feat(msg-bus): add DPoP support, fix floow from client, correct deletion

frontend/src/lib/message-bus/client.svelte.ts

@@ -18,7 +18,10 @@
 // and the console logger so users can diagnose without a redeploy.
 
 import log from 'loglevel';
+import { untrack } from 'svelte';
 
+import { apiJson } from '$lib/api/client';
+import { getCsrfHeaders } from '$lib/api/csrf';
 import { RtErrorCode } from './error-codes';
 import {
 	parseIncoming,
@@ -30,6 +33,20 @@ import {
 import type RtEventParams from '$lib/generated/message-bus/RtEventParams';
 import type RtRevokedParams from '$lib/generated/message-bus/RtRevokedParams';
 
+/** Response body from `POST /api/rt/ticket`. Matches the Rust
+ *  `RtTicketResponse` shape — see `handlers/rt_ticket_handler.rs`. */
+interface RtTicketResponse {
+	/** Opaque ticket UUID. Redeemed once server-side. */
+	ticket: string;
+	/** Seconds until server-side expiry (informational; the client
+	 *  should open the WS immediately). */
+	expires_in_seconds: number;
+	/** Full `Sec-WebSocket-Protocol` value the client MUST pass on
+	 *  the upgrade — assembled server-side so a FE bug can't emit
+	 *  the wrong prefix. */
+	subprotocol: string;
+}
+
 /** Logger namespace — matches `frontend/AGENTS.md § Logging`. Users
  *  tune with `oxi.setLogLevel('oxi:message-bus', 'debug')`. */
 const busLog = log.getLogger('oxi:message-bus');
@@ -73,6 +90,16 @@ export interface MessageBusError {
 const RECONNECT_MIN_MS = 250;
 const RECONNECT_MAX_MS = 30_000;
 
+/** Circuit breaker — after N consecutive failed attempts (either a
+ *  ticket-exchange rejection or a WS close before `onopen` fires),
+ *  give up and stay `disconnected` until the caller explicitly asks
+ *  to `reconnect()`. Prevents an unrecoverable auth state (revoked
+ *  session, wrong CSRF cookie, missing DPoP nonce) from flooding
+ *  logs. Ten attempts × exponential-backoff-with-jitter is roughly a
+ *  minute of trying — long enough for a transient blip, short enough
+ *  to stop before it's noise. */
+const MAX_CONSECUTIVE_FAILURES = 10;
+
 interface SubEntry {
 	count: number;
 	handlers: Set<EventHandler>;
@@ -102,6 +129,11 @@ export class MessageBusClient {
 	/** setTimeout handle for a scheduled reconnect. Cleared on
 	 *  explicit `close()` so we don't reconnect after teardown. */
 	#reconnectTimer: ReturnType<typeof setTimeout> | null = null;
+	/** Consecutive failures — incremented on every attempt that dies
+	 *  before `#onOpen()` gets to reset it. Once it hits
+	 *  `MAX_CONSECUTIVE_FAILURES` the client stops reconnecting and
+	 *  requires an explicit `reconnect()` from the caller. */
+	#consecutiveFailures = 0;
 
 	/** `topic` → `{count, handlers, revokedHandlers, acked}`. Refcount
 	 *  drives the wire: first refcount ⇒ send `rt.subscribe`; last drop
@@ -139,49 +171,68 @@ export class MessageBusClient {
 	 * to the local handlers for `topic`, sends `rt.subscribe` on the
 	 * wire only for the first ref, and returns an unsubscribe fn that
 	 * drops that same ref (last ref out sends `rt.unsubscribe`).
+	 *
+	 * Wrapped in `untrack` because `this.state` is `$state`. Without
+	 * this, a caller invoking `subscribe` from a Svelte `$effect`
+	 * (which `useTopic` does) would take a reactive dep on `state`.
+	 * Every `state` transition (idle → connecting → disconnected →
+	 * connecting → …) would then re-fire the caller's `$effect`,
+	 * which re-calls `subscribe`, which flips `state`, which re-fires
+	 * the effect — a 1000+/s runaway loop, observed on server-down
+	 * (2026-09-11). `subscribe` is a mutation entry point; its reads
+	 * of internal state MUST NOT contaminate reactive callers.
 	 */
 	subscribe(topic: string, onEvent: EventHandler, onRevoked?: RevokedHandler): UnsubscribeHandle {
-		let entry = this.#subs.get(topic);
+		return untrack(() => {
-		if (!entry) {
+			let entry = this.#subs.get(topic);
-			// Plain Sets: internal callback registries, not reactive. Same
+			if (!entry) {
-			// rationale as `#subs` / `#pending` — see the doc there.
+				// Plain Sets: internal callback registries, not reactive.
-			entry = {
+				// Same rationale as `#subs` / `#pending` — see the doc
-				count: 0,
+				// there.
-				// eslint-disable-next-line svelte/prefer-svelte-reactivity
+				entry = {
-				handlers: new Set(),
+					count: 0,
-				// eslint-disable-next-line svelte/prefer-svelte-reactivity
+					// eslint-disable-next-line svelte/prefer-svelte-reactivity
-				revokedHandlers: new Set(),
+					handlers: new Set(),
-				acked: false
+					// eslint-disable-next-line svelte/prefer-svelte-reactivity
+					revokedHandlers: new Set(),
+					acked: false
+				};
+				this.#subs.set(topic, entry);
+			}
+			entry.count += 1;
+			entry.handlers.add(onEvent);
+			if (onRevoked) entry.revokedHandlers.add(onRevoked);
+
+			// Kick the connection if nothing is holding it yet, otherwise
+			// send `rt.subscribe` if this is the first ref on this topic.
+			if (this.state === 'idle' || this.state === 'disconnected') {
+				this.#connect();
+			} else if (entry.count === 1 && this.state === 'connected') {
+				this.#sendSubscribe(topic).catch((err) =>
+					busLog.warn('subscribe failed', { topic, error: err })
+				);
+			}
+
+			let released = false;
+			return () => {
+				if (released) return;
+				released = true;
+				// Cleanup path — Svelte `$effect` cleanup doesn't track
+				// anyway, but stay defensive: untrack around the
+				// internal state reads inside #releaseOne.
+				untrack(() => this.#releaseOne(topic, onEvent, onRevoked));
 			};
-			this.#subs.set(topic, entry);
+		});
-		}
-		entry.count += 1;
-		entry.handlers.add(onEvent);
-		if (onRevoked) entry.revokedHandlers.add(onRevoked);
-
-		// Kick the connection if nothing is holding it yet, otherwise
-		// send `rt.subscribe` if this is the first ref on this topic.
-		if (this.state === 'idle' || this.state === 'disconnected') {
-			this.#connect();
-		} else if (entry.count === 1 && this.state === 'connected') {
-			this.#sendSubscribe(topic).catch((err) =>
-				busLog.warn('subscribe failed', { topic, error: err })
-			);
-		}
-
-		let released = false;
-		return () => {
-			if (released) return;
-			released = true;
-			this.#releaseOne(topic, onEvent, onRevoked);
-		};
 	}
 
 	/** Force a fresh reconnect — for a live-updates toggle or a manual
-	 *  "reconnect" button. Rare; not part of the normal flow. */
+	 *  "reconnect" button. Rare; not part of the normal flow. Also the
+	 *  escape hatch after the circuit breaker trips: zeroes the
+	 *  consecutive-failure counter so the next attempt actually fires. */
 	reconnect(): void {
 		if (this.#ws) this.#ws.close();
 		this.#backoffMs = RECONNECT_MIN_MS;
+		this.#consecutiveFailures = 0;
 		this.#scheduleReconnect(0);
 	}
 
@@ -207,9 +258,40 @@ export class MessageBusClient {
 		if (this.state === 'connecting' || this.state === 'connected') return;
 		this.state = 'connecting';
 		busLog.debug('connecting', { url: this.#url });
+		// Ticket exchange runs off a Promise; the connection is
+		// finalised inside its `.then`. Errors during exchange land in
+		// `#onTicketFailure`, which mirrors the WS-close reconnect path
+		// so a transient auth blip retries with backoff.
+		void this.#exchangeAndOpen();
+	}
+
+	/** POST `/api/rt/ticket`, then open the WS with the returned
+	 *  subprotocol. The POST runs through `apiFetch` — DPoP proof
+	 *  and session cookie handled by the interceptor — and we attach
+	 *  the CSRF header ourselves per every state-changing endpoint's
+	 *  convention (see `endpoints/shares.ts` for the pattern). */
+	async #exchangeAndOpen(): Promise<void> {
+		let subprotocol: string;
+		try {
+			const res = await apiJson<RtTicketResponse>('/api/rt/ticket', {
+				method: 'POST',
+				headers: getCsrfHeaders()
+			});
+			subprotocol = res.subprotocol;
+			busLog.debug('ticket issued', { expires_in_seconds: res.expires_in_seconds });
+		} catch (err) {
+			this.#onTicketFailure(err);
+			return;
+		}
+		// A close/reconnect could have raced this in-flight exchange;
+		// bail if we lost the "connecting" role in the meantime.
+		if (this.state !== 'connecting') {
+			busLog.debug('ticket exchange raced with close — discarding', { state: this.state });
+			return;
+		}
 		let ws: WebSocket;
 		try {
-			ws = new this.#WebSocketCtor(this.#url);
+			ws = new this.#WebSocketCtor(this.#url, [subprotocol]);
 		} catch (err) {
 			busLog.warn('WebSocket ctor threw — reconnect scheduled', { error: err });
 			this.state = 'disconnected';
@@ -223,10 +305,21 @@ export class MessageBusClient {
 		ws.onclose = (ev) => this.#onClose(ev);
 	}
 
