CompositeCode · Adron · Sep 16, 2026 · Sep 16, 2026
diff --git a/...Test/kotlin/com/interlinedlist/android/feature/messages/ui/feed/MessagesFeedScreenTest.kt b/...Test/kotlin/com/interlinedlist/android/feature/messages/ui/feed/MessagesFeedScreenTest.kt
@@ -12,6 +12,7 @@ import androidx.compose.ui.test.junit4.createComposeRule
 import androidx.compose.ui.test.onNodeWithTag
 import androidx.compose.ui.test.onNodeWithText
 import androidx.compose.ui.test.performClick
+import androidx.compose.ui.test.performTextInput
 import androidx.test.ext.junit.runners.AndroidJUnit4
 import com.google.common.truth.Truth.assertThat
 import com.interlinedlist.android.core.designsystem.theme.InterlinedListTheme
@@ -20,6 +21,7 @@ import com.interlinedlist.android.feature.messages.domain.LinkedNetwork
 import com.interlinedlist.android.feature.messages.domain.Message
 import com.interlinedlist.android.feature.messages.domain.MessageVisibility
 import com.interlinedlist.android.feature.messages.domain.PushedMessage
+import com.interlinedlist.android.feature.messages.domain.TagSuggestion
 import com.interlinedlist.android.feature.messages.ui.components.EditMessageSheetTags
 import com.interlinedlist.android.feature.messages.ui.components.MessageCardTags
 import com.interlinedlist.android.feature.messages.ui.components.MessageMediaTags
@@ -44,6 +46,7 @@ class MessagesFeedScreenTest {
         publiclyVisible: Boolean = true,
         pushCount: Int = 0,
         pushedMessage: PushedMessage? = null,
+        tags: List<String> = emptyList(),
     ) = Message(
         id = id, content = body, authorId = "u1", authorUsername = "adron",
         authorDisplayName = "Adron", authorAvatarUrl = null, createdAt = null,
@@ -52,6 +55,7 @@ class MessagesFeedScreenTest {
         pushCount = pushCount,
         pushedMessageId = pushedMessage?.id,
         pushedMessage = pushedMessage,
+        tags = tags,
     )
 
     private fun original(
@@ -74,6 +78,7 @@ class MessagesFeedScreenTest {
         onViewingPreferenceChange: ((ViewingPreference) -> Unit)? = null,
         onPush: (Message) -> Unit = {},
         onQuote: (Message) -> Unit = {},
+        onSelectTagSuggestion: (TagSuggestion) -> Unit = {},
     ) {
         composeRule.setContent {
             var state by mutableStateOf(initial)
@@ -107,6 +112,26 @@ class MessagesFeedScreenTest {
                     onBlockUser = onBlockUser,
                     onMuteUser = onMuteUser,
                     onReportUser = onReportUser,
+                    onTagQueryChange = { state = state.copy(tagQuery = it) },
+                    onCommitTag = {
+                        val tag = state.tagQuery.trim()
+                        state = if (tag.isEmpty() || tag in state.composeTags) {
+                            state.copy(tagQuery = "")
+                        } else {
+                            state.copy(composeTags = state.composeTags + tag, tagQuery = "")
+                        }
+                    },
+                    onSelectTagSuggestion = { suggestion ->
+                        state = state.copy(
+                            composeTags = state.composeTags + suggestion.tag,
+                            tagQuery = "",
+                            tagSuggestions = emptyList(),
+                        )
+                        onSelectTagSuggestion(suggestion)
+                    },
+                    onRemoveTag = { tag ->
+                        state = state.copy(composeTags = state.composeTags - tag)
+                    },
                     onPush = onPush,
                     onQuote = { quoted ->
                         state = state.copy(isComposeOpen = true, quoteTarget = quoted)
@@ -542,4 +567,71 @@ class MessagesFeedScreenTest {
 
