Delete mcp.json if it exists since this will only be confusing. (#10107)

* Delte mcp.json if it exists since this will only be confusing to the user.

* Test

Author: christhompsongoogle

src/firebase_studio/migrate.spec.ts

@@ -56,6 +56,7 @@ describe("migrate", () => {
     let commandStub: sinon.SinonStub;
     let trackStub: sinon.SinonStub;
     let confirmStub: sinon.SinonStub;
+    let unlinkStub: sinon.SinonStub;
     let spawnStub: sinon.SinonStub;
 
     beforeEach(() => {
@@ -103,7 +104,7 @@ describe("migrate", () => {
 
       writeFileStub = sandbox.stub(fs, "writeFile").resolves();
       mkdirStub = sandbox.stub(fs, "mkdir").resolves();
-      sandbox.stub(fs, "unlink").resolves();
+      unlinkStub = sandbox.stub(fs, "unlink").resolves();
       sandbox.stub(fs, "readdir").resolves([]);
       accessStub = sandbox.stub(fs, "access").rejects({ code: "ENOENT" });
 
@@ -503,6 +504,11 @@ describe("migrate", () => {
       expect(confirmStub.called).to.be.true;
     });
 
+    it("should delete .idx/mcp.json if it exists", async () => {
+      await migrate(testRoot);
+      expect(unlinkStub.calledWith(path.join(testRoot, ".idx", "mcp.json"))).to.be.true;
+    });
+
     it("should configure Dart MCP server for Flutter apps if dart is available", async () => {
       accessStub.withArgs(sinon.match("pubspec.yaml")).resolves();
       commandStub.withArgs("dart").returns(true);

src/firebase_studio/migrate.ts

@@ -587,6 +587,15 @@ async function cleanupUnusedFiles(rootPath: string): Promise<void> {
     const message = err instanceof Error ? err.message : String(err);
     logger.debug(`Could not delete ${modifiedPath}: ${message}`);
   }
+
+  const mcpJsonPath = path.join(rootPath, ".idx", "mcp.json");
+  try {
+    await fs.unlink(mcpJsonPath);
+    logger.info("✅ Cleaned up .idx/mcp.json");
+  } catch (err: unknown) {
+    const message = err instanceof Error ? err.message : String(err);
+    logger.debug(`Could not delete ${mcpJsonPath}: ${message}`);
+  }
 }
 
 /**