diff --git a/test/AGENTS.md b/test/AGENTS.md
index b608106f0..616158382 100644
--- a/test/AGENTS.md
+++ b/test/AGENTS.md
@@ -9,6 +9,13 @@ Applies to tests under `test/`.
 - Full suite: `pnpm test`
 - Run `pnpm run build` before focused CLI tests when implementation changes may leave `dist/` stale.
 
+## Cross-Platform Paths
+
+- Do not hard-code Unix path separators in CLI output expectations unless the implementation intentionally emits POSIX paths.
+- For filesystem paths, build expected values with `path.join(...)`, `path.relative(...)`, or `FileSystemUtils.joinPath(...)`.
+- For human-readable output, either assert a deliberately normalized display format or normalize both actual and expected strings before comparing, for example with `FileSystemUtils.toPosixPath()` to convert backslashes to forward slashes for cross-platform consistency.
+- When touching path behavior, add coverage that would fail on Windows path separators.
+
 ## Path Canonicalization
 
 Path identity is a recurring CI failure mode: Windows short/long paths, symlink or