SE Dev Mod Skill

Mod development for Space Engineers version 1.

⚠️ CRITICAL: Commands run in a UNIX shell. Use bash syntax. On Windows this is BusyBox; on Linux use the native shell.

Examples:

• ✅ test -f file.txt && echo exists
• ✅ ls -la | head -10
• ❌ if exist file.txt (echo exists) - This will NOT work

Actions:

• prepare: Run one-time preparation (Prepare.bat on Windows, prepare.sh on Linux)
• bash: Run UNIX shell commands via busybox
• search: Search mod code using search_mods.py

Routing Decision

Check these patterns in order - first match wins:

Priority	Pattern	Example	Route
1	Empty or bare invocation	se-dev-mod	Show this help
2	Prepare keywords	se-dev-mod prepare, se-dev-mod setup, se-dev-mod init	prepare
3	Bash/shell keywords	se-dev-mod bash, se-dev-mod grep, se-dev-mod cat	bash
4	Search keywords	se-dev-mod search, se-dev-mod find class, se-dev-mod lookup	search

Getting Started

⚠️ CRITICAL: Before running ANY commands, read CommandExecution.md to avoid common mistakes that cause command failures.

If Prepare.DONE file is missing in this folder, you MUST run one-time preparation steps first. See prepare action.

Essential Documentation

• CommandExecution.md - ⚠️ READ THIS FIRST - Windows command execution details; on Linux keep bash syntax and use prepare.sh

Mod Development

Use only names matching Mod API whitelist: ModApiWhitelist.txt Whitelist exported from game version 1.208.015 using MDK2's Mdk.Extractor.

Mods released on Steam Workshop or Mod.IO, mostly the former. Game compiles mods on world loading with Mod API whitelist enforced, supposed to guarantee safety and security. Mods may still crash game with an exception.

Use se-dev-game-code skill to search game's decompiled code. May need this to understand how game's internals work and how to interface with it properly. Stick to game code searches corresponding to names on Mod API whitelist for efficiency.

Graphify Graph

Preparation builds a separate Graphify graph for the local mod folder (or SE_DEV_MOD_PROJECT_ROOT). With the fast Rust clustering backend (Python 3.12 via uv, provisioned automatically) prepare builds it automatically; this corpus is small so it is quick either way. Where the fast backend is unavailable it stays opt-in with SE_DEV_GRAPHIFY=1; SE_DEV_GRAPHIFY=0 disables it. Read on demand — skip for normal search work: build via GraphifyPrepare.md, query via GraphifyUsage.md.

Folder Structure

• Data/ — junction/symlink to per-user persistent mod data folder (%USERPROFILE%\.se-dev\mod on Windows, ~/.se-dev/mod on Linux). Persistent skill data lives here:
  • Data/mods.json — quick inventory of all installed mods (workshop_id, path, has_scripts, ...).
  • Data/mod_hashes.json — per-mod aggregate sha1 used by indexer for change detection.
  • Data/CodeIndex/ — full Tree-sitter C# index (one CSV per category, plus hierarchy trees).
• LocalMods/ — junction/symlink to game's local-mod folder (%AppData%\SpaceEngineers\Mods on Windows, Proton appdata equivalent on Linux).
• Steam Workshop content read in-place from Steam folder; not copied or symlinked into skill. Workshop folder resolved from SE_GAME_ROOT (env var) or Steam registry entry for app id 244850.

References

• Mod Template repo Mod template repository to start a new mod project which will include scripts. See ModTemplate.md
• Mod API for script mods Structured Mod API documentation
• Mod API documentation by Keen Software House May be outdated
• Mod Development Kit (MDK2) Mod development tooling mostly for VS2022

Mod Code Search

Search source code of Steam and local mods for examples and patterns:

# Search for patterns
uv run search_mods.py class declaration MyBlock
uv run search_mods.py method usage Update
uv run search_mods.py class children MyGameLogicComponent

# Count results before viewing (useful for large result sets)
uv run search_mods.py class usage Init --count

# Limit number of results
uv run search_mods.py class usage Init --limit 10

Before searching, ensure index exists. If Data/CodeIndex/ missing, run:

uv run list_mods.py     # quick inventory (always cheap)
uv run index_mods.py    # full code index (incremental: only changed mods reparsed)

Re-indexing after new subscriptions: When you subscribe to new mods on Steam Workshop, load them in a world once (so game downloads them), then re-run the two commands above (or just Prepare.bat). Indexer hashes each mod's .cs files and only reparses mods whose hash changed since previous run, so reruns are fast.

See search action for complete documentation.

Action References

Follow detailed instructions in:

• prepare action - One-time preparation
• bash action - Running UNIX shell commands via busybox
• search action - Search mod code for examples

Remarks

Original source of this skill: https://github.com/CometWorks/skills