# Import Brick Set

> Import a LEGO or DUPLO set into this playground, deduplicate its inventory and CAD models, and audit how every specialty part connects and renders.

- Skill: `am-will/import-brick-set` (Agent Skill)
- Install (CLI): `npx skillmds@latest add am-will/import-brick-set`
- Raw SKILL.md: https://api.skillmd.com/api/skills/am-will/import-brick-set/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Security
- Author: am-will (https://skillmd.com/u/am-will)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/am-will/import-brick-set

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# Import a brick set

Work from the repository root. The useful precedent is `sources/10416-1.json`, `src/farmInventory.ts`, `docs/farm-10416.md`, and `tests/farm.test.ts`. Read only the relevant files. This workflow changes the catalog and connection engine; importing a set does not authorize replacing the user's live assembly.

## Inventory and identity

- Start with the exact set number and LEGO's instruction PDF. Its last inventory page is often more reliable than a replacement-parts feed, which can include alternates. Render the assembly pages too: a list of part names does not reveal attachment behavior.
- Cross-check the rows against a parts catalog. Save a compact source snapshot in `sources/` with part/design number, color, quantity, LEGO element ID, source URLs, reviewed date, and any count discrepancy. Count figures, exclude spares unless requested, and assert the total.
- Match existing **design + color + print/mold variant**, not names. DUPLO `40666` is the catalog's `4538`; `76371` maps to `4066`. Keep existing public part IDs and saved anchors. Different printed designs or real mold differences remain distinct even when their base CAD is shared.
- Keep quantities per kit. `collectionInventory()` sums identical IDs across kits; do not pre-sum shared counts or mutate `INVENTORY`. Add the kit to `KITS` and its part entries to `PARTS`. Reuse existing connection metadata when adding only a color.

## CAD import

1. Check the official LDraw complete archive, cached at the platform temp path `lego-ldraw-complete.zip`. A quick Python `zipfile` scan of `ldraw/parts/*.dat` headers finds design aliases without downloading individual files. Check aliases and decorated variants before declaring a model absent. Do not use a similarly named standard LEGO animal in place of a DUPLO animal.
2. Extend `scripts/fetch-ldraw.py`'s selected IDs from the pinned source snapshot, then run it with the archive path. It recursively extracts type-1 subfile references, retains license headers, and builds the local file map. Keep its path-traversal guard and licensing files.
3. Compile **only added/changed IDs** with `npx tsx scripts/compile-cad.ts --parts=id1,id2`. This merges into the existing bundle and updates both dimension files. A full rebuild is unnecessary for additions and can churn unrelated models.
4. The compiler uses `0.025` scene units/LDU for DUPLO, `0.05` for standard LEGO. Do not put DUPLO IDs in `manifest.legoParts`. DUPLO layers are `0.6` scene units; standard LEGO plates are `0.4`.
5. Models missing from the licensed library need original, clearly marked approximate meshes. Use instruction/part photographs as shape references; give each distinct animal or utility item recognizable geometry. A generic rectangular fallback is not a finished specialty model. Do not claim approximations are imported CAD.

## Connections, orientation, and clearance

For **every unique design**, record top studs, bottom sockets, their heights, non-stud fittings, hollow clearances, evidence, and remaining uncertainty. All color variants inherit the design rules.

- Use `topStudAreas` / `bottomStudAreas` for discrete regions and `y` for raised sockets or lower shelves. A roof's slope, pot rim, animal head, and pane bars are not studs.
- Run `npx tsx scripts/audit-duplo.ts --farm --write` for the 10416 precedent (extend the selector for a new set). It recursively transforms actual `stud7.dat` references into the rendered coordinate system and compares **positions and heights**, not only counts. For standard LEGO use the LEGO audit scripts.
- The renderer normalizes CAD bounds, auto-rotates long axes, centers X/Z, then applies `cadOffset`. Asymmetrical features can move the visual center away from the stud grid. The two door frames need `cadOffset.x = 0.075`; do not infer their alignment from bounding-box dimensions alone.
- Use local CAD primitive transforms to derive mating positions. Example: 10416's tall frame sockets are at different heights than the short frame's. The correct fit has a fractional layer offset even though ordinary DUPLO bricks use integer layers.
- `fits` offsets describe the child's entire footprint at host rotation zero; `fittingCandidates()` rotates that footprint and the child's orientation. `requiresFit` prevents a hinge insert from being accepted as a ground brick. Named `slot` values prevent two children occupying one hand or hinge fitting.
- Do not impose integer-only schema checks before the host is known. The assembly validator accepts exact registered fits and aligned centered sockets, while rejecting arbitrary off-grid placement.
- Use `collisionVolumes` to preserve arch openings, furniture legs, basins, and space below hanging parts. A single bounding box can prevent valid connections. Conservative envelopes are acceptable when identified; a blanket collision exemption is only for an exact mating transform.
- Model resting separately from clutch connections. The farm grooming tile supports animals without acquiring fictitious studs.
- Engine support and viewport snapping must agree. A connection reachable only through the API is incomplete UI support. Check all quarter-turn orientations and reject wrong hosts, shifted fits, occupied slots, and removal of needed supports.

## Verify and finish

Run focused assembly tests, the independent CAD stud audit, then `npm test` and `npm run build`. Include tests for total inventory, shared-color deduplication, print identity, required fittings, clearances, and save/load behavior. Check actual rendered specialty models and representative clicks in a browser. Use a separate `PORT` and temporary `DUPLO_DATA_DIR` for destructive fixtures; supply the current `expectedRevision` on HTTP commands. Preserve user data and unrelated dirty changes.

Document a complete per-design checklist and specific approximations in `docs/`. Report separately: imported CAD count, original fallback models, implemented connection behavior, verification, and any remaining motion/pose limitations.