+	/** Handle a failed ticket exchange. Same shape as a WS close —
+	 *  we're not going to retry inline (a bad auth state won't fix
+	 *  itself in 250 ms), so schedule the next attempt through the
+	 *  standard reconnect path. */
+	#onTicketFailure(err: unknown): void {
+		busLog.warn('ticket exchange failed — reconnect scheduled', { error: err });
+		this.state = 'disconnected';
+		if (this.#subs.size > 0) this.#scheduleReconnect();
+	}
+
 	#onOpen(): void {
 		busLog.debug('connected');
 		this.state = 'connected';
 		this.#backoffMs = RECONNECT_MIN_MS;
+		this.#consecutiveFailures = 0;
 		// Replay every already-known topic. `entry.acked` is reset here
 		// because the fresh connection has no server-side memory of
 		// prior subscriptions.
@@ -258,6 +351,16 @@ export class MessageBusClient {
 					busLog.debug('event for unknown topic', { topic: frame.params.topic });
 					return;
 				}
+				// Trace each delivered event so devs can watch the bus
+				// live in the console. Level `debug` — silent under the
+				// default `warn`. See `frontend/AGENTS.md § Logging`
+				// for the tune knob (`oxi.setLogLevel('oxi:message-bus',
+				// 'debug')`).
+				busLog.debug('event received', {
+					topic: frame.params.topic,
+					kind: frame.params.event,
+					actor: (frame.params.data as { actor?: string })?.actor
+				});
 				for (const handler of entry.handlers) {
 					try {
 						handler(frame.params);
@@ -330,11 +433,30 @@ export class MessageBusClient {
 
 	#scheduleReconnect(overrideMs?: number): void {
 		if (this.#reconnectTimer !== null) return;
+		this.#consecutiveFailures += 1;
+		// Circuit breaker: after too many failures in a row, stop
+		// retrying and require an explicit `reconnect()` call from
+		// the caller. Prevents a bad auth state (session revoked,
+		// CSRF cookie stripped, DPoP nonce mismatch) from flooding
+		// server logs with the same 401/403 forever. `reconnect()`
+		// zeroes the counter and re-arms.
+		if (this.#consecutiveFailures >= MAX_CONSECUTIVE_FAILURES) {
+			busLog.error('circuit breaker tripped — reconnect suspended after too many failures', {
+				consecutiveFailures: this.#consecutiveFailures,
+				max: MAX_CONSECUTIVE_FAILURES,
+				remedy: 'call messageBus.reconnect() to retry, or refresh the page'
+			});
+			return;
+		}
 		const delay = overrideMs ?? this.#backoffMs;
 		// Full jitter — random in [0, backoff]. Prevents thundering
 		// herd if the server was momentarily overloaded.
 		const jittered = Math.floor(Math.random() * (delay + 1));
-		busLog.warn('reconnect scheduled', { attemptBackoffMs: delay, jitteredMs: jittered });
+		busLog.warn('reconnect scheduled', {
+			attemptBackoffMs: delay,
+			jitteredMs: jittered,
+			consecutiveFailures: this.#consecutiveFailures
+		});
 		this.#reconnectTimer = setTimeout(() => {
 			this.#reconnectTimer = null;
 			this.#backoffMs = Math.min(this.#backoffMs * 2, RECONNECT_MAX_MS);

frontend/vite.config.ts

@@ -34,8 +34,17 @@ const DEV_ORIGIN_HEADERS = {
 };
 const p = (target: string) => ({ target, changeOrigin: true, headers: DEV_ORIGIN_HEADERS });
 
+// Same as `p()` but with WebSocket upgrade forwarding enabled. Vite's
+// `http-proxy-middleware` treats HTTP and WS as two separate transports —
+// without `ws: true` the upgrade request is silently dropped and the
+// browser hangs in `readyState = CONNECTING` until Chrome's ~30 s
+// handshake timeout fires. Needed for `/api/rt/ws` (message bus). Kept
+// as a separate helper so paths that don't upgrade don't pay the extra
+// listener setup.
+const pWs = (target: string) => ({ ...p(target), ws: true });
+
 const proxy = {
-	'/api': p(BACKEND),
+	'/api': pWs(BACKEND),
 	'/locales': p(BACKEND),
 	'/.well-known': p(BACKEND),
 	'/remote.php': p(BACKEND),

src/application/services/trash_service.rs

@@ -14,6 +14,7 @@ use crate::application::dtos::trash_dto::{
 };
 use crate::application::ports::authorization_ports::AuthorizationEngine;
 use crate::application::ports::file_lifecycle::FileLifecycleHook;
+use crate::application::ports::message_bus_ports::{MessageBus, MessageBusEvent, Topic};
 use crate::application::ports::storage_ports::FileWritePort;
 use crate::application::ports::trash_ports::TrashUseCase;
 use crate::common::errors::{DomainError, ErrorKind, Result};
@@ -71,6 +72,16 @@ pub struct TrashService {
     /// so trash listings filter by drive membership instead of the legacy
     /// per-user scope.
     drive_repo: Arc<crate::infrastructure::repositories::pg::DrivePgRepository>,
+
+    /// Message bus — publishes `FolderDeleted` on `Topic::Folder(parent)`
+    /// after a folder is trashed, so subscribers of the parent folder's
+    /// live-view refresh. `None` when the bus isn't wired (tests / stubs).
+    /// File trash is intentionally NOT published here: the FE hits
+    /// `DELETE /api/files/{id}` directly (bypasses the trash service)
+    /// and `FileManagementService::delete_and_cleanup_with_perms`
+    /// publishes on that path. If a future endpoint routes file delete
+    /// through this service, add the file-arm publish here too.
+    bus: Option<Arc<dyn MessageBus>>,
 }
 
 impl TrashService {
@@ -93,6 +104,7 @@ impl TrashService {
             content_cache,
             authz,
             drive_repo,
+            bus: None,
         }
     }
 
@@ -102,6 +114,15 @@ impl TrashService {
         self
     }
 
+    /// Wire the message bus. Enables the `FolderDeleted` publish on
+    /// `Topic::Folder(parent)` after a folder is trashed — folder-live
+    /// views subscribe to the parent topic and refresh on receipt.
+    /// Silent no-op if never called (unit tests skip this).
+    pub fn with_message_bus(mut self, bus: Arc<dyn MessageBus>) -> Self {
+        self.bus = Some(bus);
+        self
+    }
+
     /// Converts a TrashedItem entity to a DTO
     fn to_dto(&self, item: TrashedItem) -> TrashedItemDto {
         // Calculate days_until_deletion before moving item fields
@@ -236,6 +257,28 @@ impl TrashUseCase for TrashService {
                     )
                     .await?;
 
+                // Snapshot the parent BEFORE the trash UPDATE — the row
+                // still exists at this point (soft-delete flips
+                // `is_trashed`, keeps the parent_id). We need parent_id
+                // to publish `FolderDeleted` on `Topic::Folder(parent)`
+                // after commit, so subscribers of the folder view refresh.
+                // If the bus isn't wired, skip the read to save a query.
+                let parent_snapshot = if self.bus.is_some() {
+                    match self.folder_storage_port.get_folder(item_id).await {
+                        Ok(folder) => folder.parent_id().and_then(|s| Uuid::parse_str(s).ok()),
+                        Err(e) => {
+                            debug!("trash-folder parent lookup failed: {}", e);
+                            None
+                        }
+                    }
+                } else {
+                    None
+                };
+                debug!(
+                    "trash-folder parent snapshot for {}: {:?}",
+                    item_id, parent_snapshot
+                );
+
                 // Soft-delete model — same as the file branch above: the
                 // cascade UPDATE below is the whole operation; no folder
                 // fetch or trash-index write needed.
@@ -253,6 +296,32 @@ impl TrashUseCase for TrashService {
                     })?;
 
                 debug!("Folder moved to trash: {}", item_id);
+
+                // Bus publish AFTER the trash commits. Root folders
+                // have `parent_id = None`; the trash endpoint refuses
+                // those via the mount / drive-root guards, but keep
+                // the `Some` gate anyway so a future permissive path
+                // doesn't panic here.
+                if let (Some(bus), Some(parent_uuid)) = (&self.bus, parent_snapshot) {
+                    debug!(
+                        "publishing FolderDeleted folder={} parent={} actor={}",
+                        folder_id, parent_uuid, user_id
+                    );
+                    bus.publish(
+                        &Topic::Folder(parent_uuid),
+                        MessageBusEvent::FolderDeleted {
+                            folder_id,
+                            parent_id: parent_uuid,
+                            actor: user_id,
+                        },
+                    );
+                } else {
+                    debug!(
+                        "trash-folder publish skipped: bus={} parent={:?}",
+                        self.bus.is_some(),
+                        parent_snapshot
+                    );
+                }
                 Ok(())
             }
             _ => Err(DomainError::validation_error(format!(