         composeRule.onNodeWithTag(MessagesFeedTags.VISIBILITY_PRIVATE).assertHasClickAction()
     }
+
+    // --- tags ---------------------------------------------------------------
+
+    @Test
+    fun tags_areRendered_onTheCard() {
+        setFeed(
+            MessagesFeedUiState(
+                // Straight from the feed payload's tags[] — no extra fetch.
+                messages = listOf(message("1", "tagged post", tags = listOf("lists", "Lego"))),
+            ),
+        )
+        composeRule.onNodeWithTag(MessageCardTags.TAGS).assertIsDisplayed()
+        composeRule.onNodeWithTag(MessageCardTags.tagTag("lists")).assertIsDisplayed()
+        composeRule.onNodeWithTag(MessageCardTags.tagTag("Lego")).assertIsDisplayed()
+        composeRule.onNodeWithText("lists").assertIsDisplayed()
+    }
+
+    @Test
+    fun aTagWithSpacesAndPunctuation_isRendered_whole() {
+        val tag = "life is short, o brave girl"
+        setFeed(MessagesFeedUiState(messages = listOf(message("1", "tagged", tags = listOf(tag)))))
+        // One label, not four: tags are free-form strings, never word tokens.
+        composeRule.onNodeWithTag(MessageCardTags.tagTag(tag)).assertIsDisplayed()
+        composeRule.onNodeWithText(tag).assertIsDisplayed()
+    }
+
+    @Test
+    fun noTagRow_isShown_forAnUntaggedMessage() {
+        setFeed(MessagesFeedUiState(messages = listOf(message("1", "plain"))))
+        composeRule.onNodeWithTag(MessageCardTags.TAGS).assertDoesNotExist()
+    }
+
+    @Test
+    fun composer_addsATypedTag_asAChip() {
+        setFeed(MessagesFeedUiState(isComposeOpen = true))
+        composeRule.onNodeWithTag(MessagesFeedTags.COMPOSE_TAG_INPUT).performTextInput("lists")
+        composeRule.onNodeWithTag(MessagesFeedTags.COMPOSE_TAG_ADD).performClick()
+
+        composeRule.onNodeWithTag(MessagesFeedTags.composeTagTag("lists")).assertIsDisplayed()
+    }
+
+    @Test
+    fun composer_removesACommittedTag() {
+        setFeed(MessagesFeedUiState(isComposeOpen = true, composeTags = listOf("lists")))
+        composeRule.onNodeWithTag(MessagesFeedTags.composeTagTag("lists")).performClick()
+        composeRule.onNodeWithTag(MessagesFeedTags.composeTagTag("lists")).assertDoesNotExist()
+    }
+
+    @Test
+    fun composer_showsSuggestions_andAddsTheTappedOne() {
+        var selected: TagSuggestion? = null
+        setFeed(
+            MessagesFeedUiState(
+                isComposeOpen = true,
+                tagQuery = "l",
+                // The server matched case-insensitively; the app shows its answer
+                // exactly as given, in its order.
+                tagSuggestions = listOf(TagSuggestion("lists", 8), TagSuggestion("Lego", 2)),
+            ),
+            onSelectTagSuggestion = { selected = it },
+        )
+        composeRule.onNodeWithTag(MessagesFeedTags.TAG_SUGGESTIONS).assertIsDisplayed()
+        composeRule.onNodeWithTag(MessagesFeedTags.tagSuggestionTag("Lego")).performClick()
+
+        assert(selected?.tag == "Lego")
+        composeRule.onNodeWithTag(MessagesFeedTags.composeTagTag("Lego")).assertIsDisplayed()
+    }
 }
diff --git a/...main/kotlin/com/interlinedlist/android/feature/messages/data/DefaultMessagesRepository.kt b/...main/kotlin/com/interlinedlist/android/feature/messages/data/DefaultMessagesRepository.kt
@@ -24,6 +24,7 @@ import com.interlinedlist.android.feature.messages.domain.LinkedNetwork
 import com.interlinedlist.android.feature.messages.domain.Message
 import com.interlinedlist.android.feature.messages.domain.MessageVisibility
 import com.interlinedlist.android.feature.messages.domain.ReportReason
+import com.interlinedlist.android.feature.messages.domain.TagSuggestion
 import com.interlinedlist.android.feature.messages.domain.asPushedOriginal
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.first
@@ -119,6 +120,7 @@ class DefaultMessagesRepository @Inject constructor(
         crossPost: CrossPostSelection,
         visibility: MessageVisibility,
         pushedMessageId: String?,
+        tags: List<String>,
     ): ApiResult<CreatedMessage> = withContext(dispatchers.io) {
         val isReshare = pushedMessageId != null
         val request = CreateMessageRequest(
@@ -138,6 +140,9 @@ class DefaultMessagesRepository @Inject constructor(
             imageUrls = imageUrls.ifEmpty { null },
             videoUrls = videoUrls.ifEmpty { null },
             scheduledAt = scheduledAt,
+            // Sent verbatim — a tag may contain spaces and punctuation. Omitted
+            // entirely (explicitNulls = false) when the composer added none.
+            tags = tags.ifEmpty { null },
             // Encode cross-post targets per the create schema. explicitNulls=false
             // drops these when empty/false, so a plain post keeps its original body.
             mastodonProviderIds = crossPost.mastodonProviderIds.ifEmpty { null },
@@ -418,6 +423,21 @@ class DefaultMessagesRepository @Inject constructor(
         }
     }
 
