Re-pin to the cached chromium-1243 revision; full E2E suite green on 1.63.0. Approval recorded in the PLAN.md review history. LLM-Generated: true
Introduce .agents/ (PLAN.md with locked architectural anchors, phase roadmap under phases/todo/) and AGENTS.md rules for agents working in the repo. Queues the pending phases: fix history XSS, simulate fetch commands, and nginx security headers.