Designed comprehensive test plans and detailed test cases from system requirements and user stories, writing scenarios and acceptance criteria in Gherkin and keeping plans ready for ~90% of features before development started. Performed structured manual, regression, and exploratory testing on a SaaS logistics platform, validating 3-6 features per week across API endpoints, web UI, and mobile interfaces with a one-day average turnaround. Validated API endpoints and user interfaces end-to-end, uncovering edge cases in third-party integrations and complex routing business rules, blocking ~25% of tested tasks from release with documented defects. Tracked, documented and managed defects through their full lifecycle using Jira and Xray, collaborating closely with developers and PMs under Scrum to ensure timely resolution. Developed and maintained automated test scripts in Playwright (TypeScript) over three years, integrated into CI/CD pipelines triggered on deploy tags, plus API automation in Postman and mobile automation bootstrapped with Appium. Built AI-powered QA agents that compare pull requests against test plans and assess automation scope, applying reusable ISTQB-based skills for consistent, auditable test design.