+    /**
+     * Asks the server for suggestions and hands back exactly what it said, in the
+     * order it said it. The matching rule (case-insensitive literal prefix) lives
+     * on the server; re-filtering here would misrepresent it.
+     */
+    override suspend fun autocompleteTags(
+        query: String,
+        limit: Int,
+    ): ApiResult<List<TagSuggestion>> = withContext(dispatchers.io) {
+        when (val result = safeCall { api.autocompleteTags(query = query, limit = limit) }) {
+            is ApiResult.Success -> ApiResult.Success(result.data.toDomain())
+            is ApiResult.Failure -> result
+        }
+    }
+
     override suspend fun search(query: String): ApiResult<List<Message>> = withContext(dispatchers.io) {
         when (val result = safeCall {
             api.search(query = query, limit = PaginationDto.DEFAULT_LIMIT, offset = 0)

diff --git a/...es/src/main/kotlin/com/interlinedlist/android/feature/messages/data/MessagesRepository.kt b/...es/src/main/kotlin/com/interlinedlist/android/feature/messages/data/MessagesRepository.kt
@@ -8,6 +8,7 @@ import com.interlinedlist.android.feature.messages.domain.LinkedNetwork
 import com.interlinedlist.android.feature.messages.domain.Message
 import com.interlinedlist.android.feature.messages.domain.MessageVisibility
 import com.interlinedlist.android.feature.messages.domain.ReportReason
+import com.interlinedlist.android.feature.messages.domain.TagSuggestion
 import kotlinx.coroutines.flow.Flow
 
 /**
@@ -87,6 +88,9 @@ interface MessagesRepository {
      * **quote**, and [pushMessage] is the no-comment **push**. Amplifying someone
      * else's message is always public, so a non-null [pushedMessageId] overrides
      * [visibility] with [MessageVisibility.PUSH_OR_QUOTE].
+     *
+     * [tags] are sent as `tags[]`, verbatim: free-form labels that may contain
+     * spaces and punctuation. An empty list omits the field entirely.
      */
     suspend fun createMessage(
         content: String,
@@ -96,8 +100,20 @@ interface MessagesRepository {
         crossPost: CrossPostSelection = CrossPostSelection.NONE,
         visibility: MessageVisibility = MessageVisibility.PUBLIC,
         pushedMessageId: String? = null,
+        tags: List<String> = emptyList(),
     ): ApiResult<CreatedMessage>
 
+    /**
+     * Tag suggestions for the prefix the user is typing, from
+     * `GET /api/tags/autocomplete` (query parameter **`q`**).
+     *
+     * The server does the matching: a **case-insensitive literal prefix** over
+     * existing public tags. The result is returned in the server's order and is
+     * never re-filtered or fuzzy-matched here — doing so would show (or hide)
+     * suggestions the server never chose. Network-only: suggestions are not cached.
+     */
+    suspend fun autocompleteTags(query: String, limit: Int = TAG_SUGGESTION_LIMIT): ApiResult<List<TagSuggestion>>
+
     /**
      * Pushes (reposts) [messageId] as-is: posts `pushedMessageId` with **no**
      * content, always publicly. A quote — the same repost with the user's own
@@ -181,4 +197,9 @@ interface MessagesRepository {
 
