fix(cloud): make direct launch replay-safe

web/src/app/auth/space/callback/page.tsx

@@ -29,6 +29,7 @@ type SpaceOAuthLoginResult = {
   token: string;
   user: string;
   workspace_uuid?: string;
+  return_path?: string;
 };
 
 const pendingSpaceOAuthLogins = new Map<
@@ -63,6 +64,10 @@ function SpaceOAuthCallbackContent() {
   const [searchParams] = useSearchParams();
   const { t } = useTranslation();
   const isMountedRef = useRef(true);
+  const directLaunchFragmentRef = useRef<{
+    workspaceUuid: string | null;
+    launchAssertion: string | null;
+  } | null>(null);
 
   const [status, setStatus] = useState<
     'loading' | 'confirm' | 'success' | 'error'
@@ -106,7 +111,13 @@ function SpaceOAuthCallbackContent() {
           throw new Error('No Workspace is available for this Account');
         }
         if (response.workspace_uuid) {
-          navigate('/home', { replace: true });
+          const returnPath =
+            typeof response.return_path === 'string' &&
+            response.return_path.startsWith('/') &&
+            !response.return_path.startsWith('//')
+              ? response.return_path
+              : '/home';
+          navigate(returnPath, { replace: true });
           return;
         }
         setStatus('success');
@@ -207,16 +218,29 @@ function SpaceOAuthCallbackContent() {
     const errorDescription = searchParams.get('error_description');
     const mode = searchParams.get('mode');
     const state = searchParams.get('state');
-    const fragmentParams = new URLSearchParams(
-      window.location.hash.startsWith('#')
-        ? window.location.hash.slice(1)
-        : window.location.hash,
-    );
+    if (directLaunchFragmentRef.current === null) {
+      const fragmentParams = new URLSearchParams(
+        window.location.hash.startsWith('#')
+          ? window.location.hash.slice(1)
+          : window.location.hash,
+      );
+      directLaunchFragmentRef.current = {
+        workspaceUuid: fragmentParams.get('workspace_uuid'),
+        launchAssertion: fragmentParams.get('launch_assertion'),
+      };
+      if (window.location.hash) {
+        window.history.replaceState(
+          null,
+          '',
+          `${window.location.pathname}${window.location.search}`,
+        );
+      }
+    }
     const workspaceUuid =
-      fragmentParams.get('workspace_uuid') ?? searchParams.get('workspace_uuid');
+      directLaunchFragmentRef.current.workspaceUuid ??
+      searchParams.get('workspace_uuid');
     const launchAssertion =
-      fragmentParams.get('launch_assertion') ??
-      searchParams.get('launch_assertion');
+      directLaunchFragmentRef.current.launchAssertion;
 
     if (error) {
       setStatus('error');

web/tests/unit/space-launch-callback.test.mjs

@@ -0,0 +1,24 @@
+import assert from 'node:assert/strict';
+import fs from 'node:fs';
+import test from 'node:test';
+
+const source = fs.readFileSync(
+  new URL('../../src/app/auth/space/callback/page.tsx', import.meta.url),
+  'utf8',
+);
+
+test('direct launch assertion is fragment-only and removed before exchange', () => {
+  assert.doesNotMatch(source, /searchParams\.get\(['"]launch_assertion['"]\)/);
+  const readIndex = source.indexOf("fragmentParams.get('launch_assertion')");
+  const clearIndex = source.indexOf('window.history.replaceState');
+  const exchangeIndex = source.indexOf('handleOAuthCallback(', clearIndex);
+  assert.ok(readIndex >= 0, 'fragment assertion read is missing');
+  assert.ok(clearIndex > readIndex, 'URL fragment is not cleared after copying the assertion');
+  assert.ok(exchangeIndex > clearIndex, 'assertion exchange starts before the fragment is cleared');
+});
+
+test('direct launch honors only a local signed return path', () => {
+  assert.match(source, /response\.return_path\.startsWith\(['"]\/['"]\)/);
+  assert.match(source, /!response\.return_path\.startsWith\(['"]\/\/['"]\)/);
+  assert.match(source, /navigate\(returnPath, \{ replace: true \}\)/);
+});