Agents sometimes fail to resolve relative paths to reference files

[williamthorsen]

Paths to reference files are given in Markdown link format relative to the containing SKILL.md file (e.g., Follow the naming rules in [naming-conventions.md](../_data/naming-conventions.md):). This is normal Markdown practice.

But sometimes an agent will resolve the file relative to its ~/.{agent}/skills directory and fail to find the reference document.

[williamthorsen]

Implementation insights

Anchor-only link bug caught by review cycle. The regex in rewriteMarkdownPaths matched [text](#section) as a relative path because the guard conditions only checked for https?://, /, and ~ prefixes. When target = '#saving', hashIndex is 0, so pathPart = '' and path.posix.join(fileDir, '') collapses to fileDir — rewriting the link to ~/.claude/skills/prepare-pr#saving instead of leaving it unchanged. At least 10 skill files use anchor-only links and would have been corrupted in copy-mode install. Fix: target.startsWith('#') guard.

Integration test target selection. commit/SKILL.md uses backtick-quoted paths (`../_data/commit-format.md`) rather than Markdown link syntax, making it unsuitable as an integration test target despite being the most obvious candidate. Tests use code-patterns/SKILL.md and review-criteria/SKILL.md instead, which contain actual [text](path) links.