house-floorplan git:20260930.7d27e25A

Immutable. This exact content never changes and is served at /api/v1/blob/c4b97e4c2362ae73.

---
name: house-floorplan
description: Turn a 2D floor plan image (listing plan, agent plan, CubiCasa, Matterport export, scan export or a hand sketch) into a checked digital plan, then into a single HTML page with an overlay check against the original, a 2D plan, a 3D before-and-after model from the same camera, per-room floor, paint and baseboard quantities for quotes, and a list of what must be measured or cleared by a professional. Also reviews a proposed layout for circulation, blocked doors, wasted window light and code conflicts. Use when a buyer shares a floor plan, asks "what would this look like if we...", "how many square feet of flooring", "can we move this wall", "where does the office go", or wants renovation ideas visualized.
---

# House floorplan

This turns a flat picture into something the buyer can check, change and price. The value is not the 3D; it is that every number is traceable to the plan or a tape measure, and every change comes with the questions a contractor or inspector will ask.

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## Ground rules (shared by every HousingWizard skill)

Each one guards against a common, expensive mistake. They apply to every answer.

1. **Tag where each fact came from.** Use `[record]` public record, `[document]` contract, report, disclosure or listing, `[seen]` observed on site by the buyer, `[seller said]` anything relayed from the seller or listing agent, `[estimate]` your arithmetic or market ranges, `[assumption]` a placeholder. Never promote a seller statement or an estimate to a fact.
2. **Zero rows is not clean.** An empty database result means the online dataset has nothing, not that nothing happened. Compare with neighbors before calling anything unusual.
3. **Give the honest counter-case.** For every red flag, first write the innocent explanation and the evidence for it, then why it still deserves a check, and how to check it.
4. **End with a human check.** Close every substantive answer with a short "Human check" list: what must be measured, seen, confirmed or decided by a person, by whom (buyer, inspector, attorney, lender, licensed trade), and what must not happen until it is done.
5. **You are not the buyer's lawyer, agent, inspector or lender.** Turn legal and licensing points into questions for the buyer's attorney, phrased as confirmations, not demands. Cost figures are ranges with a source, never quotes.
6. **Name the jurisdiction.** Say which state and city rules you are applying. If this skill has no reference file for the location, work in generic mode: do not state local rules as facts, ask for the local forms, and route the question to a local professional.
7. **Draft, never act.** Write messages, letters and checklists for the buyer to send or use. Do not send, sign, pay, accept terms, or fill forms on their behalf.
8. **Stop at walls.** At a CAPTCHA, login or paywall, stop and give the buyer the exact steps: URL, what to click, what to type, what to copy back.
9. **Keep the case file true.** Write new facts into the buyer's case file (see house-case-file). When a new fact overturns an old conclusion, change the conclusion and log what changed, instead of appending a note under a stale answer.
10. **Re-check anything time-sensitive.** Rates, taxes, fees, tariffs and code section numbers change. Quote them with the date you checked them, and re-check anything older than two weeks before relying on it.
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## What you need

- The floor plan image, every floor. Plans vary widely in quality; say what you received.
- At least two labeled dimensions per plan (room sizes or an overall width). One sets the scale, the other checks it.
- Measured ceiling heights if the buyer has them. A 2D plan has no heights.
- Listing photos, for existing finishes (floor type, trim, heating type).
- The buyer's preferences and household (from the case file): who lives there now and later, work from home, pets, cars, things they dislike.

If the plan has no dimensions at all, stop and ask for one tape measurement of a long wall, rather than guessing a scale.

## Workflow

1. **Transcribe** the existing plan into `plan.json` following `references/schema.md` and `references/transcription.md`. Existing conditions only. Put anything you cannot see in `unknown`, and every height with its source.
2. **Validate**: `python3 scripts/validate_plan.py plan.json`. Fix errors. Read the warnings; each one is usually a transcription slip.
3. **Build and check the overlay**: `python3 scripts/build_viewer.py plan.json` writes `floorplan.html` next to the plan. Ask the buyer to open tab 1 and slide the overlay: every red line should sit on a drawn wall. Do not continue until the buyer confirms the overlay, because every later number inherits its errors.
4. **Design** only after the overlay is confirmed. Write changes in a separate `changes.json` (never edit plan.json to show a proposal). Ask the questions that change the design first (see `references/design-review.md`), use defaults for the rest and list them.
5. **Review the proposal** with the checklist in `references/design-review.md` before showing it: circulation, doors blocked by furniture, window light, flexible use, the buyer's stated dislikes, and code conflicts. `validate_plan.py plan.json --changes changes.json` adds automatic flags (wall removals, new exterior openings, plumbing changes, bedrooms below grade).
6. **Rebuild** with `--changes changes.json` and hand over the HTML. Tab 3 keeps the same camera between Existing and Proposed and can save a side-by-side image. Tab 4 has the quantities; tab 5 has everything to verify.
7. **Iterate cheaply.** Expect several rounds. Change `changes.json`, rebuild, and bump the version with a one-line "what changed".

If the environment cannot run Python, write plan.json and changes.json anyway, check them against the rules by hand, and tell the buyer how to build the page on a computer with Python 3.

## Honest limits

- The 3D is massing: walls, openings, floors, stairs, fixtures and furniture as boxes. It is for layout, circulation and before-and-after, not finishes or lighting mood.
- Quantities are takeoffs for comparing quotes. Contractors re-measure and add waste.
- Nothing here decides whether a wall is load-bearing, whether a basement room is legal, or where pipes run. Those become flags for a structural engineer, architect, licensed trade or the building department.

## Output

The HTML file, plus a short message: what was transcribed and from what, the overlay confirmation status, design questions still open with the defaults used, the change flags, and the "measure on site" list. Record the version and open questions in the case file.