fix(failover): classify ZenMux quota-refresh 402 as rate_limit (#43917)

Merged via squash.

Prepared head SHA: 1d58a36a77
Co-authored-by: bwjoke <1284814+bwjoke@users.noreply.github.com>
Co-authored-by: altaywtf <9790196+altaywtf@users.noreply.github.com>
Reviewed-by: @altaywtf

src/agents/failover-error.test.ts

@@ -204,6 +204,13 @@ describe("failover-error", () => {
         message: "Workspace spend limit reached. Contact your admin.",
       }),
     ).toBe("rate_limit");
+    expect(
+      resolveFailoverReasonFromError({
+        status: 402,
+        message:
+          "You have reached your subscription quota limit. Please wait for automatic quota refresh in the rolling time window, upgrade to a higher plan, or use a Pay-As-You-Go API Key for unlimited access. Learn more: https://zenmux.ai/docs/guide/subscription.html",
+      }),
+    ).toBe("rate_limit");
     expect(
       resolveFailoverReasonFromError({
         status: 402,

src/agents/pi-embedded-helpers/errors.ts

@@ -288,6 +288,13 @@ function hasExplicit402BillingSignal(text: string): boolean {
   );
 }
 
+function hasQuotaRefreshWindowSignal(text: string): boolean {
+  return (
+    text.includes("subscription quota limit") &&
+    (text.includes("automatic quota refresh") || text.includes("rolling time window"))
+  );
+}
+
 function hasRetryable402TransientSignal(text: string): boolean {
   const hasPeriodicHint = includesAnyHint(text, PERIODIC_402_HINTS);
   const hasSpendLimit = text.includes("spend limit") || text.includes("spending limit");
@@ -313,6 +320,10 @@ function classify402Message(message: string): PaymentRequiredFailoverReason {
     return "billing";
   }
 
+  if (hasQuotaRefreshWindowSignal(normalized)) {
+    return "rate_limit";
+  }
+
   if (hasExplicit402BillingSignal(normalized)) {
     return "billing";
   }