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diff --git a/src/features/workspaces/logic/view-model.ts b/src/features/workspaces/logic/view-model.ts
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+++ b/src/features/workspaces/logic/view-model.ts
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+/**
+ * Pure view-model helpers for the workspaces feature — zero DOM, zero effects.
+ */
+
+import type { WorkspaceEntry } from "@dispatch/wire";
+import type { Route } from "./route";
+
+/**
+ * The browser tab / page (`document.title`) text for a route. The home route
+ * (`/`) is "Dispatch"; a workspace route (`/<id>`) is "Dispatch: {title}",
+ * using the workspace's display title and falling back to the URL slug (`id`)
+ * until the workspace list has loaded it — the backend defaults a workspace's
+ * title to its id, so the slug is the correct transient value. Pure: route +
+ * workspaces in, string out.
+ */
+export function pageTitle(route: Route, workspaces: readonly WorkspaceEntry[]): string {
+  if (route.kind === "home") return "Dispatch";
+  const ws = workspaces.find((w) => w.id === route.id);
+  return `Dispatch: ${ws?.title ?? route.id}`;
+}
+
+/**
+ * Sort workspaces for display: starred first, then most-recently-active. Pure:
+ * the list in, a NEW sorted array out (the input is not mutated). Starred
+ * workspaces jump to the top (the FE-side echo of their concurrency-priority);
+ * within each group (starred / not) `lastActivityAt` desc breaks ties, matching
+ * the backend's list ordering. Stable for equal `lastActivityAt`.
+ */
+export function sortWorkspaces<T extends WorkspaceEntry>(workspaces: readonly T[]): T[] {
+  return [...workspaces].sort((a, b) => {
+    if (a.starred !== b.starred) return a.starred ? -1 : 1;
+    return b.lastActivityAt - a.lastActivityAt;
+  });
+}
+
+/**
+ * Return a NEW list with the one workspace's `starred` flag set (immutably —
+ * the entry is replaced, the rest keep their identity). Pure: the optimistic
+ * star/unstar transformation shared by the apply + the error revert. A missing
+ * `id` (not yet in the list — e.g. starring a workspace the home view hasn't
+ * loaded) leaves the list unchanged; the backend's create-on-miss still applies
+ * server-side and a subsequent refresh reconciles.
+ */
+export function applyStarred<T extends WorkspaceEntry>(
+  workspaces: readonly T[],
+  id: string,
+  starred: boolean,
+): T[] {
+  return workspaces.map((w) => (w.id === id ? { ...w, starred } : w));
+}
+
+/**
+ * Format an epoch-ms timestamp as a short relative string ("now", "3m", "2h",
+ * "5d", or a date). Pure: `now` + `then` in, string out. Future timestamps
+ * (a workspace just created) read as "now".
+ */
+export function relativeTime(then: number, now: number): string {
+  const diff = now - then;
+  if (diff < 60_000) return "now";
+  const mins = Math.floor(diff / 60_000);
+  if (mins < 60) return `${mins}m`;
+  const hours = Math.floor(mins / 60);
+  if (hours < 24) return `${hours}h`;
+  const days = Math.floor(hours / 24);
+  if (days < 7) return `${days}d`;
+  // Beyond a week: a short date (MM/DD). Uses UTC parts for determinism in tests.
+  const d = new Date(then);
+  const month = String(d.getUTCMonth() + 1).padStart(2, "0");
+  const day = String(d.getUTCDate()).padStart(2, "0");
+  return `${month}/${day}`;
+}