feat(core): implement robust fetch utilities and stream management
Introduce a centralized `fetch-utils.ts` to handle retry logic with proxy fallback, SSE line buffering to prevent chunk-boundary corruption, and graceful shutdown via active reader tracking. Key changes: - Add `fetchWithRetry` for automatic direct-to-proxy failover. - Implement `SSELineBuffer` to ensure reliable parsing of split SSE chunks. - Add `createStreamBodyLimiter` to enforce payload limits on streaming requests. - Refactor `ProxyPool` to decouple failure marking from rotation. - Standardize CORS handling and environment variable configuration. - Clean up documentation and remove obsolete skill files.
This commit is contained in:
MythEclipse
+42
-37
@@ -7,8 +7,7 @@
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* Reuses the same relay logic from `src/lib/` and `src/middleware/` as
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* the standalone Bun.serve() server, but:
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* - Uses `env` for configuration (Workers don't have process.env)
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* - Does NOT support WebSocket upgrades (Workers can proxy WS but
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* this handler only handles HTTP relay)
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* - Does NOT support WebSocket upgrades
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* - Rate limiter is per-isolate (resets on cold start)
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*/
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@@ -21,6 +20,7 @@ import {
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classifyFetchError,
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createErrorResponse,
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createCorsPreflightResponse,
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getCorsHeaders,
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} from "./lib/relay-utils";
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import { checkBodySize } from "./middleware/body-limiter";
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@@ -29,7 +29,7 @@ import { logRelayEvent } from "./middleware/logger";
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import { handleChatCompletion, listModels } from "./lib/ai-proxy";
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import { handleAnthropicMessages } from "./lib/anthropic-proxy";
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// ─── Types ───────────────────────────────────────────────────────────────────────
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// --- Types -------------------------------------------------------------------
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export interface Env {
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/** Upstream fetch timeout in ms (default: 30000) */
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@@ -44,7 +44,21 @@ export interface Env {
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API_KEY?: string;
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}
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// ─── Helpers ─────────────────────────────────────────────────────────────────────
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// --- Singletons (per-isolate, survives warm starts) ---------------------------
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let rateLimiter: ReturnType<typeof createRateLimiter> | null = null;
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function getRateLimiter(env: Env) {
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if (!rateLimiter) {
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rateLimiter = createRateLimiter({
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maxRequests: getNumericEnv(env, "RATE_LIMIT_MAX", 100),
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windowMs: getNumericEnv(env, "RATE_LIMIT_WINDOW_MS", 60000),
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});
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}
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return rateLimiter;
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}
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// --- Helpers ------------------------------------------------------------------
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function getNumericEnv(
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env: Env,
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@@ -68,19 +82,20 @@ function getClientIP(req: Request): string {
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return "unknown";
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}
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// ─── Auth Helper ─────────────────────────────────────────────────────────────────
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// --- Auth Helper ---------------------------------------------------------------
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function requireAuth(req: Request): Response | null {
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const apiKey = process.env.API_KEY ?? "sk-dummy-key";
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const header = req.headers.get("authorization") ?? req.headers.get("x-api-key") ?? "";
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const key = header.replace(/^Bearer\s+/i, "").trim();
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if (key === "sk-dummy-key") return null;
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if (key === apiKey) return null;
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return new Response(
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JSON.stringify({ error: { message: "Unauthorized", type: "auth_error" } }),
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{ status: 401, headers: { "Content-Type": "application/json", "Access-Control-Allow-Origin": "*" } },
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{ status: 401, headers: { "Content-Type": "application/json", ...getCorsHeaders() } },
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);
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}
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// ─── Route Handlers ──────────────────────────────────────────────────────────────
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// --- Route Handlers ------------------------------------------------------------
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const SERVER_START_TIME = Date.now();
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const RELAY_VERSION = "1.0.0";
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@@ -96,7 +111,7 @@ function handleHealth(): Response {
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status: 200,
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headers: {
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"Content-Type": "application/json",
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"Access-Control-Allow-Origin": "*",
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...getCorsHeaders(),
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},
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},
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);
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@@ -183,7 +198,7 @@ function handleDocs(): Response {
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status: 200,
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headers: {
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"Content-Type": "text/html; charset=utf-8",
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"Access-Control-Allow-Origin": "*",
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...getCorsHeaders(),
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},
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});
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}
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@@ -222,7 +237,7 @@ function handleIndex(): Response {
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});
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}
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// ─── Relay Logic ─────────────────────────────────────────────────────────────────
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// --- Relay Logic ---------------------------------------------------------------
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async function handleRelay(req: Request, env: Env): Promise<Response> {
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const startTime = performance.now();
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@@ -232,18 +247,14 @@ async function handleRelay(req: Request, env: Env): Promise<Response> {
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const RELAY_TIMEOUT_MS = getNumericEnv(env, "RELAY_TIMEOUT_MS", 30000);
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// Per-isolate rate limiter (recreated on each cold start)
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const rateLimiter = createRateLimiter({
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maxRequests: getNumericEnv(env, "RATE_LIMIT_MAX", 100),
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windowMs: getNumericEnv(env, "RATE_LIMIT_WINDOW_MS", 60000),
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});
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const limiter = getRateLimiter(env);
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// ── Pre-flight CORS ──────────────────────────────────────────────
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// -- Pre-flight CORS --------------------------------------------------------
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if (method === "OPTIONS") {
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return createCorsPreflightResponse();
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}
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// ── Middleware: Body size check ──────────────────────────────────
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// -- Middleware: Body size check -------------------------------------------
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const bodyError = checkBodySize(req);
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if (bodyError) {
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logRelayEvent({
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@@ -256,8 +267,8 @@ async function handleRelay(req: Request, env: Env): Promise<Response> {
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return bodyError;
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}
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// ── Middleware: Rate limiting ────────────────────────────────────
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const rateCheck = rateLimiter.check(clientIP);
