fix: measure and trace the sign-in check's calls to Stalwart

lib/auth/verify-jmap-auth.ts

@@ -5,6 +5,7 @@ import {
   type PublicFetchResponse,
 } from '@/lib/security/url-guard';
 import { forwardedClientHeaders } from '@/lib/auth/client-address';
+import { observeUpstream } from '@/lib/metrics/upstream';
 
 const VERIFY_TIMEOUT_MS = 10000;
 const MAX_REDIRECTS = 3;
@@ -150,7 +151,7 @@ export function assertBasicAuthMatchesUsername(authHeader: string, claimedUserna
 
 export interface VerifiedJmapSession {
   apiUrl: string;
-  /** Canonical login name the server reports for the credential (RFC 8620 §2). */
+  /** Canonical login name the server reports for the credential (RFC 8620 §2). */
   username?: string;
   primaryAccounts?: Record<string, string>;
   accounts: Record<string, unknown>;
@@ -361,9 +362,13 @@ async function fetchIdentityEmails(
     };
     // No redirect handling here: a redirect on the POST would downgrade it to
     // a GET and can only come from a misconfigured proxy - treat as failure.
-    const response = options.trusted
-      ? await fetch(apiUrl, { ...requestInit, redirect: 'manual' })
-      : await fetchPublicUrl(apiUrl, requestInit);
+    // Measured and traced like every call to Stalwart (lib/metrics/upstream.ts).
+    const response = await observeUpstream('stalwart', async (trace) => {
+      const init = { ...requestInit, headers: { ...requestInit.headers, ...trace } };
+      return options.trusted
+        ? await fetch(apiUrl, { ...init, redirect: 'manual' })
+        : await fetchPublicUrl(apiUrl, init);
+    });
     if (!response.ok) {
       throw new JmapAuthVerificationError(
         response.status === 401 || response.status === 403
@@ -435,9 +440,13 @@ async function fetchVerifiedSession(
       // Untrusted (user-supplied) endpoints connect through the rebinding-safe
       // fetch so the address validated above is the one the socket uses.
       // Admin-configured servers may legitimately live on private addresses.
-      response = options.trusted
-        ? await fetch(currentUrl, { ...requestInit, redirect: 'manual' })
-        : await fetchPublicUrl(currentUrl, requestInit);
+      const target = currentUrl;
+      response = await observeUpstream('stalwart', async (trace) => {
+        const init = { ...requestInit, headers: { ...requestInit.headers, ...trace } };
+        return options.trusted
+          ? await fetch(target, { ...init, redirect: 'manual' })
+          : await fetchPublicUrl(target, init);
+      });
 
       if (response.status >= 300 && response.status < 400) {
         const location = response.headers.get('location');

lib/tracing/__tests__/tracing.test.ts

@@ -13,6 +13,7 @@ import { markTracingActive } from '../config';
 import { scrubAttributes, scrubSpanName } from '../scrub';
 import { observeUpstream } from '@/lib/metrics/upstream';
 import { fetchJmapServer } from '@/lib/stalwart/server-fetch';
+import { verifyJmapAuth } from '@/lib/auth/verify-jmap-auth';
 
 const exporter = new InMemorySpanExporter();
 const provider = createProvider(exporter, false);
@@ -56,6 +57,20 @@ describe('spans for upstream calls', () => {
     }
   });
 
+  it('reach Stalwart from the sign-in check too', async () => {
+    const fetchSpy = vi.fn().mockResolvedValue(new Response(JSON.stringify({ apiUrl: 'https://mail.example.org/jmap/', username: 'u@example.org' }), { status: 200 }));
+    vi.stubGlobal('fetch', fetchSpy);
+    try {
+      await verifyJmapAuth('https://mail.example.org', 'Basic dTpw', { trusted: true }).catch(() => undefined);
+      const headers = new Headers((fetchSpy.mock.calls[0][1] as RequestInit).headers);
+      expect(String(fetchSpy.mock.calls[0][0])).toBe('https://mail.example.org/.well-known/jmap');
+      expect(headers.get('traceparent')).toMatch(/^00-[0-9a-f]{32}-[0-9a-f]{16}-01$/);
+      expect(headers.get('authorization')).toBe('Basic dTpw');
+    } finally {
+      vi.unstubAllGlobals();
+    }
+  });
+
   it('mark 5xx and thrown errors as errors, without the error message', async () => {
     await expect(observeUpstream('translate', async () => { throw new Error(`refused for ${ADDRESS}`); })).rejects.toThrow();
     const [span] = exporter.getFinishedSpans();