Create test plans and conduct user testing to validate product quality. Use this skill whenever the user needs a test plan, says 'test plan', '测试计划', '验收测试', 'QA plan', '用户测试', '可用性测试', 'usability test', or needs to verify features work as expected. Also trigger when the user says 'how do we test this', 'verify it works', 'what should we test', or 'let's test with users'. Converts vague 'it should work' into structured test cases covering happy paths, edge cases, and error handling.
