feat(msg-bus): notify the deleted folder himself

cas where a client is browsing a folder being deleted

docs/plan/message-bus.md

@@ -992,11 +992,55 @@ Output JSON schema (for post-mortem assertions in shell):
 }
 ```
 
-### Coverage — four scenarios, each in the same test file
+### Coverage — eleven scenarios, all green
 
-Orchestrated by a single `tests/api/rt_bus_check.sh` invoked from
-`tests/api/run.sh` after the main hurl block. Follows the
-`refcount_cascade` / `thumb_import_check` patterns already in place.
+The four MVP scenarios sketched below expanded to **S1–S11** as
+Slice C, D, and F shipped. All orchestrated by
+`tests/api/rt_bus_check.sh` invoked from `tests/api/run.sh` after the
+main hurl block. Follows the `refcount_cascade` /
+`thumb_import_check` patterns already in place.
+
+Scenarios live today:
+
+- **S1** — Positive delivery: subscribe A, upload into A, one
+  `file_created`.
+- **S2** — Topic isolation: subscribe A, upload into B then A;
+  observe A's event only.
+- **S3** — AuthZ denial: user2 subscribes to A without a grant →
+  `no_read`.
+- **S4** — Anti-enumeration parity: subscribe to a nonexistent
+  folder returns the SAME `no_read` as S3.
+- **S5** — Server keepalive: 3 s idle surfaces multiple RFC 6455
+  Pings; session still delivers afterwards.
+- **S6** — `file_deleted`: DELETE fires the publish hook.
+- **S7** — Move fan-out: subscribe A+B, MOVE A→B, observe two
+  `file_moved` (one per topic).
+- **S8** — Grant-revoke eviction (Slice C): user2 subscribes to
+  A+B (both granted); user1 revokes only A → `rt.revoked` for A,
+  upload to B still delivers. Session survives.
+- **S9** — Cross-user identity gate: user1 subscribes to
+  `user:{user2_id}:authz` → `topic_forbidden` (identity mismatch;
+  audit reason `identity_mismatch`; wire response indistinguishable
+  from unknown topic per anti-enum).
+- **S10** — Ticket happy path (Slice F): `POST /api/rt/ticket`,
+  open WS with `oxi.ticket.<uuid>` subprotocol, subscribe +
+  deliver.
+- **S11** — Ticket single-use (Slice F): reusing a redeemed
+  ticket fails the upgrade with 401 + audit
+  `message_bus.upgrade_rejected reason=ticket_invalid`.
+
+**Ready-file race fix**: the shell script uses a `wait_ready`
+function that blocks on the helper's `--ready-file` (touched the
+instant every requested subscribe is ack'd) instead of a
+`sleep 0.4` heuristic that flaked on cold-cache runs. See
+`rt-hurl-helper::Args::ready_file` and the wait_ready doc in the
+shell script.
+
+**Always rebuild the helper** — the guard `[[ ! -x $HELPER_BIN ]]`
+was removed 2026-09-11 because it silently reused stale binaries
+whenever the helper's source changed without touching the caller
+shell. Cargo incremental short-circuits in ~50 ms; the cost is
+negligible, the trap-free experience is worth it.
 
 **Scenario 1 — Positive delivery** (fan-out works)
 

frontend/src/routes/files/[...path]/+page.svelte

@@ -476,7 +476,27 @@
 		onFolderCreated: (d) => scheduleLiveReload(d.actor),
 		onFolderRenamed: (d) => scheduleLiveReload(d.actor),
 		onFolderMoved: (d) => scheduleLiveReload(d.actor),
-		onFolderDeleted: (d) => scheduleLiveReload(d.actor),
+		onFolderDeleted: (d) => {
+			// Two cases fanned out from the server-side publish:
+			//   * `d.folder_id !== currentId` — a SUBFOLDER of the
+			//     current view was deleted. Refetch the listing so
+			//     the row disappears (existing behavior).
+			//   * `d.folder_id === currentId` — the VIEWED folder
+			//     itself just got trashed. The FolderService trashes
+			//     the subtree (soft-delete cascade); staying here
+			//     would show a zombie view. Toast + navigate to
+			//     `/files`, same UX as `onRevoked` for grant
+			//     eviction. See `TrashService::move_to_trash` and
+			//     `docs/plan/message-bus.md § Status` for the
+			//     dual-topic publish rationale.
+			if (d.folder_id === currentId) {
+				ui.notify(t('files.folder_was_deleted', 'This folder was moved to trash.'), 'warning');
+				busLog.warn('viewed folder was deleted', { folder_id: d.folder_id });
+				void goto(resolve('/files'));
+				return;
+			}
+			scheduleLiveReload(d.actor);
+		},
 		onRevoked: (params) => {
 			// The subscription is already gone server-side. Notify the
 			// user and send them back to their home so they don't sit

src/application/services/trash_service.rs

@@ -304,17 +304,33 @@ impl TrashUseCase for TrashService {
                 // doesn't panic here.
                 if let (Some(bus), Some(parent_uuid)) = (&self.bus, parent_snapshot) {
                     debug!(
-                        "publishing FolderDeleted folder={} parent={} actor={}",
+                        "publishing FolderDeleted folder={} parent={} actor={} (2 topics)",
                         folder_id, parent_uuid, user_id
                     );
-                    bus.publish(
-                        &Topic::Folder(parent_uuid),
-                        MessageBusEvent::FolderDeleted {
-                            folder_id,
-                            parent_id: parent_uuid,
-                            actor: user_id,
-                        },
-                    );
+                    let event = MessageBusEvent::FolderDeleted {
+                        folder_id,
+                        parent_id: parent_uuid,
+                        actor: user_id,
+                    };
+                    // Publish on BOTH the parent's topic AND the deleted
+                    // folder's own topic:
+                    //
+                    //   * Parent topic — viewers of the parent see the
+                    //     child disappear from their listing (existing
+                    //     behavior, verified by tests).
+                    //   * Deleted-folder topic — viewers INSIDE the
+                    //     folder that just got trashed are stranded on a
+                    //     folder that no longer exists. Delivering the
+                    //     same `folder_deleted` event on this topic lets
+                    //     the FE `onFolderDeleted` handler detect
+                    //     `data.folder_id === currentId` and navigate
+                    //     away with a toast (same UX as `onRevoked`
+                    //     surfaces for grant-revocation eviction).
+                    //     Otherwise the sub would silently stop
+                    //     receiving events and the tab would sit on a
+                    //     zombie view.
+                    bus.publish(&Topic::Folder(parent_uuid), event.clone());
+                    bus.publish(&Topic::Folder(folder_id), event);
                 } else {
                     debug!(
                         "trash-folder publish skipped: bus={} parent={:?}",