unreal-project-preflight

unreal-project-preflight

Version: 1.0.1 Last Updated: 2026-09-08 Dependencies: Unreal Engine 5.8 (launcher install), Python 3.10+, curl on PATH, UE 5.8 native MCP on the project's configured port for --live Status: Production-ready (probed against two real 5.8 projects on 2026-09-08)

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Why this skill exists

Every Unreal build session that went wrong in the same way: the plan was approved, the agent started creating things, and the first real step failed because a plugin was off (ImagePlate, ProceduralVegetationEditor, MovieRenderPipeline), a project setting was not on (Nanite Foliage for MegaPlants, SM6 for Nanite), or the fix needed an editor restart that then lost unsaved component edits. The unreal-* skills document APIs, not the switches those APIs sit behind.

This skill puts ONE pass between "plan approved" and "step 1": read what the project actually has, list every change the plan needs, apply them as a batch, restart ONCE, read the result back, and only then start building.

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CRITICAL: MANDATORY FIRST STEP

Run the checker against the project the plan targets before writing any Step 0 by hand. Never list prerequisites from memory.

# The editor is running: ask it which project it has open and read plugins back
python <skill-dir>/scripts/ue_preflight.py --live --features <feature,list> --plan-block

# The editor is closed: check the files the next launch will load
python <skill-dir>/scripts/ue_preflight.py --project <path>/Show.uproject --features <feature,list> --plan-block

Read the project : line. If --live reports the editor has a DIFFERENT project open than the one the plan targets, stop: the live readings describe the other project, and building would land in the wrong place. (This happened during the skill's own commissioning: the production project was the intended target, the editor had a dev-tests project open.)

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Standard Workflows

Workflow 1: The ritual (where it sits in a plan)

1. Plan is written and approved (vfx-plan, goal-criteria-planning, or a plain plan in chat).
2. Derive the feature list from the plan's steps. Every step that names an Unreal subsystem maps to one or more catalog features (--list-features). "Forest with a road through it" is at least pcg,megaplants,landscape-patch and usually mrq for the check render. Add ad-hoc --require specs for anything the catalog lacks.
3. Run the checker (above) and paste its --plan-block output into the plan as Step 0 - Environment preflight. The block already contains the change list, the restart plan and the feature notes.
4. Get the operator's OK on Step 0 - plugin toggles and renderer settings are project-wide and land in source control.
5. Execute Step 0 as written: save, operator closes the editor, --apply, relaunch, --live re-run must report 0 need changes. That read-back is the gate; a summary line with anything but 0 means Step 1 does not start.
6. Only now Step 1.