feat(sse): restate agentrouter quota 403/400 to 429 before classification

open-sse/handlers/chatCore.ts

@@ -184,6 +184,7 @@ import {
   DEFAULT_MAX_TOKENS,
   STREAM_DISCONNECT_GRACE_PERIOD_MS,
 } from "../config/constants.ts";
+import { applyStatusRestatement } from "../config/upstreamStatusRestatement.ts";
 import { createRecoverableStream, makeContinuationBody } from "../services/streamRecovery.ts";
 import {
   resolveResilienceSettings,
@@ -3650,6 +3651,27 @@ export async function handleChatCore({
       upstreamErrorType = details.errorType as string | undefined;
     }
 
+    // Gateways like agentrouter misstate temporary quota exhaustion as 403/400,
+    // which downstream classification treats as AUTH_ERROR and clients like
+    // Claude Code treat as permanent. Restate to 429 (+ synthetic Retry-After)
+    // BEFORE any classification so both the fallback engine and the surfaced
+    // client status see a retryable error. Registry-scoped per provider.
+    const restatement = applyStatusRestatement({
+      provider,
+      status: statusCode,
+      message,
+      body: upstreamErrorBody,
+      retryAfterMs,
+    });
+    if (restatement.ruleId) {
+      statusCode = restatement.status;
+      retryAfterMs = restatement.retryAfterMs;
+      log?.info?.(
+        "STATUS_RESTATE",
+        `${provider} ${restatement.fromStatus}→${statusCode} (${restatement.ruleId})`
+      );
+    }
+
     const signatureRecovery = await recoverAnthropicThinkingSignature({
       provider,
       statusCode,

tests/unit/upstream-status-restatement.test.ts

@@ -107,3 +107,20 @@ test("R9: registry exposes agentrouter so future gateways copy the one-line reci
   const rules = statusRestatementRegistry.get("agentrouter");
   assert.ok(rules && rules.length > 0);
 });
+
+test("R10: chatCore wires applyStatusRestatement into the providerFailure block", async () => {
+  // chatCore is a god-file that cannot be imported standalone in unit tests
+  // (side-effectful DB/env wiring), so the wiring contract is asserted at the
+  // source level: the hook must exist, run against the parsed error, and
+  // reassign both statusCode and retryAfterMs BEFORE classification.
+  const { readFile } = await import("node:fs/promises");
+  const src = await readFile(
+    new URL("../../open-sse/handlers/chatCore.ts", import.meta.url),
+    "utf8"
+  );
+  assert.match(src, /applyStatusRestatement\(/, "chatCore must call applyStatusRestatement");
+  const hookIndex = src.indexOf("applyStatusRestatement(");
+  const classifyIndex = src.indexOf("classifyProviderError(statusCode");
+  assert.ok(hookIndex > -1 && classifyIndex > -1 && hookIndex < classifyIndex,
+    "restatement must run BEFORE classifyProviderError so fallback sees the corrected status");
+});