Add a sentinel-file escape hatch: if `.claude/skip-plan-file-check`
exists in the project's cwd, the ExitPlanMode hook exits 0 without
demanding a local *-PLAN.md file.
Needed by projects (e.g. agent-runtimes) that manage plans via an
external system (work-items CP) rather than local repo files.
Includes: spec-driven and test-driven development best practices,
reproduce-before-fixing debugging workflow, require-plan-file hook,
find-project-root script, session logs, memory files for decisions/
gotchas/process-lessons, and updates to existing best practice topics.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>