Prompt Templates

You are about to implement a new API endpoint. You open Cursor and type: “Add a POST endpoint for creating orders.” Agent generates something, but it misses validation, uses the wrong error format, and does not follow your existing patterns. So you spend the next five messages correcting it: “add Zod validation,” “use our error format,” “follow the pattern in users.ts.” By message six, you have typed more corrective instructions than it would have taken to write the endpoint yourself.

The fix is not better prompting intuition. It is prompt templates — pre-built, tested prompts that you paste and customize in seconds. They front-load the instructions the AI needs so the first output is usable.

What You’ll Walk Away With

• A library of copy-paste prompts for the most common development tasks
• A framework for building your own project-specific prompt templates
• Techniques for storing prompts as Cursor rules and custom commands
• Understanding of what makes a prompt effective versus wasteful

What Makes a Good Prompt Template

An effective Cursor prompt has four elements:

1. The task — What you want the AI to do
2. The constraints — What patterns, files, or conventions to follow
3. The boundaries — What NOT to do (prevents scope creep)
4. The verification — How to confirm the output is correct

Feature Implementation Templates

New API Endpoint

Tip

Copy-paste prompt: New API endpoint

Create a POST /api/orders endpoint.

Requirements:
- Validate the request body with Zod (schema in src/schemas/order.ts)
- Use the order service from @src/services/order-service.ts
- Return 201 on success with the created order
- Return 400 for validation errors using our error format from @src/lib/errors.ts
- Require authentication via the withAuth middleware

Follow the exact pattern in @src/routes/users.ts for route structure, error handling, and response format.

After creating the endpoint, add it to the route registry in @src/app.ts.
Do NOT modify any existing endpoints.

New React Component

Tip

Copy-paste prompt: New React component

Create a UserNotificationPreferences component in src/components/UserNotificationPreferences.tsx.

Requirements:
- Accept props: { userId: string, onSave: (prefs: NotificationPrefs) => void }
- Fetch current preferences from GET /api/users/:userId/notification-preferences
- Show toggles for: email, push, sms, weekly digest
- Include a Save button that calls PATCH with the updated preferences
- Handle loading, error, and success states
- Use our existing UI components from @src/components/ui/ (Button, Switch, Card)
- Follow the component pattern in @src/components/UserProfile.tsx

Do NOT create new API endpoints. The endpoints already exist.

Database Migration

Tip

Copy-paste prompt: Database migration

Create a database migration to add an orders table.

Columns:
- id: UUID primary key (default gen_random_uuid())
- user_id: UUID foreign key to users.id, not null
- status: enum ('pending', 'confirmed', 'shipped', 'delivered', 'cancelled'), default 'pending'
- total_amount: decimal(10,2), not null
- created_at: timestamp with timezone, default now()
- updated_at: timestamp with timezone, default now()

Add an index on user_id and status.

Follow the migration pattern in @src/db/migrations/. Use our ORM (Drizzle) for the schema definition in @src/db/schema.ts.

Run the migration to verify it works.

Debugging Templates

General Bug Investigation

Tip

Copy-paste prompt: Bug investigation

I am seeing this error: [PASTE ERROR MESSAGE HERE]

It happens when: [DESCRIBE THE TRIGGER]
Expected behavior: [WHAT SHOULD HAPPEN]
Actual behavior: [WHAT ACTUALLY HAPPENS]

Relevant files: @src/services/[relevant-service].ts

Investigate the root cause. Do not make changes yet -- just explain what is causing the issue and propose a fix with your reasoning.

Performance Investigation

Tip

Copy-paste prompt: Performance debugging

The [ENDPOINT/PAGE] is slow -- taking [X] seconds when it should take under [Y] seconds.

Analyze @src/[relevant-path] and identify:
1. Any N+1 database queries
2. Any synchronous operations that could be parallelized
3. Any unnecessary data fetching
4. Any missing database indexes

For each issue found, explain the performance impact and provide a specific fix.
Do not make changes yet -- I want to review your analysis first.

Refactoring Templates

Extract and Restructure

Tip

Copy-paste prompt: Refactoring

Refactor @src/services/user-service.ts to split it into focused modules:

1. @src/services/user/authentication.ts -- login, logout, token refresh
2. @src/services/user/profile.ts -- get profile, update profile, delete account
3. @src/services/user/preferences.ts -- notification settings, privacy settings

Requirements:
- Preserve all existing function signatures (no breaking changes)
- Re-export everything from a new @src/services/user/index.ts barrel file
- Update all imports across the codebase
- Run the test suite after changes to verify nothing broke

Commit-worthy output: all tests should pass after this refactor.

Testing Templates

Test Suite Generation

Tip

Copy-paste prompt: Generate test suite

Write a comprehensive test suite for @src/services/order-service.ts.

Test file: src/services/__tests__/order-service.test.ts

Requirements:
- Use Vitest with the patterns from @src/services/__tests__/user-service.test.ts
- Mock the database layer (never hit a real database)
- Mock external API calls (payment provider, email service)
- Cover: happy path, validation errors, permission errors, database errors, edge cases
- Use factory functions for test data, not inline objects
- Each test should have a descriptive name: "should [expected behavior] when [condition]"

Run the tests after writing them. Fix any failures.

Code Review Template

Tip

Copy-paste prompt: Pre-PR review

Review all changes on the current branch compared to main (use git diff main...HEAD).

Check for:
1. Security: injection vulnerabilities, missing auth, hardcoded secrets
2. Error handling: uncaught promises, missing try/catch, generic error messages
3. Performance: N+1 queries, unnecessary re-renders, blocking operations
4. Consistency: does the code follow our existing patterns?
5. Testing: are new code paths covered by tests?
6. Imports: any packages imported that are not in package.json?

For each issue, provide the file, line number, the problem, and a specific fix.
Do not make any changes.

Storing Templates as Rules and Commands

As a Custom Command

Save frequently used prompts as custom commands in .cursor/commands/:

---
description: Generate a comprehensive test suite for a service
---

Write a comprehensive test suite for the file I mention.

- Use Vitest
- Mock external dependencies
- Cover happy path, error cases, and edge cases
- Use factory functions for test data
- Run tests after writing them

Invoke with /generate-tests @src/services/payment-service.ts in chat.

As a Rule

For patterns that should always apply to certain file types:

---
globs: "src/routes/**/*.ts"
---

When creating or modifying API routes:
- Always validate request bodies with Zod
- Always use withAuth middleware unless the route is explicitly public
- Always return errors using AppError from @src/lib/errors.ts
- Always log the request and response using the logger

When This Breaks

Templates produce output that does not match your project. The template references patterns from a generic project. Update the @file references to point to your actual canonical examples.

Agent ignores parts of the template. Very long prompts (over 500 words) cause the agent to lose focus on later instructions. Move recurring constraints into rules so the prompt only contains task-specific information.

Templates feel rigid. They are starting points, not scripts. Delete the parts that do not apply and add context specific to the current task.

What’s Next

• Context Patterns — How to provide the right @file references in your prompts
• Debugging Workflows — Systematic debugging beyond the template level
• Testing Patterns — Deep dive into AI-assisted testing strategies