What is a collection?
On this page
In one sentence
A collection is a small app of your own that Claude builds for you.
Say “I want to keep track of restaurants — name, cuisine, whether I’ve been, and a rating” and Claude builds a table with exactly those fields. What you get:
- A table you can sort and search
- A calendar, if there is a date
- A kanban board (cards you drag between columns), if there is a choice like “To do / Doing / Done”
- Reminders, such as “notify me while it’s unfinished” or “10 days before the due date”
- Buttons such as “Create invoice” that make Claude do the work
- Custom views — screens with a look you design yourself
And after it exists, you can say “add a notes field” or “only let me rate after I’ve visited” and it changes on the spot. We call this vibe crafting: building your tools by talking.
Inside: a blueprint and records
A collection is just two things:
| What | Example | |
|---|---|---|
| Blueprint | schema.json — which fields exist and how to show them |
“Name is text, rating is 1–5” |
| Records | One file per record (<id>.json) |
ramen-taro.json holds one restaurant |
There is no database. The folder and its files are the app. So you can open the data as ordinary files, back it up, or hand it to someone.
Curious about the blueprint? See How schema.json works. You do not need it to create or use a collection.
Where are the files?
Inside your workspace (normally ~/mulmoclaude):
~/mulmoclaude/
├── data/
│ ├── skills/
│ │ └── restaurants/ ← the collection itself (blueprint, etc.)
│ │ ├── SKILL.md ← instructions for Claude
│ │ ├── schema.json ← the blueprint
│ │ ├── views/ ← custom views (if any)
│ │ └── templates/ ← what a button asks Claude to do (if any)
│ └── restaurants/
│ └── items/ ← records, one file each
│ ├── ramen-taro.json
│ └── sushi-hana.json
└── .claude/skills/restaurants/ ← a copy MulmoClaude makes automatically
.claude/skills/ holds a copy MulmoClaude maintains for you. Do not edit it by hand.
To change the blueprint, asking Claude is the most reliable way.
The collection’s folder name (e.g. restaurants) is its slug. It is also its address:
http://localhost:3001/collections/restaurants.
How does Claude know how to build one?
At startup MulmoClaude places a how-to for collections in your workspace’s config/helps/, and Claude
reads it before writing a blueprint. Every blueprint is checked before it is saved, so a broken one
is very unlikely to end up on disk.
Next: Create a collection.