d2r-tools

D2R modding toolkit for Linux and Steam Deck (Proton). YAML-driven character builder, data modding pipeline, and an MCP server that exposes the tools to agentic clients (Claude Code, Codex, Cursor, etc.).

Features

• YAML character builder - declare characters in YAML, build .d2s save files
• Data mod pipeline - YAML overlays applied to game tables, built and deployed
• JSON string patches - rename or add item / UI strings via YAML, no string-table surgery
• CASC read/write - pure Python, no external tools needed
• Integrated validation - scanner catches structural problems before loading the game
• Reign of the Warlock expansion support (8 classes including Warlock)

Quickstart

git clone <repo-url>
cd d2r-tools
pip3 install -e .
d2r-mod extract        # extracts + generates data from your D2R install
d2r-chargen build MyChar

(or pip install -e . if pip points to Python 3 on your system)

Three commands from clone to working. The extract step generates Python data modules from your D2R installation (required for legal reasons - no game data is distributed).

# If D2R is not auto-detected:
d2r-mod extract --game-dir /path/to/Diablo\ II\ Resurrected
# Or set the environment variable:
export D2R_GAME_DIR="/path/to/Diablo II Resurrected"

An example character YAML is included in chars/ExamplePaladin.yaml. Create your own characters in the chars/ directory.

D2R install path is auto-detected on Linux/Steam Deck and Windows. Use --game-dir to override.

Character Definition (YAML)

Characters are defined in YAML files placed in a chars/ directory. Here's a complete example:

schema_version: 1
name: MyPaladin
class: paladin
level: 85

stats:
  strength: 156
  dexterity: 100
  vitality: 250
  energy: 15

skills:
  Holy Shield: 20
  Smite: 20
  Fanaticism: 20
  Charge: 1
  Salvation: 1
  Cleansing: 1

equipment:
  # Unique items - resolved automatically from game data
  - slot: helm
    unique: Guillaume's Face

  # Runeword items - specify runeword name and base item code
  - slot: body
    runeword: Fortitude
    base: utp         # Archon Plate

  # Rare/crafted items with explicit properties
  - slot: hands
    rare: true
    base: uvg          # Vampirebone Gloves
    ilvl: 90
    properties:
      fire_res: 30
      cold_res: 30
      light_res: 30
      life: 20

  - slot: weapon
    unique: Grief
    base: 7cr          # Phase Blade

  - slot: shield
    unique: Herald of Zakarum

  - slot: belt
    unique: Verdungo's Hearty Cord

  - slot: feet
    unique: Gore Rider

  - slot: neck
    rare: true
    ilvl: 90
    properties:
      class_skills: [2, paladin]
      fcr: 10
      fire_res: 30
      light_res: 25

  - slot: ring_right
    unique: Bul Katho's Wedding Band

  - slot: ring_left
    unique: Ravenfrost

inventory:
  charms:
    # Unique charms
    - unique: Annihilus
      properties:
        all_skills: 1
        strength: 20
        dexterity: 20
        fire_res: 20
        cold_res: 20
        light_res: 20
        poison_res: 20
        add_exp: 10

    # Repeatable magic charms
    - magic_grand_charm:
        count: 8
        properties:
          skill_tab: [1, 15]   # Combat skills (paladin)
          life: 40

    - magic_small_charm:
        count: 5
        properties:
          life: 20
          light_res: 11

merc:
  equipment:
    - slot: weapon
      unique: The Reaper's Toll
      ethereal: true

Slot Names

helm, body, weapon, shield, hands, belt, feet, neck, ring_right, ring_left, weapon_switch, shield_switch

Item Types

Classes

amazon, sorceress, necromancer, paladin, barbarian, druid, assassin, warlock

CLI Reference

d2r-chargen

d2r-chargen build <name> [--phase N] [--force]   # Build character (phases 1-4)
d2r-chargen validate <name> [--yaml-only]         # Validate YAML definition
d2r-chargen list                                   # List defined characters
d2r-chargen scan <name>                           # Run scanner diagnostics
d2r-chargen import <name> [--force]               # Import .d2s -> YAML
d2r-chargen diff <file1> <file2>                  # Compare .d2s files

d2r-mod

d2r-mod extract [--game-dir PATH]    # Extract game data + generate Python modules
d2r-mod build [--no-regen]           # Build mod from vanilla + overlays
d2r-mod deploy [--force] [--no-casc] # Deploy mod to game directory
d2r-mod undeploy                     # Remove mod from game
d2r-mod diff [--summary]             # Compare vanilla vs modded tables
d2r-mod inject [--from-dir PATH]     # Inject files into CASC archive
d2r-mod audit [--skills] [--items]   # Audit game data
d2r-mod clean                        # Remove build/ and reset data
d2r-mod update                       # Re-extract after game update

Data Mod Overlays

Overlays modify D2R data tables declaratively using YAML. Place overlay files in an overlays/ directory and run d2r-mod build.

