Keep forked chats focused in new tabs (#2038)

* fix(app): focus explicitly opened workspace tabs

Explicit tab navigation could be overwritten by attention-aware workspace
navigation when the visible agent had just finished. Make workspace navigation
own both normal attention selection and explicit targets so callers cannot
sequence them inconsistently.

* test(app): strengthen forked tab focus assertion

packages/app/src/utils/workspace-navigation.test.ts

@@ -1,6 +1,6 @@
 import { describe, expect, it } from "vitest";
 import type { WorkspaceTabTarget } from "@/stores/workspace-tabs-store";
-import { navigateToPreparedWorkspaceTab, prepareWorkspaceTab } from "@/utils/prepare-workspace-tab";
+import { prepareWorkspaceTab } from "@/utils/prepare-workspace-tab";
 
 const SERVER_ID = "server-1";
 const WORKSPACE_ID = "/repo/worktree";
@@ -16,11 +16,6 @@ interface RecordedPin {
   agentId: string;
 }
 
-interface RecordedNavigation {
-  serverId: string;
-  workspaceId: string;
-}
-
 function createFakeLayout() {
   const openedTabs: RecordedOpenedTab[] = [];
   const pinnedAgents: RecordedPin[] = [];
@@ -37,21 +32,11 @@ function createFakeLayout() {
   };
 }
 
-function createFakeNavigator() {
-  const navigations: RecordedNavigation[] = [];
-  return {
-    navigations,
-    navigateToWorkspace: (serverId: string, workspaceId: string) => {
-      navigations.push({ serverId, workspaceId });
-    },
-  };
-}
-
 describe("prepareWorkspaceTab", () => {
   it("opens and focuses an agent tab", () => {
     const layout = createFakeLayout();
 
-    const route = prepareWorkspaceTab(
+    prepareWorkspaceTab(
       {
         serverId: SERVER_ID,
         workspaceId: WORKSPACE_ID,
@@ -60,30 +45,9 @@ describe("prepareWorkspaceTab", () => {
       layout,
     );
 
-    expect(route).toBe("/h/server-1/workspace/b64_L3JlcG8vd29ya3RyZWU");
     expect(layout.openedTabs).toEqual([
       { key: "server-1:/repo/worktree", target: { kind: "agent", agentId: AGENT_ID } },
     ]);
     expect(layout.pinnedAgents).toEqual([]);
   });
-
-  it("prepares a tab and navigates through the workspace navigation helper", () => {
-    const layout = createFakeLayout();
-    const navigator = createFakeNavigator();
-
-    const route = navigateToPreparedWorkspaceTab(
-      {
-        serverId: SERVER_ID,
-        workspaceId: WORKSPACE_ID,
-        target: { kind: "agent", agentId: AGENT_ID },
-      },
-      { ...layout, navigateToWorkspace: navigator.navigateToWorkspace },
-    );
-
-    expect(route).toBe("/h/server-1/workspace/b64_L3JlcG8vd29ya3RyZWU");
-    expect(layout.openedTabs).toEqual([
-      { key: "server-1:/repo/worktree", target: { kind: "agent", agentId: AGENT_ID } },
-    ]);
-    expect(navigator.navigations).toEqual([{ serverId: SERVER_ID, workspaceId: WORKSPACE_ID }]);
-  });
 });