detect() only read .gitignore/.graphifyignore in the scan root and its
ancestor directories (up to the nearest VCS root), loaded once before the
walk began. A .gitignore sitting in a descendant directory — e.g.
vendor/sub/.gitignore — was never read, so files/dirs it excluded leaked
into the graph. Real git (and every other gitignore-aware tool) honors
.gitignore at every directory level, not just the ancestor chain.
Extracts the per-directory read+parse logic into a shared
_load_dir_own_ignore() helper (used by both the existing ancestor-chain
loader and the new call site) and invokes it live inside detect()'s
os.walk loop for every directory visited, before that directory's
children are pruned — so a nested ignore file governs its own subtree
with the same closer-file-wins precedence git uses.
Adds three regression tests: nested file exclude, nested directory prune
(the walk never descends into it), and nested negation overriding a
broader root-level rule.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
