# Forge Brief > Forge suite — define the 3D asset brief and write FORGE.md (the project-memory file every other Forge skill reads). Produces: a completed FORGE.md at the project root with target engine, coordinate system, poly/texel budgets, render settings, PBR workflow, the determinism contract (seed + sample counts for idempotent rebuilds), output paths, and (when ATELIER.md is present) the extracted world/aesthetic/signature-moment/OKLCH-hue that drives look-dev. Use this FIRST whenever starting any Forge 3D pipeline — including "define the asset", "set up a 3D project", "what are the budgets for this mesh", "create FORGE.md", "brief a 3D asset", "extract the aesthetic from ATELIER.md for Blender", "what engine is the target", "set poly budget", "set texel density", "configure render engine". (The bare "init Forge" / "forge init" phrase is owned by the `forge` router's `init` mode, which scaffolds FORGE.md inline and then calls this skill — this skill does not claim that trigger.) HEADLESS-ONLY: driven from code, output - Skill: `luminary19/forge-brief` (Agent Skill, multi-file: 6 files) - Install (CLI): `npx skillmds@latest add luminary19/forge-brief` - Raw SKILL.md: https://api.skillmd.com/api/skills/luminary19/forge-brief/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: DevOps & Infra - Author: luminary19 (https://skillmd.com/u/luminary19) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/luminary19/forge-brief --- # Forge — Asset Brief & Project Memory The foundation skill. Before any geometry, material, or render work starts, the pipeline needs a single shared truth: what is being built, for what target, at what budget, in what style. **forge-brief writes that truth into `FORGE.md`.** Every downstream Forge skill reads it first. > **Project memory:** if **`FORGE.md`** already exists at the project root, **read it first** — > honor its decisions and update only the fields the user explicitly changes. > If **`ATELIER.md`** exists, also read it — it carries the web aesthetic that the 3D look-dev > must harmonize with. See §3 below and `references/atelier-extraction.md` for the extraction logic. --- > **Forge suite — skill map** > > | Role | Skill | When | > |---|---|---| > | **Brief (you are here)** | **`forge-brief`** | Define asset + write FORGE.md | > | Standards | **`forge-standards`** | 3D design tokens: units/naming/pivots/budgets | > | Router | **`forge`** | Probe + dispatch to all Forge skills | > | Model | **`forge-model`** | bpy/bmesh polygonal modeling | > | Parametric | **`forge-parametric`** | OpenSCAD / CadQuery / FreeCAD | > | Procedural | **`forge-procedural`** | Geometry Nodes / SDF / L-systems | > | Topology | **`forge-topology`** | Retopo / LOD / decimation / booleans | > | UV | **`forge-uv`** | Unwrap / seams / packing / texel density | > | Material | **`forge-material`** | PBR shading / glTF material model | > | Texture | **`forge-texture`** | Baking / procedural textures | > | Light | **`forge-light`** | Lighting rigs / HDRI / color management | > | Render | **`forge-render`** | Headless Cycles render / turntable QA | > | Rig | **`forge-rig`** | Armatures / IK-FK / skinning | > | Animate | **`forge-animate`** | Keyframes / F-curves / skeletal export | > | Sim | **`forge-sim`** | Cloth / rigid / fluid / hair | > | Export | **`forge-export`** | Format matrix: GLB / FBX / USD / engine import | > | Optimize | **`forge-optimize`** | gltf-transform / KTX2 / LOD / web budgets | > | Intake | **`forge-intake`** | Photogrammetry / AI-to-3D / cleanup | > | Validate | **`forge-validate`** | Manifold / normals / scale / UV / glTF-Validator | > | Data | **`forge-data`** | BM25 reference library (tool cheatsheets / budgets) | > > Atelier seam: **`atelier-webgl`** ↔ **`forge-export`** / **`forge-optimize`** (GLB + poster handoff). > Also connects to **`atelier-direction`** (Direction Doc → aesthetic brief) and > **`atelier-perf-a11y`** (post-handoff CWV / a11y gate). --- ## Decide first: tool and target engine Before writing FORGE.md, lock two decisions that gate everything downstream: **1. Target engine / delivery format** | Intent | Target | Notes | |---|---|---| | Web hero (three.js / R3F) | `three.js/R3F` | GLB + DRACO + Meshopt; < 5 MB; Y-up | | iOS / Android AR | `AR/USDZ` | GLB for Android; USDZ for ARKit | | Unreal Engine 5 | `Unreal` | FBX + UE5 naming; Z-up; 1 unit = 1 cm | | Unity / Godot 4 | `Unity` / `Godot` | FBX or GLB; 1 unit = 1 m; Y-up | | 3D print | `print` | STL / 3MF; manifold; real-world mm | | Archive / interchange | `USD` | USDA/USDC; Y-up; meters | | Blender/film render | `render-only` | Stays in Blender; no engine export needed | **2. Modeling tool** Run `python "$env:CLAUDE_CONFIG_DIR\skills\forge\scripts\probe.py" --json` (the **`forge`** router's preflight probe — calls it via Skill if available) to confirm tool availability before committing. Deep invocation reference: `references/tool-availability.md`. | Use | Tool | Headless invocation | |---|---|---| | Polygonal / organic / subdivision | **Blender** `bpy` | `blender -b scene.blend -P s.py -- ` | | Parametric / precision / CAD | **OpenSCAD** | `openscad.com -o out.stl model.scad` | | Parametric (Python) | **CadQuery** / **build123d** | `python script.py` | | STEP / IGES exchange | **FreeCAD** | `freecadcmd script.py` | **WINDOWS HEADLESS TRUTHS — apply everywhere:** - Cycles only (not EEVEE Next) for headless renders on Windows. - `blender -b scene -P s.py -- ` — the `--` separator is **mandatory**. - `openscad.com` not `openscad.exe` (the `.com` wrapper handles DPI/HiDPI correctly). - `python` not `python3`. - Absolute forward-slash paths in Blender `filepath` — never `//relative`. - `--python-exit-code 1` so Python errors fail the Blender process. --- ## The flow **1. Read existing state** - If `FORGE.md` exists → read it; note what is already decided. - If `ATELIER.md` exists → read it; extract fields using the regex patterns in `references/atelier-extraction.md`. Particularly: `Interactivity`, `World`, `Aesthetic`, `Concept/signature moment`, and the OKLCH primary hue from `## Tokens`. **2. Gather missing decisions (AskUserQuestion if needed)** The minimum set for FORGE.md: - **Asset description** — what is the object/scene (one sentence) - **Target engine/delivery** — pick from the table above - **Asset class** — hero prop / character / environment / web hero / CAD / print - **Poly budget** — derive from class table in `references/budgets-and-standards.md` or ask if unusual - **Texel density** — derive from target tier; see `references/budgets-and-standards.md §texel` Use `AskUserQuestion` only when the target cannot be inferred. Note: the picker caps at 4 options — for engine choices, list all options in the message body and use the picker only for the binary "confirm / let me pick differently". **3. Determine coordinate system and scale unit** Full table in `references/coordinate-systems.md`. Quick lookup: | Target | Up axis | Scale unit | Forward axis | |---|---|---|---| | glTF / three.js / R3F | Y-up | meters | -Z | | Unreal Engine 5 | Z-up | cm (1 unit = 1 cm) | X | | Unity | Y-up | meters | Z | | Godot 4 | Y-up | meters | -Z | | OpenSCAD default | Z-up | mm | Y | | Blender default | Z-up | meters | -Y | | USD / Omniverse | Y-up | meters (configurable) | -Z | **4. Write FORGE.md** Use the schema from FORGE_PLAN.md §G. Full annotated template in `references/forge-md-template.md`. Minimum viable content: ``` ## Target + ## Coordinate system , , , ## Budgets : tri LOD0; texel density px/m; tex max ## Render Cycles (headless Windows default); QA / final; color view AgX ## Determinism Seed: 0 (all procedural/sim/Cycles ops); Cycles use_animated_seed: off; ## rebuild contract: same FORGE.md + same source => byte-identical GLB, comparable PNG ## PBR workflow metallic-roughness (glTF default); ORM channel-pack (AO→R, Rough→G, Metal→B) ## Output paths .forge-build/out/ working; public/forge/-* for web handoff ## Atelier link (omit if no ATELIER.md) world: ; aesthetic: ; ## signature: ; primary OKLCH hue: ``` Write with `Write` tool to `/FORGE.md`. If FORGE.md already exists, use `Edit` to update only changed fields. **5. Confirm and summarize** - Read back the written FORGE.md to confirm correctness. - Print a brief summary: target engine, coordinate system, poly budget, render engine, and whether ATELIER.md was found and its aesthetic extracted. - Name the next Forge skill the user should invoke: typically **`forge-standards`** (for the full 3D design-token ruleset) or directly to **`forge-model`** / **`forge-parametric`** for a simple asset. **Run = call the Skill tool with the exact skill name. Writing "next: run forge-model" in prose runs nothing — invoke `Skill("forge-model")` or `Skill("forge-standards")`.