From e03351a108bfdc72da621e64905d188411d529a5 Mon Sep 17 00:00:00 2001
From: David Zhang <9387252+Git-on-my-level@users.noreply.github.com>
Date: Fri, 28 Aug 2026 19:35:35 -0400
Subject: [PATCH] fix(desktop-backend): admit the gateway route in the
 candidate probe

#12337 routed company-paid desktop Gemini traffic through the LLM
gateway; since then the desktop proxy stamps X-Omi-Provider:
llm_gateway (backend/utils/llm/desktop_gemini_gateway.py), a value the
Auto Deploy candidate probe's REAL_GEMINI_PROVIDER_ROUTES did not
admit, so "Prove candidate chat compatibility" fail-closed on every
promotion (run 33219770852) and dev desktop-backend stayed on the
stale revision.

Admit llm_gateway: the probed surface (gemini-2.5-flash
generateContent) maps to the gateway's desktop-vertex-flash lane,
whose primary provider is VertexGeminiProvider with no fallbacks
(config_loader.py), so the hop is real Gemini-on-Vertex. Stubs,
unknown, and empty routes stay rejected fail-closed; the offline-stub
rejection test is unchanged and a new test pins the post-gateway
route as admitted end to end through _gemini_request.

Verification: python3 .github/scripts/test_desktop_backend_candidate_probe.py
19 tests OK (incl. test_gemini_probe_admits_post_gateway_llm_gateway_route).

Failure-Class: FC-client-model-outside-proxy-allowlist
Co-authored-by: multica-agent <github@multica.ai>
---
 .../desktop_backend_candidate_probe.py        |  8 +++++-
 .../test_desktop_backend_candidate_probe.py   | 27 +++++++++++++++++--
 2 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/.github/scripts/desktop_backend_candidate_probe.py b/.github/scripts/desktop_backend_candidate_probe.py
index d9d2053d86b..2c1d4df77d9 100644
--- a/.github/scripts/desktop_backend_candidate_probe.py
+++ b/.github/scripts/desktop_backend_candidate_probe.py
@@ -36,7 +36,13 @@
 MAX_FIRST_EVENT_SECONDS = 20
 SHA_PATTERN = re.compile(r"^[0-9a-f]{40}$")
 CONTRACT_PATTERN = re.compile(r"^[1-9][0-9]{0,5}$")
-REAL_GEMINI_PROVIDER_ROUTES = frozenset({"vertex_ai", "ai_studio", "ai_studio_byok"})
+REAL_GEMINI_PROVIDER_ROUTES = frozenset({"vertex_ai", "ai_studio", "ai_studio_byok", "llm_gateway"})
+# `llm_gateway` is the route the desktop proxy stamps on X-Omi-Provider for
+# company-paid Gemini traffic since #12337 routed it through the LLM gateway
+# (backend/utils/llm/desktop_gemini_gateway.py proxy_company_paid_via_gateway).
+# The gateway's desktop-vertex lanes pin the Vertex provider with no fallbacks
+# (backend/llm_gateway/gateway/config_loader.py), so the hop is still real
+# Gemini-on-Vertex; stub and unknown routes stay rejected fail-closed.
 
 
 class ProbeError(RuntimeError):
diff --git a/.github/scripts/test_desktop_backend_candidate_probe.py b/.github/scripts/test_desktop_backend_candidate_probe.py
index 7d519d1861f..f79055803a1 100644
--- a/.github/scripts/test_desktop_backend_candidate_probe.py
+++ b/.github/scripts/test_desktop_backend_candidate_probe.py
@@ -74,10 +74,33 @@ def read(self) -> bytes:
                 PROBE._gemini_request("https://candidate.example", token="token")
 
     def test_gemini_probe_rejects_stub_or_unknown_provider_routes(self) -> None:
-        for provider in ("offline_stub", "unknown", ""):
+        for provider in ("offline_stub", "desktop_llm_stub", "unknown", ""):
             with self.assertRaisesRegex(PROBE.ProbeError, "admitted provider"):
                 PROBE._require_real_gemini_provider(provider)
-        self.assertEqual(PROBE._require_real_gemini_provider("vertex_ai"), "vertex_ai")
+        for admitted in ("vertex_ai", "ai_studio", "ai_studio_byok"):
+            self.assertEqual(PROBE._require_real_gemini_provider(admitted), admitted)
+
+    def test_gemini_probe_admits_post_gateway_llm_gateway_route(self) -> None:
+        # Since #12337 the desktop proxy serves company-paid Gemini traffic via
+        # the LLM gateway's Vertex-backed desktop-vertex lanes and stamps
+        # `llm_gateway` on X-Omi-Provider; the probe must admit that real route.
+        self.assertEqual(PROBE._require_real_gemini_provider("llm_gateway"), "llm_gateway")
+
+        class GatewayResponse:
+            headers = {"x-omi-provider": "llm_gateway", "x-omi-request-id": "server-request-id"}
+
+            def __enter__(self):
+                return self
+
+            def __exit__(self, *_args):
+                return False
+
+            def read(self) -> bytes:
+                return b'{"candidates":[{"content":{"parts":[{"text":"OK"}]}}]}'
+
+        with mock.patch.object(PROBE.urllib.request, "urlopen", return_value=GatewayResponse()):
+            summary = PROBE._gemini_request("https://candidate.example", token="token")
+        self.assertEqual(summary["provider_route"], "llm_gateway")
 
     def test_gemini_request_cannot_pass_against_offline_stub(self) -> None:
         class StubResponse: