design-reference

# Design references Research the Internet before selecting a construction design. Use authoritative sources for specifications and licensed analogous designs for construction patterns; never replace the user's reference image, dimensions or requested exterior with the nearest-looking result. ## Boundary - The product-level survey — what existing products of a kind look like, which features they share, what size they are, what their reviews complain about — is `$product-design`'s step 2, and it is the one place a product-category query belongs. This skill starts after it, from one named construction question. - Use this skill for shape archetypes, feature ordering, parametric CAD idioms, mechanism construction examples, and sourced design constraints. - Use manufacturer documentation, standards, or an official technical source for numerical specifications. A third-party analogous model is not authority for the user's dimensions, ratings or scale. - Use `step-parts` for a bought motor, bearing, fastener, board, connector or other standard component the model must physically fit. Download its canonical STEP into `<project-dir>/ref/`, derive the seat with `$cad`'s `cadmount`, declare it in `measure/mounts.json`, and run `check_mount`. - Use `$electromechanical-integration` when the question includes power, control, wiring, electrical ratings, exact lamp/socket contacts or removable powered interfaces. A design repository is not electrical authority. - A design reference is not proof of likeness, manufacturability, assembly or physical fit. Those claims remain with the project gates. ## Internet research workflow 1. Read and measure the user's evidence first. Name the one or two exact design questions research must answer; do not browse with only a product-category query. 2. Write a research contract for each question: required facts, acceptable source authority, geometry or operation uncertainty, packaging constraints, license needs, and the condition that would reject a candidate. 3. Search the Internet with form, feature and operation terms. For example, search `tapered shell vent slots parametric CAD`, not merely `enclosure`. 4. Review no more than five strong candidates. Prefer, in order: - manufacturer documents, standards and official technical pages for dimensions, ratings and compatibility facts; - repositories with source CAD or build123d/CadQuery/OpenSCAD code, an explicit license, and an immutable commit or release for construction patterns; - authoritative CAD/kernel documentation for operation-specific questions. 5. Record every used result and meaningful rejection: query, stable URL, repository plus commit/release when available, license/use, exact claim or specification taken, relevant feature, construction lesson, and status (`used`, `rejected`, `miss`, or `unavailable`). 6. Compare the evidence against the research contract, select the design, and re-measure every user-specific dimension from the user's image/spec. Do not copy an analogous model's placement, scale or silhouette. A login wall or network failure is `unavailable`, never a miss. A page with no explicit permission may support a factual citation or visual comparison, but its code or geometry may not be copied. If no useful source exists, record the query as a miss and author the design from the user's evidence plus official CAD operation documentation. A weak analogy is worse than no analogy. ## Build-spec record Add each used or outcome-defining result to build-spec section **6d** with: - research query and status; - source authority/type; - stable URL and revision/commit/release when available; - relevant feature; - exact specification or constraint taken, with units and applicability; - construction lesson used; - license/use. Section 6g then compares the evidence and records the selected construction design. Project-local `measure/check_spec.py` checks that every selected design has the required source URL, claim/specification and license record; final CAD verification does not re-fetch the Internet. ## Integration with image-to-cad and product-design Research after the overall read (or, for `$product-design`, the concept selection) and the feature tree have named the construction question, and before section 6g selects the design or the feature-operation table is written. The research must leave enough sourced specifications and construction evidence for CAD to build without choosing among alternatives.