** --- ## §3 — ATELIER.md extraction When `ATELIER.md` is present at the project root, forge-brief is also the **aesthetic bridge**: it reads the Atelier Direction Doc and writes the extracted context into FORGE.md's `## Atelier link` section so every downstream Forge skill (forge-material, forge-light, forge-render) can harmonize look-dev with the web design system without re-reading ATELIER.md. Full extraction logic (regex patterns + Python pseudocode): **`references/atelier-extraction.md`** — read it before attempting extraction. Fields to extract: | ATELIER.md field | Where it lives | Maps to FORGE.md | |---|---|---| | `Interactivity` | `## Interactivity` section | Sanity check: must be Award-grade to justify authored 3D | | `World` | `**World:**` bold inline | `## Atelier link → world` | | `Aesthetic` | `**Aesthetic:**` bold inline | `## Atelier link → aesthetic` | | Signature moment | `**Concept.*signature moment.*:**` | `## Atelier link → signature` | | Primary OKLCH hue | First `oklch(... ... )` in `## Tokens` | `## Atelier link → primary OKLCH hue` | If ATELIER.md is absent, omit the `## Atelier link` section from FORGE.md entirely. If Interactivity is not Award-grade and the user has requested authored 3D, **pause** and suggest running **`Skill(atelier-direction)`** first to sanction the 3D moment — do NOT proceed to build geometry that will violate the project's budget. --- ## References Deep material lives here — read the relevant file before each step: - **`references/forge-md-template.md`** — fully-annotated FORGE.md template with per-field guidance, examples for each target engine, and the complete schema. - **`references/budgets-and-standards.md`** — polycount tables (mobile / console / web / print), texel density tiers, LOD ratios, UV utilization targets, draw-call ceiling, Git LFS rules. - **`references/coordinate-systems.md`** — up-axis, handedness, scale, forward-axis per target; Blender → UE5 unit correction; glTF standard; USD conventions. - **`references/atelier-extraction.md`** — Python regex patterns to extract world/aesthetic/ OKLCH hue from ATELIER.md; AskUserQuestion option-cap note (max 4 picker items); aesthetic → look-dev direction table; sanction-check logic. - **`references/tool-availability.md`** — preflight probe patterns (PowerShell + Python), Blender path lookup on Windows, OpenSCAD `.com` gotcha, CadQuery install check. --- ## Operating principles - **Write FORGE.md first, always.** No Forge skill should execute without a project-memory file. forge-brief is the mandatory step 0. If it already exists, update it; never silently skip it. - **Honor ATELIER.md when present.** An ATELIER.md aesthetic is not a suggestion — it is the design contract. Poly budgets, texel density, and render engine are your decisions; aesthetic and OKLCH harmony are the project's decisions. - **Derive, don't ask.** Poly budgets, texel density, coordinate system, and output paths can all be derived from the target engine and asset class. Only ask when something is genuinely ambiguous (e.g. a custom constraint the dossier does not cover). - **Sanction 3D before building it.** If ATELIER.md exists and Interactivity is not Award-grade, do not build geometry. Run `Skill(atelier-direction)` first. An unsanctioned 3D moment is a performance and accessibility liability the project did not budget for. - **Fail loudly at the gate.** A target engine the probe cannot verify, a missing tool, or a contradictory constraint (e.g. Z-up asset for a Y-up web target) must surface here as a clear error — before any geometry is written. Downstream skills depend on FORGE.md being correct.