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/git/actions-store.ts

@@ -13,10 +13,7 @@ import {
   clearWorkspaceArchivePending,
   markWorkspaceArchivePending,
 } from "@/contexts/session-workspace-upserts";
-import {
-  resolveWorkspaceIdByDirectory,
-  resolveWorkspaceMapKeyByIdentity,
-} from "@/utils/workspace-identity";
+import { resolveWorkspaceMapKeyByIdentity } from "@/utils/workspace-identity";
 import { invalidateCheckoutGitQueriesForClient } from "@/git/query-keys";
 import { i18n } from "@/i18n/i18next";
 
@@ -155,15 +152,11 @@ function isWorktreeListQuery(input: { queryKey: QueryKey; serverId: string }): b
 
 function snapshotWorktreeArchiveState(input: {
   serverId: string;
-  worktreePath: string;
+  workspaceId: string | undefined;
 }): WorktreeArchiveSnapshot {
   const workspaces = useSessionStore.getState().sessions[input.serverId]?.workspaces;
-  const workspaceId = resolveWorkspaceIdByDirectory({
-    workspaces: workspaces?.values(),
-    workspaceDirectory: input.worktreePath,
-  });
-  const workspaceKey = workspaceId
-    ? resolveWorkspaceMapKeyByIdentity({ workspaces, workspaceId })
+  const workspaceKey = input.workspaceId
+    ? resolveWorkspaceMapKeyByIdentity({ workspaces, workspaceId: input.workspaceId })
     : null;
   return {
     workspace: workspaceKey ? (workspaces?.get(workspaceKey) ?? null) : null,
@@ -506,16 +499,16 @@ export const useCheckoutGitActionsStore = create<CheckoutGitActionsStoreState>()
       actionId: "archive-worktree",
       run: async () => {
         const client = resolveClient(serverId);
-        const snapshot = snapshotWorktreeArchiveState({ serverId, worktreePath });
+        const snapshot = snapshotWorktreeArchiveState({ serverId, workspaceId });
         // The server archive is keyed by worktreePath and must always run. The
         // optimistic client-side updates are keyed by workspace id, so they only
-        // apply when the workspace is resolved in the local store.
+        // apply when the caller passes the workspace id and it resolves in the
+        // local store.
         const workspace = snapshot.workspace;
         if (workspace) {
           markWorkspaceArchivePending({
             serverId,
             workspaceId: workspace.id,
-            workspaceDirectory: workspace.workspaceDirectory,
           });
           removeWorktreeFromSessionStore({ serverId, workspaceId: workspace.id });
         }