.vitorpamplona.amethyst.commons.ui.components.GenericLoadable
 import com.vitorpamplona.amethyst.commons.ui.note.ReplyToLabel
-import com.vitorpamplona.amethyst.commons.ui.note.replyingDirectlyTo
 import com.vitorpamplona.amethyst.model.LocalCache
 import com.vitorpamplona.amethyst.ui.components.SensitivityWarning
 import com.vitorpamplona.amethyst.ui.components.TranslatableRichTextViewer

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/note/types/ZapPoll.kt

@@ -34,8 +34,8 @@ import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.text.style.TextOverflow
 import com.vitorpamplona.amethyst.commons.model.EmptyTagList
 import com.vitorpamplona.amethyst.commons.model.Note
+import com.vitorpamplona.amethyst.commons.model.replyingDirectlyTo
 import com.vitorpamplona.amethyst.commons.model.toImmutableListOfLists
-import com.vitorpamplona.amethyst.commons.ui.note.replyingDirectlyTo
 import com.vitorpamplona.amethyst.model.LocalCache
 import com.vitorpamplona.amethyst.ui.components.SensitivityWarning
 import com.vitorpamplona.amethyst.ui.components.TranslatableRichTextViewer

commons/ARCHITECTURE.md

@@ -75,7 +75,7 @@ in `commonsUI`, under the same package.
 ### Domain models & data
 | Package        | UI? | Purpose |
 |----------------|-----|---------|
-| `model`        | no¹ | Core domain types (`Note`, `User`, `Channel`), thread assembly, and per-NIP event model extensions in `model/nipNN…` subpackages. `model/cache` holds the in-memory event-store interfaces + `UserMetadataCache`. `model/account`, `model/observables`. The largest package; keep it organized by NIP. |
+| `model`        | no¹ | Core domain types (`Note`, `User`, `Channel`), thread assembly (`ThreadAssembler`, `ThreadLevelCalculator`, `ReplyContext`, `replyingDirectlyTo`), and per-NIP event model extensions in `model/nipNN…` subpackages. `model/cache` holds the in-memory event-store interfaces + `UserMetadataCache`. `model/account`, `model/observables`. The largest package; keep it organized by NIP. |
 | `defaults`     | no  | Static bootstrap data (default relays, channels). |
 
 ¹ `model` uses only the `@Stable`/`@Immutable` runtime annotations — CLI-safe.
@@ -126,7 +126,7 @@ type (`LazyListState`, `TextFieldValue`, `TextFieldState`) goes to `commonsUI`.
 ### UI (Compose — lives in **`commonsUI`**)
 | Package        | UI? | Purpose |
 |----------------|-----|---------|
-| `ui`           | yes | **Cross-cutting** shared composables only, organized by area: `ui/components`, `ui/theme`, `ui/signing`, `ui/thread`, `ui/note`, `ui/richtext`, `ui/search`, `ui/notifications`, `ui/screens`, `ui/layouts`, `ui/markdown`, `ui/privacylock`, plus Compose helpers in `ui/state` (cached-state) and `ui/text` (TextField extensions). Feature-specific UI lives in `<feature>/ui`, **not** here. **Exception:** `ui/note/ParentNote`+`ReplyContext` (pure thread logic) stay in *this* module. The `ui/feeds` composables (`NewPostsChip`, `RelayReachMarker`…) are in `commonsUI`; the feed DAL that used to share that package now lives in `feeds/` here. |
+| `ui`           | yes | **Cross-cutting** shared composables only, organized by area: `ui/components`, `ui/theme`, `ui/signing`, `ui/thread`, `ui/note`, `ui/richtext`, `ui/search`, `ui/notifications`, `ui/screens`, `ui/layouts`, `ui/markdown`, `ui/privacylock`, plus Compose helpers in `ui/state` (cached-state) and `ui/text` (TextField extensions). Feature-specific UI lives in `<feature>/ui`, **not** here. Nothing under `ui.*` lives in *this* module any more: the feed DAL that used to sit in `ui/feeds` is now `feeds/`, and the reply-context logic that sat in `ui/note` (`replyingDirectlyTo`, `ReplyContext`) is now in `model/` next to `ThreadAssembler`. |
 | `nip23LongContent` | yes | Long-form (NIP-23) article UI: `nip23LongContent/ui/article` (reader) + `…/ui/editor` (authoring). The model lives in `model/nip23LongContent` (here). |
 | `icons`        | yes | `ImageVector` icon definitions + builders, Material Symbols codepoints, the icon-font glyph tables. |
 | `hashtags`     | yes | Custom hashtag `ImageVector`s. |
@@ -232,9 +232,13 @@ compiles: `commonMain` → `jvmAndroid` → platform-specific. See
 
 These are intentionally *documented*, not silently tolerated. Fix opportunistically.
 
