The previous fix in fs.ListDirectory was insufficient — main.go's
dispatcher calls os.Stat(absPath) before reaching ServeDirectory,
and 404s on the missing path before the listing code ever runs.
Symptom: GET <project>/working/ on a fresh project still returned
"Not Found" despite the read-side fallback being committed.
Add the same fallback at the dispatcher level: when os.Stat returns
NotExist AND the URL ends with "/" AND the path matches
IsProjectRootFolder, fall through to ServeDirectory rather than
404. ServeDirectory's ACL check + ListDirectory's empty-listing
behavior take it from there.
Separately, fs.ListDirectory now initializes its result slice to
make([]listing.FileInfo, 0) instead of `var result []listing.FileInfo`,
so the JSON encoder emits "[]" rather than "null" for empty
listings — clients (browse, archive) expect an array and choke on
null.
New test TestDispatchEmptyCanonicalProjectFolders covers the four
canonical names (archive/working/staging/reviewing) on a project
where none of them exist on disk yet, plus the negative case (a
non-canonical missing path still 404s).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>