Surface cross-workspace subagents in their workspaces (#2061)

* fix(workspaces): show provider subagent activity

Provider subagent lifecycle lives outside managed agent snapshots, so workspace aggregation dropped it after the parent turn finished. Count running provider subagents against the delegation root and emit workspace updates when their status changes.

* fix(workspaces): surface cross-workspace subagents

packages/app/e2e/helpers/subagents.ts

@@ -14,6 +14,17 @@ export interface SeededSubagentPair {
   workspaceId: string;
 }
 
+export interface SeededCrossWorkspaceSubagentPair {
+  parent: {
+    id: string;
+    workspaceId: string;
+  };
+  child: {
+    id: string;
+    workspaceId: string;
+  };
+}
+
 export async function seedParentWithSubagent(
   workspace: Pick<SeededWorkspace, "client" | "repoPath" | "workspaceId">,
   input: { parentTitle: string; childTitle: string },
@@ -51,6 +62,60 @@ export async function seedParentWithSubagent(
   };
 }
 
+export async function seedParentWithCrossWorkspaceSubagent(
+  workspace: Pick<SeededWorkspace, "client" | "repoPath" | "workspaceId" | "projectId">,
+  input: { parentTitle: string; childTitle: string },
+): Promise<SeededCrossWorkspaceSubagentPair> {
+  const parent = await workspace.client.createAgent({
+    provider: "mock",
+    cwd: workspace.repoPath,
+    workspaceId: workspace.workspaceId,
+    title: input.parentTitle,
+    modeId: "load-test",
+    model: "ten-second-stream",
+  });
+  const createdWorkspace = await workspace.client.createWorkspace({
+    source: {
+      kind: "directory",
+      path: workspace.repoPath,
+      projectId: workspace.projectId,
+    },
+    title: "Subagent workspace",
+  });
+  if (!createdWorkspace.workspace) {
+    throw new Error(createdWorkspace.error ?? "Failed to create subagent workspace");
+  }
+
+  const child = await workspace.client.createAgent({
+    provider: "mock",
+    cwd: workspace.repoPath,
+    workspaceId: createdWorkspace.workspace.id,
+    title: input.childTitle,
+    modeId: "load-test",
+    model: "five-minute-stream",
+    initialPrompt: "stay running",
+    labels: {
+      [PARENT_AGENT_ID_LABEL]: parent.id,
+    },
+  });
+  await workspace.client.waitForAgentUpsert(
+    child.id,
+    (snapshot) => snapshot.status === "running",
+    15_000,
+  );
+
+  return {
+    parent: {
+      id: parent.id,
+      workspaceId: workspace.workspaceId,
+    },
+    child: {
+      id: child.id,
+      workspaceId: createdWorkspace.workspace.id,
+    },
+  };
+}
+
 export async function openSubagentsTrack(page: Page): Promise<void> {
   await page.getByTestId("subagents-track-header").click();
 }

packages/app/e2e/workspace-model-regressions.spec.ts

@@ -1,4 +1,5 @@
 import { test, expect } from "./fixtures";
+import { expectWorkspaceTabVisible } from "./helpers/archive-tab";
 import { expectComposerEditable, expectComposerVisible, submitMessage } from "./helpers/composer";
 import { clickNewChat, gotoWorkspace } from "./helpers/launcher";
 import {
@@ -12,6 +13,11 @@ import {
 } from "./helpers/new-workspace";
 import { getServerId } from "./helpers/server-id";
 import { seedWorkspace, type SeededWorkspace } from "./helpers/seed-client";
+import {
+  expectSubagentRowVisible,
+  openSubagentsTrack,
+  seedParentWithCrossWorkspaceSubagent,
+} from "./helpers/subagents";
 import { expectWorkspaceHeader, waitForSidebarHydration } from "./helpers/workspace-ui";
 import { getVisibleWorkspaceAgentTabIds } from "./helpers/workspace-tabs";
 
@@ -527,4 +533,39 @@ test.describe("Workspace model regressions", () => {
       await seeded.cleanup();
     }
   });
+
+  test("cross-workspace subagent opens in its workspace and keeps its parent relationship", async ({
+    page,
+  }) => {
+    const serverId = getServerId();
+    const seeded = await seedWorkspace({ repoPrefix: "workspace-cross-subagent-" });
+
+    try {
+      const agents = await seedParentWithCrossWorkspaceSubagent(seeded, {
+        parentTitle: "Parent agent",
+        childTitle: "Cross-workspace subagent",
+      });
+
+      await gotoWorkspace(page, agents.child.workspaceId);
+      await waitForSidebarHydration(page);
+      await expectWorkspaceTabVisible(page, agents.child.id);
+
+      const parentRowTestId = `sidebar-workspace-row-${serverId}:${agents.parent.workspaceId}`;
+      const childRowTestId = `sidebar-workspace-row-${serverId}:${agents.child.workspaceId}`;
+      await expectWorkspaceRowHasOnlyIndicator(page, {
+        rowTestId: childRowTestId,
+        indicator: "running",
+      });
+      await expectWorkspaceRowHasOnlyIndicator(page, {
+        rowTestId: parentRowTestId,
+        indicator: "done",
+      });
+
+      await gotoWorkspace(page, agents.parent.workspaceId);
+      await openSubagentsTrack(page);
+      await expectSubagentRowVisible(page, agents.child.id);
+    } finally {
+      await seeded.cleanup();
+    }
+  });
 });

