Upgraded three TypeScript rules from "warn" to "error": - explicit-function-return-type: Functions must declare return types - prefer-nullish-coalescing: Enforce ?? over || for null checks - prefer-optional-chain: Enforce ?. over && chains This tightens pre-commit enforcement to catch more issues mechanically before code review, reducing agent iteration cycles. Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>