Enhance provider models and chat handling with new thinking configurations

src/mitm/handlers/antigravity.js

@@ -8,7 +8,7 @@ async function intercept(req, res, bodyBuffer, mappedModel) {
   try {
     const body = JSON.parse(bodyBuffer.toString());
     body.model = mappedModel;
-    const routerRes = await fetchRouter(body);
+    const routerRes = await fetchRouter(body, "/v1/chat/completions", req.headers);
     await pipeSSE(routerRes, res);
   } catch (error) {
     err(`[antigravity] ${error.message}`);

src/mitm/handlers/base.js

@@ -6,13 +6,26 @@ const ROUTER_BASE = String(process.env.MITM_ROUTER_BASE || DEFAULT_LOCAL_ROUTER)
   .replace(/\/+$/, "") || DEFAULT_LOCAL_ROUTER;
 const API_KEY = process.env.ROUTER_API_KEY;
 
+// Headers that must not be forwarded to 9Router
+const STRIP_HEADERS = new Set([
+  "host", "content-length", "connection", "transfer-encoding",
+  "content-type", "authorization"
+]);
+
 /**
- * Send body to 9Router at the given path and return the fetch Response object
+ * Send body to 9Router at the given path and return the fetch Response object.
+ * Optionally forwards client headers (stripped of hop-by-hop / overridden keys).
  */
-async function fetchRouter(openaiBody, path = "/v1/chat/completions") {
+async function fetchRouter(openaiBody, path = "/v1/chat/completions", clientHeaders = {}) {
+  const forwarded = {};
+  for (const [k, v] of Object.entries(clientHeaders)) {
+    if (!STRIP_HEADERS.has(k.toLowerCase())) forwarded[k] = v;
+  }
+
   const response = await fetch(`${ROUTER_BASE}${path}`, {
     method: "POST",
     headers: {
+      ...forwarded,
       "Content-Type": "application/json",
       ...(API_KEY && { "Authorization": `Bearer ${API_KEY}` })
     },

src/mitm/handlers/copilot.js

@@ -23,7 +23,7 @@ async function intercept(req, res, bodyBuffer, mappedModel) {
     const body = JSON.parse(bodyBuffer.toString());
     body.model = mappedModel;
     const routerPath = resolveRouterPath(req.url);
-    const routerRes = await fetchRouter(body, routerPath);
+    const routerRes = await fetchRouter(body, routerPath, req.headers);
     await pipeSSE(routerRes, res);
   } catch (error) {
     err(`[copilot] ${error.message}`);

src/mitm/handlers/kiro.js

@@ -8,7 +8,7 @@ async function intercept(req, res, bodyBuffer, mappedModel) {
   try {
     const body = JSON.parse(bodyBuffer.toString());
     body.model = mappedModel;
-    const routerRes = await fetchRouter(body);
+    const routerRes = await fetchRouter(body, "/v1/chat/completions", req.headers);
     await pipeSSE(routerRes, res);
   } catch (error) {
     err(`[Kiro] ${error.message}`);