feat(kap-server): expose the subagent registry id in /tasks responses

packages/kap-server/src/protocol/task.ts

@@ -30,5 +30,6 @@ export const taskSchema = z.object({
   model: z.string().optional(),
   /** Subagent tasks only: the child's effective thinking effort at spawn. */
   thinking_effort: z.string().optional(),
+  agent_id: z.string().optional(),
 });
 export type Task = z.infer<typeof taskSchema>;

packages/kap-server/src/routes/tasks.ts

@@ -375,6 +375,9 @@ function toWireTask(
   if (info.kind === 'agent' && info.thinkingEffort !== undefined) {
     base.thinking_effort = info.thinkingEffort;
   }
+  if (info.kind === 'agent' && info.agentId !== undefined) {
+    base.agent_id = info.agentId;
+  }
   if (output !== undefined) {
     base.output_preview = output.preview;
     base.output_bytes = output.bytes;

packages/kap-server/test/tasks.test.ts

@@ -35,6 +35,7 @@ interface TaskWire {
   completed_at?: string;
   output_preview?: string;
   output_bytes?: number;
+  agent_id?: string;
 }
 
 interface ListWire {
@@ -214,6 +215,7 @@ describe('server-v2 /api/v1/sessions/{sid}/tasks', () => {
       status: 'running',
       model: 'provider/secondary', // subagent tasks expose the bound display model
       thinking_effort: 'low', // …and its effective thinking effort
+      agent_id: 'sub-1',
     });
     expect(byId.get(agentId)?.command).toBeUndefined();
 
@@ -223,6 +225,8 @@ describe('server-v2 /api/v1/sessions/{sid}/tasks', () => {
       kind: 'tool', // question → tool
       status: 'running',
     });
+    expect(byId.get(processId)?.agent_id).toBeUndefined();
+    expect(byId.get(questionId)?.agent_id).toBeUndefined();
   });
 
   it('filters the list by wire status', async () => {
@@ -245,11 +249,22 @@ describe('server-v2 /api/v1/sessions/{sid}/tasks', () => {
     const id = await createSession();
     const tasks = await mainAgentTasks(id);
     const taskId = tasks.registerTask(fakeTask('process'));
+    const subagentId = tasks.registerTask(fakeTask('agent'));
     await flush();
 
     const got = await getJson<TaskWire>(`/api/v1/sessions/${id}/tasks/${taskId}`);
     expect(got.body.code).toBe(0);
     expect(got.body.data).toMatchObject({ id: taskId, session_id: id, kind: 'bash' });
+    expect(got.body.data.agent_id).toBeUndefined();
+
+    const gotSubagent = await getJson<TaskWire>(`/api/v1/sessions/${id}/tasks/${subagentId}`);
+    expect(gotSubagent.body.code).toBe(0);
+    expect(gotSubagent.body.data).toMatchObject({
+      id: subagentId,
+      session_id: id,
+      kind: 'subagent',
+      agent_id: 'sub-1',
+    });
 
     const missing = await getJson<null>(`/api/v1/sessions/${id}/tasks/nope`);
     expect(missing.body.code).toBe(40406);

packages/protocol/src/task.ts

@@ -30,6 +30,7 @@ export const taskSchema = z.object({
   model: z.string().optional(),
   /** Subagent tasks only: the child's effective thinking effort at spawn. */
   thinking_effort: z.string().optional(),
+  agent_id: z.string().optional(),
 });
 export type Task = z.infer<typeof taskSchema>;