fix(spa): normalize angular api client base URL for django endpoints

frontend/src/api/angular-client.ts

@@ -52,6 +52,14 @@ function normalizeCode(code: string): string {
   return code.trim().toUpperCase();
 }
 
+function normalizeBaseUrl(baseUrl: string): string {
+  return baseUrl.endsWith('/') ? baseUrl.slice(0, -1) : baseUrl;
+}
+
+function buildUrl(baseUrl: string, path: string): string {
+  return `${normalizeBaseUrl(baseUrl)}${path}`;
+}
+
 async function wrap<T>(call: () => Promise<T>): Promise<ApiResult<T>> {
   try {
     const data = await call();
@@ -67,17 +75,17 @@ async function wrap<T>(call: () => Promise<T>): Promise<ApiResult<T>> {
 
 export function createAngularApiClient(http: AngularHttpClientLike, baseUrl = ''): AngularApiClient {
   return {
-    health: () => wrap(() => http.get<HealthResponse>(`${baseUrl}/healthz`, { withCredentials: true })),
+    health: () => wrap(() => http.get<HealthResponse>(buildUrl(baseUrl, '/healthz'), { withCredentials: true })),
     getSession: (code: string) =>
       wrap(() =>
-        http.get<SessionDetailResponse>(`${baseUrl}/lobby/sessions/${encodeURIComponent(normalizeCode(code))}`, {
+        http.get<SessionDetailResponse>(buildUrl(baseUrl, `/lobby/sessions/${encodeURIComponent(normalizeCode(code))}`), {
           withCredentials: true
         })
       ),
     joinSession: (payload: JoinSessionRequest) =>
       wrap(() =>
         http.post<JoinSessionResponse>(
-          `${baseUrl}/lobby/sessions/join`,
+          buildUrl(baseUrl, '/lobby/sessions/join'),
           {
             code: normalizeCode(payload.code),
             nickname: payload.nickname.trim()
@@ -88,7 +96,7 @@ export function createAngularApiClient(http: AngularHttpClientLike, baseUrl = ''
     startRound: (code: string, payload: StartRoundRequest) =>
       wrap(() =>
         http.post<StartRoundResponse>(
-          `${baseUrl}/lobby/sessions/${encodeURIComponent(normalizeCode(code))}/rounds/start`,
+          buildUrl(baseUrl, `/lobby/sessions/${encodeURIComponent(normalizeCode(code))}/rounds/start`),
           payload,
           { withCredentials: true }
         )

frontend/tests/angular-api-client.test.ts

@@ -109,6 +109,86 @@ describe('createAngularApiClient', () => {
     );
   });
 
+  it('normalizes baseUrl with trailing slash to keep Django endpoint paths canonical', async () => {
+    const get = vi.fn<AngularHttpClientLike['get']>(async <T>(url: string) => {
+      if (url === '/api/healthz') {
+        return { ok: true, service: 'partyhub' } as T;
+      }
+      if (url === '/api/lobby/sessions/ABCD12') {
+        return {
+          session: { code: 'ABCD12', status: 'lobby', host_id: 1, current_round: 1, players_count: 2 },
+          players: [],
+          round_question: null,
+          phase_view_model: {
+            status: 'lobby',
+            round_number: 1,
+            players_count: 2,
+            constraints: {
+              min_players_to_start: 2,
+              max_players_mvp: 8,
+              min_players_reached: true,
+              max_players_allowed: true
+            },
+            host: {
+              can_start_round: true,
+              can_show_question: false,
+              can_mix_answers: false,
+              can_calculate_scores: false,
+              can_reveal_scoreboard: false,
+              can_start_next_round: false,
+              can_finish_game: false
+            },
+            player: {
+              can_join: true,
+              can_submit_lie: false,
+              can_submit_guess: false,
+              can_view_final_result: false
+            }
+          }
+        } as T;
+      }
+      throw { status: 404, error: { error: 'Not found' } };
+    });
+
+    const post = vi.fn<AngularHttpClientLike['post']>(async <T>(url: string) => {
+      if (url === '/api/lobby/sessions/join') {
+        return {
+          player: { id: 9, nickname: 'Maja', session_token: 'token-1', score: 0 },
+          session: { code: 'ABCD12', status: 'lobby' }
+        } as T;
+      }
+      if (url === '/api/lobby/sessions/ABCD12/rounds/start') {
+        return {
+          session: { code: 'ABCD12', status: 'lie', current_round: 1 },
+          round: { number: 1, category: { slug: 'history', name: 'History' } }
+        } as T;
+      }
+      throw { status: 404, error: { error: 'Not found' } };
+    });
+
+    const client = createAngularApiClient({ get, post } as AngularHttpClientLike, '/api/');
+
+    await client.health();
+    await client.getSession('abcd12');
+    await client.joinSession({ code: 'abcd12', nickname: 'Maja' });
+    await client.startRound('abcd12', { category_slug: 'history' });
+
+    expect(get).toHaveBeenNthCalledWith(1, '/api/healthz', { withCredentials: true });
+    expect(get).toHaveBeenNthCalledWith(2, '/api/lobby/sessions/ABCD12', { withCredentials: true });
+    expect(post).toHaveBeenNthCalledWith(
+      1,
+      '/api/lobby/sessions/join',
+      { code: 'ABCD12', nickname: 'Maja' },
+      { withCredentials: true }
+    );
+    expect(post).toHaveBeenNthCalledWith(
+      2,
+      '/api/lobby/sessions/ABCD12/rounds/start',
+      { category_slug: 'history' },
+      { withCredentials: true }
+    );
+  });
+
   it('maps HttpErrorResponse-style failures to ApiResult errors', async () => {
     const http = {
       get: vi.fn<AngularHttpClientLike['get']>(async () => {