src/bin/generate-asyncapi.rs

@@ -76,21 +76,32 @@ Phase C (sync-client push, album live) extend the same channels — see
                     },
                 },
                 "protocolVersion": "13",
-                // Subprotocol advertised in the WS handshake. Handler
+                // Subprotocol advertised in the WS handshake. The handler
-                // accepts `oxi.rt.v1` and the optional bearer element
+                // accepts one of two shapes:
-                // `authorization.bearer.<jwt>` alongside it.
+                //   * `oxi.ticket.<uuid>` — the browser path. Redeems a
+                //     one-shot 30 s ticket minted by
+                //     `POST /api/rt/ticket` (that endpoint runs under the
+                //     full auth + DPoP stack, so the ticket effectively
+                //     inherits the proofed session).
+                //   * (no subprotocol) — falls back to
+                //     `Authorization: Bearer <jwt>`, used by programmatic
+                //     clients that can set headers (e.g. rt-hurl-helper).
                 "bindings": {
-                    "ws": { "subProtocol": "oxi.rt.v1" }
+                    "ws": { "subProtocol": "oxi.ticket.{ticket}" }
                 },
-                // Every request MUST be authenticated. Programmatic
+                // Every request MUST be authenticated. Two paths:
-                // clients set `Authorization: Bearer <jwt>` on the WS
+                //   * `bearerAuth` — programmatic clients set
-                // upgrade (same header the REST API uses); browser
+                //     `Authorization: Bearer <jwt>` on the WS upgrade
-                // clients — which can't set headers on `new WebSocket()`
+                //     (same header the REST API uses).
-                // — will use the deferred ticket flow (a plain HTTP
+                //   * `ticketAuth` — browser clients POST
-                // POST issues a short-lived one-shot ticket bound to
+                //     `/api/rt/ticket` with full auth + DPoP, receive
-                // the WS URL, see the plan's DPoP-gap section).
+                //     an opaque one-shot token, and pass it via
+                //     `Sec-WebSocket-Protocol: oxi.ticket.<uuid>`
+                //     (browsers cannot set arbitrary headers on
+                //     `new WebSocket()`). See `docs/plan/message-bus.md § F`.
                 "security": [
-                    { "$ref": "#/components/securitySchemes/bearerAuth" }
+                    { "$ref": "#/components/securitySchemes/bearerAuth" },
+                    { "$ref": "#/components/securitySchemes/ticketAuth" }
                 ],
             }
         },
@@ -299,7 +310,16 @@ fn components() -> Value {
                 "type": "http",
                 "scheme": "bearer",
                 "bearerFormat": "JWT",
-                "description": "OxiCloud JWT — same access_token minted by `POST /api/auth/login` (or the OPAQUE handshake). Programmatic clients set `Authorization: Bearer <jwt>` on the WS upgrade request. Browsers, which cannot set headers on `new WebSocket()`, will use the deferred ticket flow (`POST /api/rt/ticket` → short-lived one-shot ticket in the WS URL); see the plan's DPoP-gap section.",
+                "description": "OxiCloud JWT — same access_token minted by `POST /api/auth/login` (or the OPAQUE handshake). Programmatic clients set `Authorization: Bearer <jwt>` on the WS upgrade request. DPoP-bound tokens are refused on this path (the WS handshake cannot carry a DPoP proof); browsers use `ticketAuth` instead.",
+            },
+            // `httpApiKey` (not bare `apiKey`) — AsyncAPI 3.0 reserves
+            // `apiKey` for server-variable-based schemes; a header-
+            // scoped key is `httpApiKey` with `in: header`.
+            "ticketAuth": {
+                "type": "httpApiKey",
+                "in": "header",
+                "name": "Sec-WebSocket-Protocol",
+                "description": "Browser path — the FE first calls `POST /api/rt/ticket` under the full REST middleware stack (auth + DPoP-proofed request), receives an opaque one-shot UUID with a 30 s TTL, then sets `Sec-WebSocket-Protocol: oxi.ticket.<uuid>` on the WS upgrade. The server redeems the ticket (single-use — a second attempt fails) and treats the WS session as authenticated for the caller who issued it. See `docs/plan/message-bus.md § F` and `handlers/rt_ticket_handler.rs`.",
             }
         }
     });

src/bin/rt-hurl-helper.rs

@@ -62,12 +62,29 @@ use tokio_tungstenite::tungstenite::http::HeaderValue;
 struct Args {
     mode: Mode,
     url: String,
-    token: String,
+    /// Either `--token <jwt>` (Authorization: Bearer path — the original
+    /// helper flow) or `--ticket <uuid>` (Sec-WebSocket-Protocol path
+    /// — exercises F). Exactly one MUST be set; parse_args enforces.
+    auth: WsAuth,
     subscribe: Vec<String>,
     expect_events: Option<usize>,
     reason: Option<String>,
     timeout: Duration,
     output: Option<String>,
+    /// Optional path the helper `touch`es the instant EVERY requested
+    /// `--subscribe` topic has been ack'd by the server. Shell tests
+    /// wait on this file before firing the upload that publishes to
+    /// the topic, closing the "sleep 0.4 hoping the subscribe landed
+    /// in time" race that occasionally dropped events on slow /
+    /// cold-cache runs. Off by default; only used by the smoke test.
+    ready_file: Option<String>,
+}
+
+/// How the helper authenticates the WS upgrade. Mirrors the two paths
+/// `rt_ws_handler::authenticate_upgrade` accepts.
+enum WsAuth {
+    Bearer(String),
+    Ticket(String),
 }
 
 enum Mode {
@@ -105,11 +122,13 @@ fn parse_args() -> Result<Args, String> {
 
     let mut url = None;
     let mut token = None;
+    let mut ticket = None;
     let mut subscribe = Vec::new();
     let mut expect_events = None;
     let mut reason = None;
     let mut timeout = Duration::from_secs(3);
     let mut output = None;
+    let mut ready_file = None;
 
     while let Some(flag) = it.next() {
         let value = it
@@ -118,6 +137,7 @@ fn parse_args() -> Result<Args, String> {
         match flag.as_str() {
             "--url" => url = Some(value),
             "--token" => token = Some(value),
+            "--ticket" => ticket = Some(value),
             "--subscribe" => subscribe.push(value),
             "--expect-events" => {
                 expect_events = Some(
@@ -129,19 +149,31 @@ fn parse_args() -> Result<Args, String> {
             "--reason" => reason = Some(value),
             "--timeout" => timeout = parse_duration(&value)?,
             "--output" => output = Some(value),
+            "--ready-file" => ready_file = Some(value),
             other => return Err(format!("unknown flag: {other}")),
         }
     }
 
+    // Exactly one credential MUST be set. Emitting a specific error
+    // makes shell-script drift ("forgot to swap --token for --ticket")
+    // debuggable at a glance.
+    let auth = match (token, ticket) {
+        (Some(_), Some(_)) => return Err("pass exactly one of --token or --ticket".into()),
+        (Some(t), None) => WsAuth::Bearer(t),
+        (None, Some(t)) => WsAuth::Ticket(t),
+        (None, None) => return Err("--token or --ticket required".into()),
+    };
+
     Ok(Args {
         mode,
         url: url.ok_or("--url required")?,
-        token: token.ok_or("--token required")?,
+        auth,
         subscribe,
         expect_events,
         reason,
         timeout,
         output,
+        ready_file,
     })
 }
 
@@ -202,14 +234,20 @@ impl<E: std::fmt::Display> From<E> for HelperError {
 // WS connection
 // ════════════════════════════════════════════════════════════════════════════
 
-/// Open a WS connection to `url` with the given bearer token attached
+/// Open a WS connection to `url` with the given [`WsAuth`] applied.
-/// via `Authorization: Bearer <jwt>`. Programmatic client — this is the
+///
-/// path native clients (this helper, future sync-client integrations)
+/// - `Bearer(jwt)` sets `Authorization: Bearer <jwt>` on the upgrade
-/// take. Browser clients that can't set the header will use the
+///   — the programmatic-client path.
-/// `Sec-WebSocket-Protocol` subprotocol fallback (Phase A follow-up).
+/// - `Ticket(uuid)` sets `Sec-WebSocket-Protocol: oxi.ticket.<uuid>`
+///   — the browser-equivalent path used by F's smoke scenarios.
+///
+/// The subprotocol prefix matches
+/// `infrastructure::services::rt_ticket_store::SUBPROTOCOL_PREFIX`; kept
+/// as a literal here so the test binary has no dependency on the
+/// application crate.
 async fn connect_ws(
     url: &str,
-    token: &str,
+    auth: &WsAuth,
 ) -> Result<
     tokio_tungstenite::WebSocketStream<tokio_tungstenite::MaybeTlsStream<tokio::net::TcpStream>>,
     HelperError,
@@ -217,12 +255,24 @@ async fn connect_ws(
     let mut req = url
         .into_client_request()
         .map_err(|e| HelperError::Protocol(format!("bad url: {e}")))?;
-    let bearer = format!("Bearer {token}");
+    match auth {
-    req.headers_mut().insert(
+        WsAuth::Bearer(token) => {
-        "Authorization",
+            let bearer = format!("Bearer {token}");
-        HeaderValue::from_str(&bearer)
+            req.headers_mut().insert(
-            .map_err(|e| HelperError::Protocol(format!("bad token: {e}")))?,
+                "Authorization",
-    );
+                HeaderValue::from_str(&bearer)
+                    .map_err(|e| HelperError::Protocol(format!("bad token: {e}")))?,
+            );
+        }
+        WsAuth::Ticket(ticket) => {
+            let subprotocol = format!("oxi.ticket.{ticket}");
+            req.headers_mut().insert(
+                "Sec-WebSocket-Protocol",
+                HeaderValue::from_str(&subprotocol)
+                    .map_err(|e| HelperError::Protocol(format!("bad ticket: {e}")))?,
+            );
+        }
+    }
     let (ws, _resp) = tokio_tungstenite::connect_async(req)
         .await
         .map_err(|e| HelperError::Protocol(format!("connect failed: {e}")))?;
@@ -241,7 +291,7 @@ async fn subscribe_and_collect(args: Args) -> Result<(), HelperError> {
     }
     let expect_events = args.expect_events.unwrap_or(0);
 
-    let mut ws = connect_ws(&args.url, &args.token).await?;
+    let mut ws = connect_ws(&args.url, &args.auth).await?;
 
