Add OpenCode Zen CORS proxy (Deno Deploy)

Author: Android-PowerUser

cloudflare-worker/opencode-proxy/opencode_proxy.ts

@@ -0,0 +1,81 @@
+/**
+ * Deno Deploy: CORS proxy for opencode.ai/zen
+ * Forwards POST /zen/v1/chat/completions to opencode.ai
+ * and adds Access-Control-Allow-Origin: * so Android WebViews can reach it.
+ */
+
+const TARGET_BASE = "https://opencode.ai";
+
+const CORS_HEADERS: Record<string, string> = {
+  "Access-Control-Allow-Origin": "*",
+  "Access-Control-Allow-Methods": "POST, GET, OPTIONS",
+  "Access-Control-Allow-Headers": "Content-Type, Authorization, X-Requested-With",
+  "Access-Control-Expose-Headers": "Content-Type, X-Request-Id",
+  "Access-Control-Max-Age": "86400",
+};
+
+Deno.serve(async (request: Request): Promise<Response> => {
+  // CORS preflight – must respond immediately with 200 (not 204, some WebViews reject 204)
+  if (request.method === "OPTIONS") {
+    return new Response(null, { status: 200, headers: CORS_HEADERS });
+  }
+
+  if (request.method !== "POST") {
+    return new Response("Method not allowed", { status: 405, headers: CORS_HEADERS });
+  }
+
+  const url = new URL(request.url);
+  const targetUrl = TARGET_BASE + url.pathname + url.search;
+
+  // Forward headers (pass Authorization through if present)
+  const forwardHeaders = new Headers();
+  forwardHeaders.set("Content-Type", "application/json");
+  forwardHeaders.set("Accept", "text/event-stream, application/json");
+  const auth = request.headers.get("Authorization");
+  if (auth) forwardHeaders.set("Authorization", auth);
+
+  let body: string;
+  try {
+    body = await request.text();
+  } catch (e) {
+    const msg = e instanceof Error ? e.message : String(e);
+    return new Response(
+      JSON.stringify({ error: { message: "Failed to read request body: " + msg, type: "proxy_error" } }),
+      { status: 400, headers: { ...CORS_HEADERS, "Content-Type": "application/json" } }
+    );
+  }
+
+  let upstreamResponse: Response;
+  try {
+    upstreamResponse = await fetch(targetUrl, {
+      method: "POST",
+      headers: forwardHeaders,
+      body,
+    });
+  } catch (e) {
+    const msg = e instanceof Error ? e.message : String(e);
+    return new Response(
+      JSON.stringify({ error: { message: "Proxy could not reach opencode.ai: " + msg, type: "proxy_error" } }),
+      { status: 502, headers: { ...CORS_HEADERS, "Content-Type": "application/json" } }
+    );
+  }
+
+  // Build response headers: start from upstream, overlay CORS headers
+  const responseHeaders = new Headers();
+  // Copy safe upstream headers
+  for (const [k, v] of upstreamResponse.headers.entries()) {
+    const kl = k.toLowerCase();
+    if (kl === "content-type" || kl === "x-request-id" || kl === "transfer-encoding") {
+      responseHeaders.set(k, v);
+    }
+  }
+  // Always set CORS headers (overrides anything upstream sent)
+  for (const [k, v] of Object.entries(CORS_HEADERS)) {
+    responseHeaders.set(k, v);
+  }
+
+  return new Response(upstreamResponse.body, {
+    status: upstreamResponse.status,
+    headers: responseHeaders,
+  });
+});