Building a WoW TBC Classic Addon with Claude Code and Mechanic

BoneyardTBC is a guild management addon for WoW TBC Classic Anniversary Edition. GearScore tracking, a bulletin board, a dungeon optimizer, officer analytics. I built it with Claude Code and Mechanic as the development backbone.

What It Does

BoneyardTBC gives guilds visibility into their own roster:

• GearScore for every guild member — addon users and non-users alike (silent background inspection)
• Bulletin Board — guild-wide in-game announcements with timers
• DungeonOptimizer — route planner that tracks rep grind progress across TBC heroics and raids
• Officer Analytics — weekly activity charts and GearScore progression graphs

The addon syncs over WoW’s GUILD addon message channel. Everyone with it installed shares data automatically. Don’t have the addon? Your GearScore still gets populated whenever someone inspects you.

The Toolchain

Mechanic

Mechanic is a dev hub for WoW addon development. Python CLI, MCP server, web dashboard, and a sandbox for running unit tests without launching the game.

The killer feature is the SavedVariables bridge. Mechanic watches WoW’s SavedVariables files after a /reload, parses them, and surfaces errors and print() output in the dashboard. That closes the loop between writing code and seeing what it does in-game.

Claude Code

Claude Code did the actual coding. With Mechanic exposed via MCP, Claude could:

• Look up TBC API signatures (api.search)
• Lint code (addon.lint) with Luacheck mid-conversation
• Run unit tests (sandbox.test) and see failures inline
• Read in-game errors (addon.output) after a /reload

The loop:

1. Describe a feature
2. Claude reads the files, writes the code
3. I /reload in WoW
4. Claude reads the errors itself and fixes them
5. Repeat

No copy-pasting errors. No switching between terminal and game. Claude sees everything through Mechanic.

The Hard Parts

TBC Classic API Surface

TBC Classic Anniversary runs a completely different API surface from retail. Many C_* namespaces don’t exist. I had to:

• Clone Gethe/wow-ui-source on the classic_anniversary branch
• Parse the FrameXML into a local API database (3,459 TBC APIs)
• Generate Luacheck stubs and sandbox stubs from that

After that, Claude searched against TBC-accurate docs instead of retail.

Silent Inspection

Populating GearScore for guild members who don’t have the addon was the interesting problem. The approach:

• Hook INSPECT_READY when the inspect frame opens
• Verify the target is a guild member via GetGuildRosterInfo() — not just guild name, because connected realms share a channel
• Calculate GearScore from equipped items silently
• Broadcast to all addon users over the GUILD channel

The annoying part was realm names. Connected realms give you names like Pensatankki-Spineshatter. Every lookup had to strip the realm suffix before matching roster keys.

Unit Testing Without WoW

WoW addons normally need the game client to run. Mechanic’s sandbox fakes it with generated API stubs and a Busted test runner.

Final count: 37 tests for the core addon, 94 tests for DungeonOptimizer. The full suite runs in seconds and catches regressions before they touch the game.

Keeping Claude Oriented

The project grew to multiple modules — Core.lua, GearScore.lua, Sync.lua, Inspection.lua, BulletinBoard.lua, AddonDetection.lua, plus a UI layer and the DungeonOptimizer companion addon.

Two things kept Claude from getting lost across sessions:

• ARCHITECTURE.md — 782 lines covering every module, data flow, and message protocol
• MEMORY.md — Claude Code’s persistent memory tracking version history and architectural decisions

What Worked

The MCP loop. Everything flowed through the conversation. Claude linted, tested, and read output without me relaying anything.

Incremental releases. Each version (r7 through r10) added one or two features with tests first. Small steps, clean codebase.

Separate SavedVariables for DungeonOptimizer. The core addon works standalone. Install or remove the companion without touching core data.

What Didn’t

In-game UI debugging is still awful. Lua errors in WoW are cryptic one-liners. Taint errors are worse — protected UI code gets called from addon code and fails silently. No error, no log. Just nothing happening.

TBC API gaps. Some APIs in the FrameXML source aren’t actually callable in the Anniversary client, or have different signatures. The only way to know is to try it in-game and watch it break.

The Result

BoneyardTBC runs in production for my guild on Spineshatter-EU. GearScore leaderboard, bulletin board, officer analytics — all actively used.

Built in one week of evening sessions. Zero prior Lua knowledge. Higher test coverage than any addon I’ve written before. Mechanic made it possible — an error bridge, a correct API database, and MCP tools turning WoW addon dev into something that resembles actual software engineering.