Lease management app architecture
Lease management app architecture: the decisions that matter
The architecture of a lease management app comes down to 3 choices: idempotent monthly charge generation from lease versions, database exclusion constraint for overlapping leases and owner statements are locked snapshots. Each is explained below with the alternatives that were rejected and what you accept by choosing it.
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Idempotent monthly charge generation from lease versions
Situation: Rent must be billed once per period at the rent in force even after retries or amendments.
Choice: A job inserts charges with a unique key (lease, kind, period) reading the lease version effective at period start.
- Rejected: Compute rent on read: no immutable ledger.
- Rejected: Manual entry: error prone at scale.
- Consequence: Backdated amendments create adjustment charges.
- Consequence: Charges are the source for statements.
Database exclusion constraint for overlapping leases
Situation: Double-booked units create legal disputes and are easy to cause through concurrent edits.
Choice: Use a Postgres exclusion constraint on (unit_id, daterange) for active leases.
- Rejected: Application check: racy.
- Rejected: Locking on the unit row: complex.
- Consequence: Requires btree_gist extension in tenant databases.
- Consequence: Errors must be translated to friendly messages.
Owner statements are locked snapshots
Situation: Owners dispute numbers that change after being reported.
Choice: Close a period into a locked snapshot with checksum; later adjustments appear in the next period.
- Rejected: Live statements: numbers drift.
- Rejected: Spreadsheet export only: no control.
- Consequence: Late corrections need adjustment entries.
- Consequence: Closing needs a precondition check.
How the data is indexed
Indexes are chosen from the questions the app asks most often. Each line below names a table and the question its main index answers.
- owners: (org_id, name) — owner lookup.
- properties: (org_id, owner_id) — owner's properties.
- units: unique (property_id, label) — unit label within a property.
- leases: (unit_id, starts_on) — lease history of a unit.
- lease_versions: unique (lease_id, version) — version history.
- lease_parties: unique (lease_id, person_id) — one role per person per lease.
- people: (org_id, blind_index) — duplicate detection without decrypting.
- charges: unique (lease_id, kind, period_start) — monthly generation is idempotent.
What Forge64 provides underneath
Forge64 matches your description to one of 25 reference architectures, writes the plan and data model into the project, generates the app, and runs a quality gate over the code before you see it. Each app gets its own Postgres database and sign-in with no per-user fee. Hosting on Forge Cloud and Forge Payments are rolling out.
This is a reference design for the category, not a promise that every item is generated today. Built-ins such as background jobs, file uploads and search are rolling out; email sent from your app is coming soon, so anything here that needs it is something you add yourself for now.
FAQ
- What is the most important architecture decision for a lease management app?
- Idempotent monthly charge generation from lease versions. A job inserts charges with a unique key (lease, kind, period) reading the lease version effective at period start.
- Do I have to make these decisions myself?
- No. Forge AI plans them from your description and writes the decisions into the project as architecture records you can read and change.
- What do the alternatives cost me?
- For example, for "Database exclusion constraint for overlapping leases": Application check: racy. Locking on the unit row: complex.
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