     /** Full-text search over top-level messages (does not touch the feed cache). */
     suspend fun search(query: String): ApiResult<List<Message>>
+
+    companion object {
+        /** How many tag suggestions to ask for (server default 10, max 50). */
+        const val TAG_SUGGESTION_LIMIT = 10
+    }
 }
diff --git a/...s/src/main/kotlin/com/interlinedlist/android/feature/messages/data/local/MessageEntity.kt b/...s/src/main/kotlin/com/interlinedlist/android/feature/messages/data/local/MessageEntity.kt
@@ -33,6 +33,8 @@ data class MessageEntity(
     val videoUrls: List<String> = emptyList(),
     /** Link-preview card, stored via [MessageConverters]; null when none. */
     val linkPreview: LinkPreview? = null,
+    /** Free-form tags, stored as JSON via [MessageConverters]. */
+    val tags: List<String> = emptyList(),
     /** Future send time for a scheduled message; null for a normal message. */
     val scheduledAt: String? = null,
     /** Last-edited instant; null when the message has not been edited. */
@@ -66,6 +68,7 @@ fun MessageEntity.toDomain(): Message = Message(
     imageUrls = imageUrls,
     videoUrls = videoUrls,
     linkPreview = linkPreview,
+    tags = tags,
     scheduledAt = scheduledAt,
     editedAt = editedAt,
     publiclyVisible = publiclyVisible,
@@ -91,6 +94,7 @@ fun Message.toEntity(feedOrder: Long): MessageEntity = MessageEntity(
     imageUrls = imageUrls,
     videoUrls = videoUrls,
     linkPreview = linkPreview,
+    tags = tags,
     scheduledAt = scheduledAt,
     editedAt = editedAt,
     publiclyVisible = publiclyVisible,

diff --git a/...rc/main/kotlin/com/interlinedlist/android/feature/messages/data/local/MessagesDatabase.kt b/...rc/main/kotlin/com/interlinedlist/android/feature/messages/data/local/MessagesDatabase.kt
@@ -10,7 +10,7 @@ import androidx.room.TypeConverters
  */
 @Database(
     entities = [MessageEntity::class],
-    version = 4,
+    version = 5,
     exportSchema = false,
 )
 @TypeConverters(MessageConverters::class)

diff --git a/...es/src/main/kotlin/com/interlinedlist/android/feature/messages/data/remote/MessagesApi.kt b/...es/src/main/kotlin/com/interlinedlist/android/feature/messages/data/remote/MessagesApi.kt
@@ -10,6 +10,7 @@ import com.interlinedlist.android.feature.messages.data.remote.dto.MessagesRespo
 import com.interlinedlist.android.feature.messages.data.remote.dto.MetadataResponse
 import com.interlinedlist.android.feature.messages.data.remote.dto.ReportRequest
 import com.interlinedlist.android.feature.messages.data.remote.dto.ScheduledMessagesResponse
+import com.interlinedlist.android.feature.messages.data.remote.dto.TagAutocompleteResponse
 import com.interlinedlist.android.feature.messages.data.remote.dto.UserReportRequest
 import okhttp3.MultipartBody
 import retrofit2.http.Body
@@ -113,6 +114,22 @@ interface MessagesApi {
     @GET("api/user/identities")
     suspend fun getIdentities(): IdentitiesResponse
 
+    /**
+     * Tag suggestions for a prefix the user is typing.
+     *
+     * The query parameter is **`q`** — the endpoint 400s with
+     * `{"error":"Query parameter 'q' is required","code":"bad_request"}` for
+     * anything else (notably `prefix`). Matching is a **case-insensitive literal
+     * prefix** over existing public tags (`%` and `_` are not wildcards) and a
+     * single leading `#` is stripped server-side; an empty `q` is a 400.
+     * [limit] defaults to 10 server-side and is clamped to 50.
+     */
+    @GET("api/tags/autocomplete")
+    suspend fun autocompleteTags(
+        @Query("q") query: String,
+        @Query("limit") limit: Int? = null,
+    ): TagAutocompleteResponse
+
     /** Reports a message with a reason (and optional free-text detail). */
     @POST("api/messages/{id}/report")
     suspend fun report(@Path("id") id: String, @Body body: ReportRequest)

diff --git a/...src/main/kotlin/com/interlinedlist/android/feature/messages/data/remote/dto/MessageDto.kt b/...src/main/kotlin/com/interlinedlist/android/feature/messages/data/remote/dto/MessageDto.kt
@@ -35,6 +35,12 @@ data class MessageDto(
     val videoUrls: List<String> = emptyList(),
     /** Fetched link-preview metadata for the first URL in the body, if any. */
     val linkMetadata: LinkMetadataDto? = null,
+    /**
+     * Free-form tags on the message. The feed already carries these, so the card
+     * renders them without a second fetch. Values may contain spaces and
+     * punctuation — never split or normalise them.
+     */
+    val tags: List<String> = emptyList(),
     /** Future send time for a scheduled message; null once published. */
     val scheduledAt: String? = null,
     /** False when the message is private (visible only to its author). */
@@ -114,6 +120,8 @@ fun MessageDto.toDomain(currentUserId: String?): Message {
         imageUrls = imageUrls,
         videoUrls = videoUrls,
         linkPreview = linkMetadata?.toDomain(),
+        // Kept verbatim: a tag is a label, not a token.
+        tags = tags,
         scheduledAt = scheduledAt,
         publiclyVisible = publiclyVisible,
         pushCount = pushCount,

