feat(#532): add process.list + process.kill manager screen (#556)

Co-authored-by: M57 <m57@hermes-control.app>

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

@@ -0,0 +1,50 @@
+package com.m57.hermescontrol.data.model
+
+/**
+ * A single background process owned by a session, as returned by the gateway
+ * `process.list` RPC.
+ *
+ * Field names match the gateway JSON exactly (Gson deserializes by name,
+ * snake_case). See `tui_gateway/server.py::_session_processes` and
+ * `tools/process_registry.list_sessions` for the canonical shape.
+ *
+ * @property sessionId Stable process id used by `process.kill` as `process_id`.
+ * @property command First 200 chars of the spawned command line.
+ * @property cwd Working directory the process was launched in.
+ * @property pid OS process id (0 / null for detached or not-yet-spawned).
+ * @property startedAt ISO-8601 local timestamp string from the backend.
+ * @property uptimeSeconds Seconds since spawn (backend-computed).
+ * @property status `"running"` or `"exited"`.
+ * @property outputPreview Last 200 chars of buffered output.
+ * @property outputTail Last 4000 chars of buffered output (richer preview).
+ * @property exitCode Present only when [status] == `"exited"`.
+ * @property sessionScoped True when surfaced only because it shares the gateway
+ *   session (not the current task) — a possibly-forgotten long-lived process.
+ */
+data class ProcessInfo(
+    val sessionId: String,
+    val command: String? = null,
+    val cwd: String? = null,
+    val pid: Int? = null,
+    val startedAt: String? = null,
+    val uptimeSeconds: Int? = null,
+    val status: String? = null,
+    val outputPreview: String? = null,
+    val outputTail: String? = null,
+    val exitCode: Int? = null,
+    val sessionScoped: Boolean = false,
+) {
+    val isRunning: Boolean get() = status != "exited"
+
+    /** A short, human-readable title derived from the command line. */
+    val title: String
+        get() =
+            (command ?: "")
+                .lineSequence()
+                .firstOrNull()
+                ?.trim()
+                .orEmpty()
+                .ifEmpty { "background process" }
+
+    companion object
+}

app/src/main/java/com/m57/hermescontrol/data/session/ActiveSessionHolder.kt

@@ -0,0 +1,28 @@
+package com.m57.hermescontrol.data.session
+
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
+
+/**
+ * App-wide mirror of the active chat session id.
+ *
+ * The desktop `process.list` / `process.kill` RPCs are session-scoped — the
+ * gateway returns `4001 "session not found"` without a valid `session_id`, and
+ * mobile has no global "current session" holder (ChatViewModel keeps it
+ * privately). This singleton holds the last-known active session id so
+ * session-scoped drawer screens (e.g. the Processes screen, issue #532) can
+ * issue those RPCs. ChatViewModel writes here on every switch/resume; it is a
+ * best-effort mirror and may be null when no chat session has been opened yet.
+ */
+object ActiveSessionHolder {
+    private val _activeSessionId = MutableStateFlow<String?>(null)
+
+    /** The currently active chat session id, or null if none is known yet. */
+    val activeSessionId: StateFlow<String?> = _activeSessionId.asStateFlow()
+
+    /** Update the active session id. Pass null to clear (e.g. on logout). */
+    fun set(sessionId: String?) {
+        _activeSessionId.value = sessionId
+    }
+}

app/src/main/java/com/m57/hermescontrol/data/ws/WsMethods.kt

@@ -32,4 +32,12 @@ object WsMethods {
 
     /** Stage a non-image file (data URL) for agent access. */
     const val FILE_ATTACH = "file.attach"
+
+    // ── Background process manager (issue #532) ──────────────────────────
+
+    /** List background processes owned by the active session. */
+    const val PROCESS_LIST = "process.list"
+
+    /** Kill a single background process (scoped to the active session). */
+    const val PROCESS_KILL = "process.kill"
 }