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// -- Middleware: Rate limiting ---------------------------------------------
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const rateCheck = limiter.check(clientIP);
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if (!rateCheck.allowed) {
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logRelayEvent({
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method,
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@@ -278,7 +289,7 @@ async function handleRelay(req: Request, env: Env): Promise<Response> {
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status: 429,
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headers: {
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"Content-Type": "application/json",
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"Access-Control-Allow-Origin": "*",
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...getCorsHeaders(),
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"Retry-After": String(
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Math.ceil((rateCheck.retryAfterMs ?? 60_000) / 1000),
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),
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@@ -287,11 +298,11 @@ async function handleRelay(req: Request, env: Env): Promise<Response> {
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);
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}
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// ── Extract relay parameters from headers ───────────────────────
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// -- Extract relay parameters from headers ---------------------------------
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const target = req.headers.get("x-relay-target");
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const relayPath = req.headers.get("x-relay-path") ?? "/";
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// ── SSRF: Normalize and validate target URL ─────────────────────
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// -- SSRF: Normalize and validate target URL --------------------------------
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const targetUrl = normalizeTargetUrl(target, relayPath);
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if (!targetUrl) {
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logRelayEvent({
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@@ -325,7 +336,7 @@ async function handleRelay(req: Request, env: Env): Promise<Response> {
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});
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}
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// ── Build the upstream request ──────────────────────────────────
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// -- Build the upstream request ---------------------------------------------
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const filteredHeaders = filterRequestHeaders(req.headers);
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const fetchOptions = buildRelayRequest(
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req,
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@@ -335,7 +346,7 @@ async function handleRelay(req: Request, env: Env): Promise<Response> {
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const targetUrlString = targetUrl.toString();
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// ── Execute upstream fetch ──────────────────────────────────────
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// -- Execute upstream fetch -------------------------------------------------
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let response: Response;
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try {
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response = await fetch(targetUrlString, fetchOptions);
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@@ -353,7 +364,7 @@ async function handleRelay(req: Request, env: Env): Promise<Response> {
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return createErrorResponse(classified);
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}
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// ── Build relay response ────────────────────────────────────────
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// -- Build relay response ---------------------------------------------------
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const relayedResponse = createRelayResponse(response);
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logRelayEvent({
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@@ -368,13 +379,12 @@ async function handleRelay(req: Request, env: Env): Promise<Response> {
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return relayedResponse;
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}
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// ─── Exported Worker Handler ─────────────────────────────────────────────────────
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// --- Exported Worker Handler ---------------------------------------------------
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export default {
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async fetch(req: Request, env: Env): Promise<Response> {
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const url = new URL(req.url);
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// Static routes — show index only when no relay target is requested
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if (url.pathname === "/health") return handleHealth();
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if (url.pathname === "/docs") return handleDocs();
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if (
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@@ -385,7 +395,6 @@ export default {
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return handleIndex();
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}
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// WebSocket upgrade — not fully supported in this handler
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if (
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req.method === "GET" &&
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req.headers.get("upgrade")?.toLowerCase() === "websocket"
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@@ -400,13 +409,12 @@ export default {
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status: 400,
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headers: {
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"Content-Type": "application/json",
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"Access-Control-Allow-Origin": "*",
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...getCorsHeaders(),
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},
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},
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);
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}
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// AI proxy routes — OpenAI-compatible
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if (url.pathname === "/v1/chat/completions") {
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if (req.method === "OPTIONS") return createCorsPreflightResponse();
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if (req.method !== "POST") return new Response("Method Not Allowed", { status: 405 });
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@@ -418,12 +426,11 @@ export default {
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} catch {
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return new Response(
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JSON.stringify({ error: { message: "Invalid JSON body", type: "invalid_request_error" } }),
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{ status: 400, headers: { "Content-Type": "application/json", "Access-Control-Allow-Origin": "*" } },
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{ status: 400, headers: { "Content-Type": "application/json", ...getCorsHeaders() } },
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);
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}
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}
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// AI proxy routes — Anthropic-compatible
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if (url.pathname === "/v1/messages") {
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if (req.method === "OPTIONS") return createCorsPreflightResponse();
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if (req.method !== "POST") return new Response("Method Not Allowed", { status: 405 });
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@@ -435,12 +442,11 @@ export default {
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} catch {
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return new Response(
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JSON.stringify({ error: { message: "Invalid JSON body", type: "invalid_request_error" } }),
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{ status: 400, headers: { "Content-Type": "application/json", "Access-Control-Allow-Origin": "*" } },
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{ status: 400, headers: { "Content-Type": "application/json", ...getCorsHeaders() } },
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);
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}
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}
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// Models list
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if (url.pathname === "/v1/models" && req.method === "GET") {
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const authErr = requireAuth(req);
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if (authErr) return authErr;
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@@ -452,11 +458,10 @@ export default {
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}));
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return new Response(
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JSON.stringify({ object: "list", data: models }),
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{ status: 200, headers: { "Content-Type": "application/json", "Access-Control-Allow-Origin": "*" } },
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{ status: 200, headers: { "Content-Type": "application/json", ...getCorsHeaders() } },
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);
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}
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// Generic HTTP relay
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return handleRelay(req, env);
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},
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};
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