     // Subscribe to every requested topic; track pending request ids so
     // we know when all acks have arrived before we start counting
@@ -327,6 +377,20 @@ async fn subscribe_and_collect(args: Args) -> Result<(), HelperError> {
             if let Some(topic) = topic {
                 subscribed.push(topic);
             }
+            // Every requested subscribe is now ack'd — signal the
+            // orchestrator that publishes targeted at these topics
+            // will land on a live subscriber. See `Args::ready_file`
+            // for the race this closes. Empty content is fine; the
+            // shell only checks existence, not payload. Errors are
+            // logged to stderr but not fatal: the smoke test's
+            // `wait_ready` timeout will surface the failure with
+            // more context than a mid-run panic here.
+            if pending_subs.is_empty()
+                && let Some(path) = args.ready_file.as_deref()
+                && let Err(e) = std::fs::write(path, b"")
+            {
+                eprintln!("rt-hurl-helper: could not touch --ready-file {path}: {e}");
+            }
             continue;
         }
 
@@ -391,7 +455,7 @@ async fn expect_denied(args: Args) -> Result<(), HelperError> {
         .ok_or_else(|| HelperError::Protocol("--subscribe required for expect-denied".into()))?
         .clone();
 
-    let mut ws = connect_ws(&args.url, &args.token).await?;
+    let mut ws = connect_ws(&args.url, &args.auth).await?;
 
     let req_id: u64 = 1;
     let frame = json!({

src/common/di.rs

@@ -1041,6 +1041,7 @@ impl AppServiceFactory {
         core: &CoreServices,
         authz: &Arc<PgAclEngine>,
         drive_repo: &Arc<crate::infrastructure::repositories::pg::DrivePgRepository>,
+        bus: &Arc<crate::infrastructure::services::in_process_message_bus::InProcessMessageBus>,
     ) -> Option<Arc<TrashService>> {
         if !self.config.features.enable_trash {
             tracing::info!("Trash service is disabled in configuration");
@@ -1049,7 +1050,12 @@ impl AppServiceFactory {
 
         let trash_repo = repos.trash_repository.as_ref()?;
 
-        // Wire ports directly to TrashService — no adapter layer needed
+        // Wire ports directly to TrashService — no adapter layer needed.
+        // Bus upcast to the trait object so the service takes the port,
+        // not the concrete impl — mirrors the pattern in
+        // `create_application_services`.
+        let bus_trait: Arc<dyn crate::application::ports::message_bus_ports::MessageBus> =
+            bus.clone();
         let service = Arc::new(
             TrashService::new(
                 trash_repo.clone(),
@@ -1060,7 +1066,8 @@ impl AppServiceFactory {
                 authz.clone(),
                 drive_repo.clone(),
             )
-            .with_file_deleted_hook(core.file_lifecycle.clone()),
+            .with_file_deleted_hook(core.file_lifecycle.clone())
+            .with_message_bus(bus_trait),
         );
 
         // Initialize cleanup service (bulk-deletes expired items in 2 SQL
@@ -1742,9 +1749,29 @@ impl AppServiceFactory {
         let drive_repo =
             Arc::new(crate::infrastructure::repositories::pg::DrivePgRepository::new(pool.clone()));
 
+        // Message bus: constructed BEFORE the trash service so trash-first
+        // deletes can publish `FolderDeleted` on the parent folder's
+        // topic (folder-view live refresh). Wired with a no-op replicator
+        // — multi-instance broker is a follow-up per
+        // `docs/plan/message-bus.md § Roadmap`. Spawns its own GC task in
+        // `with_replicator`; no supervisor setup required.
+        let bus = crate::infrastructure::services::in_process_message_bus::InProcessMessageBus::with_replicator(
+            Arc::new(crate::application::ports::message_bus_ports::NoopReplicator),
+        );
+
+        // WebSocket ticket store — see `rt_ticket_store` module doc for
+        // why this exists (DPoP-bound sessions can't be re-proofed on
+        // a browser-issued WS upgrade). Reaper task runs for the app
+        // lifetime; its handle is dropped intentionally — the task
+        // survives on the runtime, and cancellation is handled by
+        // graceful shutdown killing the runtime.
+        let rt_ticket_store =
+            crate::infrastructure::services::rt_ticket_store::RtTicketStore::new();
+        let _reaper = Arc::clone(&rt_ticket_store).spawn_reaper();
+
         // 3b. Trash service (needed before application services)
         let trash_service = self
-            .create_trash_service(&repos, &core, &authorization, &drive_repo)
+            .create_trash_service(&repos, &core, &authorization, &drive_repo, &bus)
             .await;
 
         // 3c. Storage usage / quota service (needed by the instant-upload
@@ -1794,17 +1821,6 @@ impl AppServiceFactory {
             crate::application::services::external_mount_router::MountRouter::new(mount_registry),
         );
 
-        // Message bus: single instance for the app lifetime, wired
-        // with a no-op replicator (multi-instance broker is a follow-up
-        // per `docs/plan/message-bus.md § Roadmap`). Constructed here
-        // so `create_application_services` can hand it to services that
-        // publish after their DB commits (`FolderService`,
-        // `FileUploadService`, …). Spawns its own GC task in
-        // `with_replicator` — no supervisor setup required.
-        let bus = crate::infrastructure::services::in_process_message_bus::InProcessMessageBus::with_replicator(
-            Arc::new(crate::application::ports::message_bus_ports::NoopReplicator),
-        );
-
         let mut apps = self.create_application_services(
             &core,
             &repos,
@@ -2316,6 +2332,7 @@ impl AppServiceFactory {
             maintenance_pool: Some(maintenance_pool),
             mount_router,
             bus,
+            rt_ticket_store,
             auth_service: auth_services,
             opaque_service,
             opaque_repo,
@@ -3223,6 +3240,16 @@ pub struct AppState {
     pub bus: Arc<
         crate::infrastructure::services::in_process_message_bus::InProcessMessageBus,
     >,
+    /// Short-lived tickets that authenticate a WebSocket upgrade
+    /// without the browser needing to attach a DPoP proof (which
+    /// `new WebSocket()` cannot set — only `Sec-WebSocket-Protocol`
+    /// is settable). FE POSTs `/api/rt/ticket` with a normal
+    /// DPoP-signed request, receives an opaque one-shot token, and
+    /// hands it to the WS upgrade via subprotocol. Always populated;
+    /// see `rt_ticket_store` module doc.
+    pub rt_ticket_store: Arc<
+        crate::infrastructure::services::rt_ticket_store::RtTicketStore,
+    >,
     pub auth_service: Option<AuthServices>,
     /// OPAQUE aPAKE substrate (RFC 9807). Populated only when
     /// [`OpaqueConfig::effective_mode`] is not `Off` — that method

src/infrastructure/services/in_process_message_bus.rs

@@ -127,6 +127,27 @@ impl MessageBus for InProcessMessageBus {
         // replicators must background their I/O themselves.
         self.replicator.on_local_publish(topic, &event);
 
+        // Structured trace of every publish so operators can watch the
+        // bus with `RUST_LOG=oxicloud::message_bus=debug`. Cheap:
+        // shows the wire-form topic (uses the same Display we return
+        // to WS clients), the event's discriminator (via serde), and
+        // whether anyone was listening at publish time. Payload bodies
+        // are NOT emitted here to keep the log line short and stable
+        // across variant additions — `debug_span` or a per-service
+        // publish site can log the payload if needed.
+        let sub_count = self
+            .topics
+            .get(topic)
+            .map(|s| s.receiver_count())
+            .unwrap_or(0);
+        tracing::debug!(
+            target: "oxicloud::message_bus",
+            topic = %topic.to_wire_key(),
+            kind = event_kind(&event),
+            subscribers = sub_count,
+            "📤 bus publish",
+        );
+
         // If nobody is subscribed, don't allocate a sender just to drop
         // its message. `broadcast::Sender::send` returns Err when there
         // are no receivers — cheaper still to short-circuit here.
@@ -155,6 +176,27 @@ impl MessageBus for InProcessMessageBus {
     }
 }
 
+/// Snake-case discriminator string for the event, matching the wire
+/// `event` field. Lifted out of the `publish` hot path so the debug
+/// log stays a one-liner. Kept in sync with the `#[serde(tag =
+/// "event", rename_all = "snake_case")]` shape in
+/// `MessageBusEvent` — new variants get a new arm here to render
+/// nicely in the trace log; adding one that lands in the default is
+/// harmless (still readable), just less specific.
+fn event_kind(event: &MessageBusEvent) -> &'static str {
+    match event {
+        MessageBusEvent::FileCreated { .. } => "file_created",
+        MessageBusEvent::FileRenamed { .. } => "file_renamed",
+        MessageBusEvent::FileMoved { .. } => "file_moved",
+        MessageBusEvent::FileDeleted { .. } => "file_deleted",
+        MessageBusEvent::FolderCreated { .. } => "folder_created",
+        MessageBusEvent::FolderRenamed { .. } => "folder_renamed",
+        MessageBusEvent::FolderMoved { .. } => "folder_moved",
+        MessageBusEvent::FolderDeleted { .. } => "folder_deleted",
+        MessageBusEvent::AuthzChanged { .. } => "authz_changed",
+    }
+}
+
 // ════════════════════════════════════════════════════════════════════════════
 // Tests
 // ════════════════════════════════════════════════════════════════════════════

src/infrastructure/services/mod.rs

@@ -52,6 +52,7 @@ pub mod pg_acl_engine;
 pub mod plugins;
 pub mod recent_recording_hook;
 pub mod retry_blob_backend;
+pub mod rt_ticket_store;
 pub mod s3_blob_backend;
 pub mod satellites_consistency_service;
 pub mod search_index;

