diff --git a/extensions/google-gemini-cli-auth/oauth.test.ts b/extensions/google-gemini-cli-auth/oauth.test.ts
index 018eae78dd6..3d5df634ff6 100644
--- a/extensions/google-gemini-cli-auth/oauth.test.ts
+++ b/extensions/google-gemini-cli-auth/oauth.test.ts
@@ -96,6 +96,41 @@ describe("extractGeminiCliCredentials", () => {
     return layout;
   }
 
+  function installNpmShimLayout(params: { oauth2Exists?: boolean; oauth2Content?: string }) {
+    const binDir = join(rootDir, "fake", "npm-bin");
+    const geminiPath = join(binDir, "gemini");
+    const resolvedPath = geminiPath;
+    const oauth2Path = join(
+      binDir,
+      "node_modules",
+      "@google",
+      "gemini-cli",
+      "node_modules",
+      "@google",
+      "gemini-cli-core",
+      "dist",
+      "src",
+      "code_assist",
+      "oauth2.js",
+    );
+    process.env.PATH = binDir;
+
+    mockExistsSync.mockImplementation((p: string) => {
+      const normalized = normalizePath(p);
+      if (normalized === normalizePath(geminiPath)) {
+        return true;
+      }
+      if (params.oauth2Exists && normalized === normalizePath(oauth2Path)) {
+        return true;
+      }
+      return false;
+    });
+    mockRealpathSync.mockReturnValue(resolvedPath);
+    if (params.oauth2Content !== undefined) {
+      mockReadFileSync.mockReturnValue(params.oauth2Content);
+    }
+  }
+
   beforeEach(async () => {
     vi.clearAllMocks();
     originalPath = process.env.PATH;
@@ -127,6 +162,19 @@ describe("extractGeminiCliCredentials", () => {
     });
   });
 
+  it("extracts credentials when PATH entry is an npm global shim", async () => {
+    installNpmShimLayout({ oauth2Exists: true, oauth2Content: FAKE_OAUTH2_CONTENT });
+
+    const { extractGeminiCliCredentials, clearCredentialsCache } = await import("./oauth.js");
+    clearCredentialsCache();
+    const result = extractGeminiCliCredentials();
+
+    expect(result).toEqual({
+      clientId: FAKE_CLIENT_ID,
+      clientSecret: FAKE_CLIENT_SECRET,
+    });
+  });
+
   it("returns null when oauth2.js cannot be found", async () => {
     installGeminiLayout({ oauth2Exists: false, readdir: [] });
 
diff --git a/extensions/google-gemini-cli-auth/oauth.ts b/extensions/google-gemini-cli-auth/oauth.ts
index 7977ab52981..bba4c6b1f39 100644
--- a/extensions/google-gemini-cli-auth/oauth.ts
+++ b/extensions/google-gemini-cli-auth/oauth.ts
@@ -71,41 +71,45 @@ export function extractGeminiCliCredentials(): { clientId: string; clientSecret:
     }
 
     const resolvedPath = realpathSync(geminiPath);
-    const geminiCliDir = dirname(dirname(resolvedPath));
-
-    const searchPaths = [
-      join(
-        geminiCliDir,
-        "node_modules",
-        "@google",
-        "gemini-cli-core",
-        "dist",
-        "src",
-        "code_assist",
-        "oauth2.js",
-      ),
-      join(
-        geminiCliDir,
-        "node_modules",
-        "@google",
-        "gemini-cli-core",
-        "dist",
-        "code_assist",
-        "oauth2.js",
-      ),
-    ];
+    const geminiCliDirs = resolveGeminiCliDirs(geminiPath, resolvedPath);
 
     let content: string | null = null;
-    for (const p of searchPaths) {
-      if (existsSync(p)) {
-        content = readFileSync(p, "utf8");
+    for (const geminiCliDir of geminiCliDirs) {
+      const searchPaths = [
+        join(
+          geminiCliDir,
+          "node_modules",
+          "@google",
+          "gemini-cli-core",
+          "dist",
+          "src",
+          "code_assist",
+          "oauth2.js",
+        ),
+        join(
+          geminiCliDir,
+          "node_modules",
+          "@google",
+          "gemini-cli-core",
+          "dist",
+          "code_assist",
+          "oauth2.js",
+        ),
+      ];
+
+      for (const p of searchPaths) {
+        if (existsSync(p)) {
+          content = readFileSync(p, "utf8");
+          break;
+        }
+      }
+      if (content) {
         break;
       }
-    }
-    if (!content) {
       const found = findFile(geminiCliDir, "oauth2.js", 10);
       if (found) {
         content = readFileSync(found, "utf8");
+        break;
       }
     }
     if (!content) {
@@ -124,6 +128,30 @@ export function extractGeminiCliCredentials(): { clientId: string; clientSecret:
   return null;
 }
 
+function resolveGeminiCliDirs(geminiPath: string, resolvedPath: string): string[] {
+  const binDir = dirname(geminiPath);
+  const candidates = [
+    dirname(dirname(resolvedPath)),
+    join(dirname(resolvedPath), "node_modules", "@google", "gemini-cli"),
+    join(binDir, "node_modules", "@google", "gemini-cli"),
+    join(dirname(binDir), "node_modules", "@google", "gemini-cli"),
+    join(dirname(binDir), "lib", "node_modules", "@google", "gemini-cli"),
+  ];
+
+  const deduped: string[] = [];
+  const seen = new Set<string>();
+  for (const candidate of candidates) {
+    const key =
+      process.platform === "win32" ? candidate.replace(/\\/g, "/").toLowerCase() : candidate;
+    if (seen.has(key)) {
+      continue;
+    }
+    seen.add(key);
+    deduped.push(candidate);
+  }
+  return deduped;
+}
+
 function findInPath(name: string): string | null {
   const exts = process.platform === "win32" ? [".cmd", ".bat", ".exe", ""] : [""];
   for (const dir of (process.env.PATH ?? "").split(delimiter)) {