fix(gemini-adapter): pass request URL context for model extraction

src/adapters/gemini.ts

@@ -38,14 +38,28 @@ export const geminiAdapter: ProviderAdapter = {
       throw new Error("TokenFirewall: Invalid Gemini response format");
     }
 
-    // Extract model from request or use default
+    // Extract model from request context or use default
     let model = "gemini-1.5-flash";
     if (request && typeof request === "object") {
-      const req = request as { model?: string };
-      if (req.model) {
-        model = req.model;
+      const req = request as { url?: string; model?: string };
+
+      // Try to extract model from the Gemini URL: /models/MODEL_NAME:generateContent
+      if (req.url) {
+        const match = req.url.match(/\/models\/([^/:]+)[:/]/);
+        if (match) {
+          model = match[1];
+        }
+      }
+
+      // Fallback: explicit model field in request body
+      if (!model || model === "gemini-1.5-flash") {
+        if (req.model) {
+          model = req.model;
+        }
       }
     }
+
+    // modelVersion in the response always wins if present (most accurate)
     if (resp.modelVersion) {
       model = resp.modelVersion;
     }

src/interceptors/fetchInterceptor.ts

@@ -75,9 +75,15 @@ async function standardFetch(
   // Process response and track budget BEFORE returning
   try {
     const responseData = await clonedResponse.json();
-
+
+    // Build a request context so adapters can read the model/URL
+    const url = typeof input === 'string'
+      ? input
+      : (input instanceof Request ? input.url : String(input));
+    const requestContext = { url, body: init?.body };
+
     // Try to process with adapter registry
-    const normalizedUsage = adapterRegistry.process(responseData);
+    const normalizedUsage = adapterRegistry.process(responseData, requestContext);
 
     if (normalizedUsage) {
       // Calculate cost

tsconfig.json

@@ -2,7 +2,7 @@
   "compilerOptions": {
     "target": "ES2020",
     "module": "commonjs",
-    "lib": ["ES2020"],
+    "lib": ["ES2020", "DOM"],
     "declaration": true,
     "outDir": "./dist",
     "rootDir": "./src",