feat(chat): add @bot mention autocomplete to ChatComposer (#980)

app/src/main/java/com/m57/hermescontrol/ui/chat/ChatInputPolicy.kt

@@ -56,4 +56,48 @@ object ChatInputPolicy {
         commands: List<String>,
         usageCounts: Map<String, Int>,
     ): List<String> = commands.sortedByDescending { usageCounts[it.lowercase()] ?: 0 }
+
+    /**
+     * Extracts the active mention query (without the '@') if the cursor is currently
+     * positioned within an '@' mention token (e.g. "hello @res" -> "res").
+     * Returns null if not in a mention context.
+     */
+    fun extractMentionQuery(
+        text: String,
+        cursorPosition: Int,
+    ): String? {
+        if (text.isEmpty() || cursorPosition < 0 || cursorPosition > text.length) return null
+        val prefix = text.substring(0, cursorPosition)
+        val lastAt = prefix.lastIndexOf('@')
+        if (lastAt == -1) return null
+
+        // Ensure '@' is at start of string or preceded by whitespace
+        if (lastAt > 0 && !prefix[lastAt - 1].isWhitespace()) return null
+
+        val query = prefix.substring(lastAt + 1)
+        // Mention handle cannot contain whitespace
+        if (query.any { it.isWhitespace() }) return null
+        return query
+    }
+
+    /**
+     * Inserts a selected bot handle into the TextFieldValue at the active '@' mention position.
+     */
+    fun applyMention(
+        current: TextFieldValue,
+        botName: String,
+    ): TextFieldValue {
+        val text = current.text
+        val cursor = current.selection.end.coerceIn(0, text.length)
+        val prefix = text.substring(0, cursor)
+        val lastAt = prefix.lastIndexOf('@')
+        if (lastAt == -1) return current
+
+        val beforeAt = text.substring(0, lastAt)
+        val afterCursor = text.substring(cursor)
+        val inserted = "@$botName "
+        val newText = "$beforeAt$inserted$afterCursor"
+        val newCursor = beforeAt.length + inserted.length
+        return TextFieldValue(newText, TextRange(newCursor))
+    }
 }

app/src/main/java/com/m57/hermescontrol/ui/chat/ChatScreen.kt

@@ -767,6 +767,7 @@ fun ChatScreen(
                 isAgentTyping = state.isAgentTyping,
                 isConnected = state.isConnected,
                 commandCatalog = state.commandCatalog,
+                availableBots = state.availableBots,
                 slashUsageCounts = state.slashUsageCounts,
                 pendingAttachments = state.pendingAttachments,
                 onCameraTap = {

app/src/main/java/com/m57/hermescontrol/ui/chat/ChatViewModel.kt

@@ -14,6 +14,7 @@ import com.m57.hermescontrol.data.model.Attachment
 import com.m57.hermescontrol.data.model.ModelCapabilities
 import com.m57.hermescontrol.data.model.ModelProvider
 import com.m57.hermescontrol.data.model.PinnedModel
+import com.m57.hermescontrol.data.model.ProfileInfo
 import com.m57.hermescontrol.data.model.parseContextBreakdown
 import com.m57.hermescontrol.data.model.parseUsageSnapshot
 import com.m57.hermescontrol.data.remote.ApiClient
@@ -304,6 +305,7 @@ data class ChatUiState(
     val typingEffectDelayMs: Int = 30,
     // Commands catalog
     val commandCatalog: CommandCatalog = CommandCatalog(),
+    val availableBots: List<ProfileInfo> = emptyList(),
     // Per-command usage counts for the slash-autocomplete ranking (issue
     // #865). Empty until the local store loads; commands without recorded
     // usage keep their catalog order.
@@ -1894,6 +1896,12 @@ class ChatViewModel(
                 WsMethods.COMMANDS_CATALOG,
                 onSent = { id -> trackRequest(id, WsMethods.COMMANDS_CATALOG) },
             )
+            // Fetch available bot profiles for @ autocomplete
+            val profilesResult = safeApiCall { ApiClient.hermesApi.getProfiles() }
+            if (profilesResult is NetworkResult.Success) {
+                val profiles = profilesResult.data.profiles.orEmpty()
+                _uiState.update { it.copy(availableBots = profiles) }
+            }
         }
     }
 

app/src/main/java/com/m57/hermescontrol/ui/chat/components/ChatComposer.kt

@@ -12,6 +12,7 @@ import androidx.compose.animation.slideInVertically
 import androidx.compose.animation.slideOutVertically
 import androidx.compose.animation.togetherWith
 import androidx.compose.foundation.BorderStroke
+import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
@@ -60,9 +61,11 @@ import androidx.compose.ui.unit.sp
 import coil.compose.AsyncImage
 import com.m57.hermescontrol.R
 import com.m57.hermescontrol.data.model.Attachment
+import com.m57.hermescontrol.data.model.ProfileInfo
 import com.m57.hermescontrol.data.ws.CommandBlocklist
 import com.m57.hermescontrol.data.ws.CommandCatalog
 import com.m57.hermescontrol.ui.chat.ChatInputPolicy
+import com.m57.hermescontrol.ui.common.BotAvatar
 
