feat: add tag autocomplete in Composer with suggestions and chips

ComposerViewModel fetches available tags from TagRepository on init,
filters suggestions as user types, supports addTag/removeTag. ComposerScreen
shows tag input field with dropdown suggestions (name + post count),
"Create new" option, and FlowRow of InputChip tags with close icons.

app/src/main/java/com/swoosh/microblog/ui/composer/ComposerScreen.kt

@@ -45,6 +45,7 @@ import androidx.lifecycle.viewmodel.compose.viewModel
 import coil.compose.AsyncImage
 import com.swoosh.microblog.data.HashtagParser
 import com.swoosh.microblog.data.model.FeedPost
+import com.swoosh.microblog.data.model.GhostTagFull
 import com.swoosh.microblog.data.model.PostStats
 import com.swoosh.microblog.ui.animation.SwooshMotion
 import kotlinx.coroutines.delay
@@ -323,49 +324,16 @@ fun ComposerScreen(
                         }
                     )
 
-                    // Extracted tags preview chips
+                    // Tags section: input + suggestions + chips
-                    AnimatedVisibility(
+                    Spacer(modifier = Modifier.height(12.dp))
-                        visible = state.extractedTags.isNotEmpty(),
+                    TagsSection(
-                        enter = fadeIn(SwooshMotion.quick()) + expandVertically(animationSpec = SwooshMotion.snappy()),
+                        tagInput = state.tagInput,
-                        exit = fadeOut(SwooshMotion.quick()) + shrinkVertically(animationSpec = SwooshMotion.snappy())
+                        onTagInputChange = viewModel::updateTagInput,
-                    ) {
+                        tagSuggestions = state.tagSuggestions,
-                        Column {
+                        extractedTags = state.extractedTags,
-                            Spacer(modifier = Modifier.height(8.dp))
+                        onAddTag = viewModel::addTag,
-                            Row(
+                        onRemoveTag = viewModel::removeTag
-                                modifier = Modifier.fillMaxWidth(),
+                    )
-                                horizontalArrangement = Arrangement.spacedBy(6.dp)
-                            ) {
-                                Icon(
-                                    Icons.Default.Tag,
-                                    contentDescription = "Tags",
-                                    modifier = Modifier.size(18.dp),
-                                    tint = MaterialTheme.colorScheme.onSurfaceVariant
-                                )
-                                @OptIn(ExperimentalLayoutApi::class)
-                                FlowRow(
-                                    horizontalArrangement = Arrangement.spacedBy(6.dp),
-                                    verticalArrangement = Arrangement.spacedBy(4.dp)
-                                ) {
-                                    state.extractedTags.forEach { tag ->
-                                        SuggestionChip(
-                                            onClick = {},
-                                            label = {
-                                                Text(
-                                                    "#$tag",
-                                                    style = MaterialTheme.typography.labelSmall
-                                                )
-                                            },
-                                            colors = SuggestionChipDefaults.suggestionChipColors(
-                                                containerColor = MaterialTheme.colorScheme.primaryContainer,
-                                                labelColor = MaterialTheme.colorScheme.onPrimaryContainer
-                                            ),
-                                            border = null
-                                        )
-                                    }
-                                }
-                            }
-                        }
-                    }
 
                     Spacer(modifier = Modifier.height(12.dp))
 
