Every project is a tribe. Every session is an avatar that marches out and works. Every subagent is a drone. Tools become resources to harvest, errors make units stumble, compaction summons a storm. It draws itself — live — from your Claude Code hooks.
Leave it open on a second monitor. Glance at it across days and weeks. A repo you've poured months into is a walled Citadel with a gilded keep and mossy walls; one you touched last weekend is a thatch Outpost. The busy ones bustle; the neglected ones go quiet and grey — until you return to them and colour floods back. It's an ambient, honest record of where your attention actually went.
Everything below is derived from real data — lifetime tool & session counts, first-seen dates, and the clock. No faked activity, no invented numbers.
Outpost → Hamlet → Walled Town → Citadel → Capital. Each tier unlocks real structure: palisades become stone walls, the keep gains a gilded roof, towers rise. Cross a threshold while you're away and the town is structurally different when you come back.
Banners droop, colour drains, and moss creeps over the walls of a project gone quiet — honest neglect, never deletion. The instant a real session fires, life floods back over a couple of seconds and a worker spawns. Age leaves a permanent patina; idleness only veils it.
On the overview, each town is sized by its lifetime work and ringed by a colour that says worked-today vs idle-for-weeks. A Bash-heavy project grows forge chimneys; a Read-heavy one sprouts watchtowers. You learn each town's silhouette like a fingerprint.
And when you open it after time away, a town crier greets you with exactly what changed — “4 days away: +3 sessions, +812 tools, Null Pointers reached Citadel.”
The whole thing is a state machine fed by Claude Code's hook events. Nothing scripted, nothing faked — your actual workflow choreographs the world.
SessionStarta worker awakens — spawns from the base in a burstUserPromptSubmitthat worker perks up with a ! — new ordersPreToolUse · Bashmarches to the gas geyser to run commandsPreToolUse · Edit/Writeharvests mineral crystals — building thingsPreToolUse · Read/Grepheads to the watchtower to scoutPreToolUse · Taskspawns a drone that fans out — your subagentPostToolUsehauls the resource home, +1, stockpile growsPostToolUse · errorthe unit stumbles in a puff of redSubagentStopa drone zooms back to base and mergesStopthe worker heads home and takes a nap (z)SessionEndit salutes and walks back in — but its work counts foreverPreCompacta memory storm swirls units around the baseThis isn't a dashboard that resets when you blink. The server keeps lifetime stats per tribe — tools harvested, sessions ever run, subagents deployed — and each tribe levels up. Higher level means bigger territory, more outlying buildings, taller coral, a longer neon perimeter.
Leave it running a week and your busiest repo becomes a sprawling capital while that thing you touched twice stays a humble outpost.
Click any base. Rename it, give it a motto, pick its color and one of twelve procedural crests. async-armada becomes Async Armada, Breaker of Builds and stays that way. Build your little lore. Nobody's stopping you.
Names default from your folder, prettified — my-cool-app → "My Cool App".
A hook drops a line in a file, a tiny local server reads the file, your browser draws a world. That's the whole trick. Zero dependencies — Node built-ins and a canvas.
Claude Code ──fires a hook on every event──▶ arena-hook.sh (tiny, fast, never blocks Claude) │ appends one line ▼ ~/.claude/claude-arena/events.ndjson │ tailed + normalized ▼ server.js ──static UI + live SSE stream──▶ your browser (lifetime tribe stats · eras) (sim + procedural renderer · all canvas)
The server binds to 127.0.0.1 only. The browser is told that something happened — event type, project name, tool name, and which projects interacted — but never the file paths, prompt text, or tool output. Paths are resolved to a project identity on the server and never leave it. Nothing is sent anywhere; there's no analytics. The arena doesn't need to know what you're working on to draw your world.
Node 18+. No npm install, no build step, no account. It backs up your settings before touching anything.
# 1. wire the capture hook into Claude Code (backs up settings first) node install.js # 2. start the arena node server.js # 3. open it open http://localhost:4787
Then go use Claude Code like you normally would. The world fills itself in.