src/infrastructure/services/rt_ticket_store.rs

@@ -0,0 +1,229 @@
+//! Short-lived tickets for authenticating a WebSocket upgrade.
+//!
+//! # Problem
+//!
+//! A DPoP-bound session must carry a fresh `DPoP:` header on every
+//! request. `new WebSocket(url)` in browsers cannot set arbitrary
+//! headers — only `Sec-WebSocket-Protocol` — so the upgrade GET
+//! arrives without a DPoP proof and `require_dpop_layer` refuses with
+//! 401 `proof_missing_on_bound_session`. See
+//! `docs/plan/message-bus.md § F`.
+//!
+//! # Solution
+//!
+//! Ticket exchange. The FE first `POST /api/rt/ticket` — a normal
+//! HTTP request, so `apiFetch` attaches the DPoP proof and every other
+//! middleware runs. The server mints an opaque one-shot ticket, tied
+//! to the caller_id and a 30 s expiry. The FE then opens the WS with
+//! `Sec-WebSocket-Protocol: oxi.ticket.<uuid>`; the WS handler
+//! redeems the ticket via this store to recover the caller_id, then
+//! runs the session with zero auth-middleware involvement.
+//!
+//! # Invariants
+//!
+//! - **Single-use** — `redeem` removes the entry atomically, so a
+//!   captured ticket can be replayed at most once (the race is decided
+//!   by the first successful `remove`; every other caller gets `None`).
+//! - **Short-lived** — 30 s TTL. A captured ticket that isn't burned
+//!   inside that window is inert.
+//! - **Opaque** — the token carries no user identity itself. All the
+//!   auth data lives in the store keyed by the token. Losing the store
+//!   invalidates every issued ticket; that's the correct failure mode.
+//! - **In-process** — one store per process. Multi-instance
+//!   deployments will need a shared backend (Redis, PG); calling it
+//!   out here so the seam is visible when the day comes.
+
+use std::sync::Arc;
+use std::time::{Duration, Instant};
+
+use dashmap::DashMap;
+use tokio::task::JoinHandle;
+use uuid::Uuid;
+
+/// TTL for a freshly-minted ticket. 30 s covers the round-trip from
+/// `/api/rt/ticket` response to `new WebSocket()` handshake on any
+/// realistic network — well under the shortest sensible clock skew
+/// budget, well above the 100–500 ms actually needed on localhost or
+/// LAN. Kept as a compile-time constant; if operators ever want to
+/// tune it, promote to config.
+pub const TICKET_TTL: Duration = Duration::from_secs(30);
+
+/// Reaper cadence. Every N seconds the store walks its entries and
+/// drops expired ones. Redemption also lazily short-circuits on
+/// expiry, so the reaper is a memory-hygiene backstop rather than a
+/// correctness gate — a ticket that expires and is never redeemed
+/// stays around for up to `TICKET_TTL + REAPER_INTERVAL` before its
+/// row is freed.
+pub const REAPER_INTERVAL: Duration = Duration::from_secs(60);
+
+/// Wire prefix identifying our tickets in `Sec-WebSocket-Protocol`.
+/// The full value on the wire is `oxi.ticket.<uuid>` — one
+/// subprotocol string, opaque to intermediaries. Kept short so
+/// stripping proxies don't hit an arbitrary length limit.
+pub const SUBPROTOCOL_PREFIX: &str = "oxi.ticket.";
+
+struct Entry {
+    caller_id: Uuid,
+    expires_at: Instant,
+}
+
+/// In-process ticket store. Cheap to construct; the reaper task is
+/// spawned by DI when the store is wired.
+pub struct RtTicketStore {
+    entries: DashMap<Uuid, Entry>,
+}
+
+impl RtTicketStore {
+    pub fn new() -> Arc<Self> {
+        Arc::new(Self {
+            entries: DashMap::new(),
+        })
+    }
+
+    /// Issue a fresh ticket for `caller_id`. Returns the opaque token
+    /// (a UUIDv4 string) — the FE puts this on the wire as
+    /// `Sec-WebSocket-Protocol: oxi.ticket.<uuid>`.
+    ///
+    /// Ticket IDs are v4 (random) — 122 bits of entropy, well above
+    /// the "unguessable-token" bar even without server-side rate
+    /// limiting. A serial or timestamped id would leak issue-order
+    /// signal to anyone with a wire tap.
+    pub fn issue(&self, caller_id: Uuid) -> Uuid {
+        let ticket = Uuid::new_v4();
+        self.entries.insert(
+            ticket,
+            Entry {
+                caller_id,
+                expires_at: Instant::now() + TICKET_TTL,
+            },
+        );
+        ticket
+    }
+
+    /// Redeem `ticket` if it exists AND has not expired. Removes the
+    /// entry regardless of outcome — a valid ticket returns the
+    /// caller_id, an expired ticket is silently freed and returns
+    /// `None`. Single-use invariant holds by construction: only one
+    /// caller wins the `remove`, everyone else sees `None`.
+    pub fn redeem(&self, ticket: Uuid) -> Option<Uuid> {
+        let (_, entry) = self.entries.remove(&ticket)?;
+        if entry.expires_at < Instant::now() {
+            return None;
+        }
+        Some(entry.caller_id)
+    }
+
+    /// Background reaper. Walks the map on the configured cadence and
+    /// removes expired entries. Runs until the returned handle is
+    /// dropped or `cancel` is notified (per the standard shutdown
+    /// contract used across the crate).
+    pub fn spawn_reaper(self: Arc<Self>) -> JoinHandle<()> {
+        tokio::spawn(async move {
+            let mut ticker = tokio::time::interval(REAPER_INTERVAL);
+            // First tick fires immediately; skip it so the store has
+            // at least one TTL window's worth of entries before the
+            // first sweep.
+            ticker.tick().await;
+            loop {
+                ticker.tick().await;
+                let now = Instant::now();
+                self.entries.retain(|_, entry| entry.expires_at >= now);
+            }
+        })
+    }
+
+    /// Present count. Test-only. Not exposed to handlers — no
+    /// operational reason to peek at the queue depth from a request
+    /// path.
+    #[cfg(test)]
+    fn len(&self) -> usize {
+        self.entries.len()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn issue_then_redeem_returns_caller_id() {
+        let store = RtTicketStore::new();
+        let caller = Uuid::new_v4();
+        let ticket = store.issue(caller);
+        assert_eq!(store.redeem(ticket), Some(caller));
+    }
+
+    #[test]
+    fn redeem_is_single_use() {
+        let store = RtTicketStore::new();
+        let caller = Uuid::new_v4();
+        let ticket = store.issue(caller);
+        assert_eq!(store.redeem(ticket), Some(caller));
+        // Second redeem finds nothing — replay protection.
+        assert_eq!(store.redeem(ticket), None);
+    }
+
+    #[test]
+    fn redeem_unknown_returns_none() {
+        let store = RtTicketStore::new();
+        assert_eq!(store.redeem(Uuid::new_v4()), None);
+    }
+
+    #[test]
+    fn issued_ticket_is_present_in_store() {
+        let store = RtTicketStore::new();
+        let caller = Uuid::new_v4();
+        assert_eq!(store.len(), 0);
+        let _ticket = store.issue(caller);
+        assert_eq!(store.len(), 1);
+    }
+
+    #[test]
+    fn redeem_after_expiry_returns_none_and_frees_entry() {
+        // Use a synthetic entry with `expires_at` in the past so the
+        // test doesn't have to sleep 30 s.
+        let store = RtTicketStore::new();
+        let caller = Uuid::new_v4();
+        let ticket = Uuid::new_v4();
+        store.entries.insert(
+            ticket,
+            Entry {
+                caller_id: caller,
+                expires_at: Instant::now() - Duration::from_secs(1),
+            },
+        );
+        assert_eq!(store.len(), 1);
+        // Expired redeem returns None…
+        assert_eq!(store.redeem(ticket), None);
+        // …and the entry is gone.
+        assert_eq!(store.len(), 0);
+    }
+
+    #[test]
+    fn distinct_tickets_for_the_same_caller() {
+        // Two issues in a row must produce distinct token ids — the
+        // FE will issue one per WS reconnect, and a collision would
+        // mean the second issue clobbers the first's expiry map row.
+        let store = RtTicketStore::new();
+        let caller = Uuid::new_v4();
+        let t1 = store.issue(caller);
+        let t2 = store.issue(caller);
+        assert_ne!(t1, t2);
+    }
+
+    // Wall-clock testing of the reaper's timer needs the tokio
+    // `test-util` feature; not enabled crate-wide. The reaper body is
+    // a straight `entries.retain(|_, e| e.expires_at >= now)` and the
+    // redemption path already lazily short-circuits on expiry (see
+    // `redeem_after_expiry_returns_none_and_frees_entry`), which
+    // exercises the same expiry decision without waiting on a real
+    // clock.
+
+    #[test]
+    fn is_send_sync_arc_shareable() {
+        // Mirrors the actual usage in `AppState` — an
+        // `Arc<RtTicketStore>` shared across the axum-served tasks.
+        fn assert_send_sync<T: Send + Sync>() {}
+        assert_send_sync::<Arc<RtTicketStore>>();
+    }
+}

src/interfaces/api/handlers/mod.rs

@@ -23,6 +23,7 @@ pub mod opaque_auth_handler;
 pub mod people_handler;
 pub mod photos_handler;
 pub mod recent_handler;
+pub mod rt_ticket_handler;
 pub mod rt_ws;
 pub mod search_handler;
 pub mod share_handler;