 /**
  * The chat input bar with a two-row layout: input+send on top,
@@ -80,6 +83,7 @@ fun ChatInputBar(
     commandCatalog: CommandCatalog,
     slashUsageCounts: Map<String, Int> = emptyMap(),
     pendingAttachments: List<Attachment> = emptyList(),
+    availableBots: List<ProfileInfo> = emptyList(),
     onCameraTap: () -> Unit = {},
     onImageTap: () -> Unit = {},
     onFileTap: () -> Unit = {},
@@ -177,6 +181,91 @@ fun ChatInputBar(
                     }
                 }
 
+                // Bot mention @ suggestions
+                val mentionQuery =
+                    remember(inputFieldValue.text, inputFieldValue.selection.end) {
+                        ChatInputPolicy.extractMentionQuery(
+                            inputFieldValue.text,
+                            inputFieldValue.selection.end,
+                        )
+                    }
+
+                androidx.compose.animation.AnimatedVisibility(
+                    visible = mentionQuery != null && availableBots.isNotEmpty(),
+                    enter = androidx.compose.animation.fadeIn() + androidx.compose.animation.expandVertically(),
+                    exit = androidx.compose.animation.fadeOut() + androidx.compose.animation.shrinkVertically(),
+                ) {
+                    val filteredBots =
+                        remember(mentionQuery, availableBots) {
+                            if (mentionQuery == null) {
+                                emptyList()
+                            } else {
+                                availableBots.filter { bot ->
+                                    bot.name.startsWith(mentionQuery, ignoreCase = true) ||
+                                        bot.effectiveTitle.contains(mentionQuery, ignoreCase = true)
+                                }
+                            }
+                        }
+
+                    if (filteredBots.isNotEmpty()) {
+                        Surface(
+                            modifier =
+                                Modifier
+                                    .fillMaxWidth()
+                                    .padding(horizontal = 12.dp, vertical = 4.dp),
+                            shape = RoundedCornerShape(12.dp),
+                            color = MaterialTheme.colorScheme.surfaceVariant.copy(alpha = 0.5f),
+                            border =
+                                BorderStroke(
+                                    1.dp,
+                                    MaterialTheme.colorScheme.outline.copy(alpha = 0.2f),
+                                ),
+                        ) {
+                            LazyColumn(
+                                modifier = Modifier.heightIn(max = 200.dp),
+                            ) {
+                                items(filteredBots, key = { it.name }) { bot ->
+                                    Row(
+                                        modifier =
+                                            Modifier
+                                                .fillMaxWidth()
+                                                .clickable {
+                                                    onInputChange(
+                                                        ChatInputPolicy.applyMention(inputFieldValue, bot.name),
+                                                    )
+                                                }
+                                                .padding(horizontal = 12.dp, vertical = 8.dp),
+                                        verticalAlignment = Alignment.CenterVertically,
+                                    ) {
+                                        BotAvatar(
+                                            name = bot.name,
+                                            avatar = bot.botMeta()?.avatar,
+                                            size = 28.dp,
+                                            showPresence = false,
+                                        )
+                                        Spacer(modifier = Modifier.width(8.dp))
+                                        Column {
+                                            Text(
+                                                text = "@${bot.name}",
+                                                fontWeight = FontWeight.Bold,
+                                                style = MaterialTheme.typography.bodyMedium,
+                                                color = MaterialTheme.colorScheme.primary,
+                                            )
+                                            if (bot.effectiveTitle != bot.name) {
+                                                Text(
+                                                    text = bot.effectiveTitle,
+                                                    style = MaterialTheme.typography.labelSmall,
+                                                    color = MaterialTheme.colorScheme.onSurfaceVariant,
+                                                )
+                                            }
+                                        }
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+
                 // Attachment preview chips
                 AnimatedVisibility(
                     visible = pendingAttachments.isNotEmpty(),

app/src/test/java/com/m57/hermescontrol/ui/chat/ChatInputPolicyTest.kt

@@ -1,5 +1,7 @@
 package com.m57.hermescontrol.ui.chat
 
+import androidx.compose.ui.text.TextRange
+import androidx.compose.ui.text.input.TextFieldValue
 import org.junit.Assert.assertEquals
 import org.junit.Assert.assertFalse
 import org.junit.Assert.assertTrue
@@ -143,4 +145,22 @@ class ChatInputPolicyTest {
             ChatInputPolicy.sortSlashSuggestions(commands, mapOf("/MODEL" to 3)),
         )
     }
+
+    @Test
+    fun extractMentionQuery_variousPositions() {
+        assertEquals("res", ChatInputPolicy.extractMentionQuery("@res", 4))
+        assertEquals("scout", ChatInputPolicy.extractMentionQuery("hey @scout", 10))
+        assertEquals("", ChatInputPolicy.extractMentionQuery("ask @", 5))
+        org.junit.Assert.assertNull(ChatInputPolicy.extractMentionQuery("test@example.com", 16))
+        org.junit.Assert.assertNull(ChatInputPolicy.extractMentionQuery("hello world", 5))
+        org.junit.Assert.assertNull(ChatInputPolicy.extractMentionQuery("@bot with spaces", 15))
+    }
+
+    @Test
+    fun applyMention_insertsHandleAndAdvancesCursor() {
+        val initial = TextFieldValue("ask @sc", selection = androidx.compose.ui.text.TextRange(7))
+        val updated = ChatInputPolicy.applyMention(initial, "scout")
+        assertEquals("ask @scout ", updated.text)
+        assertEquals(11, updated.selection.end)
+    }
 }