diff --git a/frontend/src/adapters/http/wsLiveClient.test.ts b/frontend/src/adapters/http/wsLiveClient.test.ts
index 7a4afdd..3eebad1 100644
--- a/frontend/src/adapters/http/wsLiveClient.test.ts
+++ b/frontend/src/adapters/http/wsLiveClient.test.ts
@@ -46,6 +46,49 @@ function connectedClient(): { client: WsLiveClient; socket: FakeSocket } {
   return { client, socket };
 }
 
+/** Captures the URLs the client asks its socket factory to open. */
+function urlCapturingClient(token?: string): { client: WsLiveClient; urls: string[] } {
+  const urls: string[] = [];
+  const client = new WsLiveClient({
+    wsUrl: "wss://host",
+    token,
+    socketFactory: (url) => {
+      urls.push(url);
+      const socket = new FakeSocket();
+      queueMicrotask(() => socket.onopen?.());
+      return socket;
+    },
+  });
+  return { client, urls };
+}
+
+/**
+ * Regression (live validation, ticket #13): the client connected to `/ws/live`
+ * while the server's `WS_PATH` is `/api/ws`. An unknown path is not treated as an
+ * upgrade — it falls through to the SPA static fallback (`200 index.html`) — so
+ * the socket never opened and the UI sat behind a permanent reconnection banner.
+ * No test asserted the URL (every `socketFactory` ignored its argument), which is
+ * exactly how the mismatch shipped. These pin the path to the server contract.
+ */
+describe("WsLiveClient live socket URL matches the server WS_PATH", () => {
+  it("connects to {wsUrl}/api/ws", async () => {
+    const { client, urls } = urlCapturingClient();
+    await client.ensureConnected();
+
+    expect(urls).toEqual(["wss://host/api/ws"]);
+  });
+
+  it("keeps the /api/ws path when the dev/test token is used", async () => {
+    const { client, urls } = urlCapturingClient("dev tok/en");
+    await client.ensureConnected();
+
+    expect(urls).toHaveLength(1);
+    // Path is unchanged; the token is a URL-encoded query convenience.
+    expect(new URL(urls[0]).pathname).toBe("/api/ws");
+    expect(urls[0]).toBe("wss://host/api/ws?token=dev%20tok%2Fen");
+  });
+});
+
 describe("base64 helpers round-trip binary", () => {
   it("encodes and decodes arbitrary bytes", () => {
     const bytes = new Uint8Array([0, 13, 27, 255, 128, 10]);
diff --git a/frontend/src/adapters/http/wsLiveClient.ts b/frontend/src/adapters/http/wsLiveClient.ts
index ffa992b..585b4ab 100644
--- a/frontend/src/adapters/http/wsLiveClient.ts
+++ b/frontend/src/adapters/http/wsLiveClient.ts
@@ -2,7 +2,7 @@
  * WebSocket live client for the web transport — ticket #13, lot F3 (finalised
  * from the F1 skeleton).
  *
- * Owns a single WS connection to `{wsUrl}/ws/live` (authenticated by the session
+ * Owns a single WS connection to `{wsUrl}/api/ws` (authenticated by the session
  * cookie at the upgrade — same-origin, no URL secret) and multiplexes over it,
  * aligned on the **B5 frozen frame contract** (`crates/app-tauri/src/server.rs`):
  *
@@ -42,6 +42,16 @@ import {
   type StatusPayload,
 } from "./frames";
 
+/**
+ * Live WebSocket route — must match the server's `WS_PATH`
+ * (`crates/app-tauri/src/server.rs`). Any other path is not recognised as an
+ * upgrade and falls through to the SPA static fallback (a `200 index.html`), so
+ * the socket never opens and the client reconnects forever behind a permanent
+ * "connexion perdue" banner. Named once so the token/no-token branches below
+ * cannot drift apart.
+ */
+const WS_PATH = "/api/ws";
+
 /** Minimal WebSocket surface used here; injectable so tests pass a fake. */
 export interface WebSocketLike {
   send(data: string): void;
@@ -244,8 +254,8 @@ export class WsLiveClient {
       // Prod: the session cookie rides the upgrade (same-origin). The optional
       // token is a dev/test convenience only (never a prod secret in the URL).
       const url = this.token
-        ? `${this.wsUrl}/ws/live?token=${encodeURIComponent(this.token)}`
-        : `${this.wsUrl}/ws/live`;
+        ? `${this.wsUrl}${WS_PATH}?token=${encodeURIComponent(this.token)}`
+        : `${this.wsUrl}${WS_PATH}`;
       const socket = this.socketFactory(url);
       socket.onopen = () => {
         this.socket = socket;