Add a headless MCP server for agent-driven texturing

[urib94]

Add a headless MCP server for agent-driven texturing

What this is

A self-contained Model Context Protocol (MCP) server (mcp/) that exposes BumpMesh's
mesh-processing pipeline to AI agents and automation. It lets a tool/agent apply displacement
textures to a model programmatically — STL/OBJ/3MF in, displaced STL/3MF out — with no browser,
no GPU, and no data upload (same privacy guarantee as the web app).

Motivating use case: 3D-print prep. An assistant can grip-texture a handle, knurl a knob, or add
carbon-fiber to a panel as one step in a larger "design → texture → slice" workflow, driven from
natural language.

Why it's low-risk to the existing app

The whole thing reuses js/*.js directly — it does not reimplement any geometry code, so it
can't drift from the app. The export pipeline (exportPipeline.js) already depends only on
three (as math), meshIndex.js, and fflate; WebGL is confined to the viewer/preview, which
the server never touches.

Two pure, behavior-preserving refactors make the pipeline callable headlessly:

• js/exporter.js — extract buildSTLBytes(geometry) / build3MFBytes(geometry) (return
  Uint8Array). exportSTL / export3MF keep their signatures and the exact browser download
  path; output bytes are identical.
• js/stlLoader.js — extract parseModelBuffer(arrayBuffer, ext) (parse + cleanup + bounds).
  The File-based loaders (loadModelFile, loadSTLFile, …) keep their signatures and wrap it
  after FileReader.

No changes to viewer.js / previewMaterial.js or any UI behavior.

Tools

Tool	Purpose
bumpmesh_list_textures	The 24 built-in presets (name, category, description).
bumpmesh_inspect_mesh	Triangle count, bounding box, surface area, watertightness, shells.
bumpmesh_texturize	Full pipeline: model + texture (preset or custom image) + projection/UV/amplitude/masking/decimation → writes STL/3MF, returns a summary.
bumpmesh_subdivide	Adaptive subdivision only.
bumpmesh_decimate	QEM decimation to a target triangle count.
bumpmesh_validate_mesh	Open edges, non-manifold edges, shells, slivers.
bumpmesh_place_on_bed	Orient a chosen/auto face down onto Z = 0.

Plain-JS ESM, no build step, stdio transport, zod-validated strict inputs (unknown
params error), actionable error messages, stdout kept protocol-clean.

Build / install change

Adds a minimal npm-workspaces root package.json declaring three + fflate, so the shared
js/ modules resolve their dependencies from a single npm install at the repo root — this
also makes the existing bench-*.mjs / diag-*.mjs scripts reproducible. The previously untracked
manifests are now tracked (node_modules/ stays ignored). .3mf input works under Node via a
small @xmldom/xmldom DOMParser shim installed by the server before any js/ module loads
(js/ itself is untouched).

Testing

node:test suite, 26 tests, no GPU, runnable via npm test --workspace mcp:
round-trip texturize (STL byte-length invariant, re-parse, watertight output), STL/OBJ/3MF
read + round-trip, subdivide/decimate/place-on-bed, list_textures, strict-validation and
unknown-texture error paths.

Try it

npm install                 # at the repo root (workspaces)
node mcp/server.mjs         # stdio MCP server

Client config (Claude Desktop / Code):

{ "mcpServers": { "bumpmesh": { "command": "node", "args": ["/absolute/path/to/stlTexturizer/mcp/server.mjs"] } } }

See mcp/README.md for the full tool reference and parameters.