feat(registry): hard-cut META_REPO -> REGISTRY_REPO; wire mirror into startup/webhook/sweep

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/tests/test_docs_specs_vertical.py

@@ -79,19 +79,28 @@ class _UpstreamHandler:
 
 
 @pytest.fixture
-def patched_httpx(monkeypatch):
+def patched_httpx(monkeypatch, app_with_fake_gitea):  # noqa: F811
     """Provide a hook the test can call to install a MockTransport.
 
-    Same shape as the docs_sessions fixture — `app_with_fake_gitea`
-    monkeypatches `httpx.AsyncClient` for the gitea side, so we
-    construct from the unpatched class directly to avoid the
-    FakeGitea wrapper.
+    M3 note: lifespan now calls `refresh_registry` which hits FakeGitea
+    via the gitea transport. Since `httpx` is a module singleton, installing
+    the docs transport would clobber the FakeGitea mock already installed
+    by `app_with_fake_gitea`. We use a COMPOSITE handler: Gitea API
+    requests (to `http://gitea.test/`) are delegated to FakeGitea; all
+    other requests go to the test-specific handler.
     """
     from httpx._client import AsyncClient as RealAsyncClient
 
+    _fake = app_with_fake_gitea[1]
+
     def install(handler):
+        def composite(request: httpx.Request) -> httpx.Response:
+            if "gitea.test" in str(request.url):
+                return _fake.handle(request)
+            return handler(request)
+
         def patched(*args, **kwargs):
-            kwargs["transport"] = httpx.MockTransport(handler)
+            kwargs["transport"] = httpx.MockTransport(composite)
             return RealAsyncClient(*args, **kwargs)
 
         monkeypatch.setattr("app.docs_specs.httpx.AsyncClient", patched)