Summary

A filter rule like

mobile:
  - 'mobile/**'
  - '!mobile/**/*.md'
  - '!mobile/.config/**'
  - '.github/workflows/test_mobile.yml'

matched nearly every file in a PR — including completely unrelated paths like web/src/foo.tsx — under the default some predicate quantifier.

Each YAML pattern was compiled into its own picomatch matcher and combined via Array.prototype.some. A bare !**/*.md matcher returns true for any file that isn't a markdown file, so once it was OR'd with the positive patterns the whole rule collapsed into "match anything not in the negation set" — the inverse of what authors intended.

This change groups bare string patterns into a single matcher with gitignore-style semantics under the default quantifier:

A file matches a rule when it matches at least one positive pattern AND does not match any negation pattern.

The every quantifier path is left untouched: per-pattern matching under .every() already produces correct subtractive semantics with negations and is the documented escape hatch in the README's "Detect changes in folder only for some file extensions" example.

Behavior changes

The third row is the only case where previously-broken-but-permissive behavior becomes a hard error. The previous behavior matched every non-negated file, which is almost never what the author wanted — failing loudly is better than silently flipping rule polarity.

What changed

• src/filter.ts

  • parseFilterItemYaml now collects bare string patterns from a (possibly nested via YAML anchor) array and builds a single combined matcher via groupedStringMatcher.
  • New compileStatusPattern routes status-tagged string-array patterns through the same gitignore-style grouping so added: ['src/**', '!**/*.md'] behaves correctly.
  • New collectArrayItems recursively flattens nested arrays from YAML anchors and partitions leaves into raw string patterns vs. fully parsed FilterRuleItems.
  • groupedStringMatcher distinguishes leading-! gitignore-style negations from !(extglob) single-pattern strings (the latter are passed straight to picomatch).
  • Rules that resolve to only negation patterns (no positive include) are rejected via throwInvalidFormatError.

• __tests__/filter.test.ts adds five regression tests:

  • The exact filter from the issue body.
  • Negation patterns inherited via YAML anchors.
  • Mixing string patterns and status-tagged patterns.
  • Status-tagged array form (added: ['src/**', '!**/*.md']).
  • Negations-only rules (bare and status-tagged) throwing at parse time.

• dist/index.js regenerated to match.

Closes #260