DnD Tracker

DnD Tracker is a mobile-friendly web app my D&D group actually plays with: character sheets, inventory and equipment, spellcasting with mana and cooldowns, and a DM dashboard that controls a persistent world clock. Every change — a spell cast, an item equipped, a potion chugged — broadcasts to all connected players over WebSockets in real time.

The interesting parts

• An AI dungeon master’s assistant — Claude is wired in through MCP tools that can roll dice (4d6 drop lowest, cryptographic RNG), query character state, grant items, and apply effects. Tools are permission-gated (DM-only vs. player-read-only) and every mutation lands in an immutable audit log.
• A stat formula DSL — DMs define custom derived stats as expressions like ac = 10 + dex / 2. Stats compute lazily through a pipeline: base stats → permanent boosts → temporary effects → equipped items → formulas. Custom campaigns get custom rules without code changes.
• World-clock cooldowns — spell cooldowns tick down with shared game time the DM controls, not wall-clock time, so story pacing stays in the DM’s hands.
• Real auth, self-hosted — JWT with refresh-token rotation, role-based guards on every route, ticket-based WebSocket auth. Deploys to AWS ECS/Fargate via CDK or to a NAS with Docker Compose and DynamoDB Local.

Stack

Fastify + TypeScript backend over DynamoDB (10 tables), React 18 + Vite frontend with 3D dice rolling, Playwright end-to-end tests covering multi-player workflows, and a CI merge gate. 245 TypeScript files and counting.