Agent skill files and AGENTS.md can grow unbounded, making them harder to maintain and reason about. This adds a pre-commit hook that enforces a 500-line ceiling and tells contributors exactly how to fix violations.

Changes

• hooks/check-agent-file-sizes.py — new bespoke hook; scans AGENTS.md and all */SKILL.md files under a given skills directory, reports files over the limit with actionable remediation advice:
  • SKILL.md violations → split into sub-skills
  • AGENTS.md violations → move general instructions into separate referenced files
• .pre-commit-config.yaml — wires the hook at priority: 0 alongside check-skills-documented; all limits and paths are passed as args so the script is project-agnostic

ERROR: The following agent files exceed the 500-line limit:
  .agents/skills/some-big-skill/SKILL.md: 512 lines (limit: 500)

To fix these violations:
  - For SKILL.md files: split the skill into sub-skills, each in its own subdirectory under .agents/skills/.
  - For AGENTS.md: move general instructions into separate files referenced from AGENTS.md.