feat(workspaces): star toggle for concurrency priority

Backend (feature/workspace-star) shipped Workspace.starred: boolean (additive
to [email protected], no version bump) + PUT/DELETE /workspaces/:id/star endpoints
(no body; create-on-miss; return the updated Workspace). A starred workspace's
agents jump ahead of non-starred ones in the concurrency limiter queue
(oldest-agent-first within each group); takes effect immediately for
already-queued agents.

FE consumed:
- adapter/http.ts: star(id)/unstar(id) -> WorkspaceResult<Workspace>
  (PUT/DELETE /workspaces/:id/star, no body).
- logic/view-model.ts: pure sortWorkspaces (starred-first, then lastActivityAt
  desc, stable) + pure applyStarred (the optimistic apply/revert transform).
- store.svelte.ts: setStarred(id, starred) — optimistic flip with error revert;
  the list is now a $derived sorted view (starred bubble to top reactively);
  no full refresh on success (avoids flicker).
- ui/WorkspaceCard.svelte: star toggle button (filled gold when starred,
  outline when not; spinner in flight; aria-pressed/aria-label; tooltip notes
  concurrency priority).
- Re-mirrored .dispatch/wire.reference.md (starred + delta note).
- GLOSSARY.md: 'starred' term.

Tests (+27): http star/unstar (5), view-model sort+applyStarred (12), store
optimistic+revert+re-sort (6), WorkspaceCard star button (4).

Verification: typecheck 0/0, 1045 tests green, biome clean, build OK.
backend-handoff.md updated (workspace-star slice, no open backend asks).

1 files changed, 28 insertions, 2 deletions

diff --git a/src/features/workspaces/store.svelte.ts b/src/features/workspaces/store.svelte.ts
index 046c235..22d73b5 100644
--- a/src/features/workspaces/store.svelte.ts
+++ b/src/features/workspaces/store.svelte.ts
@@ -1,6 +1,7 @@
 import type { EnsureWorkspaceRequest } from "@dispatch/transport-contract";
 import type { Workspace, WorkspaceEntry } from "@dispatch/wire";
 import type { WorkspaceHttp, WorkspaceResult } from "./adapter/http";
+import { applyStarred, sortWorkspaces } from "./logic/view-model";
 
 /**
  * Workspace store — a thin reactive wrapper over the pure HTTP edge. Owns the
@@ -9,7 +10,11 @@ import type { WorkspaceHttp, WorkspaceResult } from "./adapter/http";
  * owned by the composition root.
  */
 export interface WorkspaceStore {
-  /** All workspaces (sorted by lastActivityAt desc by the backend). */
+  /**
+   * All workspaces, sorted for display: starred first (their FE-side echo of
+   * concurrency-priority), then most-recently-active. The backing list is the
+   * backend's `lastActivityAt`-desc order; this getter re-sorts reactively.
+   */
   readonly list: readonly WorkspaceEntry[];
   readonly loading: boolean;
   readonly error: string | null;
@@ -23,18 +28,27 @@ export interface WorkspaceStore {
   setDefaultCwd(id: string, defaultCwd: string | null): Promise<WorkspaceResult<Workspace>>;
   /** Set/clear a workspace's default computer (SSH `Host` alias; null = local). */
   setDefaultComputer(id: string, computerId: string | null): Promise<WorkspaceResult<Workspace>>;
+  /**
+   * Toggle a workspace's star (concurrency priority). Optimistic: the local
+   * `starred` flag flips immediately and the sorted list re-orders; on error it
+   * reverts to the prior value. No full refresh on success (avoids flicker).
+   */
+  setStarred(id: string, starred: boolean): Promise<WorkspaceResult<Workspace>>;
   /** Delete a workspace (closes its conversations, reassigns to "default"). */
   remove(id: string): Promise<WorkspaceResult<{ closedCount: number }>>;
 }
 
 export function createWorkspaceStore(http: WorkspaceHttp): WorkspaceStore {
   let list = $state<readonly WorkspaceEntry[]>([]);
+  // Sorted view (starred first, then most-recent) — derived so it recomputes
+  // only when the backing list changes, not on every read.
+  let sorted = $derived(sortWorkspaces(list));
   let loading = $state(false);
   let error = $state<string | null>(null);
 
   return {
     get list(): readonly WorkspaceEntry[] {
-      return list;
+      return sorted;
     },
     get loading(): boolean {
       return loading;
@@ -79,6 +93,18 @@ export function createWorkspaceStore(http: WorkspaceHttp): WorkspaceStore {
       return result;
     },
 
+    async setStarred(id, starred): Promise<WorkspaceResult<Workspace>> {
+      const prev = list.find((w) => w.id === id)?.starred ?? false;
+      // Optimistic: flip immediately (the sorted getter re-orders reactively).
+      list = applyStarred(list, id, starred);
+      const result = starred ? await http.star(id) : await http.unstar(id);
+      if (!result.ok) {
+        // Revert the optimistic flip on failure.
+        list = applyStarred(list, id, prev);
+      }
+      return result;
+    },
+
     async remove(id): Promise<WorkspaceResult<{ closedCount: number }>> {
       const result = await http.delete(id);
       if (result.ok) void this.refresh();