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/prepare-workspace-tab.ts

@@ -3,7 +3,6 @@ import {
   buildWorkspaceTabPersistenceKey,
   type WorkspaceTabTarget,
 } from "@/stores/workspace-tabs-store";
-import { buildHostWorkspaceRoute } from "@/utils/host-routes";
 
 export interface PrepareWorkspaceTabInput {
   serverId: string;
@@ -12,17 +11,11 @@ export interface PrepareWorkspaceTabInput {
   pin?: boolean;
 }
 
-export type NavigateToPreparedWorkspaceTabInput = PrepareWorkspaceTabInput;
-
 export interface PrepareWorkspaceTabDeps {
   openTabFocused: (workspaceKey: string, target: WorkspaceTabTarget) => string | null;
   pinAgent: (workspaceKey: string, agentId: string) => void;
 }
 
-export interface NavigateToPreparedWorkspaceTabDeps extends PrepareWorkspaceTabDeps {
-  navigateToWorkspace: (serverId: string, workspaceId: string) => void;
-}
-
 function getPreparedTarget(target: WorkspaceTabTarget): WorkspaceTabTarget {
   if (target.kind !== "draft" || target.draftId.trim() !== "new") {
     return target;
@@ -33,7 +26,7 @@ function getPreparedTarget(target: WorkspaceTabTarget): WorkspaceTabTarget {
 export function prepareWorkspaceTab(
   input: PrepareWorkspaceTabInput,
   deps: PrepareWorkspaceTabDeps,
-): string {
+): void {
   const target = getPreparedTarget(input.target);
   const key =
     buildWorkspaceTabPersistenceKey({
@@ -46,15 +39,4 @@ export function prepareWorkspaceTab(
   if (input.pin && target.kind === "agent") {
     deps.pinAgent(key, target.agentId);
   }
-
-  return buildHostWorkspaceRoute(input.serverId, input.workspaceId);
-}
-
-export function navigateToPreparedWorkspaceTab(
-  input: NavigateToPreparedWorkspaceTabInput,
-  deps: NavigateToPreparedWorkspaceTabDeps,
-): string {
-  const route = prepareWorkspaceTab(input, deps);
-  deps.navigateToWorkspace(input.serverId, input.workspaceId);
-  return route;
 }