Nouns

A Noun is something your product keeps track of. Leaseclock has two: a Unit, which is an apartment, and a Lease, which ties a renter to a Unit until a date. A Noun's name becomes its URL, its screen title, its SDK method and its CLI command.

A Noun fileCopy link to this section

Each Noun is one file in your product's Noun/ folder. This is Leaseclock's Lease, in full:

---
name: Lease
fields:
  unit: { type: link, target: Unit, required: true }
  renter: { type: email, required: true }
  endsOn: { type: date, required: true, indexed: true }
  status: { type: choice, options: [{ key: active }, { key: ended }] }
verbs:
  renew:
    does: Move the end date forward
    input: { endsOn: { says: the new end date, type: date, required: true } }
    from: [active]
  end: { does: End the lease, from: [active], to: ended }
---

name and fields describe what a lease holds. verbs lists what people do to a lease, and Verbs covers each line. Text after the closing --- opens the Lease page in your docs at leaseclock.com/docs/lease.

Push it with npx saas.dev push, and leases are live in Test on every surface:

npx saas.dev push

curl https://leaseclock.com/api/leases/4b \
  -H "Authorization: Bearer $LEASECLOCK_TOKEN"

{
  "$id": "https://leaseclock.com/api/leases/4b",
  "$type": "Lease",
  "unit": "4b",
  "renter": "dana.whitfield@example.com",
  "endsOn": "2026-11-30",
  "status": "active"
}

In the app, Priya Shah, the leasing coordinator at Northgate Rentals, opens the same lease at leaseclock.com/app/leases/4b. Your customers' agents find it with the MCP server's search tool and read it with fetch.

NamesCopy link to this section

The name line sets what every surface calls the Noun. Change it and push, and every surface uses the new name.

A name is singular, starts with a capital letter, and holds letters and digits only, up to 64 characters. The URL uses the plural in lower case: Lease becomes leases, and a Noun named Property becomes properties. Write a two-word name joined, as RentReview, and screens show it as "Rent review".

A name that breaks a rule returns an error with the line and the fix:

422  Lease.mdx line 2: name "lease" must start upper-case. Rename it to "Lease".

Every error code links to its fix in Errors, so you or your agent correct the file and push again.

FieldsCopy link to this section

fields lists what each record holds. A field is a key, a type and any settings the field needs:

endsOn: { type: date, required: true, indexed: true }

A key starts with a lower-case letter and joins words in camelCase. Screens label the field from its key, so endsOn shows as "Ends on". Each line of Lease's fields sets what people see and what the API returns:

Settings every field takesCopy link to this section

Add a fieldCopy link to this section

Add one line and push. Leaseclock gains rent:

 fields:
   unit: { type: link, target: Unit, required: true }
   renter: { type: email, required: true }
   endsOn: { type: date, required: true, indexed: true }
   status: { type: choice, options: [{ key: active }, { key: ended }] }
+  rent: { type: money }

On the next request, the Leases list has a Rent column, the form has a money input, rent joins the API schema and the SDK's Lease type, and the changelog at leaseclock.com/blog/changelog reads "Leases now track rent". Existing leases have no rent until someone sets it, unless the field has a default.

Field typesCopy link to this section

The type says what a value is, and every surface reads it. A date gets a date picker, a date column and range filters, and a money field gets a currency input and totals, with nothing else written.

TextCopy link to this section

pattern is a regular expression every value must match: pattern: '^[0-9]+[A-Z]$' holds a unit label to the form 4B.

NumbersCopy link to this section

Money is always an amount in the currency's main unit, the same way an Offer writes its price. A money field takes the currency of your Offer unless it sets its own, as currency: EUR. range sets the least and most a value may be: range: { min: 0 }.

DatesCopy link to this section

ChoicesCopy link to this section

Each option is a key with an optional label: { key: active, label: Active }. Without a label, screens show the key with a capital letter.

Links, people and filesCopy link to this section

Worked outCopy link to this section

Lookups and rollups are read-only. Each stays current with the records it reads, and a request that sets one returns a 422.

ListsCopy link to this section

Add many: true to hold a list. phones: { type: phone, many: true } keeps every number a renter gives, and max: 3 caps it at three.

LinksCopy link to this section

A link field points at a record of another Noun. Lease's unit points at a Unit:

unit: { type: link, target: Unit, required: true }

The link reads both ways. The Lease form picks a Unit by its label, and each Unit page lists the leases that point at it, under the name reverseLabel sets. In the API, filter leases by unit with GET /api/leases?unit=4b. In the SDK, it is $.Lease.list({ unit: '4b' }).

onDelete decides what happens to Unit 4B's leases when someone deletes Unit 4B:

Every delete is recorded in the record's history, so each of these can be undone.

Read through a linkCopy link to this section

A lookup shows a field of the linked record. A rollup adds up over the records that link in. Add a building to each lease and a lease count to each Unit:

building: { type: lookup, lookup: { via: unit, field: building } }

leaseCount: { type: rollup, rollup: { via: Lease.unit, fn: count } }

via names the link: unit on Lease itself, or Lease.unit for the link that points in from Lease. A rollup's fn is count, sum, min, max or average, and every fn except count names the field it reads.

Ids and titlesCopy link to this section

Every record has an id, and the id is its address: Dana Whitfield's lease is 4b, at leaseclock.com/api/leases/4b. Screens title a record by its name, title or label field, or else its first text field, so Unit 4B shows as "4B" wherever a lease links to it.

RelatedCopy link to this section

• Verbs: what people and agents do to a Noun
• Offers: the plan your customers buy, and the limits it sets on each Noun
• Constraints: every naming and field rule, and the surface that depends on it