# Toolchain

Pinned versions for this project. Record the exact build string a tool reports, not just the version family, and re-record it after every upgrade. The most common cause of scale, material, and import mismatches is silently mixing two versions of the same tool.

Audited 2026-11-06 on the development workstation.

## Pins

| Component | Pinned | Source | Status |
| --- | --- | --- | --- |
| Bazzite | `45.20261105` (Kinoite, `bazzite-dx-nvidia`), kernel `7.2.15-ogc1.1.fc45` | `ujust update` / `rpm-ostree upgrade` | Booted and default. `44.20261026` retained as rollback. |
| NVIDIA driver | `615.78.08`, open kernel module | Bazzite image | Verified: desktop session renders through the RTX 5070 Ti; Vulkan GPU0 is the RTX 5070 Ti on driver `615.78.08`, conformance `1.4.3.3`. |
| Unreal Engine | `5.8.4` — download in progress 2026-11-06; `5.2.0` archive verified on disk as fallback | Epic download | Not extracted yet. Pin becomes 5.8.4 once the archive verifies and the editor launches on Bazzite; see [setup.md](setup.md#engine-version-decision). |
| Unreal Linux toolchain | engine-bundled clang | Engine source tree | Not installed. Do not substitute the system compiler. |
| Blender | `5.2` LTS (upstream patch `5.2.3`) | Flatpak `org.blender.Blender` | Installed. |
| MPFB | `2.0.18` (extension `mpfb`, declares Blender >= 4.2) | Blender extensions platform | Installed. Load-and-export check on 5.2 still pending. |
| Blosm | latest release at install time | blosm.com / Gumroad | Not installed. Version must be recorded before first use. |
| QGIS | `4.2.3`, Flatpak `stable`, runtime `org.kde.Platform 6.11`; bundled PROJ `9.9.0` | flathub | Installed 2026-11-06. The stale `lts` branch (`3.28.9`, EOL Qt5 runtime) is still installed beside it and should be removed. |
| Git | `2.56.0` | Bazzite image | Installed. |
| Git LFS | `3.7.1` | `rpm-ostree` layer | Installed; `git lfs install` run, lfs filter active. |
| Host build tools | `clang 23.1.4`, `cmake 4.3.0`, `ninja 1.13.2` | `rpm-ostree` layer | Installed. These are host tools, not the engine toolchain. |
| distrobox | `1.8.2.5` | Bazzite image | Installed. |
| Python (tooling) | `3.14.8` system | Bazzite image | Installed. Use a venv for geo/tool scripts. |
| ffmpeg | `8.1.3` | Bazzite image | Installed. |

Unreal Engine 5.9 is in preview and Unreal Engine 6 has been announced as of November 2026. Neither is a pin candidate for `0.x`. One engine family per milestone; a family change is a breaking change and belongs in `CHANGELOG.md`.

## Pin rules

- One engine build per release. Record the launcher or source build, the patch version, and the build date in this file and in the release entry.
- Blender stays on an LTS family (`5.2`). Every add-on version used for a shipped asset is recorded here.
- Upgrading a pinned tool mid-milestone requires re-running the scale test and the Blender→Unreal import check before further asset work.
- Never install a tool from an unverified source. Record the download origin next to the version.

## Open compatibility risks

1. **Blosm on Blender 5.2.** Blosm versions historically lag Blender releases. Verify Blosm against the installed Blender 5.2 before the blockout step. If it fails, add a side-by-side Blender 4.5 LTS Flatpak and convert that step's output only; do not mix Blender versions within one asset.
2. **MPFB 2.0.18 on Blender 5.2.** The extension declares Blender >= 4.2 but predates 5.x. The acceptance test is the `0.1.0` requirement to export one MPFB character with baked materials and a deform skeleton and import it into Unreal.
3. **Two QGIS installs.** `stable` (4.2.3, current runtime) and the old `lts` (3.28.9, EOL runtime) are both present. Nothing breaks, but launching the wrong one silently gives older PROJ data. Uninstall `lts` and keep one pin. QGIS 4.x also uses Qt6, so any processing recipe copied from a 3.x tutorial needs re-checking before it is trusted.
4. **Driver and Vulkan validation on Bazzite.** Not an officially supported Unreal distribution. Validate before asset production, as `ROADMAP.md` requires.