mechanical-drafting-gbt

GB/T Mechanical Drafting

Chinese maintenance mirror: SKILL.zh-CN.md.

Create readable manufacturing drawings, not decorative CAD illustrations. Treat geometry, line hierarchy, view layout, dimensions, and notes as one system.

Portability Contract

• Keep the core workflow agent- and vendor-neutral. Apply it in Codex, Claude Code, or another compatible skill runner without changing the engineering acceptance criteria.
• Treat SKILL.md and references/ as the authoritative instructions. Ignore optional runtime-specific metadata, such as agents/openai.yaml, when the current runner does not use it.
• Discover the available CAD application, MCP/automation bridge, shell, parsers, and renderers before execution. Map capability-level steps to exposed safe tools instead of assuming a particular tool namespace or exact operation name.
• Treat operation names and JSON payloads in the references as interface examples unless the active bridge explicitly exposes them. Never invent a tool call or claim a check ran when only an example schema exists.
• Keep deliverables and validation evidence in standard CAD/exchange/report artifacts so another agent or application can reopen and independently verify them.

Tool Inventory Preflight

Before installing, downloading, upgrading, patching, removing, or relocating any tool, dependency, browser runtime, plug-in, CAD backend, renderer, or validator:

1. Read D:\Codex\TOOLS-INVENTORY.md.
2. Check its recorded path, version, and verification command. Reuse the existing environment when verification passes; a different task or window is not a reason to reinstall it.
3. Install or repair only when the entry is absent, its path is missing, or verification fails.
4. After any change, update the inventory with the date, exact path, version, purpose, verification result, and known limitations.
5. Never store credentials, tokens, license keys, or other secrets in the inventory.

Required Workflow

1. Classify the task and load only the required references: always read references/gbt-drafting.md for engineering drawings; read references/autocad-mcp-workflow.md for AutoCAD/MCP execution, references/complex-assembly-drafting.md for engines or other multi-system assembly drawings, references/consumer-product-concept.md for new/substantially redesigned consumer products, enclosures, appliances, ports/cables/controls, moving parts, or mains-powered products, references/cad-workflows.md for 2D/3D conversion or presentation, references/cad-3d-modeling.md for 3D parts/assemblies, references/gps-inspection.md for GD&T/GPS, tolerance-stack, or inspection work, references/product-definition-release.md for configurations, BOMs, revisions, MBD/PMI, dependencies, or release packages, references/engineering-analysis.md for any physical-performance calculation or simulation claim, and references/drc-review.md for every DRC, DFM, fit, interference, or release review.
2. For a new or substantially redesigned consumer product, pass the applicable concept, purchased-component, mains/moving-part safety, early-preview, and product-design gates before detailed dimensions or production CAD. If selection or safety architecture is unresolved, stop at an explicitly provisional concept package.
3. Inspect the source CAD, drawing, screenshot, and user requirements. Record concrete defects and separate supplied values from derived or assumed values.
4. Preserve unrelated user geometry. Create a clean replacement in a separate area when extensive repair is needed; remove old geometry only when the user authorizes it.
5. Confirm the sheet size, scale, units, projection method, CAD plot style, and required deliverable before laying out views. For a GB/T mechanical drawing, default to first-angle projection only when the user, approved project template, and source drawing do not specify another method; record the assumption and keep view placement, projection symbol, and title-block data consistent.
6. Establish semantic layers and properties before geometry. Select line widths from the applicable standard series and the sheet/scale; keep a clear thick-to-thin ratio. A practical fallback is:
   • OUTLINE: thick continuous.
   • THIN: thin continuous.
   • CENTER: thin chain.
   • HIDDEN: thin dashed.
   • HATCH: thin continuous.
   • DIM: thin continuous.
   • TEXT: thin continuous.
7. Use a monochrome plotted hierarchy. Layer colors may aid CAD editing only when the configured plot style produces the required line types, widths, and monochrome output.
8. Lay out aligned orthographic views first and keep projection correspondence exact. Add sections only when they clarify internal geometry.
9. Add dimensions from the part outward. Prefer functional datums; avoid closed chains, duplicates, crossings, and dimensions attached to hidden lines.
10. Add tolerances, fits, surface texture, material, process notes, and title-block data only when supplied or technically justified. Mark unresolved production data as TBD or clearly identify it as assumed.
11. Run the selected verification tier and presentation checks. For Tier 1, inspect the active affected geometry/view and report deferred release gates; for Tier 3, inspect model space plus the current final plotted/exported sheet at readable and full-sheet zoom before declaring release readiness.