.brain — the portable decision log

The portable decision log your AI tools all read. One MCP server. Any AI tool. Plain files.

Every AI coding session starts by re-explaining context the last session already knew. .brain is a folder in your repo that Claude Code, Cursor, and Codex all read via one MCP server. Decisions, policies, plans — written once, remembered across every session and every tool.

MIT licensed. File-based (plain JSON + markdown). No embeddings. No vendor lock-in.

Three Frontiers

The core loop that makes AI reliability compound over time:

  GROUND              ALIGN               COMPOUND
  ──────              ─────               ────────
  Machine verifies    Human corrects      System learns

  AI writes code  →  You fix a mistake →  Delta recorded
  GROUND checks   →  Verdict stored    →  DPO pair created
  Receipt logged  →  Event emitted     →  Training data grows
       │                   │                    │
       └───────────────────┴────────────────────┘
                    Reliability improves

GROUND — 5-tier execution verification. Syntax, imports, tests, runtime. Goes outside the formal system to check the AI's work.

ALIGN — One-call corrections. nucleus_align(action="correct", params={context, correction}). Each correction automatically records a verdict, creates a training pair, and emits an event.

COMPOUND — Deltas measure the gap between intent and reality. Recurring patterns become strategy. Negative deltas become training signal.

Every tool response shows frontier health:

[frontiers: GROUND 42 | ALIGN 12 | COMPOUND 28]

Quick Start

pip install nucleus-mcp
nucleus init --recipe founder

Two commands. Nucleus is running. AI outputs are now verified.

What It Does

114 MCP tools across 13 facades:

• GROUND — Execution verification (5 tiers: diff, syntax, imports, tests, runtime)
• ALIGN — Human corrections (verdict + delta + DPO + event in one call)
• Memory — Engrams that persist across sessions. Write once, recall forever.
• Sessions — Save context, resume later. Session arc shows your last 3 sessions.
• Tasks — Priority queue with escalation, HITL gates, and heartbeat monitoring.
• Governance — Kill switch, compliance configs (EU DORA, MAS TRM, SOC2), audit trails.
• Orchestration — Agent slots, multi-brain sync, task dispatch.
• Archive — Training pipeline (SFT + DPO), delta tracking, frontier health dashboard.

Benchmark: decision-retention-evals — does your AI agent remember why the code is the way it is?

Nucleus Pro

Everything above is free (MIT). Nucleus Pro adds verifiable governance:

nucleus trial                              # 14-day free trial
nucleus compliance-check                   # Score your AI governance
nucleus audit-report --signed -o report.html  # Cryptographically signed report

$19/month or $149/year — nucleusos.dev/pricing

... View full README on GitHub