diff --git a/src/agents/failover-error.e2e.test.ts b/src/agents/failover-error.e2e.test.ts
index 5fb9d06e60..ab31855cbb 100644
--- a/src/agents/failover-error.e2e.test.ts
+++ b/src/agents/failover-error.e2e.test.ts
@@ -13,6 +13,7 @@ describe("failover-error", () => {
     expect(resolveFailoverReasonFromError({ status: 403 })).toBe("auth");
     expect(resolveFailoverReasonFromError({ status: 408 })).toBe("timeout");
     expect(resolveFailoverReasonFromError({ status: 400 })).toBe("format");
+    expect(resolveFailoverReasonFromError({ status: 503 })).toBe("timeout");
   });
 
   it("infers format errors from error messages", () => {
diff --git a/src/agents/failover-error.ts b/src/agents/failover-error.ts
index 6592cfc7f7..d2ec6c35c5 100644
--- a/src/agents/failover-error.ts
+++ b/src/agents/failover-error.ts
@@ -161,6 +161,9 @@ export function resolveFailoverReasonFromError(err: unknown): FailoverReason | n
   if (status === 408) {
     return "timeout";
   }
+  if (status === 503) {
+    return "timeout";
+  }
   if (status === 400) {
     return "format";
   }
diff --git a/src/agents/pi-embedded-helpers.isbillingerrormessage.e2e.test.ts b/src/agents/pi-embedded-helpers.isbillingerrormessage.e2e.test.ts
index 931a1bbe34..c62aac873b 100644
--- a/src/agents/pi-embedded-helpers.isbillingerrormessage.e2e.test.ts
+++ b/src/agents/pi-embedded-helpers.isbillingerrormessage.e2e.test.ts
@@ -348,4 +348,17 @@ describe("classifyFailoverReason", () => {
       "rate_limit",
     );
   });
+  it("classifies provider high-demand / service-unavailable messages as rate_limit", () => {
+    expect(
+      classifyFailoverReason(
+        "This model is currently experiencing high demand. Please try again later.",
+      ),
+    ).toBe("rate_limit");
+    expect(classifyFailoverReason("LLM error: service unavailable")).toBe("rate_limit");
+    expect(
+      classifyFailoverReason(
+        '{"error":{"code":503,"message":"The model is overloaded. Please try later","status":"UNAVAILABLE"}}',
+      ),
+    ).toBe("rate_limit");
+  });
 });
diff --git a/src/agents/pi-embedded-helpers/errors.ts b/src/agents/pi-embedded-helpers/errors.ts
index 5233eb9c42..088707eef5 100644
--- a/src/agents/pi-embedded-helpers/errors.ts
+++ b/src/agents/pi-embedded-helpers/errors.ts
@@ -583,7 +583,12 @@ const ERROR_PATTERNS = {
     "resource_exhausted",
     "usage limit",
   ],
-  overloaded: [/overloaded_error|"type"\s*:\s*"overloaded_error"/i, "overloaded"],
+  overloaded: [
+    /overloaded_error|"type"\s*:\s*"overloaded_error"/i,
+    "overloaded",
+    "service unavailable",
+    "high demand",
+  ],
   timeout: [
     "timeout",
     "timed out",