Update tRPC template for lazy initialization (#3974)

Aligns tRPC template with lazy warehouse initialization.

## Changes
- Add .env.example with DATABRICKS_WAREHOUSE_ID
- Integrate dotenv loading in template
- Update package dependencies
- Fix test environment setup
- Export appRouter for testing

## Dependencies
- Requires PR #3973 (lazy warehouse resolution)

## Testing
- Template files updated
- Follows lazy init pattern

Author: fjakobs

experimental/apps-mcp/lib/providers/io/provider.go

@@ -48,21 +48,19 @@ func (p *Provider) RegisterTools(server *mcpsdk.Server) error {
 
 	// Register scaffold_data_app
 	type ScaffoldInput struct {
-		WorkDir      string `json:"work_dir" jsonschema:"required" jsonschema_description:"Absolute path to the work directory"`
-		ForceRewrite bool   `json:"force_rewrite,omitempty" jsonschema_description:"Overwrite existing files if directory is not empty"`
+		WorkDir string `json:"work_dir" jsonschema:"required" jsonschema_description:"Absolute path to the work directory"`
 	}
 
 	mcpsdk.AddTool(server,
 		&mcpsdk.Tool{
 			Name:        "scaffold_data_app",
-			Description: "Initialize a project by copying template files from the default TypeScript (tRPC + React) template to a work directory. Supports force rewrite to wipe and recreate the directory. It sets up a basic project structure, and should be ALWAYS used as the first step in creating a new data or web app.",
+			Description: "Initialize a project by copying template files from the default TypeScript (tRPC + React) template to a work directory. It sets up a basic project structure, and should be ALWAYS used as the first step in creating a new data or web app.",
 		},
 		func(ctx context.Context, req *mcpsdk.CallToolRequest, args ScaffoldInput) (*mcpsdk.CallToolResult, any, error) {
 			log.Debugf(ctx, "scaffold_data_app called: work_dir=%s", args.WorkDir)
 
 			scaffoldArgs := &ScaffoldArgs{
-				WorkDir:      args.WorkDir,
-				ForceRewrite: args.ForceRewrite,
+				WorkDir: args.WorkDir,
 			}
 
 			result, err := p.Scaffold(ctx, scaffoldArgs)

experimental/apps-mcp/lib/providers/io/scaffold.go

@@ -6,17 +6,18 @@ import (
 	"errors"
 	"fmt"
 	"io/fs"
+	"os"
 	"path/filepath"
 
+	"github.com/databricks/cli/experimental/apps-mcp/lib/middlewares"
 	"github.com/databricks/cli/experimental/apps-mcp/lib/templates"
 	"github.com/databricks/cli/libs/filer"
 	"github.com/databricks/cli/libs/log"
 )
 
 // ScaffoldArgs contains arguments for scaffolding operation
 type ScaffoldArgs struct {
-	WorkDir      string `json:"work_dir"`
-	ForceRewrite bool   `json:"force_rewrite,omitempty"`
+	WorkDir string `json:"work_dir"`
 }
 
 // ScaffoldResult contains the result of a scaffold operation
@@ -52,16 +53,14 @@ func (p *Provider) Scaffold(ctx context.Context, args *ScaffoldArgs) (*ScaffoldR
 			return nil, err
 		}
 
-		if len(entries) > 0 && !args.ForceRewrite {
-			return nil, errors.New("work_dir is not empty (use force_rewrite to overwrite)")
+		allowedEntries := map[string]bool{
+			".git":    true,
+			".claude": true,
 		}
 
-		// Clear directory if force_rewrite
-		if args.ForceRewrite {
-			for _, entry := range entries {
-				if err := f.Delete(ctx, entry.Name(), filer.DeleteRecursively); err != nil {
-					return nil, fmt.Errorf("failed to delete %s: %w", entry.Name(), err)
-				}
+		for _, entry := range entries {
+			if !allowedEntries[entry.Name()] {
+				return nil, fmt.Errorf("work_dir is not empty: %s", entry.Name())
 			}
 		}
 	} else if !errors.Is(err, fs.ErrNotExist) {
@@ -93,6 +92,19 @@ func (p *Provider) Scaffold(ctx context.Context, args *ScaffoldArgs) (*ScaffoldR
 		filesCopied++
 	}
 
