agents-lint pre-commit hook (#5286) flags AGENTS.md under .claude/worktrees/ as missing frontmatter

Inspect .pre-commit-config.yaml and .agents-lint.json, starting with the agents-lint hook's filename matching and existing ignore patterns. Reproduce the failure with a nested .claude/worktrees//AGENTS.md, then verify that the exclusion prevents nested copies from being linted while the repository root file remains checked.

agents-lint pre-commit hook flags any markdown under .claude/worktrees/ as a memory file missing frontmatter

PR #5286 ("docs: add repository agent guidance with root-only enforcement", still open/draft) adds an agents-lint local hook to .pre-commit-config.yaml:

-   id: agents-lint
    name: agents-lint (AGENTS.md freshness)
    entry: agents-lint
    language: node
    additional_dependencies: [agents-lint@0.5.0]
    files: ^(AGENTS|CLAUDE|GEMINI)\.md$
    pass_filenames: true

The files regex matches by basename pattern with no path exclusions, and .agents-lint.json on that branch only carries ignorePatterns for two unrelated theme/migration paths. The Claude Code harness creates git worktrees under .claude/worktrees/<name>/ when a task runs in an isolated worktree, and each such worktree contains its own checked-out copy of the repo root, including AGENTS.md. Committing inside one of those worktrees runs pre-commit against files under .claude/worktrees/<name>/AGENTS.md, which matches the hook's basename pattern and gets linted as if it were the repository's canonical memory file — failing with "Memory file is missing frontmatter" (or whatever agents-lint@0.5.0 expects) even when AGENTS.md is completely unchanged and passes fine in CI (which only ever lints the real root-level file, never a worktree copy).

Fix: add a path exclude for .claude/ (either as a hook-level exclude regex in .pre-commit-config.yaml, or an ignorePatterns entry in .agents-lint.json if the tool supports path-based excludes) so nested worktree copies of these filenames are never linted.

Found while committing to #5286 on 2026-09-13.