src/interfaces/api/handlers/rt_ticket_handler.rs

@@ -0,0 +1,80 @@
+//! Ticket issuance for browser WebSocket authentication.
+//!
+//! `POST /api/rt/ticket` — issues a one-shot 30 s ticket for the
+//! authenticated caller. Runs under the full `/api/*` middleware
+//! stack (auth + DPoP), so the caller proves possession of the
+//! session AND (when the session is DPoP-bound) the DPoP key on the
+//! same request. The ticket then substitutes for that proof on the
+//! next WS upgrade.
+//!
+//! See `src/infrastructure/services/rt_ticket_store.rs` for the
+//! store semantics and `docs/plan/message-bus.md § F` for the
+//! architectural context.
+
+use std::sync::Arc;
+
+use axum::{Json, extract::State};
+use serde::Serialize;
+
+use crate::common::di::AppState;
+use crate::infrastructure::services::rt_ticket_store::{SUBPROTOCOL_PREFIX, TICKET_TTL};
+use crate::interfaces::middleware::auth::CurrentUserId;
+
+/// Response body for `POST /api/rt/ticket`. Deliberately minimal —
+/// callers only need the token string; the TTL is echoed so the FE
+/// doesn't hard-code the 30 s constant on its side.
+#[derive(Debug, Serialize, utoipa::ToSchema)]
+pub struct RtTicketResponse {
+    /// Opaque single-use token. Present in the WS upgrade as
+    /// `Sec-WebSocket-Protocol: oxi.ticket.<ticket>` (the prefix is
+    /// baked in by both sides — see [`SUBPROTOCOL_PREFIX`]).
+    pub ticket: String,
+
+    /// Seconds until this ticket expires server-side. Consumers should
+    /// open the WS immediately; a 30 s bound leaves generous headroom
+    /// for the handshake without letting a captured ticket live long.
+    pub expires_in_seconds: u64,
+
+    /// Full `Sec-WebSocket-Protocol` value the client MUST pass on the
+    /// upgrade. Included pre-assembled so a FE bug can't emit the
+    /// wrong prefix and blow the handshake in a way that looks like a
+    /// server-side denial.
+    pub subprotocol: String,
+}
+
+/// Issue a fresh ticket for the authenticated caller. Idempotent from
+/// the caller's perspective — each call mints a new token — but
+/// each ticket is single-use once redeemed by the WS handler.
+///
+/// No rate limiting today: even a mildly abusive client would just
+/// fill the ticket store with entries that reap in 30 s. If ever
+/// necessary, add a per-caller_id token bucket alongside the auth
+/// middleware limits.
+#[utoipa::path(
+    post,
+    path = "/api/rt/ticket",
+    tag = "message-bus",
+    responses(
+        (status = 200, description = "Ticket issued", body = RtTicketResponse),
+        (status = 401, description = "Unauthenticated"),
+    ),
+    security(("bearerAuth" = []))
+)]
+pub async fn issue_rt_ticket(
+    CurrentUserId(caller_id): CurrentUserId,
+    State(state): State<Arc<AppState>>,
+) -> Json<RtTicketResponse> {
+    let ticket = state.rt_ticket_store.issue(caller_id);
+    let ticket_str = ticket.to_string();
+    tracing::debug!(
+        target: "oxicloud::message_bus",
+        event = "message_bus.ticket_issued",
+        caller_id = %caller_id,
+        "🎫 rt.ticket issued",
+    );
+    Json(RtTicketResponse {
+        subprotocol: format!("{SUBPROTOCOL_PREFIX}{ticket_str}"),
+        ticket: ticket_str,
+        expires_in_seconds: TICKET_TTL.as_secs(),
+    })
+}

src/interfaces/api/handlers/rt_ws.rs

@@ -18,13 +18,28 @@
 //!
 //! # Auth
 //!
-//! Route sits under `protected_api` (see `src/interfaces/api/routes.rs`)
+//! Route is mounted at `/api/rt/ws` OUTSIDE the standard
-//! so `auth_middleware` runs first. Cookie AND `Authorization: Bearer`
+//! `auth_middleware` + `require_dpop_layer` stack — a browser can't
-//! paths both produce a `CurrentUserId` extension the handler extracts.
+//! attach a `DPoP:` header to `new WebSocket()` (RFC 6455 gives us
-//! Browser-side subprotocol bearer (`Sec-WebSocket-Protocol:
+//! only `Sec-WebSocket-Protocol`), and the standard chain would 401
-//! authorization.bearer.<jwt>`) is a Phase-A follow-up — the MVP relies
+//! on every DPoP-bound session. This handler self-authenticates
-//! on the Authorization header, which programmatic clients (the
+//! from two accepted sources:
-//! `rt-hurl-helper` smoke test) set directly.
+//!
+//! 1. **Ticket subprotocol** (`Sec-WebSocket-Protocol:
+//!    oxi.ticket.<uuid>`) — the primary path for browser clients.
+//!    The FE first `POST /api/rt/ticket` under the full middleware
+//!    chain (auth + DPoP proofed), receives an opaque one-shot
+//!    token, and passes it here. Verified by redeeming through
+//!    [`AppState::rt_ticket_store`]. See
+//!    `docs/plan/message-bus.md § F`.
+//! 2. **Bearer token** (`Authorization: Bearer <jwt>`) — the
+//!    programmatic-client path used by `rt-hurl-helper` in api-test.
+//!    Verified against `AuthServices::token_service`. DPoP-bound
+//!    tokens are rejected on this path to preserve the substrate's
+//!    proof-of-possession invariant.
+//!
+//! Neither → 401. Order matters: ticket first (short-lived, tied to
+//! a proofed HTTP round-trip), bearer second.
 //!
 //! # Limits
 //!
@@ -40,7 +55,8 @@ use std::time::Duration;
 use axum::body::Bytes;
 use axum::extract::State;
 use axum::extract::ws::{Message, WebSocket, WebSocketUpgrade};
-use axum::response::Response;
+use axum::http::{HeaderMap, StatusCode};
+use axum::response::{IntoResponse, Response};
 use futures::StreamExt;
 use serde::{Deserialize, Serialize};
 use serde_json::Value;
@@ -49,13 +65,14 @@ use tokio::task::JoinHandle;
 use tokio::time::MissedTickBehavior;
 use uuid::Uuid;
 
+use crate::application::ports::auth_ports::TokenServicePort;
 use crate::application::ports::authorization_ports::AuthorizationEngine;
 use crate::application::ports::message_bus_ports::{
     AuthzCheck, BusResource, MessageBus, MessageBusEvent, ParseTopicErr, Topic, error_code,
 };
 use crate::common::di::AppState;
 use crate::domain::services::authorization::{Permission, Resource, Subject};
-use crate::interfaces::middleware::auth::CurrentUserId;
+use crate::infrastructure::services::rt_ticket_store::SUBPROTOCOL_PREFIX;
 
 /// Max simultaneous subscriptions on a single WS session. Beyond this the
 /// server responds `-32005 sub_limit` and the client is expected to
@@ -151,20 +168,112 @@ struct RpcNotification<'a> {
 // Handler entrypoint
 // ════════════════════════════════════════════════════════════════════════════
 
-/// `GET /api/rt/ws` — WS upgrade handler. Sits under `protected_api` so
+/// `GET /api/rt/ws` — WS upgrade handler. Mounted outside the standard
-/// [`CurrentUserId`] resolves against a valid session before we reach
+/// `/api/*` middleware stack; self-authenticates via ticket
-/// `on_upgrade`.
+/// subprotocol OR bearer token (see the module doc).
 ///
-/// Returns whatever `WebSocketUpgrade::on_upgrade` produces (an HTTP 101
+/// Returns 101 Switching Protocols on success; 401 with an audit
-/// Switching Protocols with the WebSocket handshake headers).
+/// entry on any auth failure. The response is deliberately terse —
+/// browsers surface the status code via the `close` event's code
+/// field (1006 on a rejected upgrade), so a longer body wouldn't
+/// reach the FE anyway.
 pub async fn rt_ws_handler(
     ws: WebSocketUpgrade,
-    CurrentUserId(caller_id): CurrentUserId,
     State(state): State<Arc<AppState>>,
+    headers: HeaderMap,
 ) -> Response {
+    let auth = match authenticate_upgrade(&headers, &state).await {
+        Ok(auth) => auth,
+        Err(reason) => {
+            tracing::info!(
+                target: "audit",
+                event = "message_bus.upgrade_rejected",
+                reason = %reason,
+                "👮🏻‍♂️ WS upgrade rejected",
+            );
+            return (StatusCode::UNAUTHORIZED, "ws_auth_failed").into_response();
+        }
+    };
+    let caller_id = auth.caller_id;
+    // If the caller reached us via the ticket path, echo the exact
+    // subprotocol they sent back on the 101 response — RFC 6455 §4.2.2
+    // requires this or the client fails the connection.
+    let ws = match auth.accepted_subprotocol {
+        Some(sub) => ws.protocols([sub]),
+        None => ws,
+    };
     ws.on_upgrade(move |socket| handle_session(socket, caller_id, state))
 }
 
