fix(sse): correlate reason and resource within the same ErrorInfo detail

src/sse/services/auth.ts

@@ -1908,9 +1908,49 @@ export async function getProviderCredentialsWithQuotaPreflight(
  * lockout behavior, since that's the safer default and the actual bug this
  * plan fixes (avoid defaulting BACK toward the connection-wide cooldown this
  * plan exists to avoid).
+ *
+ * Parses the body as JSON and inspects each ErrorInfo-shaped detail object so
+ * `reason` and `resource` are correlated within the SAME detail entry — a
+ * multi-detail error body (unusual but possible) must not let one detail's
+ * resource leak into another detail's reason check. Falls back to a permissive
+ * regex scan (pre-JSON-parsing behavior) only when the body isn't parseable
+ * JSON or doesn't contain a `details` array, since Vertex error bodies aren't
+ * guaranteed to always be well-formed JSON.
  */
 function isVertexConnectionWidePermissionDenied(errorText: string | null | undefined): boolean {
   if (!errorText) return false;
+
+  try {
+    const parsed = JSON.parse(errorText);
+    const details: unknown[] =
+      parsed?.error?.details ?? parsed?.details ?? (Array.isArray(parsed) ? parsed : []);
+    if (Array.isArray(details) && details.length > 0) {
+      for (const detail of details) {
+        if (!detail || typeof detail !== "object") continue;
+        const reason = (detail as Record<string, unknown>).reason;
+        if (reason === "SERVICE_DISABLED") return true;
+        if (reason === "IAM_PERMISSION_DENIED") {
+          const metadata = (detail as Record<string, unknown>).metadata;
+          const resource =
+            metadata && typeof metadata === "object"
+              ? (metadata as Record<string, unknown>).resource
+              : undefined;
+          if (typeof resource === "string" && !resource.includes("/models/")) return true;
+        }
+      }
+      // Well-formed details array present but no detail matched a connection-wide
+      // pattern (e.g. IAM_PERMISSION_DENIED with a /models/ resource, or no
+      // recognized reason at all) — per-model lockout is correct, don't fall
+      // through to the regex heuristic (it would just re-derive the same answer
+      // less precisely, or worse, could false-positive on stray substrings).
+      return false;
+    }
+  } catch {
+    // Not parseable JSON — fall through to the regex heuristic below.
+  }
+
+  // Fallback for non-JSON or unexpected-shape error bodies (regex-based,
+  // pre-JSON-parsing heuristic — kept for robustness against malformed bodies).
   if (/"reason"\s*:\s*"SERVICE_DISABLED"/.test(errorText)) return true;
   if (/"reason"\s*:\s*"IAM_PERMISSION_DENIED"/.test(errorText)) {
     const resourceMatch = errorText.match(/"resource"\s*:\s*"([^"]*)"/);

tests/unit/vertex-passthrough-model-lockout.test.ts

@@ -239,3 +239,54 @@ test("403 with IAM_PERMISSION_DENIED reason and a project-level resource cools d
   const lockout = accountFallback.getModelLockoutInfo("vertex", conn.id, "claude-sonnet-5-high");
   assert.equal(lockout, null);
 });
+
+test("multi-detail error body correlates reason+resource per-detail, not across details", async () => {
+  // Adversarial case: detail[0] has a model-scoped resource under an unrelated reason,
+  // detail[1] carries the actual IAM_PERMISSION_DENIED with a project-level resource. A
+  // naive independent-regex scan would match detail[0]'s resource against detail[1]'s
+  // reason and wrongly conclude "model-scoped" — this must resolve to connection-wide.
+  await resetStorage();
+  const conn = await seedVertex();
+
+  const body = JSON.stringify({
+    error: {
+      status: "PERMISSION_DENIED",
+      details: [
+        {
+          "@type": "type.googleapis.com/google.rpc.ErrorInfo",
+          reason: "SOME_OTHER_REASON",
+          domain: "iam.googleapis.com",
+          metadata: {
+            resource:
+              "projects/12345/locations/us-central1/publishers/google/models/claude-sonnet-5",
+          },
+        },
+        {
+          "@type": "type.googleapis.com/google.rpc.ErrorInfo",
+          reason: "IAM_PERMISSION_DENIED",
+          domain: "iam.googleapis.com",
+          metadata: {
+            permission: "aiplatform.googleapis.com/models.predict",
+            resource: "projects/12345",
+          },
+        },
+      ],
+    },
+  });
+
+  const result = await auth.markAccountUnavailable(
+    conn.id,
+    403,
+    body,
+    "vertex",
+    "claude-sonnet-5-high"
+  );
+  assert.equal(result.shouldFallback, true);
+
+  const after2 = await providersDb.getProviderConnectionById(conn.id);
+  assert.equal(after2.testStatus, "unavailable");
+  assert.ok(after2.rateLimitedUntil, "connection must be cooled down, not left active");
+
+  const lockout2 = accountFallback.getModelLockoutInfo("vertex", conn.id, "claude-sonnet-5-high");
+  assert.equal(lockout2, null);
+});