fix(timeline): preserve activity through turn handoff

Correlate lifecycle events and snapshots with daemon-owned turn identity, and keep optimistic submissions active until their canonical row arrives. This prevents stale updates and RPC timing from exposing a false idle state.

packages/protocol/src/agent-feature-schemas.test.ts

@@ -144,6 +144,47 @@ describe("agent feature schemas", () => {
     expect(parsed.features?.[0]?.id).toBe("fast_mode");
   });
 
+  it("accepts optional active turn identity without requiring it from old daemons", () => {
+    const base = {
+      id: "agent-turn-identity",
+      provider: "codex",
+      cwd: "/tmp/project",
+      model: "gpt-5",
+      createdAt: "2026-07-31T12:00:00.000Z",
+      updatedAt: "2026-07-31T12:00:01.000Z",
+      lastUserMessageAt: "2026-07-31T12:00:00.000Z",
+      status: "running",
+      capabilities: {
+        supportsStreaming: true,
+        supportsSessionPersistence: true,
+        supportsDynamicModes: true,
+        supportsMcpServers: true,
+        supportsReasoningStream: true,
+        supportsToolInvocations: true,
+      },
+      currentModeId: null,
+      availableModes: [],
+      pendingPermissions: [],
+      persistence: null,
+      title: null,
+      labels: {},
+    };
+
+    expect(AgentSnapshotPayloadSchema.parse(base).activeTurn).toBeUndefined();
+    expect(
+      AgentSnapshotPayloadSchema.parse({
+        ...base,
+        activeTurn: {
+          turnId: "turn-1",
+          startedAt: "2026-07-31T12:00:00.000Z",
+        },
+      }).activeTurn,
+    ).toEqual({
+      turnId: "turn-1",
+      startedAt: "2026-07-31T12:00:00.000Z",
+    });
+  });
+
   it("defaults missing rewind capabilities to false", () => {
     const parsed = AgentSnapshotPayloadSchema.parse({
       id: "agent-123",

packages/protocol/src/messages.ts

@@ -612,15 +612,18 @@ export const AgentStreamEventPayloadSchema = z.discriminatedUnion("type", [
   z.object({
     type: z.literal("turn_started"),
     provider: AgentProviderSchema,
+    turnId: z.string().optional(),
   }),
   z.object({
     type: z.literal("turn_completed"),
     provider: AgentProviderSchema,
+    turnId: z.string().optional(),
     usage: AgentUsageSchema.optional(),
   }),
   z.object({
     type: z.literal("turn_failed"),
     provider: AgentProviderSchema,
+    turnId: z.string().optional(),
     error: z.string(),
     code: z.string().optional(),
     diagnostic: z.string().optional(),
@@ -628,6 +631,7 @@ export const AgentStreamEventPayloadSchema = z.discriminatedUnion("type", [
   z.object({
     type: z.literal("turn_canceled"),
     provider: AgentProviderSchema,
+    turnId: z.string().optional(),
     reason: z.string(),
   }),
   z.object({
@@ -685,6 +689,11 @@ const AgentRuntimeInfoSchema: z.ZodType<AgentRuntimeInfo> = z.object({
   extra: z.record(z.string(), z.unknown()).optional(),
 });
 
+const AgentActiveTurnPayloadSchema = z.object({
+  turnId: z.string(),
+  startedAt: z.string().nullable(),
+});
+
 export const AgentSnapshotPayloadSchema = z.object({
   id: z.string(),
   provider: AgentProviderSchema,
@@ -698,6 +707,7 @@ export const AgentSnapshotPayloadSchema = z.object({
   updatedAt: z.string(),
   lastUserMessageAt: z.string().nullable(),
   status: AgentStatusSchema,
+  activeTurn: AgentActiveTurnPayloadSchema.nullable().optional(),
   capabilities: AgentCapabilityFlagsSchema,
   currentModeId: z.string().nullable(),
   availableModes: z.array(AgentModeSchema),
@@ -2830,6 +2840,8 @@ export const ServerInfoStatusPayloadSchema = z
         selectiveAgentTimeline: z.boolean().optional(),
         // COMPAT(canonicalSubmittedPrompts): added in v0.2.6, remove gate after 2027-01-30.
         canonicalSubmittedPrompts: z.boolean().optional(),
+        // COMPAT(agentTurnIdentity): accept peers that observed pre-release v0.2.6 through 2027-01-31.
+        agentTurnIdentity: z.boolean().optional(),
         // COMPAT(stableProjectIdentity): added in v0.1.109, remove gate after 2027-01-15.
         stableProjectIdentity: z.boolean().optional(),
         // COMPAT(workspaceScriptManagement): added in v0.1.105, remove gate after 2027-01-10.