## Source Repository
-No canonical upstream repository with UFO or Glyphs sources was found.
+The `googlefontdirectory-hg` monorepo (the historical Google Font Directory Mercurial archive) contains files for this family.
-## What Was Done
+- **Repository**: `googlefontdirectory-hg`
+- **Commit**: `52f780bc9d197280a9f430574e179a5f233c56b6`
+- **Source path**: `ribeyemarrow/src/`
+
+## Source Files
+
+The `ribeyemarrow/src/` directory contains design sources in VFB (FontLab) and SFD (FontForge) formats, neither of which can be built with gftools-builder:
+
+- **VFB** (FontLab, proprietary format, not buildable with gftools): RibeyeMarrow-Regular-OTF.vfb, RibeyeMarrow-Regular-TTF.vfb
+- **SFD** (FontForge, not buildable with gftools-builder): RibeyeMarrow-Regular-TTF.sfd
+- **OTF** (compiled binaries, not design sources): RibeyeMarrow-Regular.otf
+- **Other**: RibeyeMarrow.ai
+
+## Buildability
+
+Not buildable with gftools-builder. The sources are in VFB (FontLab proprietary) and SFD (FontForge) formats. Neither format is supported by gftools-builder. Conversion to UFO or Glyphs format would be required.
+
+## Investigation Details
The same search effort as for Ribeye was applied. Brian J. Bonislawsky of Astigmatic is the designer of both Ribeye and Ribeye Marrow. The GitHub accounts `ASTIGMATIC`, `astigmatic`, and `AOETI` were checked, with no repository found for Ribeye Marrow. No public source repository was identified for any Astigmatic fonts.