Create an overlays/ directory in your project root to add custom overlays. If no overlays directory exists, d2r-mod build will proceed with vanilla data only.

target: data/global/excel/UniqueItems.txt
changes:
  - row: {index: "The Gnasher"}
    set:
      prop4: "dmg%"
      min4: "50"
      max4: "50"
    comment: "Buff The Gnasher with +50% Enhanced Damage"

Each overlay targets a specific game table (TSV file) and specifies row matches and column changes. See examples/sample_overlay.yaml for a complete example.

JSON String Patches

D2R reads item names, mercenary names, and most UI strings from JSON files in data/local/lng/strings/ (not from the older .tbl files). To add a new string or override a vanilla one, drop a YAML spec into patches/json_strings/ and rebuild.

# patches/json_strings/my_renames.yaml
description: "Rename a few potions"
target: item-names.json
entries:
  - key: "vps"                # vanilla string key (super healing potion)
    value: "Wild Rice Cake"   # what D2R should display instead
  - key: "MyCustomItem"       # new key — auto-allocated string ID
    value: "Heart of the Mountain"

If the key already exists in the target JSON, its enUS value is overridden. If it doesn't, a new entry is appended with the next free string ID (read from data/local/lng/next_string_id.txt). Targets currently used: item-names.json, mercenaries.json, ui.json.

After d2r-mod build, the patched JSONs land in build/data/local/lng/strings/; d2r-mod deploy injects them into CASC. D2R caches strings at startup, so fully exit and relaunch to see changes.

If no patches/json_strings/ directory exists, the build skips this step.

Architecture

d2r_chargen/          YAML character builder
  build_lib.py        Binary item encoder (Huffman, stat encoding, checksums)
  character.py        Build orchestrator (YAML -> items -> .d2s)
  resolve.py          Name-to-ID resolution (uniques, runewords, stats, skills)
  save.py             Save file operations (stats, skills, waypoints, items)
  scanner.py          Diagnostic validator
  data/               Game data (generated via extract, not distributed)

d2r_mod/              Data modding pipeline
  casc.py             Pure Python CASC reader (TBL, TXT, JSON)
  casc_write.py       CASC archive builder + ekey-hijack injection
  overlay.py          YAML overlay loader and applier
  build.py            Build orchestrator (vanilla + overlays -> build/)
  build_steps/        Specialized build steps:
    register_custom_uniques.py  Auto-register custom unique names in TBL
    build_string_registry.py    Diff built TBLs vs vanilla into a registry
    patch_json_strings.py       Apply patches/json_strings/*.yaml to JSON
  deploy.py           Deploy/undeploy mod files
  regen.py            Generate chargen data from extracted tables

tools/                Standalone diagnostics
  audit_string_registry.py  Categorize string_registry entries vs JSON

Platform Support

Requirements

• Python 3.10+
• PyYAML
• Diablo II: Resurrected (for data extraction)
• mcp (optional, only for the MCP server — pip install -e ".[mcp]")

License

MIT

MCP Server (Claude Code, Codex, Cursor, …)

d2r-tools ships an MCP server that exposes game-data lookups, save inspection, the chargen pipeline, and the mod pipeline as typed tools to any MCP-compatible agent. See d2r_mcp/README.md for the full tool catalog (23 tools across lookup / save / chargen / mod).

Install

pip install -e ".[mcp]"           # installs the `mcp` SDK alongside d2r-tools

Launch

python3 -m d2r_mcp                # stdio transport

Client configuration

Claude Code (user-scoped):

claude mcp add d2r-tools --transport stdio --scope user -- python3 -m d2r_mcp

Codex / Cursor / any other MCP client — add to the client's MCP config:

{
  "mcpServers": {
    "d2r-tools": {
      "command": "python3",
      "args": ["-m", "d2r_mcp"],
      "env": {}
    }
  }
}

Mutation tools (d2r_chargen_build, d2r_mod_deploy) enforce the project's safety rules structurally: they back up the live save, build to a staging file, run the scanner on the staging, and only promote to the live save if the scanner passes.

Claude Code Plugin (optional)

The plugin/ directory is a Claude Code plugin that adds slash commands and skills on top of the MCP server. Point Claude Code at the repo or symlink plugin/ into your Claude Code plugins directory.

Slash commands

Skills

• d2r-safe-edit — enforces backup→edit→scan→verify on every save file change
• d2r-parallel-agents — guides parallel-agent dispatch for multi-character work