feat(workspaces): archive option + archived-workspaces view

Consume the backend's archive contract (feature/archive-workspaces):

- adapter/http: archive(id)/unarchive(id) (PUT/DELETE /workspaces/:id/archive);
  list(archived?) passes the ?archived= query
- logic/view-model: pure applyArchived(list, id, archived)
- store.svelte: setArchived(id, archived) (optimistic + revert-on-error +
  reconciling refresh); archivedList + refreshArchived() for the archived view
- ui/TileActionBar: new Archive action (the right-click→select action bar)
- ui/HomeHeader: new Archived button opens the archived view
- ui/ArchivedWorkspaces (new): modal listing archived workspaces with
  Unarchive + View (navigates to /<id>)
- ui/WorkspacesHome: wire the Archive action + the Archived modal
- .dispatch/wire.reference.md + backend-handoff.md: record the contract delta

1 files changed, 119 insertions, 0 deletions

diff --git a/src/features/workspaces/ui/ArchivedWorkspaces.svelte b/src/features/workspaces/ui/ArchivedWorkspaces.svelte
new file mode 100644
index 0000000..584fd68
--- /dev/null
+++ b/src/features/workspaces/ui/ArchivedWorkspaces.svelte
@@ -0,0 +1,119 @@
+<script lang="ts">
+  import type { WorkspaceEntry } from "@dispatch/wire";
+  import type { WorkspaceStore } from "../store.svelte";
+  import { relativeTime } from "../logic/view-model";
+
+  let {
+    store,
+    onOpen,
+    onClose,
+  }: {
+    store: WorkspaceStore;
+    /** Open (view) a workspace — navigates to `/<id>`. */
+    onOpen: (id: string) => void;
+    onClose: () => void;
+  } = $props();
+
+  // Load the archived list when the modal mounts.
+  $effect(() => {
+    void store.refreshArchived();
+  });
+
+  let busyId = $state<string | null>(null);
+  let actionError = $state<string | null>(null);
+
+  async function unarchive(ws: WorkspaceEntry): Promise<void> {
+    if (busyId !== null) return;
+    busyId = ws.id;
+    actionError = null;
+    const result = await store.setArchived(ws.id, false);
+    busyId = null;
+    if (!result.ok) {
+      actionError = result.error;
+      return;
+    }
+    // Refresh the archived list so the unarchived workspace leaves it.
+    void store.refreshArchived();
+  }
+
+  function open(ws: WorkspaceEntry): void {
+    onOpen(ws.id);
+    onClose();
+  }
+</script>
+
+<div class="modal modal-open" role="dialog" aria-label="Archived workspaces">
+  <div class="modal-box max-w-lg">
+    <div class="flex items-start justify-between gap-2">
+      <div>
+        <h2 class="text-lg font-bold">Archived workspaces</h2>
+        <p class="text-xs opacity-50">Hidden from the home grid. Unarchive to restore.</p>
+      </div>
+      <button
+        type="button"
+        class="btn btn-circle btn-ghost btn-sm"
+        aria-label="Close archived workspaces"
+        onclick={onClose}>✕</button
+      >
+    </div>
+
+    {#if actionError}
+      <p class="mt-3 text-xs text-error">{actionError}</p>
+    {/if}
+
+    <div class="mt-4">
+      {#if store.archivedLoading && store.archivedList.length === 0}
+        <div class="flex justify-center py-8">
+          <span class="loading loading-spinner loading-md opacity-60"></span>
+        </div>
+      {:else if store.archivedList.length === 0}
+        <p class="py-8 text-center text-sm opacity-50">No archived workspaces.</p>
+      {:else}
+        <ul class="flex flex-col gap-2">
+          {#each store.archivedList as ws (ws.id)}
+            <li
+              class="flex items-center justify-between gap-3 rounded-box border border-base-content/10 bg-base-200/40 px-3 py-2"
+            >
+              <div class="min-w-0 flex-1">
+                <p class="truncate font-semibold">{ws.title}</p>
+                <p class="font-mono text-xs opacity-50">
+                  /{ws.id} · {ws.conversationCount} conv · {relativeTime(
+                    ws.lastActivityAt,
+                    Date.now(),
+                  )} ago
+                </p>
+              </div>
+              <div class="flex shrink-0 items-center gap-1">
+                <button
+                  type="button"
+                  class="btn btn-ghost btn-xs"
+                  onclick={() => open(ws)}
+                  aria-label={`Open ${ws.title}`}>View</button
+                >
+                <button
+                  type="button"
+                  class="btn btn-outline btn-xs"
+                  disabled={busyId === ws.id}
+                  onclick={() => void unarchive(ws)}
+                  aria-label={`Unarchive ${ws.title}`}
+                >
+                  {#if busyId === ws.id}
+                    <span class="loading loading-spinner loading-xs"></span>
+                  {:else}
+                    Unarchive
+                  {/if}
+                </button>
+              </div>
+            </li>
+          {/each}
+        </ul>
+      {/if}
+    </div>
+  </div>
+  <!-- Click outside closes. -->
+  <button
+    type="button"
+    class="modal-backdrop"
+    aria-label="Close archived workspaces backdrop"
+    onclick={onClose}></button>
+</div>