Schedule rent inside a lease

Use this when a bot writes dated entries that must fall inside a contract's term. GND compares every due date with the lease's start and end, refuses dates outside them, and warns about a payment due in the last week.

Files on GitHub

lease/rules.md: the rules as written
lease/model.orm.json: the model
lease/state.pop.json: the starting state
lease/app.py: the example's app (not a GND command)
core.py: the code every example app shares
lease/stand_in_bot.py: the scripted stand-in bot
the recorded runs: every model run, with caveats
this page's Markdown source: replays and included files show only as include lines there; they render on the docs site

Before you start

Set GND up first as the course planner's "Before you start" shows: GND from PyPI, or from a checkout for unreleased work on main, and python must be that environment's Python.

python -c "import gnd, pathlib, shutil; shutil.copytree(pathlib.Path(gnd.__file__).parent / 'examples/plan_apps', 'plan_apps', ignore=shutil.ignore_patterns('recordings', 'skill-sessions', '__pycache__'), dirs_exist_ok=True)"
gnd validate plan_apps/lease/model.orm.json

OK: plan_apps/lease/model.orm.json is a valid GND ORM model

Optionally, the date rules in PyRel (What PyRel is, and when you need it):

m.where(payment_due(step, l, a, due), lease_starts(step, l, start)).require(due >= start)

The lease itself is a document. Pulling its terms out of the signed PDF is the gnd-extract skill's job, and gnd verify checks that each extracted fact points at the sentence it came from; both run on GND only. In this example the lease terms are typed in, so there is nothing to anchor; the schedule rules run on GND and on PyRel.

Ask for a schedule

Set up the rent schedule for this lease.

Read the refusal

No recorded lease plan was refused on one of the lease's own rules. The refusals were malformed plans, answers that were not a plan, and steps that cancelled a payment that did not exist. Claude Code's default model wrote the rent as text, '1450', in all five of its runs. The checker refused each plan as malformed before it checked any rule, and the model fixed the type at the next attempt. This is claude-default/lease/run-1:

Transcript of the replay

attempt 1
  plan  schedule_payment(lease='apt-4b', amount='1450', due='2025-02-01')
  plan  schedule_payment(lease='apt-4b', amount='1450', due='2025-03-01')
  plan  schedule_payment(lease='apt-4b', amount='1450', due='2025-04-01')
  plan  schedule_payment(lease='apt-4b', amount='1450', due='2025-05-01')
  plan  schedule_payment(lease='apt-4b', amount='1450', due='2025-06-01')
  plan  schedule_payment(lease='apt-4b', amount='1450', due='2025-07-01')
  pyrel check: exit 3
    plan  refused  refused  <tmp>/plan.steps.json: refused: [transition:binding-type] step 1.amount is '1450', which is not a valid Integer
attempt 2
  plan  schedule_payment(lease='apt-4b', amount=1450, due='2025-02-01')
  plan  schedule_payment(lease='apt-4b', amount=1450, due='2025-03-01')
  plan  schedule_payment(lease='apt-4b', amount=1450, due='2025-04-01')
  plan  schedule_payment(lease='apt-4b', amount=1450, due='2025-05-01')
  plan  schedule_payment(lease='apt-4b', amount=1450, due='2025-06-01')
  plan  schedule_payment(lease='apt-4b', amount=1450, due='2025-07-01')
  pyrel check: exit 0 (accepted)
  executed: the new state is in <workspace>/next.pop.json

No recorded lease run was refused on a date rule and then accepted. The scripted stand-in bot shows that loop: its first schedule starts a month early.

python plan_apps/lease/app.py ask "Set up the rent schedule for this lease." --out next-lease.pop.json

attempt 1
  plan  schedule_payment(lease='apt-4b', amount=1450, due='2025-01-01')
  plan  schedule_payment(lease='apt-4b', amount=1450, due='2025-02-01')
  plan  schedule_payment(lease='apt-4b', amount=1450, due='2025-03-01')
  plan  schedule_payment(lease='apt-4b', amount=1450, due='2025-04-01')
  plan  schedule_payment(lease='apt-4b', amount=1450, due='2025-05-01')
  plan  schedule_payment(lease='apt-4b', amount=1450, due='2025-06-01')
  gnd check: exit 1
    states 1-6  due_after_start  violated  [{"$l": "apt-4b", "$a": 1450, "$due": "2025-01-01", "$start": "2025-02-01"}]
      the rule in PyRel: m.where(payment_due(step, l, a, due), lease_starts(step, l, start)).require(due >= start)
attempt 2
  plan  schedule_payment(lease='apt-4b', amount=1450, due='2025-02-01')
  plan  schedule_payment(lease='apt-4b', amount=1450, due='2025-03-01')
  plan  schedule_payment(lease='apt-4b', amount=1450, due='2025-04-01')
  plan  schedule_payment(lease='apt-4b', amount=1450, due='2025-05-01')
  plan  schedule_payment(lease='apt-4b', amount=1450, due='2025-06-01')
  plan  schedule_payment(lease='apt-4b', amount=1450, due='2025-07-01')
  gnd check: exit 0 (accepted)
  executed: the new state is in next-lease.pop.json

The repaired plan

The second schedule runs from 1 February to 1 July and GND's checker accepts it. A payment due on 31 July would also pass, with a warning: it is inside the lease but less than a week before it ends.