Build a construction estimating app for a small contractor.

1. Jobs: customer, address, scope description, status (lead, estimating, sent, won, lost, active, closed), start date.
2. Line items per estimate: type (labor, material, subcontractor, equipment, other), description, quantity, unit (each, sqft, lf, hour), rate, override flag.
3. Rate library: saved rates by trade and unit with a last updated date, searchable, with a bulk update screen so stale prices get refreshed.
4. Quick estimate: a text box for pasted job notes and photo upload, which calls the model to propose line items with quantities. Every proposed item must appear in an editable table before it counts toward the total. Never insert a number the contractor cannot see and change.
5. Money: global markup with per line overrides, show both markup on cost and margin on price clearly labeled, tax on materials only, deposit percentage.
6. Proposal: a printable PDF with logo, scope, inclusions, exclusions, total, deposit due and a signature line.
7. History: save every estimate, record actual costs when the job closes, and report estimated versus actual cost and margin per job.

Rules: keep an audit trail when a line is edited, never silently overwrite a rate, and label any quantity the AI proposed until a human confirms it.