@@ -878,3 +846,128 @@ class HashtagVisualTransformation(private val hashtagColor: Color) : VisualTrans
         return TransformedText(annotated, OffsetMapping.Identity)
     }
 }
+
+/**
+ * Tag input section with autocomplete suggestions and tag chips.
+ */
+@OptIn(ExperimentalLayoutApi::class)
+@Composable
+fun TagsSection(
+    tagInput: String,
+    onTagInputChange: (String) -> Unit,
+    tagSuggestions: List<GhostTagFull>,
+    extractedTags: List<String>,
+    onAddTag: (String) -> Unit,
+    onRemoveTag: (String) -> Unit
+) {
+    Column {
+        Text(
+            text = "Tags:",
+            style = MaterialTheme.typography.labelMedium,
+            color = MaterialTheme.colorScheme.onSurfaceVariant
+        )
+
+        Spacer(modifier = Modifier.height(4.dp))
+
+        // Tag input field
+        Box {
+            OutlinedTextField(
+                value = tagInput,
+                onValueChange = onTagInputChange,
+                modifier = Modifier.fillMaxWidth(),
+                placeholder = { Text("Add a tag...") },
+                singleLine = true,
+                leadingIcon = {
+                    Icon(
+                        Icons.Default.Tag,
+                        contentDescription = null,
+                        modifier = Modifier.size(18.dp)
+                    )
+                }
+            )
+
+            // Suggestions dropdown
+            DropdownMenu(
+                expanded = tagSuggestions.isNotEmpty() || tagInput.isNotBlank(),
+                onDismissRequest = { onTagInputChange("") },
+                modifier = Modifier.fillMaxWidth(0.9f)
+            ) {
+                tagSuggestions.take(5).forEach { tag ->
+                    DropdownMenuItem(
+                        text = {
+                            Row(
+                                modifier = Modifier.fillMaxWidth(),
+                                horizontalArrangement = Arrangement.SpaceBetween
+                            ) {
+                                Text(tag.name)
+                                if (tag.count?.posts != null) {
+                                    Text(
+                                        "(${tag.count.posts})",
+                                        style = MaterialTheme.typography.bodySmall,
+                                        color = MaterialTheme.colorScheme.onSurfaceVariant
+                                    )
+                                }
+                            }
+                        },
+                        onClick = { onAddTag(tag.name) }
+                    )
+                }
+
+                // "Create new" option when input doesn't exactly match an existing tag
+                if (tagInput.isNotBlank() && tagSuggestions.none {
+                        it.name.equals(tagInput, ignoreCase = true)
+                    }) {
+                    DropdownMenuItem(
+                        text = {
+                            Text(
+                                "+ Create '$tagInput' as new",
+                                color = MaterialTheme.colorScheme.primary
+                            )
+                        },
+                        onClick = { onAddTag(tagInput) }
+                    )
+                }
+            }
+        }
+
+        // Added tags as chips
+        AnimatedVisibility(
+            visible = extractedTags.isNotEmpty(),
+            enter = fadeIn(SwooshMotion.quick()) + expandVertically(animationSpec = SwooshMotion.snappy()),
+            exit = fadeOut(SwooshMotion.quick()) + shrinkVertically(animationSpec = SwooshMotion.snappy())
+        ) {
+            Column {
+                Spacer(modifier = Modifier.height(8.dp))
+                FlowRow(
+                    horizontalArrangement = Arrangement.spacedBy(6.dp),
+                    verticalArrangement = Arrangement.spacedBy(4.dp)
+                ) {
+                    extractedTags.forEach { tag ->
+                        InputChip(
+                            selected = false,
+                            onClick = { onRemoveTag(tag) },
+                            label = {
+                                Text(
+                                    "#$tag",
+                                    style = MaterialTheme.typography.labelSmall
+                                )
+                            },
+                            trailingIcon = {
+                                Icon(
+                                    Icons.Default.Close,
+                                    contentDescription = "Remove tag $tag",
+                                    modifier = Modifier.size(14.dp)
+                                )
+                            },
+                            colors = InputChipDefaults.inputChipColors(
+                                containerColor = MaterialTheme.colorScheme.primaryContainer,
+                                labelColor = MaterialTheme.colorScheme.onPrimaryContainer
+                            ),
+                            border = null
+                        )
+                    }
+                }
+            }
+        }
+    }
+}