+/// Successful upgrade credentials — the resolved caller and (when the
+/// ticket path was used) the subprotocol to echo on the 101 response.
+struct UpgradeAuth {
+    caller_id: Uuid,
+    accepted_subprotocol: Option<String>,
+}
+
+/// Extract `Sec-WebSocket-Protocol` and match a ticket subprotocol
+/// first; fall back to `Authorization: Bearer`. Returns a stable
+/// `reason` key on failure so the audit log stays filterable.
+async fn authenticate_upgrade(
+    headers: &HeaderMap,
+    state: &Arc<AppState>,
+) -> Result<UpgradeAuth, &'static str> {
+    if let Some(ticket_sub) = extract_ticket_subprotocol(headers) {
+        // Redeem parses the UUID; a malformed subprotocol is a
+        // structural failure ("bad_ticket_format"), an unknown-or-
+        // expired UUID is a redemption failure ("ticket_invalid").
+        let Some(ticket_str) = ticket_sub.strip_prefix(SUBPROTOCOL_PREFIX) else {
+            return Err("bad_ticket_format");
+        };
+        let Ok(ticket_uuid) = Uuid::parse_str(ticket_str) else {
+            return Err("bad_ticket_uuid");
+        };
+        let Some(caller_id) = state.rt_ticket_store.redeem(ticket_uuid) else {
+            return Err("ticket_invalid");
+        };
+        return Ok(UpgradeAuth {
+            caller_id,
+            accepted_subprotocol: Some(ticket_sub),
+        });
+    }
+    if let Some(bearer) = extract_bearer(headers) {
+        let Some(auth_service) = state.auth_service.as_ref() else {
+            return Err("auth_service_unavailable");
+        };
+        let claims = auth_service
+            .token_service
+            .validate_token(bearer)
+            .map_err(|_| "bearer_invalid")?;
+        if claims.sub_id.is_nil() {
+            return Err("bearer_bad_subject");
+        }
+        return Ok(UpgradeAuth {
+            caller_id: claims.sub_id,
+            accepted_subprotocol: None,
+        });
+    }
+    Err("no_credentials")
+}
+
+/// Find the first subprotocol value that looks like a ticket. Browsers
+/// send `Sec-WebSocket-Protocol` as a comma-separated list per RFC 6455.
+fn extract_ticket_subprotocol(headers: &HeaderMap) -> Option<String> {
+    let raw = headers.get("sec-websocket-protocol")?.to_str().ok()?;
+    raw.split(',')
+        .map(str::trim)
+        .find(|s| s.starts_with(SUBPROTOCOL_PREFIX))
+        .map(|s| s.to_string())
+}
+
+/// Extract `Authorization: Bearer <token>` if present. Returns the raw
+/// token string (never empty).
+fn extract_bearer(headers: &HeaderMap) -> Option<&str> {
+    let value = headers.get("authorization")?.to_str().ok()?;
+    let token = value.strip_prefix("Bearer ")?.trim();
+    (!token.is_empty()).then_some(token)
+}
+
 // ════════════════════════════════════════════════════════════════════════════
 // Session loop
 // ════════════════════════════════════════════════════════════════════════════

src/interfaces/api/routes.rs

@@ -674,16 +674,24 @@ pub fn create_api_routes(app_state: &Arc<AppState>) -> Router<Arc<AppState>> {
         .with_state(app_state.clone());
     router = router.nest("/users", users_router);
 
-    // Message bus WebSocket. Auth (session cookie or bearer JWT) via
+    // Message bus — ticket issuance (`POST /api/rt/ticket`). Stays in
-    // the same `auth_middleware` the rest of `/api/*` gets; the handler
+    // the protected router (auth + DPoP), so the caller proves session
-    // extracts `CurrentUserId` from the extension the middleware
+    // + DPoP-key possession before a ticket is minted. See
-    // installs. See `docs/plan/message-bus.md` and the module doc on
+    // `handlers/rt_ticket_handler.rs` and `docs/plan/message-bus.md § F`.
-    // `rt_ws` for the JSON-RPC 2.0 wire.
     router = router.route(
-        "/rt/ws",
+        "/rt/ticket",
-        get(crate::interfaces::api::handlers::rt_ws::rt_ws_handler).with_state(app_state.clone()),
+        post(crate::interfaces::api::handlers::rt_ticket_handler::issue_rt_ticket)
+            .with_state(app_state.clone()),
     );
 
+    // The WS upgrade (`GET /api/rt/ws`) is registered OUTSIDE the
+    // protected-api middleware stack — a browser cannot attach a
+    // `DPoP:` header to `new WebSocket()`, so the standard stack
+    // 401s on every DPoP-bound session. See the `rt_ws` module doc
+    // for the self-auth logic (ticket subprotocol or bearer token).
+    // Registration happens in `main.rs` where the outer router owns
+    // the middleware layering.
+
     // Collector for any unknown `/api/*` path. Without this, an
     // unmatched API URL falls through Axum's matcher to the
     // ServeDir fallback and is logged under `http::web` — wrong

src/main.rs

@@ -1042,6 +1042,22 @@ async fn run() -> Result<(), Box<dyn std::error::Error>> {
             )
             // Public API routes (share access, i18n) — no auth required
             .nest("/api", public_api_routes.layer(access_log!("http::api")))
+            // Message-bus WebSocket. Registered OUTSIDE `protected_api`
+            // because a browser cannot attach a `DPoP:` header to
+            // `new WebSocket()` (RFC 6455 only lets us set
+            // `Sec-WebSocket-Protocol`), so the standard auth + DPoP
+            // stack would 401 every DPoP-bound session. The handler
+            // self-authenticates from either a ticket subprotocol
+            // (minted by `POST /api/rt/ticket` under the full chain)
+            // or a bearer token (`rt-hurl-helper` test path).
+            // See `handlers/rt_ws.rs` module doc and
+            // `docs/plan/message-bus.md § F`.
+            .route(
+                "/api/rt/ws",
+                axum::routing::get(oxicloud::interfaces::api::handlers::rt_ws::rt_ws_handler)
+                    .with_state(app_state.clone())
+                    .layer(access_log!("http::api")),
+            )
             // All other API routes are protected by auth middleware
             .nest("/api", protected_api.layer(access_log!("http::api")))
             // RFC 6764 well-known discovery (public, no auth — just redirects)

tests/api/rt_bus_check.sh

@@ -42,6 +42,16 @@
 #                                 shape as an unknown topic — anti-enumeration).
 #                                 Guards the strict-privacy Class-2 AuthZ gate:
 #                                 no admin bypass, direct UUID equality only.
+#   S10 Ticket happy path       — user1 POSTs `/api/rt/ticket`, receives a
+#                                 short-lived opaque token, opens the WS with
+#                                 `Sec-WebSocket-Protocol: oxi.ticket.<uuid>`
+#                                 and successfully subscribes + delivers an
+#                                 event. Exercises the ticket path — the only
+#                                 path a DPoP-required browser can take.
+#   S11 Ticket single-use       — a ticket redeemed once cannot be redeemed
+#                                 again. Guards replay: a captured token
+#                                 outside its 30 s TTL, or one already
+#                                 consumed, MUST fail the upgrade with 401.
 #
 # Exit non-zero on any failure — run.sh treats that as a suite failure.
 # ─────────────────────────────────────────────────────────────────────────────
@@ -69,14 +79,19 @@ esac
 log()  { printf '\033[1;36m[rt_bus_check]\033[0m %s\n' "$*"; }
 die()  { printf '\033[1;31m[rt_bus_check FAIL]\033[0m %s\n' "$*" >&2; exit 1; }
 
-# ── Build the helper on demand (matches opaque/dpop helper convention) ──────
+# ── Rebuild the helper every run ────────────────────────────────────────────
-if [[ ! -x "$HELPER_BIN" ]]; then
+# Deliberately unconditional — the previous `[[ ! -x $HELPER_BIN ]]` guard
-  log "Building rt-hurl-helper ($BUILD_TARGET)..."
+# silently reused a stale binary whenever the helper's source changed
-  case "$BUILD_TARGET" in
+# without touching the caller shell script, producing "unknown flag"
-    debug)   (cd "$REPO_ROOT" && cargo build           --features test_utils --bin rt-hurl-helper 2>&1 | tail -n 20) || die "rt-hurl-helper build failed" ;;
+# exits that looked like test bugs (see the S10/S11 --ticket rollout).
-    release) (cd "$REPO_ROOT" && cargo build --release --features test_utils --bin rt-hurl-helper 2>&1 | tail -n 20) || die "rt-hurl-helper build failed" ;;
+# Cargo incremental short-circuits in ~50 ms when nothing changed, so
-  esac
+# the cost of the always-build is negligible; the cost of a stale binary
-fi
+# is a wild-goose chase.
+log "Building rt-hurl-helper ($BUILD_TARGET)..."
+case "$BUILD_TARGET" in
+  debug)   (cd "$REPO_ROOT" && cargo build           --features test_utils --bin rt-hurl-helper 2>&1 | tail -n 20) || die "rt-hurl-helper build failed" ;;
+  release) (cd "$REPO_ROOT" && cargo build --release --features test_utils --bin rt-hurl-helper 2>&1 | tail -n 20) || die "rt-hurl-helper build failed" ;;
+esac
 
 # ── curl wrappers ───────────────────────────────────────────────────────────
 c_post() {
@@ -93,6 +108,22 @@ c_get() {
     "$url"
 }
 
