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Why System One models change everything

Every Minecraft bot ever built is a state machine: if hostile nearby → flee. That works until reality gets complicated — what if you're hungry and being chased and it's night and you just died nearby? Priorities conflict, and hardcoded rules break.

System One models from TypeSafe are a fundamentally different kind of AI. Named after Kahneman's Thinking, Fast and Slow, they make fast, structured decisions that software can use directly — returning typed answers and calibrated probabilities instead of generating text.

The key insight: code owns the workflow, Jev supplies the common sense. This isn't an AI agent running loose — it's a primitive you call exactly where deterministic logic falls short. Every question returns a probability distribution over your defined options, so your code can act, escalate, or fall back with full confidence information.

That's what makes jev-craft possible: a bot that reads a complex, ambiguous game situation and makes a sensible call in under 100ms — not because someone wrote every if branch, but because Jev understands the situation.

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How it uses Jev

Every reactive tick (600ms), jev-craft sends its current world state to Jev and gets back four typed answers in a single parallel API call:

Every tactical tick (10s), it asks Jev to pick a goal from 13 options, assess urgency, and choose an approach — all in one more parallel call. When a goal gets stuck, Jev decides whether to retry or abandon it entirely.

No parsing. No prompt engineering. Just typed answers the bot acts on directly.

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Features

• AI-driven decisions — no hardcoded priority rules; Jev reads the full situation and decides
• Emotional state — four live emotions (fear, satisfaction, curiosity, urgency) that shape every question sent to Jev
• Persistent memory — remembers shelter, crafting stations, furnaces, death locations, animal areas, and player preferences across restarts
• Selective recall — relevant memories are surfaced contextually each tick (near a death site? Jev is warned)
• Player commands — type anything in chat; Jev reads it and picks the matching goal sequence
• Failure awareness — tracks per-step failures, asks Jev whether to retry or abandon a stuck goal
• Full progression chain — 13 goals from punching trees to iron tools, with dependency awareness

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How it works

Every 600ms (reactive loop)
  ┌─────────────────────────────────────────────────────────┐
  │  Extract game state  →  Update emotions  →  Ask Jev     │
  │                                                         │
  │  State: health, food, hostiles, position, time, goal    │
  │  Emotions: fear, satisfaction, curiosity, urgency       │
  │  Memory: recalled death sites, resources, shelter       │
  │                                                         │
  │  Jev answers (parallel):                                │
  │    threat_level · action · should_eat · flee_direction  │
  │                                                         │
  │  Execute: fight / flee / eat / goal step / look around  │
  └─────────────────────────────────────────────────────────┘

Every 10s (tactical loop)
  ┌─────────────────────────────────────────────────────────┐
  │  Build inventory + memory snapshot  →  Ask Jev          │
  │                                                         │
  │  Jev answers (parallel):                                │
  │    goal · urgency · approach                            │
  │                                                         │
  │  Switch goal if urgency >= 2.0 or player commanded      │
  └─────────────────────────────────────────────────────────┘

Goal progression

gather_wood → craft_tools → mine_stone → upgrade_tools ──→ mine_iron → smelt_iron → craft_iron_tools
                                    └──→ craft_furnace ──→ cook_food
                                                     └──→ smelt_iron

+ get_food · build_shelter · go_to_shelter · explore

Emotional system

Four continuous emotions (0–1) decay each tick and are injected into every Jev question as context:

The dominant emotion becomes a label — terrified, anxious, proud, content, eager, curious, desperate, focused, or calm — sent with every Jev question.

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Getting started

Prerequisites

• Node.js 18+ (or Bun)
• A running Minecraft server (local LAN works fine)
• A TypeSafe API key

Install

git clone https://github.com/akash-kamat/jev-craft.git
cd jev-craft
npm install

Configure

cp .env.example .env

Edit .env:

TYPESAFE_API_KEY=your_api_key_here
MC_HOST=localhost
MC_PORT=25565        # LAN port shown in chat after "Open to LAN"
MC_USERNAME=JevBot

Run

npm start
# or for hot-reload during development:
npm run dev

The bot connects, spawns, and immediately starts making decisions. You'll see a live log of its state, emotions, goals, and every action it takes.

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Chat commands

Type in Minecraft chat to control the bot in real time:

Any natural language works — Jev reads it and picks the best matching goal.

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Project structure

src/
├── index.js        # Bot setup, event handlers, loop drivers
├── config.js       # Server connection, model, intervals, thresholds
├── state.js        # extractState() — game world snapshot each tick
├── decisions.js    # Reactive Jev call — threat + action + eat + flee
├── tactics.js      # Tactical Jev call — goal selection + step execution
├── goals.js        # All 13 goals with steps, canRun guards, isDone checks
├── actions.js      # doFight / doFlee / doEat / doLookAround
├── mind.js         # Emotional state, event log, selective memory recall
└── memory.js       # Persistent bot-memory.json — locations, deaths, prefs

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Roadmap

• Phase 1 — Reactive survival (fight, flee, eat, look around)
• Phase 2 — Tactical goals + player commands + persistent memory
• Consciousness system — emotions, event log, selective recall
• Phase 3 — Universal primitives: let Jev sequence atomic actions instead of hardcoded steps
• Smarter mining — branch pattern, torch placement, gravel handling
• Async smelting — start furnace and do other things while waiting
• Jev-driven emotion updates — ask Jev how the bot should feel, not just formulas
• Emotional expression — bot says things in chat based on its emotional state

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Built with

• Jev by TypeSafe — System One AI model for fast, typed decisions
• Mineflayer — Minecraft bot framework
• mineflayer-pathfinder — Navigation

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License

MIT