From 3b33ee907528796fabab2bc8123074d0ddc87fd7 Mon Sep 17 00:00:00 2001
From: hariom888 <hariom880088@gmail.com>
Date: Sat, 16 May 2026 18:04:12 +0530
Subject: [PATCH] fix(gemini-adapter): pass request URL context so model isn't
 defaulted to gemini-1.5-flash

The standardFetch function called adapterRegistry.process(responseData) with only the response, never passing the request. The Gemini adapter's normalize() function accepts an optional request parameter to extract the model name, but it was always undefined, causing the model to always fall back to the hardcoded default 'gemini-1.5-flash'.

Fix: build a requestContext object { url, body } in standardFetch and pass it as the second argument to adapterRegistry.process(). Update the Gemini adapter to extract the model name from the URL pattern /models/MODEL:action.

The modelVersion field in the response still takes priority when present.

Other adapters (OpenAI, Anthropic) are unaffected because they ignore the extra argument.
---
 src/adapters/gemini.ts               | 22 ++++++++++++++++++----
 src/interceptors/fetchInterceptor.ts | 10 ++++++++--
 tsconfig.json                        |  2 +-
 3 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/src/adapters/gemini.ts b/src/adapters/gemini.ts
index e2bd28c..54a8020 100644
--- a/src/adapters/gemini.ts
+++ b/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;
     }
diff --git a/src/interceptors/fetchInterceptor.ts b/src/interceptors/fetchInterceptor.ts
index 3048ec4..05c8d25 100644
--- a/src/interceptors/fetchInterceptor.ts
+++ b/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
diff --git a/tsconfig.json b/tsconfig.json
index 759c90a..6b808c9 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -2,7 +2,7 @@
   "compilerOptions": {
     "target": "ES2020",
     "module": "commonjs",
-    "lib": ["ES2020"],
+    "lib": ["ES2020", "DOM"],
     "declaration": true,
     "outDir": "./dist",
     "rootDir": "./src",