Blender Add-on Development

Before you start: read this whole install prompt, tell me in a few lines what this skill does and what installing it involves, and wait for my go-ahead before you do anything else. Prerequisites: Blender itself is required to use this skill (it is a guide for writing Blender add-ons): the upstream repository targets Blender 5.2 LTS or newer, and the extension format it teaches needs Blender 4.2.0 or newer. Blender is free and open source. No account, no API key and no paid service are needed to install or use the skill. A Blender ID account is only needed later, and only if you choose to publish an add-on you wrote to extensions.blender.org; never create one during this install. Install "blender-addon-development" for me. It is a guide for writing Blender add-ons as extensions: starting from a bundled template (blender_manifest.toml, __init__.py, operators.py, ui.py), it covers operators, panels, menus, property groups and preferences, the bpy.props rules after Blender 5.0, undo/redo, modal and timer patterns, gpu drawing (no bgl), bundling Python wheels, validating, building and installing an extension with the Blender CLI, headless testing, and publishing on the extensions platform. Repository: https://github.com/EL4CTEO/blender-skills (the skill is the whole skills/blender-addon-development/ folder at the pinned commit: SKILL.md, assets/addon_template/__init__.py, assets/addon_template/blender_manifest.toml, assets/addon_template/operators.py, assets/addon_template/ui.py) Pinned version: install the code at commit 71d031dab8bc6729504d11a78cbe91945401045f exactly. Do not substitute a newer version. If this commit is unreachable, stop and tell me. 1. Clone https://github.com/EL4CTEO/blender-skills into a temporary folder, check out commit 71d031dab8bc6729504d11a78cbe91945401045f, and copy the skills/blender-addon-development/ folder from that checkout. Then compare every file in the folder with the fingerprints recorded for this listing on 2026-10-19: [FINGERPRINTS] - SKILL.md: SHA-256 072a74e87d433437ec14895312f23bb0f1bf78f9533028297f89d41bdc1df269 - assets/addon_template/__init__.py: SHA-256 93e6b738cdc7916f70db24065e0cd5368f5d5c9cdeb3cab1939f500cd6af667d - assets/addon_template/blender_manifest.toml: SHA-256 18ad0365a8239ace1924bf81073111db4b42caecc70b968c0aa127776707e155 - assets/addon_template/operators.py: SHA-256 b8ff4aa706c666a814451bf016a6c533e89540bc7168d953b1f9d84d6468eb3f - assets/addon_template/ui.py: SHA-256 50e3083d3c94f69d065ee8b8cf05fa9e8b1e86675285d0d6c144307473f19a0f If a file does not match, it changed since the listing was prepared: do not install it yet, tell me what you found and let me decide. 2. Read SKILL.md in full (and every other file in the folder) and tell me in plain words: what the skill does when used, which services it connects to, whether it reads or sends any personal information or keys, and anything that seems unusual. Stop on any red flag and tell me before going further. Confirm these points from the files: - The skill folder holds five files only: SKILL.md (the guide, 5,056 bytes) and a starter add-on template under assets/addon_template/ (__init__.py, operators.py, ui.py and blender_manifest.toml). The template is plain Blender Python (bpy): it registers an operator that offsets selected objects, a sidebar panel, preferences and a property group. It contains no network call, no file access, no subprocess and no dependency list. - Nothing is sent anywhere during installation itself; the only download at install time is the skill folder from GitHub at the pinned commit. The files name no account, no API key, no telemetry and no remote service. - At use time everything runs locally inside Blender: you copy the template, edit the manifest and the classes, then validate, build and install the extension with the local Blender CLI (blender --command extension validate / build / install-file) and test it headless. SKILL.md itself forbids network or file access at import/register time in the add-ons you write, requires declaring any [permissions] (files, network, clipboard, camera, microphone) with a reason in the manifest, and requires checking bpy.app.online_access before any network call. It also forbids pip install at runtime: third-party packages ship as .whl files bundled in the extension. - The only network step the guide describes is publishing, and it is yours, later, only if you choose it: you upload the built zip yourself to extensions.blender.org with your own Blender ID account. No upload happens during this install, and using the skill never requires it. - SKILL.md says the execution model lives in the sibling skill blender-core of the same repository, and its headless-test step points at tests/test_addon.py in the repository: neither is part of this listing and neither is installed. This skill is the add-on development guide and its template only. 3. When I say "yes, install", install it as a skill: copy the whole skills/blender-addon-development folder into the agent's skills directory, in a folder named "blender-addon-development", keeping every file (SKILL.md and assets/addon_template/). Do not run the repository's install/install.sh or install.ps1: they install all 22 skills of the repository, not just this one. 4. Verify with no network calls: frontmatter valid, files in place. Do not run Blender, do not build or install the template add-on, and do not start any use of the skill. 5. Report what was installed, where, and what I still need to do myself (for example: install Blender 5.2 or newer myself if it is missing, and provide the add-on I want to create or fix; using the skill is a separate step that only starts when I ask for it, and publishing to extensions.blender.org, with a Blender ID account, is a separate later choice of mine). GitHub is optional: if I have a GitHub account or the gh CLI, you may use it; otherwise public access is fine. Never require it unless it's in the prerequisites above. Rules: don't touch anything outside the temp folder and the install target. If anything looks off, stop and ask me.