+# Block until the helper writes `--ready-file <path>` (touched the
+# moment every requested subscribe is ack'd) or `$timeout` seconds
+# elapse. Replaces the older `sleep 0.4` heuristic that flaked on
+# cold-cache runs where the helper's fork/tokio-init/connect chain
+# crossed 400 ms and the shell's mkfile_in publish arrived at an
+# empty topic. See `Args::ready_file` in rt-hurl-helper.rs.
+wait_ready() {
+  local path="$1" timeout="${2:-5}"
+  local waited=0
+  while [[ ! -f "$path" && "$waited" -lt "$((timeout * 20))" ]]; do
+    sleep 0.05
+    waited=$((waited + 1))
+  done
+  [[ -f "$path" ]] || die "wait_ready: $path never appeared within ${timeout}s (subscribe likely never ack'd)"
+}
+
 # ── Setup: register fresh users; the test.env admin may be OPAQUE-
 # migrated and the legacy password-login path refuses those accounts,
 # so we don't use it at all — same pattern as `dedup_admin_gate.hurl`
@@ -178,17 +209,21 @@ mkfile_in() {
 # ── Scenario 1 — Positive delivery ──────────────────────────────────────────
 log "S1: subscribe to folder A, upload into A, expect one file_created event."
 out_s1="$(mktemp -t rtbus_s1.XXXXXX)"
+ready_s1="$(mktemp -t rtbus_s1_ready.XXXXXX)"
+rm -f "$ready_s1"  # mktemp creates it; ready-file semantics need "appears when subscribed"
 "$HELPER_BIN" subscribe-and-collect \
   --url "$ws_url" \
   --token "$user1_token" \
   --subscribe "folder:$folder_a" \
   --expect-events 1 \
   --timeout 5s \
+  --ready-file "$ready_s1" \
   --output "$out_s1" &
 helper_pid=$!
-# Give the ack a moment to install so the upload's post-commit publish
+# Block on the helper's ready-file signal, not a wall-clock sleep —
-# lands on a live receiver, not an orphaned map entry.
+# see wait_ready doc. Closes the "publish before subscribe installed"
-sleep 0.4
+# race that flaked S1 on cold-cache runs.
+wait_ready "$ready_s1"
 mkfile_in "$folder_a" "s1.txt" "$user1_token"
 if ! wait "$helper_pid"; then
   cat "$out_s1" >&2 || true
@@ -206,15 +241,17 @@ log "S1 OK"
 # ── Scenario 2 — Topic isolation ────────────────────────────────────────────
 log "S2: subscribe to folder A, upload into B (must be silent) and A (triggers exit)."
 out_s2="$(mktemp -t rtbus_s2.XXXXXX)"
+ready_s2="$(mktemp -t rtbus_s2_ready.XXXXXX)"; rm -f "$ready_s2"
 "$HELPER_BIN" subscribe-and-collect \
   --url "$ws_url" \
   --token "$user1_token" \
   --subscribe "folder:$folder_a" \
   --expect-events 1 \
   --timeout 5s \
+  --ready-file "$ready_s2" \
   --output "$out_s2" &
 helper_pid=$!
-sleep 0.4
+wait_ready "$ready_s2"
 # B first — should be dropped for the A subscriber.
 mkfile_in "$folder_b" "s2_in_B.txt" "$user1_token"
 # Small settle so if isolation is BROKEN, the B event has time to arrive
@@ -271,14 +308,20 @@ log "S4 OK"
 # (b) trips (event never arrives after idle).
 log "S5: server-initiated keepalive fires on idle; session still delivers."
 out_s5="$(mktemp -t rtbus_s5.XXXXXX)"
+ready_s5="$(mktemp -t rtbus_s5_ready.XXXXXX)"; rm -f "$ready_s5"
 "$HELPER_BIN" subscribe-and-collect \
   --url "$ws_url" \
   --token "$user1_token" \
   --subscribe "folder:$folder_a" \
   --expect-events 1 \
   --timeout 6s \
+  --ready-file "$ready_s5" \
   --output "$out_s5" &
 helper_pid=$!
+# Wait for the subscribe to install BEFORE starting the idle window —
+# otherwise slow helper startup eats into the 3 s and we observe
+# fewer pings than the assertion below tolerates.
+wait_ready "$ready_s5"
 # 3 s of pure idle — with 1 s keepalive on the server, that's ~3 Pings.
 sleep 3
 mkfile_in "$folder_a" "s5.txt" "$user1_token"
@@ -320,15 +363,17 @@ s6_file_id=$(printf '%s' "$s6_upload" | jq -r '.id')
   || die "S6: pre-upload failed: $s6_upload"
 
 out_s6="$(mktemp -t rtbus_s6.XXXXXX)"
+ready_s6="$(mktemp -t rtbus_s6_ready.XXXXXX)"; rm -f "$ready_s6"
 "$HELPER_BIN" subscribe-and-collect \
   --url "$ws_url" \
   --token "$user1_token" \
   --subscribe "folder:$folder_a" \
   --expect-events 1 \
   --timeout 5s \
+  --ready-file "$ready_s6" \
   --output "$out_s6" &
 helper_pid=$!
-sleep 0.4
+wait_ready "$ready_s6"
 # `DELETE /api/files/{id}` routes to `delete_and_cleanup_with_perms` —
 # the trash-first path. Publish fires on BOTH the trash and the
 # permanent-delete branch, so this covers whichever the test hits.
@@ -369,6 +414,7 @@ s7_file_id=$(printf '%s' "$s7_upload" | jq -r '.id')
   || die "S7: pre-upload failed: $s7_upload"
 
 out_s7="$(mktemp -t rtbus_s7.XXXXXX)"
+ready_s7="$(mktemp -t rtbus_s7_ready.XXXXXX)"; rm -f "$ready_s7"
 "$HELPER_BIN" subscribe-and-collect \
   --url "$ws_url" \
   --token "$user1_token" \
@@ -376,9 +422,10 @@ out_s7="$(mktemp -t rtbus_s7.XXXXXX)"
   --subscribe "folder:$folder_b" \
   --expect-events 2 \
   --timeout 5s \
+  --ready-file "$ready_s7" \
   --output "$out_s7" &
 helper_pid=$!
-sleep 0.4
+wait_ready "$ready_s7"
 # `PUT /api/files/{id}/move` — MoveFilePayload = { folder_id: <dest> }.
 curl -sS -X PUT \
   -H "Authorization: Bearer $user1_token" \
@@ -447,6 +494,7 @@ grant_b_id=$(printf '%s' "$grant_b" | jq -r '.grants[0].id')
 # 8.2 user2 subscribes to BOTH folder topics; --expect-events 1 exits
 # when the post-revoke upload lands on the SURVIVING sub.
 out_s8="$(mktemp -t rtbus_s8.XXXXXX)"
+ready_s8="$(mktemp -t rtbus_s8_ready.XXXXXX)"; rm -f "$ready_s8"
 "$HELPER_BIN" subscribe-and-collect \
   --url "$ws_url" \
   --token "$user2_token" \
@@ -454,9 +502,10 @@ out_s8="$(mktemp -t rtbus_s8.XXXXXX)"
   --subscribe "folder:$folder_b" \
   --expect-events 1 \
   --timeout 6s \
+  --ready-file "$ready_s8" \
   --output "$out_s8" &
 helper_pid=$!
-sleep 0.4  # let both subscribes install
+wait_ready "$ready_s8"  # both subscribes installed before we revoke/upload
 
 # 8.3 user1 revokes only the folder-A grant.
 curl -sS -X DELETE \
@@ -531,4 +580,65 @@ if ! "$HELPER_BIN" expect-denied \
 fi
 log "S9 OK"
 
-log "All nine message-bus scenarios passed."
+# ── Scenario 10 — Ticket happy path ─────────────────────────────────────────
+# The browser flow: POST /api/rt/ticket under the full middleware stack
+# (auth + DPoP proofed), then open the WS with `oxi.ticket.<uuid>` in
+# Sec-WebSocket-Protocol. Same delivery guarantees as the bearer path.
+# `curl` mints the ticket; `rt-hurl-helper --ticket` redeems it on the
+# upgrade.
+log "S10: issue rt ticket, open WS with subprotocol, subscribe + deliver."
+# c_post takes the raw JWT as its second arg (not the full
+# `Authorization:` line); it assembles the header itself.
+tkt_resp=$(c_post "$base_url/api/rt/ticket" "$user1_token" "")
+ticket=$(printf '%s' "$tkt_resp" | jq -r '.ticket')
+[[ -n "$ticket" && "$ticket" != "null" ]] \
+  || die "S10: no ticket in POST /api/rt/ticket response: $tkt_resp"
+out_s10="$(mktemp -t rtbus_s10.XXXXXX)"
+ready_s10="$(mktemp -t rtbus_s10_ready.XXXXXX)"; rm -f "$ready_s10"
+"$HELPER_BIN" subscribe-and-collect \
+  --url "$ws_url" \
+  --ticket "$ticket" \
+  --subscribe "folder:$folder_a" \
+  --expect-events 1 \
+  --timeout 3s \
+  --ready-file "$ready_s10" \
+  --output "$out_s10" &
+helper_pid=$!
+wait_ready "$ready_s10"
+mkfile_in "$folder_a" "s10.txt" "$user1_token"
+if ! wait "$helper_pid"; then
+  cat "$out_s10" >&2 || true
+  die "S10: helper did not observe event on ticket-authenticated WS"
+fi
+[[ "$(jq -r '.events | length' "$out_s10")" == "1" ]] \
+  || { cat "$out_s10"; die "S10: expected 1 event, got $(jq -r '.events | length' "$out_s10")"; }
+log "S10 OK"
+
+# ── Scenario 11 — Ticket single-use ─────────────────────────────────────────
+# S10 already redeemed the ticket. A second connection with the SAME
+# token MUST be refused at the upgrade with 401 (`ticket_invalid`
+# audit reason). Proves replay protection — the store removes entries
+# on first successful redeem, even if the caller reconnects before
+# the 30 s TTL would have expired anyway.
+#
+# The helper distinguishes "expectation failure" (exit 1 — WS opened
+# and then something was off) from "protocol/connect failure" (exit 2
+# — connect_ws itself refused). Ticket rejection lands in the second
+# bucket, so we assert on exit code 2. Bash's `!` inverter treats any
+# non-zero as success, so we capture the exact code.
+log "S11: reuse the redeemed ticket, expect upgrade rejected."
+set +e
+"$HELPER_BIN" subscribe-and-collect \
+  --url "$ws_url" \
+  --ticket "$ticket" \
+  --subscribe "folder:$folder_a" \
+  --expect-events 1 \
+  --timeout 2s \
+  --output /dev/null
+reuse_exit=$?
+set -e
+[[ "$reuse_exit" -eq 2 ]] \
+  || die "S11: expected exit 2 (connect refused), got $reuse_exit"
+log "S11 OK"
+
+log "All eleven message-bus scenarios passed."