Rental
Availability and contracts for an equipment rental business
A company rents construction equipment by the day. Customers see what is available for a date range, reserve it, and sign the rental agreement digitally. Equipment out on hire cannot be double booked, and overdue returns are flagged automatically.
Automatically generated draft
Written by machine against our own engineering playbook. The company is invented; the decisions are the ones we would make on a real build. A reviewed blueprint goes further — nine sections, agreed line by line, and it is what the build is tested against.
Section 01 · What has to work
Customers must be able to select a date range, reserve non-overlapping equipment, and sign a digital rental agreement without double-booking.
Section 03 · Screens
Every screen, and what it is for.
- ›Catalog — customer browses equipment, instant date availability check.
- ›Reservation — customer reviews dates, fills details, signs agreement, instant hold.
- ›Manager Dashboard — staff view active hires, overdue returns, and instant status flags.
- ›Equipment Manager — staff update asset status, maintenance logs, and instant inventory view.
Anything not on this list is not in version one. That is what keeps a fixed price fixed.
Section 04 · The data model
What it stores, and who can read a row.
Equipment
id uuid, name text, category text, daily_rate numeric(10,2), status enum(available, rented, maintenance), metadata jsonb
Access · Public read for available items; full read for authenticated staff.
Reservation
id uuid, equipment_id uuid, customer_id uuid, start_date date, end_date date, total_amount numeric(10,2), status enum(pending, confirmed, active, completed, overdue)
Access · Customer reads own rows; staff read all rows.
Agreement
id uuid, reservation_id uuid, signature_data text, signed_at timestamptz, ip_address text
Access · Customer reads own signed agreement; staff read all.
Those access rules belong in the database, not in the screens. Someone who edits the address bar still cannot read a row that is not theirs — and the test that proves it blocks delivery if it fails.
Section 05 · States
pending → confirmed → active → overdue → completed | cancelled
Most scope arguments three weeks into a build are really arguments about a state nobody named at the start.
Section 06 · Where this breaks
What bites products like this one.
Concurrent bookings for the same equipment on overlapping dates cause double-booking.
Enforce exclusion constraints at the database level using PostgreSQL daterange overlap operators.
Timezone differences between user devices and rental yards shift rental start and end dates.
Store all reservation dates as pure calendar dates (date type) anchored to the rental yard's local timezone.
Section 08 · Deliberately left out
What version one does not do.
- ×Dynamic surge pricing based on utilization — adds significant complexity, better to launch with flat daily rates in v1.
- ×Automated SMS reminder notifications for returns — email notifications suffice for v1 to reduce third-party dependency risks.
This is the section that protects the date, and the only place in the document where somebody says no. It is also why clients trust the rest of it.
Still open
What we would ask before quoting.
- What specific digital signature provider or standard will be used to validate the rental agreements?
- How should overdue returns calculate late fees, and what grace period applies before flagging?
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