feat(gateway): add auth rate-limiting & brute-force protection (#15035)

* feat(gateway): add auth rate-limiting & brute-force protection

Add a per-IP sliding-window rate limiter to Gateway authentication
endpoints (HTTP, WebSocket upgrade, and WS message-level auth).

When gateway.auth.rateLimit is configured, failed auth attempts are
tracked per client IP. Once the threshold is exceeded within the
sliding window, further attempts are blocked with HTTP 429 + Retry-After
until the lockout period expires. Loopback addresses are exempt by
default so local CLI sessions are never locked out.

The limiter is only created when explicitly configured (undefined
otherwise), keeping the feature fully opt-in and backward-compatible.

* fix(gateway): isolate auth rate-limit scopes and normalize 429 responses

---------

Co-authored-by: buerbaumer <buerbaumer@users.noreply.github.com>
Co-authored-by: Peter Steinberger <steipete@gmail.com>

src/gateway/openai-http.e2e.test.ts

@@ -2,7 +2,7 @@ import { afterAll, beforeAll, describe, expect, it } from "vitest";
 import { HISTORY_CONTEXT_MARKER } from "../auto-reply/reply/history.js";
 import { CURRENT_MESSAGE_MARKER } from "../auto-reply/reply/mentions.js";
 import { emitAgentEvent } from "../infra/agent-events.js";
-import { agentCommand, getFreePort, installGatewayTestHooks } from "./test-helpers.js";
+import { agentCommand, getFreePort, installGatewayTestHooks, testState } from "./test-helpers.js";
 
 installGatewayTestHooks({ scope: "suite" });
 
@@ -344,6 +344,49 @@ describe("OpenAI-compatible HTTP API (e2e)", () => {
     }
   });
 
+  it("returns 429 for repeated failed auth when gateway.auth.rateLimit is configured", async () => {
+    const { startGatewayServer } = await import("./server.js");
+    testState.gatewayAuth = {
+      mode: "token",
+      token: "secret",
+      rateLimit: { maxAttempts: 1, windowMs: 60_000, lockoutMs: 60_000, exemptLoopback: false },
+      // oxlint-disable-next-line typescript/no-explicit-any
+    } as any;
+    const port = await getFreePort();
+    const server = await startGatewayServer(port, {
+      host: "127.0.0.1",
+      controlUiEnabled: false,
+      openAiChatCompletionsEnabled: true,
+    });
+    try {
+      const headers = {
+        "content-type": "application/json",
+        authorization: "Bearer wrong",
+      };
+      const body = {
+        model: "openclaw",
+        messages: [{ role: "user", content: "hi" }],
+      };
+
+      const first = await fetch(`http://127.0.0.1:${port}/v1/chat/completions`, {
+        method: "POST",
+        headers,
+        body: JSON.stringify(body),
+      });
+      expect(first.status).toBe(401);
+
+      const second = await fetch(`http://127.0.0.1:${port}/v1/chat/completions`, {
+        method: "POST",
+        headers,
+        body: JSON.stringify(body),
+      });
+      expect(second.status).toBe(429);
+      expect(second.headers.get("retry-after")).toBeTruthy();
+    } finally {
+      await server.close({ reason: "rate-limit auth test done" });
+    }
+  });
+
   it("streams SSE chunks when stream=true", async () => {
     const port = enabledPort;
     try {