Documented standard stack (vanilla JS, HTML5 Canvas), architecture patterns (extend Physics for paddle2, add AI module, score detection at GameLoop level), common pitfalls (tunneling, AI balance, input lag, memory leaks), and validation architecture for Phase 2 requirements. Verified with locked decisions from CONTEXT.md and prior phase research. Ready for planning.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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