when missing on disk
Mirror of the existing IsDir-branch behavior at line 873
(<project>/working → mdedit, <project>/staging → transmittal,
<project>/archive → archive) for the case where the folder doesn't
exist on disk yet. Without this, GET <project>/working on a fresh
project 404s instead of opening mdedit rooted at the (virtual)
working directory.
Behavior matrix for canonical project-root folders that don't yet
exist on disk:
GET <project>/archive → archive tool (project-root mode)
GET <project>/archive/ → empty browse listing
GET <project>/working → mdedit rooted at working/
GET <project>/working/ → empty browse listing (with synthetic
<viewer-email>/ home entry)
GET <project>/staging → transmittal rooted at staging/
GET <project>/staging/ → empty browse listing
GET <project>/reviewing → 301 to /reviewing/ (no default app)
GET <project>/reviewing/ → empty browse listing
GET <project>/random → 404 (still — non-canonical)
GET <project>/random/ → 404 (still — non-canonical)
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>