app/src/main/java/com/swoosh/microblog/ui/composer/ComposerViewModel.kt

@@ -11,6 +11,7 @@ import com.swoosh.microblog.data.db.Converters
 import com.swoosh.microblog.data.model.*
 import com.swoosh.microblog.data.repository.OpenGraphFetcher
 import com.swoosh.microblog.data.repository.PostRepository
+import com.swoosh.microblog.data.repository.TagRepository
 import com.swoosh.microblog.worker.PostUploadWorker
 import com.google.gson.Gson
 import com.google.gson.reflect.TypeToken
@@ -25,6 +26,7 @@ import kotlinx.coroutines.launch
 class ComposerViewModel(application: Application) : AndroidViewModel(application) {
 
     private val repository = PostRepository(application)
+    private val tagRepository = TagRepository(application)
     private val appContext = application
 
     private val _uiState = MutableStateFlow(ComposerUiState())
@@ -36,6 +38,47 @@ class ComposerViewModel(application: Application) : AndroidViewModel(application
 
     private var previewDebounceJob: Job? = null
 
+    init {
+        loadAvailableTags()
+    }
+
+    private fun loadAvailableTags() {
+        viewModelScope.launch {
+            tagRepository.fetchTags().fold(
+                onSuccess = { tags ->
+                    _uiState.update { it.copy(availableTags = tags) }
+                },
+                onFailure = { /* silently ignore - tags are optional */ }
+            )
+        }
+    }
+
+    fun updateTagInput(input: String) {
+        val suggestions = if (input.isBlank()) {
+            emptyList()
+        } else {
+            _uiState.value.availableTags.filter { tag ->
+                tag.name.contains(input, ignoreCase = true) &&
+                    !_uiState.value.extractedTags.any { it.equals(tag.name, ignoreCase = true) }
+            }.take(5)
+        }
+        _uiState.update { it.copy(tagInput = input, tagSuggestions = suggestions) }
+    }
+
+    fun addTag(tagName: String) {
+        val currentTags = _uiState.value.extractedTags.toMutableList()
+        if (!currentTags.any { it.equals(tagName, ignoreCase = true) }) {
+            currentTags.add(tagName)
+        }
+        _uiState.update { it.copy(extractedTags = currentTags, tagInput = "", tagSuggestions = emptyList()) }
+    }
+
+    fun removeTag(tagName: String) {
+        val currentTags = _uiState.value.extractedTags.toMutableList()
+        currentTags.removeAll { it.equals(tagName, ignoreCase = true) }
+        _uiState.update { it.copy(extractedTags = currentTags) }
+    }
+
     fun loadForEdit(post: FeedPost) {
         editingLocalId = post.localId
         editingGhostId = post.ghostId
@@ -197,8 +240,10 @@ class ComposerViewModel(application: Application) : AndroidViewModel(application
             _uiState.update { it.copy(isSubmitting = true, error = null) }
 
             val title = state.text.take(60)
-            val extractedTags = HashtagParser.parse(state.text)
+            // Merge hashtag-parsed tags with manually-added tags (deduplicated)
-            val tagsJson = Gson().toJson(extractedTags)
+            val hashtagTags = HashtagParser.parse(state.text)
+            val allTags = (state.extractedTags + hashtagTags).distinctBy { it.lowercase() }
+            val tagsJson = Gson().toJson(allTags)
 
             val altText = state.imageAlt.ifBlank { null }
 
@@ -252,7 +297,7 @@ class ComposerViewModel(application: Application) : AndroidViewModel(application
                 state.linkPreview?.url, state.linkPreview?.title, state.linkPreview?.description,
                 altText
             )
-            val ghostTags = extractedTags.map { GhostTag(name = it) }
+            val ghostTags = allTags.map { GhostTag(name = it) }
 
             val ghostPost = GhostPost(
                 title = title,
@@ -329,6 +374,9 @@ data class ComposerUiState(
     val scheduledAt: String? = null,
     val featured: Boolean = false,
     val extractedTags: List<String> = emptyList(),
+    val availableTags: List<GhostTagFull> = emptyList(),
+    val tagSuggestions: List<GhostTagFull> = emptyList(),
+    val tagInput: String = "",
     val isSubmitting: Boolean = false,
     val isSuccess: Boolean = false,
     val isEditing: Boolean = false,