diff --git a/...in/kotlin/com/interlinedlist/android/feature/messages/data/remote/dto/MessagesResponse.kt b/...in/kotlin/com/interlinedlist/android/feature/messages/data/remote/dto/MessagesResponse.kt
@@ -115,6 +115,10 @@ data class CrossPostStatusDto(
  * push (repost), and with content it is a quote. It is mutually exclusive with
  * [parentId] and [scheduledAt], and a push/quote is always public.
  *
+ * [tags] are free-form string labels ("Case-sensitive; lowercase recommended" —
+ * `/help/api/messages`). They are sent exactly as the user committed them: a tag
+ * may contain spaces and punctuation, so nothing splits or rewrites them.
+ *
  * Only non-null fields are serialised (the shared Json uses `explicitNulls =
  * false`), so a plain InterlinedList-only post sends just
  * `{ content, publiclyVisible }` and a bare push sends no `content` at all.
@@ -129,6 +133,7 @@ data class CreateMessageRequest(
     val imageUrls: List<String>? = null,
     val videoUrls: List<String>? = null,
     val scheduledAt: String? = null,
+    val tags: List<String>? = null,
     val mastodonProviderIds: List<String>? = null,
     val crossPostToBluesky: Boolean? = null,
     val crossPostToLinkedIn: Boolean? = null,

diff --git a/...c/main/kotlin/com/interlinedlist/android/feature/messages/data/remote/dto/TagsResponse.kt b/...c/main/kotlin/com/interlinedlist/android/feature/messages/data/remote/dto/TagsResponse.kt
@@ -0,0 +1,32 @@
+package com.interlinedlist.android.feature.messages.data.remote.dto
+
+import com.interlinedlist.android.feature.messages.domain.TagSuggestion
+import kotlinx.serialization.Serializable
+
+/**
+ * Response from `GET /api/tags/autocomplete?q=…`:
+ * `{ "tags": [ { "tag": "lists", "count": 8 }, … ] }`.
+ *
+ * Suggestions arrive already ordered by count (descending), then alphabetically,
+ * and already prefix-matched case-insensitively by the server — so the app keeps
+ * the order and the contents exactly as sent.
+ */
+@Serializable
+data class TagAutocompleteResponse(
+    val tags: List<TagSuggestionDto> = emptyList(),
+) {
+    /** The suggestions as domain values, dropping any entry with no tag. */
+    fun toDomain(): List<TagSuggestion> = tags.mapNotNull { it.toDomainOrNull() }
+}
+
+/** One `{ tag, count }` entry in an autocomplete (or trending) tag response. */
+@Serializable
+data class TagSuggestionDto(
+    val tag: String = "",
+    val count: Int = 0,
+) {
+    fun toDomainOrNull(): TagSuggestion? {
+        val label = tag.takeIf { it.isNotBlank() } ?: return null
+        return TagSuggestion(tag = label, count = count)
+    }
+}
diff --git a/...re/messages/src/main/kotlin/com/interlinedlist/android/feature/messages/domain/Message.kt b/...re/messages/src/main/kotlin/com/interlinedlist/android/feature/messages/domain/Message.kt
@@ -29,6 +29,12 @@ data class Message(
     val videoUrls: List<String> = emptyList(),
     /** Link-preview card built from fetched metadata, when present. */
     val linkPreview: LinkPreview? = null,
+    /**
+     * Free-form labels attached to the message, exactly as the feed returned
+     * them (`tags[]`). They may contain spaces and punctuation, so they are never
+     * tokenised or normalised — only rendered.
+     */
+    val tags: List<String> = emptyList(),
     /**
      * ISO-8601 send time for a scheduled (not-yet-published) message; null for a
      * normal message. Present on rows returned by the scheduled endpoint.
@@ -65,6 +71,9 @@ data class Message(
     /** True when any image or video media is attached. */
     val hasMedia: Boolean get() = imageUrls.isNotEmpty() || videoUrls.isNotEmpty()
 
+    /** True when the card should render a tag row. */
+    val hasTags: Boolean get() = tags.isNotEmpty()
+
     /** True when the message has been edited since it was posted. */
     val isEdited: Boolean get() = editedAt != null