packages/app/src/stores/workspace-subagents-integration.test.ts

@@ -215,4 +215,38 @@ describe("workspace subagents integration", () => {
       ),
     ).toEqual([]);
   });
+
+  it("auto-opens a cross-workspace child while retaining it in the parent section", () => {
+    const workspaceKey = buildWorkspaceTabPersistenceKey({
+      serverId: SERVER_ID,
+      workspaceId: WORKSPACE_ID,
+    });
+    expect(workspaceKey).toBeTruthy();
+
+    const parent = makeAgent({
+      id: "parent-agent",
+      workspaceId: "ws-parent",
+      title: "Parent agent",
+    });
+    const child = makeAgent({
+      id: "child-agent",
+      parentAgentId: parent.id,
+      title: "Cross-workspace child",
+    });
+
+    initializeAgents([parent, child]);
+    reconcileWorkspaceTabs(workspaceKey!, deriveVisibilityFromSession());
+
+    expect(getWorkspaceTabIds(workspaceKey!)).toEqual(["agent_child-agent"]);
+    expect(
+      selectSubagentsForParent(
+        useSessionStore.getState(),
+        {
+          serverId: SERVER_ID,
+          parentAgentId: parent.id,
+        },
+        new Set(),
+      ).map((row) => row.id),
+    ).toEqual([child.id]);
+  });
 });

packages/app/src/subagents/auto-open-tab-policy.ts

@@ -1,5 +0,0 @@
-import type { Agent } from "@/stores/session-store";
-
-export function shouldAutoOpenAgentTab(agent: Pick<Agent, "parentAgentId">): boolean {
-  return !agent.parentAgentId;
-}

packages/app/src/subagents/index.ts

@@ -3,4 +3,4 @@ export { selectSubagentsForParent, useSubagentsForParent } from "./select";
 export { useArchiveSubagent, type UseArchiveSubagentInput } from "./use-archive-subagent";
 export { useDetachSubagent, type UseDetachSubagentInput } from "./use-detach-subagent";
 export { resolveCloseAgentTabPolicy, type CloseAgentTabPolicy } from "./close-tab-policy";
-export { shouldAutoOpenAgentTab } from "./auto-open-tab-policy";
+export { isWorkspaceRootAgent } from "./workspace-root-policy";

packages/app/src/subagents/policies.ts

@@ -6,4 +6,4 @@
 // UI surface. Use `@/subagents/policies` only when the caller is
 // non-RN infrastructure code; otherwise prefer `@/subagents`.
 export { resolveCloseAgentTabPolicy, type CloseAgentTabPolicy } from "./close-tab-policy";
-export { shouldAutoOpenAgentTab } from "./auto-open-tab-policy";
+export { isWorkspaceRootAgent } from "./workspace-root-policy";

packages/app/src/subagents/workspace-root-policy.ts

@@ -0,0 +1,17 @@
+import type { Agent } from "@/stores/session-store";
+import { normalizeWorkspaceOpaqueId } from "@/utils/workspace-identity";
+
+type WorkspaceAgent = Pick<Agent, "parentAgentId" | "workspaceId">;
+
+export function isWorkspaceRootAgent(
+  agent: WorkspaceAgent,
+  parentAgent: Pick<Agent, "workspaceId"> | undefined,
+): boolean {
+  if (!agent.parentAgentId) {
+    return true;
+  }
+
+  const workspaceId = normalizeWorkspaceOpaqueId(agent.workspaceId);
+  const parentWorkspaceId = normalizeWorkspaceOpaqueId(parentAgent?.workspaceId);
+  return Boolean(workspaceId && parentWorkspaceId && workspaceId !== parentWorkspaceId);
+}

packages/app/src/utils/workspace-agent-activity.test.ts

@@ -155,6 +155,52 @@ describe("workspace agent activity index", () => {
     });
   });
 
