feat(bots): emergency stop button and /stop slash command in group chat (#1012)

Co-authored-by: M57 <hy4ri@users.noreply.github.com>

app/src/main/java/com/m57/hermescontrol/ui/bots/group/GroupChatScreen.kt

@@ -33,6 +33,7 @@ import androidx.compose.material.icons.filled.ContentCopy
 import androidx.compose.material.icons.filled.Description
 import androidx.compose.material.icons.filled.Search
 import androidx.compose.material.icons.filled.Settings
+import androidx.compose.material.icons.filled.Stop
 import androidx.compose.material.icons.filled.Terminal
 import androidx.compose.material3.AlertDialog
 import androidx.compose.material3.Button
@@ -137,6 +138,18 @@ fun GroupChatScreen(
         },
         navigationIcon = NavIcon.Back(onBack),
         actions = {
+            if (state.activeSpeaker != null) {
+                IconButton(
+                    onClick = { viewModel.stopGeneration() },
+                    modifier = Modifier.testTag("group_chat_stop_button"),
+                ) {
+                    Icon(
+                        imageVector = Icons.Filled.Stop,
+                        contentDescription = stringResource(R.string.group_chat_action_stop),
+                        tint = MaterialTheme.colorScheme.error,
+                    )
+                }
+            }
             IconButton(
                 onClick = { showSettingsDialog = true },
                 modifier = Modifier.testTag("group_chat_settings_button"),
@@ -293,6 +306,26 @@ fun GroupChatScreen(
 
                     Spacer(modifier = Modifier.width(4.dp))
 
+                    if (state.activeSpeaker != null) {
+                        IconButton(
+                            onClick = { viewModel.stopGeneration() },
+                            colors =
+                                IconButtonDefaults.filledTonalIconButtonColors(
+                                    containerColor = MaterialTheme.colorScheme.errorContainer,
+                                    contentColor = MaterialTheme.colorScheme.onErrorContainer,
+                                ),
+                            modifier =
+                                Modifier
+                                    .size(36.dp)
+                                    .testTag("group_chat_stop_button"),
+                        ) {
+                            Icon(
+                                imageVector = Icons.Filled.Stop,
+                                contentDescription = stringResource(R.string.group_chat_action_stop),
+                                modifier = Modifier.size(18.dp),
+                            )
+                        }
+                    } else {
                         IconButton(
                             onClick = handleSend,
                             enabled = inputFieldValue.text.isNotBlank(),
@@ -312,6 +345,7 @@ fun GroupChatScreen(
                 }
             }
         }
+    }
 
     if (showSettingsDialog) {
         GroupChatSettingsDialog(

app/src/main/java/com/m57/hermescontrol/ui/bots/group/GroupChatViewModel.kt

@@ -56,6 +56,7 @@ private const val LEASE_STEP_TTL_MS = 45_000L
 private const val TURN_TIMEOUT_MS = 45_000L
 private const val HISTORY_LIMIT = 10
 private const val CAPPED_SYSTEM_TEXT = "Discussion paused (turn limit reached) — reply to continue"
+private const val STOPPED_SYSTEM_TEXT = "Discussion stopped"
 
 class GroupChatViewModel(
     private var groupName: String = "",
@@ -767,11 +768,65 @@ class GroupChatViewModel(
         }
     }
 
+    fun stopGeneration() {
+        Log.i("GroupChatViewModel", "stopGeneration requested by user")
+        val interruptedEpoch = UUID.randomUUID().toString()
+        activeEpoch = interruptedEpoch
+
+        // Send interrupt signal to any actively streaming or in-flight sessions
+        val activeSessions = activeStreamMsgId.keys.toList() + inFlightTurns.keys.toList()
+        for (sid in activeSessions.distinct()) {
+            try {
+                HermesWsClient.send(
+                    WsMethods.SESSION_INTERRUPT,
+                    mapOf("session_id" to sid),
+                )
+            } catch (e: Exception) {
+                Log.w("GroupChatViewModel", "Failed to send interrupt for session $sid: ${e.message}")
+            }
+        }
+
+        // Clean up transient in-flight tracking
+        inFlightTurns.values.forEach { it.complete("") }
+        inFlightTurns.clear()
+        activeStreamMsgId.clear()
+        sessionToBot.clear()
+
+        _uiState.update { state ->
+            // Remove any pending streaming placeholder messages
+            val cleanedMessages = state.messages.filter { !it.isStreaming }
+            val stopMessage =
+                GroupChatMessage(
+                    id = UUID.randomUUID().toString(),
+                    senderName = "system",
+                    senderDisplayName = "System",
+                    isUser = false,
+                    isSystem = true,
+                    text = STOPPED_SYSTEM_TEXT,
+                )
+            state.copy(
+                messages = cleanedMessages + stopMessage,
+                activeSpeaker = null,
+            )
+        }
+        persistSyncSnapshot(_uiState.value.messages, extendLease = false)
+    }
+
+    private fun isStopCommand(text: String): Boolean {
+        val normalized = text.trim().lowercase()
+        return normalized in setOf("/stop", "/interrupt", "/pause", "/cancel", "stop", "/brake")
+    }
+
     fun sendMessage(rawText: String) {
         val text = rawText.trim()
         Log.d("GroupChatViewModel", "sendMessage called with: '$text'")
         if (text.isBlank()) return
 
+        if (isStopCommand(text)) {
+            stopGeneration()
+            return
+        }
+
         val members = _uiState.value.members
         if (members.isEmpty()) {
             Log.w("GroupChatViewModel", "sendMessage: No members in group, ignoring")

app/src/main/res/values/strings.xml

@@ -1264,4 +1264,6 @@
     <string name="group_chat_settings_system_prompt_hint">Custom rules, tone, or context for this group (optional)…</string>
     <string name="group_chat_settings_system_prompt_desc">Custom guidelines for all bots in this room</string>
     <string name="group_chat_action_settings">Settings</string>
+    <string name="group_chat_stopped_by_user">Discussion stopped</string>
+    <string name="group_chat_action_stop">Stop generation</string>
 </resources>

app/src/test/java/com/m57/hermescontrol/ui/bots/group/GroupChatViewModelTest.kt

@@ -486,4 +486,34 @@ class GroupChatViewModelTest {
             assertEquals(1, finalMsg.toolCalls.size)
             assertFalse(finalMsg.toolCalls.first().isRunning)
         }
+
+    @Test
+    fun testStopCommand_stopsGenerationAndAppendsSystemBanner() =
+        runTest(testDispatcher) {
+            val viewModel = GroupChatViewModel("Dev Team", ioDispatcher = testDispatcher)
+            testScheduler.runCurrent()
+
+            // Trigger a message
+            viewModel.sendMessage("@scout long task")
+            testScheduler.runCurrent()
+
+            // Emit a streaming fragment
+            eventsFlow.emit(
+                WsEvent.MessageToken(
+                    token = "Thinking about...",
+                    sessionId = "session-scout-1",
+                ),
+            )
+            testScheduler.runCurrent()
+
+            // Execute /stop command
+            viewModel.sendMessage("/stop")
+            testScheduler.runCurrent()
+
+            val state = viewModel.uiState.value
+            assertNull(state.activeSpeaker)
+            val lastMsg = state.messages.last()
+            assertTrue(lastMsg.isSystem)
+            assertEquals("Discussion stopped", lastMsg.text)
+        }
 }