IrredenEngine: Skill for Claude Code

backend-parity

Fleet rules for parity work — host must match the lagging side, build-only is not done, one feature per PR, Opus for math / dispatch / buffer-lifetime ports — live in docs/agents/FLEET.md §"Cross-platform parity (OpenGL ↔ Metal)" and §"Model split". This skill is the port procedure.

Preconditions

1. Host matches the lagging backend (uname -s): Darwin ports GLSL → MSL on macos-debug; Linux or MinGW/MSYS ports MSL → GLSL on linux-debug / windows-debug. Cross-compilation is not a substitute for the build + smoke.
2. The lagging preset is already configured; never run cmake --preset (CLAUDE-BASELINE.md §"Hard rules for autonomous fleet roles").
3. gh auth status succeeds; the skill ends in a PR.
4. On a feature branch with a clean tree — a parity PR is pure parity work.

Flow

1. Resolve the scope

Take the mode from the trigger phrase or ask:

• Full audit — walk the whole render tree.
• PR-scoped — mirror PR <N>; only the files it touched.
• Commit-range — mirror everything since <ref>.
• Single feature — port one named file; skip the audit.

The mode goes at the top of the PR body.

2. Enumerate the deviation set

Layout: engine/render/src/opengl/opengl_*.cpp ↔ engine/render/src/metal/metal_*.cpp (headers mirror under engine/render/include/irreden/render/{opengl,metal}/); shaders engine/render/src/shaders/*.glsl (c_/v_/f_/g_ stage prefixes per CLAUDE-BASELINE §Naming) ↔ engine/render/src/shaders/metal/*.metal. One .metal file bundles the vertex + fragment pair — a GLSL v/f pair ports to one .metal file (framebuffer_to_screen.metal is the pattern), and a .metal file ports to both v_<key>.glsl and f_<key>.glsl.

Missing-counterpart audit, both directions, from the repo root:

python3 scripts/shader_parity_audit.py

It prints every unpaired shader with the file it expects and exits 1 on any; the shader-parity workflow runs the same command on every shader PR. The tree keeps the c_ and ir_ prefixes on the Metal side and drops the v_/f_/g_ ones, so do not strip prefixes by hand. A deliberate asymmetry goes in engine/render/src/shaders/parity_allowlist.json: by-design with a reason when the counterpart is bundled or co-located, deferred with a follow_up issue when the port is still owed.