+	// write .env file
+	warehouseID, err := middlewares.GetWarehouseID(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get warehouse ID: %w", err)
+	}
+	host := middlewares.MustGetDatabricksClient(ctx).Config.Host
+
+	envContent := fmt.Sprintf("DATABRICKS_WAREHOUSE_ID=%s\nDATABRICKS_HOST=%s", warehouseID, host)
+	envPath := filepath.Join(workDir, ".env")
+	if err := os.WriteFile(envPath, []byte(envContent), 0o644); err != nil {
+		return nil, fmt.Errorf("failed to write .env file: %w", err)
+	}
+
 	log.Infof(ctx, "scaffolded project (template=%s, work_dir=%s, files=%d)",
 		template.Name(), workDir, filesCopied)
 

experimental/apps-mcp/lib/templates/trpc/.env.example

@@ -0,0 +1 @@
+DATABRICKS_WAREHOUSE_ID=<warehouse_id>

experimental/apps-mcp/lib/templates/trpc/server/drizzle.config.ts

@@ -1,4 +1,3 @@
-import 'dotenv/config';
 import { defineConfig } from 'drizzle-kit';
 
 export default defineConfig({

experimental/apps-mcp/lib/templates/trpc/server/package-lock.json

@@ -4,20 +4,19 @@
   "scripts": {
     "build": "tsc -p tsconfig.json",
     "check": "tsc -p tsconfig.json --noEmit",
-    "start": "tsx src/index.ts",
-    "dev": "tsx watch src/index.ts",
-    "db:push": "drizzle-kit push --force",
+    "start": "tsx --env-file-if-exists=../.env src/index.ts",
+    "dev": "tsx --env-file-if-exists=../.env watch src/index.ts",
+    "db:push": "drizzle-kit --env-file-if-exists=../.env push --force",
     "db:push-ci": "yes | npm run db:push",
     "lint": "eslint --cache src/index.ts",
-    "test": "node --test --import tsx src/*.test.ts"
+    "test": "node --env-file-if-exists=../.env --test --import tsx src/*.test.ts"
   },
   "dependencies": {
     "@databricks/sdk-experimental": "^0.14.2",
     "@databricks/sql": "^1.12.0",
     "@trpc/server": "^11.6.0",
     "@types/express": "^5.0.3",
     "cors": "2.8.5",
-    "dotenv": "16.4.7",
     "drizzle-orm": "0.40.0",
     "express": "^5.1.0",
     "pg": "8.14.0",

experimental/apps-mcp/lib/templates/trpc/server/package.json

@@ -22,7 +22,6 @@ import { type HeadersInit, Headers, ApiClient, Config } from "@databricks/sdk-ex
 import { DBSQLClient } from "@databricks/sql";
 import { z } from "zod";
 
-// Environment variables
 const warehouseId: string = process.env["DATABRICKS_WAREHOUSE_ID"] || "";
 const httpPath = `/sql/1.0/warehouses/${warehouseId}`;
 

experimental/apps-mcp/lib/templates/trpc/server/src/databricks.ts

@@ -1,4 +1,3 @@
-import 'dotenv/config';
 import { drizzle } from 'drizzle-orm/node-postgres';
 import { Pool } from 'pg';
 import * as schema from './schema';

experimental/apps-mcp/lib/templates/trpc/server/src/db/index.ts

@@ -1,7 +1,6 @@
 import { initTRPC } from "@trpc/server";
 import { createExpressMiddleware } from "@trpc/server/adapters/express";
 import express from "express";
-import "dotenv/config";
 import superjson from "superjson";
 import path from "node:path";
 import { z } from "zod";
@@ -29,6 +28,7 @@ const appRouter = router({
   // }),
 });
 
+export { appRouter };
 export type AppRouter = typeof appRouter;
 
 export const app = express();

experimental/apps-mcp/lib/templates/trpc/server/src/index.ts

@@ -1,6 +1,8 @@
 import { test } from "node:test";
 import { strict as assert } from "node:assert";
 import type { Server } from "node:http";
+import path from "node:path";
+import superjson from "superjson";
 
 test("server starts and responds to healthcheck", async () => {
   // dynamic import to ensure env vars are set first
@@ -38,7 +40,7 @@ test("server starts and responds to healthcheck", async () => {
 //   const { initTRPC } = await import("@trpc/server");
 //
 //   // create tRPC caller - no HTTP server needed
-//   const t = initTRPC.create();
+//   const t = initTRPC.create({transformer: superjson});
 //   const caller = t.createCallerFactory(appRouter)({});
 //
 //   const result = await caller.getUsers();
@@ -58,7 +60,7 @@ test("server starts and responds to healthcheck", async () => {
 //   const t = initTRPC.create();
 //   const caller = t.createCallerFactory(appRouter)({});
 //
-//   const result = await caller.getMetrics({ category: "sales" });
+//   const result = await caller['getMetrics']({ category: "sales" });
 //
 //   assert.ok(Array.isArray(result));
 //   // add assertions for your expected data structure