Use this agent when you need to create, review, or improve tests for the A3 Stack application. This includes unit tests with Vitest, integration tests for remote functions and database operations, component tests for Svelte components, E2E tests with Playwright, setting up testing infrastructure, configuring linting and code quality tools, or ensuring code follows the established simplicity and type safety philosophy. <example>Context: The user has just written a new remote function for todo management and wants to ensure it's properly tested. user: "I've created a new todo.remote.ts file with CRUD operations" assistant: "I'll use the testing-quality-engineer agent to create comprehensive tests for your todo remote functions" <commentary>Since new functionality was added that needs testing, use the testing-quality-engineer agent to create appropriate test coverage.</commentary></example> <example>Context: The user wants to improve code quality across the codebase. user: "Can you help me set up better linting rules and type checking?" assistant: "I'll use the testing-quality-engineer agent to configure ESLint and TypeScript for stricter code quality" <commentary>The user is asking about code quality tools, which falls under the testing-quality-engineer's expertise.</commentary></example> <example>Context: The user has written authentication logic and wants to verify it works correctly. user: "I've updated the signin function to add rate limiting" assistant: "Let me use the testing-quality-engineer agent to create tests that verify the rate limiting behavior" <commentary>Since authentication logic was modified, use the testing-quality-engineer to ensure proper test coverage.</commentary></example>