+  it("treats a cross-workspace subagent as activity in its own workspace", () => {
+    const index = buildWorkspaceAgentActivityIndex(
+      new Map([
+        [
+          "parent",
+          agent({
+            id: "parent",
+            workspaceId: "workspace-a",
+            updatedAt: "2026-06-01T10:00:00.000Z",
+          }),
+        ],
+        [
+          "child",
+          agent({
+            id: "child",
+            workspaceId: "workspace-b",
+            status: "running",
+            updatedAt: "2026-06-01T10:03:00.000Z",
+            parentAgentId: "parent",
+          }),
+        ],
+      ]),
+    );
+
+    expect(index).toEqual(
+      new Map([
+        [
+          "workspace-a",
+          {
+            agentId: "parent",
+            status: "done",
+            enteredAt: new Date("2026-06-01T10:00:00.000Z"),
+          },
+        ],
+        [
+          "workspace-b",
+          {
+            agentId: "child",
+            status: "running",
+            enteredAt: new Date("2026-06-01T10:03:00.000Z"),
+          },
+        ],
+      ]),
+    );
+  });
+
   it("preserves the activity index while the same agent remains in the same status", () => {
     const previous = buildWorkspaceAgentActivityIndex(
       new Map([

packages/app/src/utils/workspace-agent-activity.ts

@@ -1,4 +1,5 @@
 import type { Agent, WorkspaceDescriptor } from "@/stores/session-store";
+import { isWorkspaceRootAgent } from "@/subagents/policies";
 import { deriveSidebarStateBucket } from "./sidebar-agent-state";
 
 export interface WorkspaceAgentActivity {
@@ -15,7 +16,8 @@ export function buildWorkspaceAgentActivityIndex(
   const latestActivityAtByWorkspaceId = new Map<string, Date>();
 
   for (const agent of agents.values()) {
-    if (agent.archivedAt || agent.parentAgentId || !agent.workspaceId) {
+    const parentAgent = agent.parentAgentId ? agents.get(agent.parentAgentId) : undefined;
+    if (agent.archivedAt || !agent.workspaceId || !isWorkspaceRootAgent(agent, parentAgent)) {
       continue;
     }
 

packages/app/src/workspace-tabs/agent-visibility.test.ts

@@ -131,6 +131,32 @@ describe("workspace agent visibility", () => {
     expect(result.knownAgentIds).toEqual(new Set(["child-agent", "parent-agent"]));
   });
 
+  it("auto-opens a subagent whose parent belongs to another workspace", () => {
+    const parent = makeAgent({
+      id: "parent-agent",
+      cwd: "/repo",
+      workspaceId: "ws-parent",
+    });
+    const child = makeAgent({
+      id: "child-agent",
+      cwd: "/repo/worktree",
+      workspaceId: WORKSPACE_ID,
+      parentAgentId: parent.id,
+    });
+
+    const result = deriveWorkspaceAgentVisibility({
+      sessionAgents: new Map<string, Agent>([
+        [parent.id, parent],
+        [child.id, child],
+      ]),
+      workspaceId: WORKSPACE_ID,
+    });
+
+    expect(result.activeAgentIds).toEqual(new Set(["child-agent"]));
+    expect(result.autoOpenAgentIds).toEqual(new Set(["child-agent"]));
+    expect(result.knownAgentIds).toEqual(new Set(["child-agent"]));
+  });
+
   it("keeps archived agents out of activeAgentIds but present in knownAgentIds", () => {
     const visible = makeAgent({
       id: "visible-agent",

packages/app/src/workspace-tabs/agent-visibility.ts

@@ -1,6 +1,6 @@
 import type { Agent } from "@/stores/session-store";
 import type { WorkspaceTabSnapshot } from "@/stores/workspace-layout-actions";
-import { shouldAutoOpenAgentTab } from "@/subagents/policies";
+import { isWorkspaceRootAgent } from "@/subagents/policies";
 import { normalizeWorkspaceOpaqueId } from "@/utils/workspace-identity";
 
 export interface WorkspaceAgentVisibility {
@@ -31,6 +31,10 @@ export function deriveWorkspaceAgentVisibility(input: {
   const activeAgentIds = new Set<string>();
   const autoOpenAgentIds = new Set<string>();
   const knownAgentIds = new Set<string>();
+  const agentsById = new Map<string, Agent>([
+    ...(agentDetails?.entries() ?? []),
+    ...(sessionAgents?.entries() ?? []),
+  ]);
   for (const agent of sessionAgents?.values() ?? []) {
     if (!agentBelongsToWorkspace(agent, workspaceId)) {
       continue;
@@ -38,7 +42,8 @@ export function deriveWorkspaceAgentVisibility(input: {
     knownAgentIds.add(agent.id);
     if (!agent.archivedAt) {
       activeAgentIds.add(agent.id);
-      if (shouldAutoOpenAgentTab(agent)) {
+      const parentAgent = agent.parentAgentId ? agentsById.get(agent.parentAgentId) : undefined;
+      if (isWorkspaceRootAgent(agent, parentAgent)) {
         autoOpenAgentIds.add(agent.id);
       }
     }