The campaign is a folder. The apps just visit.

What Hexes writes

One export produces a region tree like this. Every note carries a stable oa_id, so links keep working after renames.

your-campaign/
├── regions/greenfield/
│   ├── region.md              overview, factions sketch, road & travel table
│   ├── hexes/                 one note per content hex (terrain, features,
│   │   ├── hex-0302.md        obstacles, residents, field description)
│   │   └── ...
│   ├── settlements/           a stub per town — Towns on Automatic's future inbox
│   ├── sites/                 a stub per dungeon site
│   └── state/                 the machine copy Hexes reopens (hoa-*.json)
├── factions/              faction notes + relationship map
├── commissions/
│   └── the-sunken-grotto.request.json   work order for Dungeons on Automatic
└── _index/                compiled ids and relationships (validator output)

The rules that keep it safe

• One writer per file. Each note is owned by the app that minted it; nothing else touches it. Cross-app references live in oa_refs frontmatter, never in app state.
• Generated prose sits in fences. Machine text lives between oa:generated markers. Everything you write outside them is never overwritten, on any re-export.
• Locks freeze what you've settled. Mark a note's content, narrative or geometry with oa_locks and regeneration leaves it alone.
• No app required. It's markdown. Obsidian gets wikilinks and the relationship map for free; git, grep and a text editor all work.

Sites become dungeons by paperwork

Hexes places a dungeon site and knows only what the overworld knows: where it sits, what terrain surrounds it, roughly what lives nearby. That's exactly what goes in the work order.

• Every site export includes commissions/<site>.request.json: a SiteCommission envelope with a coordinate-derived seed, terrain and context. Existing files are never overwritten.
• Dungeons on Automatic reads the envelope and builds the keyed dungeon — maps, room key, encounters, treasure, VTT exports.
• The linkage is recorded in the vault. The dungeon never learns about the world, and the world never reaches into the dungeon; the folder holds the thread between them.