feat(chat): surface session terminal_backend (ssh/docker) in header (#869)

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

app/src/main/java/com/m57/hermescontrol/data/model/SessionListResponse.kt

@@ -22,6 +22,7 @@ data class SessionInfo(
     val parent_session_id: String? = null,
     val display_name: String? = null,
     val model: String? = null,
+    val terminal_backend: String? = null,
 )
 
 @Serializable

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

@@ -32,6 +32,7 @@ import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.lazy.rememberLazyListState
 import androidx.compose.foundation.shape.CircleShape
+import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.Add
 import androidx.compose.material.icons.filled.Close
@@ -44,6 +45,7 @@ import androidx.compose.material3.Snackbar
 import androidx.compose.material3.SnackbarHost
 import androidx.compose.material3.SnackbarHostState
 import androidx.compose.material3.Surface
+import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.derivedStateOf
@@ -423,6 +425,24 @@ fun ChatScreen(
                                 .background(LocalHermesStatusColors.current.error),
                     )
                 }
+                // Terminal backend chip (issue #860) — ssh/docker/... next to the
+                // title; hidden when local (default) or absent.
+                val terminalBackend = state.terminalBackend
+                if (!terminalBackend.isNullOrBlank() && terminalBackend != "local") {
+                    Spacer(modifier = Modifier.width(8.dp))
+                    Surface(
+                        shape = RoundedCornerShape(6.dp),
+                        color = MaterialTheme.colorScheme.surfaceVariant,
+                        contentColor = MaterialTheme.colorScheme.onSurfaceVariant,
+                    ) {
+                        Text(
+                            text = terminalBackend,
+                            modifier = Modifier.padding(horizontal = 6.dp, vertical = 1.dp),
+                            style = MaterialTheme.typography.labelSmall,
+                            maxLines = 1,
+                        )
+                    }
+                }
             }
         },
         navigationIcon = onOpenDrawer?.let { NavIcon.Menu(it) },

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

@@ -282,6 +282,7 @@ data class ChatUiState(
     val currentSessionModel: String? = null,
     // Reasoning effort level for the current session
     val reasoningLevel: String? = null,
+    val terminalBackend: String? = null,
     // Context-window meter (issue #756): tokens currently used by the session
     // prompt (numerator) and the active model's full context window (denominator).
     // Both null until the first successful fetch.
@@ -727,6 +728,7 @@ class ChatViewModel(
                     val model = info["model"] as? String
                     val provider = info["provider"] as? String
                     val reasoningEffort = info["reasoning_effort"] as? String
+                    val terminalBackend = info["terminal_backend"] as? String
                     val newModelLabel =
                         if (model != null && provider != null) {
                             "$provider/$model"
@@ -752,6 +754,7 @@ class ChatViewModel(
                                 } else {
                                     reasoningEffort
                                 },
+                            terminalBackend = terminalBackend ?: state.terminalBackend,
                             fullContextTokens = if (modelSwapped) null else state.fullContextTokens,
                         )
                     }
@@ -988,6 +991,7 @@ class ChatViewModel(
                 val model = infoMap?.get("model") as? String
                 val provider = infoMap?.get("provider") as? String
                 val reasoningEffort = infoMap?.get("reasoning_effort") as? String
+                val terminalBackend = infoMap?.get("terminal_backend") as? String
 
                 // B8 (Jun 20 2026, kanban t_session_resume): do NOT reload
                 // cached messages here — switchSession() already did so before
@@ -1011,6 +1015,7 @@ class ChatViewModel(
                             } else {
                                 reasoningEffort
                             },
+                        terminalBackend = terminalBackend ?: it.terminalBackend,
                     )
                 }
                 // Mirror the active runtime session id app-wide (issue #532).
@@ -1983,6 +1988,7 @@ class ChatViewModel(
                 modelPickerLoading = false,
                 currentSessionModel = null,
                 reasoningLevel = null,
+                terminalBackend = null,
                 usedContextTokens = null,
                 fullContextTokens = null,
                 contextBreakdown = null,

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

@@ -1494,7 +1494,12 @@ class ChatViewModelTest {
             mockEventsFlow.emit(WsEvent.SecretRequest("secret-1", sessionId))
             mockEventsFlow.emit(
                 WsEvent.SessionInfo(
-                    mapOf("model" to "model-a", "provider" to "provider-a", "reasoning_effort" to "high"),
+                    mapOf(
+                        "model" to "model-a",
+                        "provider" to "provider-a",
+                        "reasoning_effort" to "high",
+                        "terminal_backend" to "docker",
+                    ),
                 ),
             )
             mockEventsFlow.emit(
@@ -1520,6 +1525,7 @@ class ChatViewModelTest {
             assertNotNull(oldState.sudoPrompt)
             assertNotNull(oldState.secretPrompt)
             assertNotNull(oldState.currentSessionModel)
+            assertEquals("docker", oldState.terminalBackend)
             assertTrue(oldState.subagentIndicators.isNotEmpty())
             assertTrue(oldState.todos.isNotEmpty())
             assertTrue(oldState.showModelPicker)
@@ -1536,6 +1542,7 @@ class ChatViewModelTest {
             assertNull(state.secretPrompt)
             assertNull(state.currentSessionModel)
             assertNull(state.reasoningLevel)
+            assertNull(state.terminalBackend)
             assertTrue(state.subagentIndicators.isEmpty())
             assertTrue(state.todos.isEmpty())
             assertFalse(state.showModelPicker)