Dedup skill files by exact path, not case-folded path

[PratikDhanave]

Problem

discoverResourceFiles and discoverScriptFiles deduplicate discovered files using a case-folded key:

key := strings.ToLower(filePath)
if seen[key] { return }
seen[key] = true

but keep the original-case path as the file Name. On a case-sensitive filesystem (Linux — the primary CI target) two genuinely distinct files in the same skill directory that differ only in case collapse to one seen key, so the second is silently dropped:

• Data.json and data.json → only one resource discovered
• Run.py and run.py → only one script discovered

The lowercasing isn't needed for the dedup's actual purpose (guarding against the same path being visited twice) and has no comment justifying case-insensitivity.

Fix

Dedup by the exact filePath. Same-path revisits are still collapsed; distinct files differing only in case are both kept.

Test

TestFileSource_CaseSensitiveFS_KeepsDistinctlyCasedFiles (black-box) uses a case-sensitive fstest.MapFS (map keys are always case-sensitive, unlike os.DirFS on a case-insensitive host such as macOS) containing Data.json/data.json and Run.py/run.py, and asserts 2 resources and 2 scripts are discovered. Fails on main (gets 1 each), passes with the fix.

[Copilot]

Pull request overview

This PR fixes file discovery deduplication in the file-system-backed skills source so that it deduplicates by the exact discovered path rather than a case-folded path, preserving distinct files that differ only by case on case-sensitive filesystems (e.g., Linux).

Changes:

• Update discoverResourceFiles to deduplicate by filePath (exact path) instead of strings.ToLower(filePath).
• Update discoverScriptFiles to deduplicate by filePath (exact path) instead of strings.ToLower(filePath).
• Add a regression test using fstest.MapFS to ensure distinctly-cased resource and script files are both discovered.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
agent/skills/fsskills/source.go	Switch resource/script dedup keys from case-folded paths to exact paths to avoid collapsing distinct files on case-sensitive FS.
agent/skills/fsskills/source_script_test.go	Add a black-box regression test validating discovery keeps Data.json/data.json and Run.py/run.py as separate entries.

---

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