Key workspace status and ownership by ID, not directory

Multiple workspaces can share one checkout directory. Agent and terminal
status, sidebar tabs, and ownership now attribute strictly by workspace ID,
so a running or blocked agent in one workspace no longer shows up on its
same-directory siblings.

A one-time startup migration backfills workspace IDs onto legacy agents, and
every agent and terminal is created with one thereafter. Directory lookups
remain only for genuinely folder-derived git facts (branch, diff) and the
archive-by-path adapter.

packages/app/src/utils/navigate-to-agent/index.ts

@@ -11,8 +11,7 @@ export function navigateToAgent(input: NavigateToAgentInput): string {
       const session = useSessionStore.getState().sessions[serverId];
       const agent = session?.agents.get(agentId) ?? session?.agentDetails.get(agentId);
       return {
-        workspaces: session?.workspaces.values(),
-        agentCwd: agent?.cwd,
+        agentWorkspaceId: agent?.workspaceId,
       };
     },
     navigateToHostAgent: (route) => {

packages/app/src/utils/navigate-to-agent/resolve.test.ts

@@ -1,5 +1,4 @@
 import { describe, expect, it } from "vitest";
-import type { WorkspaceDescriptor } from "@/stores/session-store";
 import {
   resolveNavigateToAgent,
   type AgentNavTarget,
@@ -11,24 +10,6 @@ const SERVER_ID = "server-1";
 const WORKSPACE_ID = "workspace-1";
 const AGENT_ID = "agent-1";
 
-function createWorkspace(): WorkspaceDescriptor {
-  return {
-    id: WORKSPACE_ID,
-    projectId: "project-1",
-    projectDisplayName: "Project",
-    projectRootPath: "/repo",
-    workspaceDirectory: "/repo/worktree",
-    projectKind: "git",
-    workspaceKind: "local_checkout",
-    name: "worktree",
-    status: "done",
-    archivingAt: null,
-    statusEnteredAt: null,
-    diffStat: null,
-    scripts: [],
-  };
-}
-
 interface RecordedHostNav {
   route: string;
 }
@@ -59,10 +40,9 @@ function createFakeNavigators(target: AgentNavTarget): {
 }
 
 describe("resolveNavigateToAgent", () => {
-  it("opens the resolved workspace tab when the agent's cwd matches a workspace", () => {
+  it("opens the workspace tab carried by the agent's workspaceId", () => {
     const { deps, hostNavigations, tabNavigations } = createFakeNavigators({
-      workspaces: [createWorkspace()],
-      agentCwd: "/repo/worktree",
+      agentWorkspaceId: WORKSPACE_ID,
     });
 
     const route = resolveNavigateToAgent(
@@ -83,10 +63,9 @@ describe("resolveNavigateToAgent", () => {
     ]);
   });
 
-  it("falls back to the host agent route when the workspace is unknown", () => {
+  it("falls back to the host agent route when the agent has no workspaceId", () => {
     const { deps, hostNavigations, tabNavigations } = createFakeNavigators({
-      workspaces: [],
-      agentCwd: null,
+      agentWorkspaceId: null,
     });
 
     const route = resolveNavigateToAgent({ serverId: SERVER_ID, agentId: "missing-agent" }, deps);

packages/app/src/utils/navigate-to-agent/resolve.ts

@@ -1,6 +1,5 @@
-import type { WorkspaceDescriptor } from "@/stores/session-store";
 import { buildHostAgentDetailRoute } from "@/utils/host-routes";
-import { resolveWorkspaceIdByDirectory } from "@/utils/workspace-identity";
+import { normalizeWorkspaceOpaqueId } from "@/utils/workspace-identity";
 import type { NavigateToPreparedWorkspaceTabInput } from "@/utils/prepare-workspace-tab";
 
 export interface NavigateToAgentInput {
@@ -11,8 +10,7 @@ export interface NavigateToAgentInput {
 }
 
 export interface AgentNavTarget {
-  workspaces: Iterable<WorkspaceDescriptor> | null | undefined;
-  agentCwd: string | null | undefined;
+  agentWorkspaceId: string | null | undefined;
 }
 
 export interface NavigateToAgentDeps {
@@ -25,14 +23,11 @@ export function resolveNavigateToAgent(
   input: NavigateToAgentInput,
   deps: NavigateToAgentDeps,
 ): string {
-  const { workspaces, agentCwd } = deps.readAgentNavTarget({
+  const { agentWorkspaceId } = deps.readAgentNavTarget({
     serverId: input.serverId,
     agentId: input.agentId,
   });
-  const workspaceId = resolveWorkspaceIdByDirectory({
-    workspaces,
-    workspaceDirectory: agentCwd,
-  });
+  const workspaceId = normalizeWorkspaceOpaqueId(agentWorkspaceId);
 
   if (!workspaceId) {
     const route = buildHostAgentDetailRoute(input.serverId, input.agentId);