lake-dayz

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An MCP server that pre-flights DayZ Enforce mods — compiler-style pass/fail checks that catch boot-crashing mistakes (deprecated/commented-out classes, wrong config classes, bad modded/overrides) before you pack a PBO.

🎮 Built while making dayzlake.online — a DayZ territory-control (점령전) server.

Why

DayZ Enforce has no offline compile check — a broken mod only reveals its error when you launch the game.

A real incident:

modded class ActionFishing { override string GetText() { ... } }

→ on boot: Can't compile World script module! Unknown type 'ActionFishing' → the whole game UI dies.

The cause was not "ActionFishing was removed." DayZ leaves deprecated code commented out instead of deleting it — lines 1–52 of actionfishing.c are one /* ... */ block, and the live class is ActionFishingNew. A raw grep "class ActionFishing" catches the dead code inside the comment → "oh, the code exists!" → modding it = dead boot.

Lesson: "defined ≠ alive." Is it commented out? Defined but unused? You have to check the usage, not just the name.

check_modded("ActionFishing") → ㄴㄴ (no) in one line. That's why this exists.

Related MCP server: mcp-policy-guardian

What it does

Every tool is verdict/evidence first — the first line is the conclusion (ㅇㅇ = pass / ㄴㄴ = no).

How it works

index_local.py  ─ P:\scripts + (optional) your mod source, comment-aware parse (commented_out flag) ─┐
index_config.py ─ P:\DZ\**\config.cpp → item→CfgXxx mapping                                          ├→ data/dayz_scripts.db
DayZ-script Doxygen reference ─ members + signatures + References/Referenced-by                       ─┘  (pre-built into the DB)
server.py       ─ serves the tools from that DB (stdio MCP)

• commented_out flag — whether code is commented-out dead code, plus file:line. P:\ is the authority source, kept in sync with the game.

• members / cross-references — extracted from a DayZ-script Doxygen (comment code excluded), pre-built and shipped in the DB, so it works out of the box.

• Inheritance authority = local source.

• Current DB: 7,378 symbols / 31,877 methods / 32,259 members / 75,548 cross-refs / 90,870 config classes.

Install

The DB (data/dayz_scripts.db) ships with the repo, so it works right after cloning. You can query/validate without DayZ or DayZ Tools installed; you only need DayZ Tools' extracted P:\ to rebuild the DB for a new game version.

A. Native (simplest)

cd <repo>
python -m venv .venv
.venv\Scripts\python.exe -m pip install -r requirements.txt

claude mcp add -s user lake-dayz ^
  <repo>\.venv\Scripts\python.exe ^
  <repo>\server.py

B. Docker (server only)

docker build -t lake-dayz .

claude mcp add -s user lake-dayz -- ^
  docker run -i --rm ^
    -v "<repo>\data:/data:ro" ^
    -v "<your-mod-source-root>:/modset:ro" ^
    -v "<dir-with-enforce-script-guide.md>:/docs:ro" ^
    lake-dayz

Mounts are read-only, so rebuilding the DB on the host is picked up automatically. Env vars: DAYZ_MCP_DB / DAYZ_MCP_MODSET / DAYZ_MCP_GUIDE.

enforce_doc serves enforce-script-guide.md — put it at the repo root (or DAYZ_MCP_GUIDE) for native, or the /docs mount for Docker.

Updating data (after a game update)

.venv\Scripts\python.exe index_local.py     REM re-index P:\scripts (+ modset if DAYZ_MCP_MODSET is set)
.venv\Scripts\python.exe index_config.py    REM re-index P:\DZ config

1. Game updates → re-extract P:\ with DayZ Tools (P:\ is the authority source).

2. index_local.py — almost always just this (the core data for modded-class verdicts).

3. To cover your own mod, set DAYZ_MCP_MODSET to your mod source root (e.g. @YourMod\source); each subfolder = one mod.

Rule of use

Any code with modded class X / class X : Y / extends Y must pass check_modded(X) + enforce_lint(file) before packing. Item config overrides: check_config.

If the verdict is ㄴㄴ (no), don't pack. This one step stops "the code exists!? → dead boot."

Background

This started while building dayzlake.online, a DayZ territory-control server. I kept getting bitten by Enforce mistakes that only blow up after you launch the game — so I got fed up and built this MCP to catch them before packing. Hoping DayZ keeps growing, the Korean community included. Drop by the server sometime. 🇰🇷

License

• This project's own code (server.py, indexers, etc.) — GPLv3, see LICENSE.

• DayZ script data indexed in data/dayz_scripts.db is derived from DayZ © Bohemia Interactive and remains subject to the DayZ Public License – No Derivatives (DPL-ND): https://www.bohemia.net/community/licenses/dayz-public-license-no-derivatives-dpl-nd

• This is an independent, unofficial modding tool, not affiliated with or endorsed by Bohemia Interactive.

Credits

• Structure reference: steffenbk/enfusion-mcp-BK — an Enfusion MCP for Arma Reforger (skeleton only; the data here is DayZ).