diff --git a/open-sse/config/providerErrorRules.ts b/open-sse/config/providerErrorRules.ts
index ce5c74e702..15e82adf4e 100644
--- a/open-sse/config/providerErrorRules.ts
+++ b/open-sse/config/providerErrorRules.ts
@@ -176,6 +176,41 @@ function buildOpenrouterRules(): ProviderErrorRule[] {
   ];
 }
 
+// ─── AgentRouter ────────────────────────────────────────────────────────────
+// agentrouter.org misstates temporary quota exhaustion as 403/400 with a
+// Chinese body. upstreamStatusRestatement.ts rewrites the status to 429
+// BEFORE classification, so rules here accept both the raw 403/400 and the
+// restated 429 (text is the real discriminator either way).
+//  - "额度不足": account-wide temporary quota → quota_exhausted, scope
+//    "connection" (mirror of the Opencode account-wide rationale above).
+//  - "无权访问模型": this key permanently lacks access to ONE model → lock only
+//    the model so the connection keeps serving the rest (Model Lockout tier).
+function buildAgentrouterRules(): ProviderErrorRule[] {
+  const AGENTROUTER_ERROR_STATUSES = new Set([400, 403, 429]);
+  return [
+    {
+      id: "agentrouter-user-quota-exhausted",
+      match: ({ status, body }) => {
+        if (!AGENTROUTER_ERROR_STATUSES.has(status)) return null;
+        const text = JSON.stringify(body ?? "").toLowerCase();
+        if (!text.includes("额度不足")) return null;
+        return { reason: "quota_exhausted", scope: "connection" };
+      },
+    },
+    {
+      id: "agentrouter-model-access-denied",
+      match: ({ status, body }) => {
+        if (status !== 403) return null;
+        const text = JSON.stringify(body ?? "").toLowerCase();
+        if (!text.includes("无权访问模型")) return null;
+        // 6h: effectively "until the operator fixes the key's model grants",
+        // without being an unrecoverable terminal state.
+        return { reason: "auth_error", scope: "model", cooldownMs: 6 * 60 * 60 * 1000 };
+      },
+    },
+  ];
+}
+
 /**
  * Global registry. Provider name → ordered list of rules (first match wins).
  * Add new providers here; the matcher in classifyError will pick them up
@@ -189,6 +224,7 @@ export const providerRuleRegistry = new Map<string, ProviderErrorRule[]>([
   ["minimax-passthrough", buildMinimaxRules()],
   ["cloudflare-ai", buildCloudflareAiRules()],
   ["openrouter", buildOpenrouterRules()],
+  ["agentrouter", buildAgentrouterRules()],
 ]);
 
 /**
diff --git a/tests/unit/agentrouter-error-rules.test.ts b/tests/unit/agentrouter-error-rules.test.ts
new file mode 100644
index 0000000000..0923f3e83d
--- /dev/null
+++ b/tests/unit/agentrouter-error-rules.test.ts
@@ -0,0 +1,78 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+
+/**
+ * agentrouter.org quota model:
+ *  - "额度不足" (quota insufficient) is ACCOUNT-wide and temporary → lock the
+ *    connection (scope "connection") so combo routing moves to another
+ *    account/provider instead of hammering the same key.
+ *  - "无权访问模型" (no access to this model) is permanent PER MODEL → lock only
+ *    the model (scope "model"); the connection keeps serving other models.
+ * Status matching accepts both the raw upstream 403 AND the restated 429
+ * (upstreamStatusRestatement.ts rewrites 403→429 before classification).
+ */
+
+const { providerRuleRegistry, getProviderErrorRuleMatch } = await import(
+  "../../open-sse/config/providerErrorRules.ts"
+);
+const { classifyError, checkFallbackError } = await import(
+  "../../open-sse/services/accountFallback.ts"
+);
+const { RateLimitReason } = await import("../../open-sse/config/constants.ts");
+
+test("A1: agentrouter is registered in providerRuleRegistry", () => {
+  const rules = providerRuleRegistry.get("agentrouter");
+  assert.ok(rules && rules.length > 0);
+});
+
+test("A2: quota body → quota_exhausted scope connection (restated 429)", () => {
+  const match = getProviderErrorRuleMatch("agentrouter", 429, {}, {
+    error: { message: "用户额度不足，请充值" },
+  });
+  assert.ok(match, "quota body must match");
+  assert.equal(match.reason, "quota_exhausted");
+  assert.equal(match.scope, "connection");
+});
+
+test("A3: quota body also matches the raw (pre-restatement) 403", () => {
+  const match = getProviderErrorRuleMatch("agentrouter", 403, {}, "用户额度不足");
+  assert.ok(match);
+  assert.equal(match.reason, "quota_exhausted");
+});
+
+test("A4: 无权访问模型 → auth_error scope model (model lockout, not connection)", () => {
+  const match = getProviderErrorRuleMatch("agentrouter", 403, {}, {
+    error: { message: "无权访问模型 claude-sonnet-4" },
+  });
+  assert.ok(match);
+  assert.equal(match.reason, "auth_error");
+  assert.equal(match.scope, "model");
+});
+
+test("A5: classifyError integration — quota text wins over the 403→AUTH_ERROR status fallback", () => {
+  const reason = classifyError(403, "用户额度不足", {
+    provider: "agentrouter",
+    headers: {},
+    body: { error: { message: "用户额度不足" } },
+  });
+  assert.equal(reason, RateLimitReason.QUOTA_EXHAUSTED);
+});
+
+test("A6: guard — restated quota error is retryable, never terminal", () => {
+  const result = checkFallbackError(429, "用户额度不足", 0, null, "agentrouter", null);
+  assert.equal(result.shouldFallback, true);
+  assert.ok(!result.permanent, "quota misstatus must never be permanent");
+  assert.ok(!result.creditsExhausted, "must not trip CREDITS_EXHAUSTED_SIGNALS");
+  assert.ok(result.cooldownMs > 0, "must carry a real cooldown");
+});
+
+test("A7: guard — raw 403 quota (hook bypassed) is still not account-deactivation", () => {
+  const result = checkFallbackError(403, "用户额度不足", 0, null, "agentrouter", null);
+  assert.equal(result.shouldFallback, true);
+  assert.ok(!result.permanent);
+});
+
+test("A8: plain agentrouter 403 (no quota text) keeps the default apikey auth path", () => {
+  const match = getProviderErrorRuleMatch("agentrouter", 403, {}, "Invalid API key");
+  assert.equal(match, null);
+});