fix(GRO-563): stabilize OAuth login - upgrade better-auth, fix service worker, add 503 handling

Phase 1 Better Auth stabilization:
- Upgrade better-auth to ^1.5.6 in apps/web (matches api)
- Switch OAuth state to cookie storage (BA v1.5+ requirement)
- Remove manual redirectURI overrides
- Exclude /api/auth/* from service worker caching
- Add 503 error handling when auth not configured
- Display login errors inline on login page
- Update infra submodule with social auth env vars

Closes GRO-563

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/api/src/index.ts

@@ -105,7 +105,13 @@ api.use("*", resolveStaffMiddleware);
 // Better-Auth handler — mounted as sub-app to handle all /api/auth/* routes
 // authMiddleware and resolveStaffMiddleware both skip /api/auth/ paths
 const authRouter = new Hono();
-authRouter.all("/*", (c) => getAuth().handler(c.req.raw));
+authRouter.all("/*", (c) => {
+  try {
+    return getAuth().handler(c.req.raw);
+  } catch {
+    return c.json({ error: "Authentication not configured" }, 503);
+  }
+});
 api.route("/auth", authRouter);
 
 // ── Role guards ────────────────────────────────────────────────────────────────

apps/api/src/lib/auth.ts

@@ -170,8 +170,6 @@ export async function initAuth(): Promise<void> {
     const hasGoogle = !!(process.env.GOOGLE_CLIENT_ID && process.env.GOOGLE_CLIENT_SECRET);
     const hasGitHub = !!(process.env.GITHUB_CLIENT_ID && process.env.GITHUB_CLIENT_SECRET);
 
-    const callbackBase = `${BETTER_AUTH_URL}/api/auth/callback`;
-
     // Build Better-Auth instance using resolved config
     authInstance = betterAuth({
       database: drizzleAdapter(db, {
@@ -179,6 +177,9 @@ export async function initAuth(): Promise<void> {
       }),
       secret: BETTER_AUTH_SECRET,
       baseURL: BETTER_AUTH_URL,
+      account: {
+        storeStateStrategy: "cookie" as const,
+      },
       plugins: [
         genericOAuth({
           config: [
@@ -205,14 +206,12 @@ export async function initAuth(): Promise<void> {
           google: {
             clientId: process.env.GOOGLE_CLIENT_ID!,
             clientSecret: process.env.GOOGLE_CLIENT_SECRET!,
-            redirectURI: `${callbackBase}/google`,
           },
         } : {}),
         ...(hasGitHub ? {
           github: {
             clientId: process.env.GITHUB_CLIENT_ID!,
             clientSecret: process.env.GITHUB_CLIENT_SECRET!,
-            redirectURI: `${callbackBase}/github`,
           },
         } : {}),
       },

apps/api/src/middleware/auth.ts

@@ -23,7 +23,6 @@ if (process.env.AUTH_DISABLED === "true") {
 }
 
 export const authMiddleware: MiddlewareHandler = async (c, next) => {
-  // Better-Auth's own routes handle their own auth (OAuth callbacks, session mgmt)
   if (c.req.path.startsWith("/api/auth/")) {
     await next();
     return;
@@ -37,7 +36,14 @@ export const authMiddleware: MiddlewareHandler = async (c, next) => {
     return;
   }
 
-  const session = await getAuth().api.getSession({
+  let auth;
+  try {
+    auth = getAuth();
+  } catch {
+    return c.json({ error: "Authentication not configured" }, 503);
+  }
+
+  const session = await auth.api.getSession({
     headers: c.req.raw.headers,
   });