-- **`ui/note` in `commons`** still hosts `ParentNote` + `ReplyContext` (pure
-  thread logic used by ViewModels) under a `ui.*` package name. Candidate for
-  `model/` when touched next.
+- **`commons` applies the Compose *compiler* plugin without declaring any
+  composable.** Deliberate, not debt: the plugin's `@StabilityInferred`
+  stamps are what keep unannotated commons classes stable from the apps'
+  point of view. Measured on full recompiles (2026-09-12): without it,
+  unstable composable params go 20→28 in `commonsUI`, 33→65 in `desktopApp`,
+  90→149 in `amethyst`. Don't remove it; if a class must be stable for a
+  hot path, annotate it explicitly as well.
 - **Same package tree in two modules.** Intentional (zero-import-churn split),
   but it means a package's module is not visible from its name. Rule of
   thumb: if it imports Compose UI it is in `commonsUI`; check §2 when unsure.

commons/build.gradle.kts

@@ -11,9 +11,13 @@ plugins {
     alias(libs.plugins.androidKotlinMultiplatformLibrary)
     // Kept on purpose even though no @Composable lives here anymore: the
     // Compose compiler stamps @StabilityInferred on every class it compiles,
-    // which is what lets the apps' composables treat commons models (Note,
-    // User, states) as stable/skippable. Dropping it would silently make all
-    // of them "unstable" from the UI's point of view.
+    // which is what lets the apps' composables treat unannotated commons
+    // classes (TopFilter, TorSettings, ProfileBroadcastStatus, …) as stable.
+    // Measured with Compose compiler reports on full recompiles (2026-09-12):
+    // removing this plugin turns 20→28 composable params unstable in
+    // :commonsUI, 33→65 in :desktopApp and 90→149 in :amethyst. Inference is
+    // also self-maintaining, unlike hand-written @Immutable annotations that
+    // silently lie once a `var` is added — so this stays.
     alias(libs.plugins.jetbrainsComposeCompiler)
     alias(libs.plugins.serialization)
 }

commons/plans/2026-09-12-commons-ui-split.md

@@ -84,11 +84,29 @@ next to the `:commons` ones on macOS.
   existing `feeds` package, next to `feeds/custom`). Consumer imports rewritten.
 - **Chess composables moved to `nip64Chess/ui`** in `commonsUI`; the logic
   stays in `commons/…/nip64Chess/`.
+- **`ui/note/ParentNote` + `ReplyContext` moved to `commons/…/model/`** next to
+  `ThreadAssembler` (with the `StubCache` test fixture). No `ui.*` package is
+  left in `commons`.
 
-## Open
+## Decided: `commons` keeps the Compose compiler plugin
+
+Measured rather than guessed. With `composeCompiler { reportsDestination }`
+on the three GUI modules and full (non-incremental, `--rerun`) compiles in
+both configurations, removing the plugin from `commons` flips composable
+parameters typed with unannotated commons classes from runtime-stable to
+unstable:
+
+| Module | unstable params, plugin on | plugin off |
+|---|---|---|
+| `commonsUI` | 20 | 28 |
+| `desktopApp` | 33 | 65 |
+| `amethyst` (fdroidDebug) | 90 | 149 |
+
+The classes involved (`TopFilter`, `TorSettings`, `TorServiceStatus`,
+`ProfileBroadcastStatus`, `ScheduledPost`, `EmojiPackState`,
+`Nip65RelayListState`, `PendingAuthApproval`, `UserSearchEngine`, …) are
+all-`val` classes with no `@Stable`/`@Immutable` annotation; the plugin infers
+their stability and keeps inferring it as they evolve. Hand-annotating them
+would reproduce today's result but rot silently the first time a `var` is
+added, so the plugin stays. Recorded in `commons/build.gradle.kts`.
 
-- `commons` still applies the Compose *compiler* plugin on purpose (stability
-  inference for its model classes as seen from the apps' composables).
-  Revisit if a `runtime-annotation`-only setup proves sufficient.
-- `ui/note/ParentNote` + `ReplyContext` remain in `commons` under a `ui.*`
-  package name (pure logic; candidate for `model/`).

