Detach subagents without archiving them (#1612)

* Add detach action for subagents

* Translate detached subagent connection error

* Address subagent detach review feedback

* Fix subagent integration test import

* Focus detached subagents as tabs

packages/protocol/src/messages.test.ts

@@ -2,6 +2,8 @@ import { describe, expect, test } from "vitest";
 import {
   FileExplorerRequestSchema,
   PaseoWorktreeArchiveRequestSchema,
+  parseServerInfoStatusPayload,
+  SessionInboundMessageSchema,
   SessionOutboundMessageSchema,
 } from "./messages.js";
 
@@ -131,6 +133,51 @@ describe("workspace descriptor message compatibility", () => {
   });
 });
 
+describe("agent detach RPC", () => {
+  test("parses the namespaced detach request", () => {
+    const parsed = SessionInboundMessageSchema.parse({
+      type: "agent.detach.request",
+      agentId: "child-agent",
+      requestId: "req-detach",
+    });
+
+    expect(parsed).toEqual({
+      type: "agent.detach.request",
+      agentId: "child-agent",
+      requestId: "req-detach",
+    });
+  });
+
+  test("parses the namespaced detach response", () => {
+    const parsed = SessionOutboundMessageSchema.parse({
+      type: "agent.detach.response",
+      payload: {
+        requestId: "req-detach",
+        agentId: "child-agent",
+        accepted: true,
+        error: null,
+      },
+    });
+
+    expect(parsed.type).toBe("agent.detach.response");
+  });
+
+  test("parses the agentDetach server feature gate", () => {
+    const parsed = parseServerInfoStatusPayload({
+      status: "server_info",
+      serverId: "srv-test",
+      features: {
+        agentDetach: true,
+      },
+    });
+
+    if (!parsed) {
+      throw new Error("Expected server info payload to parse");
+    }
+    expect(parsed.features?.agentDetach).toBe(true);
+  });
+});
+
 describe("file explorer request compatibility", () => {
   test("acceptBinary is optional for old clients and accepted for new clients", () => {
     expect(

packages/protocol/src/messages.ts

@@ -1308,6 +1308,17 @@ export const SetAgentFeatureResponseMessageSchema = z.object({
   payload: AgentActionResponsePayloadSchema,
 });
 
+export const AgentDetachRequestMessageSchema = z.object({
+  type: z.literal("agent.detach.request"),
+  agentId: z.string(),
+  requestId: z.string(),
+});
+
+export const AgentDetachResponseMessageSchema = z.object({
+  type: z.literal("agent.detach.response"),
+  payload: AgentActionResponsePayloadSchema,
+});
+
 export const AgentRewindModeSchema = z.enum(["conversation", "files", "both"]);
 
 export const AgentRewindRequestMessageSchema = z.object({
@@ -2021,6 +2032,7 @@ export const SessionInboundMessageSchema = z.discriminatedUnion("type", [
   SetAgentModelRequestMessageSchema,
   SetAgentThinkingRequestMessageSchema,
   SetAgentFeatureRequestMessageSchema,
+  AgentDetachRequestMessageSchema,
   AgentRewindRequestMessageSchema,
   AgentPermissionResponseMessageSchema,
   CheckoutStatusRequestSchema,
@@ -2280,6 +2292,8 @@ export const ServerInfoStatusPayloadSchema = z
         projectRemove: z.boolean().optional(),
         // COMPAT(worktreeRestore): added in v0.1.97, drop the gate when floor >= v0.1.97
         worktreeRestore: z.boolean().optional(),
+        // COMPAT(agentDetach): added in v0.1.98, remove gate after 2026-12-19 once daemon floor >= v0.1.98.
+        agentDetach: z.boolean().optional(),
       })
       .optional(),
   })
@@ -4019,6 +4033,7 @@ export const SessionOutboundMessageSchema = z.discriminatedUnion("type", [
   SetAgentModelResponseMessageSchema,
   SetAgentThinkingResponseMessageSchema,
   SetAgentFeatureResponseMessageSchema,
+  AgentDetachResponseMessageSchema,
   AgentRewindResponseMessageSchema,
   UpdateAgentResponseMessageSchema,
   ProjectRenameResponseSchema,
@@ -4166,6 +4181,7 @@ export type SetAgentModeResponseMessage = z.infer<typeof SetAgentModeResponseMes
 export type SetAgentModelResponseMessage = z.infer<typeof SetAgentModelResponseMessageSchema>;
 export type SetAgentThinkingResponseMessage = z.infer<typeof SetAgentThinkingResponseMessageSchema>;
 export type SetAgentFeatureResponseMessage = z.infer<typeof SetAgentFeatureResponseMessageSchema>;
+export type AgentDetachResponseMessage = z.infer<typeof AgentDetachResponseMessageSchema>;
 export type AgentRewindResponseMessage = z.infer<typeof AgentRewindResponseMessageSchema>;
 export type UpdateAgentResponseMessage = z.infer<typeof UpdateAgentResponseMessageSchema>;
 export type ProjectRenameResponse = z.infer<typeof ProjectRenameResponseSchema>;
@@ -4299,6 +4315,7 @@ export type SetAgentModeRequestMessage = z.infer<typeof SetAgentModeRequestMessa
 export type SetAgentModelRequestMessage = z.infer<typeof SetAgentModelRequestMessageSchema>;
 export type SetAgentThinkingRequestMessage = z.infer<typeof SetAgentThinkingRequestMessageSchema>;
 export type SetAgentFeatureRequestMessage = z.infer<typeof SetAgentFeatureRequestMessageSchema>;
+export type AgentDetachRequestMessage = z.infer<typeof AgentDetachRequestMessageSchema>;
 export type AgentPermissionResponseMessage = z.infer<typeof AgentPermissionResponseMessageSchema>;
 export type CheckoutStatusRequest = z.infer<typeof CheckoutStatusRequestSchema>;
 export type CheckoutStatusResponse = z.infer<typeof CheckoutStatusResponseSchema>;