fix(types): restore provider breaker status guard (#10088)

src/sse/handlers/chat.ts

@@ -88,6 +88,7 @@ import {
 import { buildModalityBridgeHeader } from "@/lib/guardrails/modalityBridge/bridgeStats";
 import {
   isAntigravityMissingProjectError,
+  isProviderBreakerFailureStatus,
   PROVIDER_BREAKER_FAILURE_STATUSES,
   resolveStreamReadinessClassificationError,
   shouldTripProviderBreakerForResult,

tests/unit/circuit-breaker-abort-provider-trip-7907.test.ts

@@ -16,6 +16,7 @@
 import { test } from "node:test";
 import assert from "node:assert/strict";
 import { shouldTripProviderBreakerForResult } from "../../src/sse/handlers/chat.ts";
+import { isProviderBreakerFailureStatus } from "../../src/sse/handlers/chatPredicates.ts";
 import { shouldRecordProviderBreakerFailure } from "../../open-sse/services/combo/comboPredicates.ts";
 
 // The exact abort shape described in the PR body / issue #7907: no upstream
@@ -26,6 +27,11 @@ const ABORT_RESULT = {
   error: "request_signal_aborted",
 } as const;
 
+test("single-model breaker status guard accepts only provider-level failures", () => {
+  assert.equal(isProviderBreakerFailureStatus(502), true);
+  assert.equal(isProviderBreakerFailureStatus(429), false);
+});
+
 test("chat.ts single-model path: breaker stays CLOSED on a client abort (502 default, no errorCode)", () => {
   assert.equal(shouldTripProviderBreakerForResult(ABORT_RESULT, false, false), false);
 });