fromInternalFilesDir
fun FileArtifactService.Companion.fromInternalFilesDir(context: Context, subDir: String = FileArtifactService.DEFAULT_ARTIFACTS_SUBDIR): FileArtifactService
Builds a FileArtifactService rooted at <internal files dir>/<subDir> (Context.getFilesDir).
Internal storage is always available and app-private. Prefer fromExternalFilesDir for artifacts (user content); use this when you specifically want internal storage.
Multiple agents in the same app can isolate their artifacts by passing a distinct subDir. Uses Context.getApplicationContext internally to avoid leaking an Activity.