TemporaryBRepManager.booleanOperation() mutates its first argument and returns a bool. Write the natural-looking acc = tbm.booleanOperation(acc, b, op) and your body silently becomes True, and the next call explodes with a C++ template error that names the wrong argument. The docs do not mention this. This repo is a list of everything like it.
Field notes from roughly 400 AI-agent code iterations against the Autodesk Fusion 360 Python API, collected across several long modeling and CAM sessions. Every item in here cost real time at least once. Most of them cost it more than once. Nothing is copied from the docs: each idiom was verified live against a running Fusion instance, and each gotcha is a bug that actually happened, with the error text it produced and the fix that worked.
The most recent session these notes enabled went from an empty document to a modeled part, two CAM operations, generated toolpaths, and a posted quarter-million-line Fanuc program in a handful of script calls, unattended. The first session, before the notes existed, spent hours rediscovering what is now one line in a bullet list. That difference is the point of writing things down.
Humans scripting Fusion. If you write Python against adsk.core, adsk.fusion, or adsk.cam, the gotchas apply the same whether the code comes from you or from a model. The API has a lot of behavior the docs do not mention, and this is a list of the parts that bite.
AI coding agents. This folder doubles as a drop-in skill for Claude Code:
git clone https://github.com/JoshBolding/fusion360-api-field-notes ~/.claude/skills/fusion360-api
The SKILL.md wires the notes into any session that touches the Fusion API. Not a Claude user? It is all plain markdown; paste the relevant file into whatever context window your agent reads. The whole point is to stop each new session from rediscovering the same bugs.
People building agent-to-Fusion bridges. mcp-bridge-notes.md documents the failure patterns of driving Fusion through an MCP server: transaction rollback semantics, timeout retries duplicating geometry, and the workspace state that can deadlock a bridge entirely.
| File | What it covers |
|---|---|
| api-gotchas.md | The main bestiary: units, constructors, construction planes, booleans, fillets, stale handles, sketch edits, exports, plus verified working idioms |
| cam.md | CAM (Manufacture) scripting: product activation, real strategy names, tool library iteration, toolpath generation polling, post-processing |
| mcp-bridge-notes.md | Notes specific to driving Fusion through an MCP bridge: timeouts, retry duplication, workspace deadlocks. Skip this file if you are scripting Fusion directly |
| SKILL.md | The Claude Code skill entry point |
Verified on Fusion 360 on Windows through mid 2026, on one install. The API surface shifts between builds, and several notes are explicitly build-dependent (marked with the date they were last verified). If something here contradicts what your Fusion build does, trust your build and test small.