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/ParentNote.kt

@@ -18,7 +18,7 @@
  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
-package com.vitorpamplona.amethyst.commons.ui.note
+package com.vitorpamplona.amethyst.commons.model
 
 import com.vitorpamplona.amethyst.commons.model.Note
 import com.vitorpamplona.amethyst.commons.model.cache.ICacheProvider

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/ReplyContext.kt

@@ -18,7 +18,7 @@
  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
-package com.vitorpamplona.amethyst.commons.ui.note
+package com.vitorpamplona.amethyst.commons.model
 
 import com.vitorpamplona.amethyst.commons.model.cache.ICacheProvider
 import com.vitorpamplona.quartz.nip10Notes.BaseThreadedEvent

commons/src/commonTest/kotlin/com/vitorpamplona/amethyst/commons/model/ParentNoteTest.kt

@@ -18,7 +18,7 @@
  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
-package com.vitorpamplona.amethyst.commons.ui.note
+package com.vitorpamplona.amethyst.commons.model
 
 import com.vitorpamplona.amethyst.commons.model.AddressableNote
 import com.vitorpamplona.amethyst.commons.model.Note

commons/src/commonTest/kotlin/com/vitorpamplona/amethyst/commons/model/ReplyContextTest.kt

@@ -18,7 +18,7 @@
  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
-package com.vitorpamplona.amethyst.commons.ui.note
+package com.vitorpamplona.amethyst.commons.model
 
 import com.vitorpamplona.amethyst.commons.model.Note
 import com.vitorpamplona.amethyst.commons.model.User

commons/src/commonTest/kotlin/com/vitorpamplona/amethyst/commons/model/StubCache.kt

@@ -18,7 +18,7 @@
  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
-package com.vitorpamplona.amethyst.commons.ui.note
+package com.vitorpamplona.amethyst.commons.model
 
 import com.vitorpamplona.amethyst.commons.model.AddressableNote
 import com.vitorpamplona.amethyst.commons.model.Channel

desktopApp/src/jvmMain/kotlin/com/vitorpamplona/amethyst/desktop/ui/FeedScreen.kt

@@ -92,6 +92,7 @@ import com.vitorpamplona.amethyst.commons.feeds.FeedState
 import com.vitorpamplona.amethyst.commons.icons.symbols.Icon
 import com.vitorpamplona.amethyst.commons.icons.symbols.MaterialSymbols
 import com.vitorpamplona.amethyst.commons.model.Note
+import com.vitorpamplona.amethyst.commons.model.ReplyContext
 import com.vitorpamplona.amethyst.commons.model.nip02FollowList.FollowAction
 import com.vitorpamplona.amethyst.commons.model.nip05DnsIdentifiers.namecoin.NamecoinResolveState
 import com.vitorpamplona.amethyst.commons.model.nip25Reactions.ReactionAction
@@ -110,7 +111,6 @@ import com.vitorpamplona.amethyst.commons.ui.feeds.NewPostsChip
 import com.vitorpamplona.amethyst.commons.ui.feeds.StickToTopOnPrepend
 import com.vitorpamplona.amethyst.commons.ui.feeds.rememberNewPostsChipState
 import com.vitorpamplona.amethyst.commons.ui.layouts.GenericRepostLayout
-import com.vitorpamplona.amethyst.commons.ui.note.ReplyContext
 import com.vitorpamplona.amethyst.commons.util.toTimeAgo
 import com.vitorpamplona.amethyst.desktop.DesktopPreferences
 import com.vitorpamplona.amethyst.desktop.SearchHistoryStore

desktopApp/src/jvmMain/kotlin/com/vitorpamplona/amethyst/desktop/ui/note/NoteCard.kt

@@ -56,12 +56,12 @@ import androidx.compose.ui.unit.dp
 import coil3.compose.AsyncImage
 import com.vitorpamplona.amethyst.commons.model.EmptyTagList
 import com.vitorpamplona.amethyst.commons.model.ImmutableListOfLists
+import com.vitorpamplona.amethyst.commons.model.ReplyContext
 import com.vitorpamplona.amethyst.commons.relayClient.event.EventFinderFilterAssemblerSubscription
 import com.vitorpamplona.amethyst.commons.relayClient.user.UserFinderFilterAssemblerSubscription
 import com.vitorpamplona.amethyst.commons.richtext.CachedRichTextParser
 import com.vitorpamplona.amethyst.commons.richtext.RichTextParser
 import com.vitorpamplona.amethyst.commons.richtext.UrlParser
-import com.vitorpamplona.amethyst.commons.ui.note.ReplyContext
 import com.vitorpamplona.amethyst.commons.ui.note.ReplyToLabel
 import com.vitorpamplona.amethyst.desktop.cache.DesktopLocalCache
 import com.vitorpamplona.amethyst.desktop.ui.components.ToggleableTimeAgoText