feat(core): orphan and reachability-based unused file detection

[ElijahKotyluk]

Changes:

• Switch unused file detection to a dependency-graph approach
• Files are now considered used if reachable from entry points via imports or re-exports
• When no entry points are present, fall back to orphan-file detection
• This fixes barrel modules and reduces false positives

[Copilot]

Pull request overview

This PR implements reachability-based file detection to improve unused file detection by building a file dependency graph and checking reachability from entry points. When entry points are detected (via package.json exports or conventions), files are marked as unused only if they're unreachable from those entry points; otherwise, the system falls back to orphan detection for files with no incoming references.

Key Changes:

• Enhanced entry point detection to parse package.json exports field (including conditional exports and arrays)
• Implemented file dependency graph construction that tracks both import and re-export relationships
• Added reachability analysis using graph traversal from entry points

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
tests/integrate/barrel.test.ts	Adds test verifying re-exported files aren't flagged as unused
tests/entrypoints/entrypoint-export.test.ts	New test suite for package.json exports field parsing (string, conditional object, array formats)
src/core/usage/buildUsageGraph.ts	Implements file dependency graph, reachability analysis, and module resolution logic for unused file detection
src/core/fileSystem/normalizePath.ts	Refactors variable names for clarity (normalizeCache → normalizedFileCache, abs → absolutePath)
src/core/entrypoints/detectEntryPoints.ts	Extends entry point detection to handle exports field, refactors mapping logic into separate functions

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 4 comments.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 8 comments.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.