The Six-Layer Stack

Brain is a layered protocol. Information flows up; control flows down.

Raw → Ledger → Wiki → Policy → Agent → Audit

Each tenant has its own logical instance of every layer, with hard isolation at the database, KMS, and policy boundaries. Off-chain state lives in Postgres with pgvector and Azure Blob-backed raw artifacts. On-chain commitments and smart-account execution live on Base L2.

The Six Layers at a Glance

1️⃣ Raw

Lossless ingestion of evidence from any authorized source.

Raw and Ledger

2️⃣ Ledger

Deterministic structuring into immutable records with provenance.

Raw and Ledger

3️⃣ Wiki

Continuously updated memory graph per tenant.

The Wiki

4️⃣ Policy

Plain-English rules compiled to deterministic guards.

Policy and Permissioning

5️⃣ Agent

Internal and external agents executing within policy.

Agents

6️⃣ Audit

Per-tenant Merkle tree anchored on Base L2.

Audit and Proof

Why Six Layers, in This Order

The stack is not a stylistic choice. Each layer enforces a property the layer above it requires.

Layer	What It Enforces	Why It Matters
Raw	Lossless, replayable storage	Higher layers can be rebuilt deterministically if extraction logic changes
Ledger	Deterministic structure with provenance	Reasoning never reinterprets raw documents on the fly
Wiki	Continuously refreshed memory linked to Ledger	Answers compound over time; citations are always traceable
Policy	Tenant-signed deterministic rules	No agent action runs unchecked
Agent	Scoped, attestable execution	Internal and external agents share one verified substrate
Audit	Hash-chained, Merkle-anchored events	History cannot be silently rewritten

This is the same separation that exists in any serious system between the database and the cache: structure first, reasoning second, memory bound to citations.

Information Flow

Information flows up. Each layer enriches the one below.

Source webhook
   ↓
[ Raw ]            artifact stored, content-addressed by SHA-256
   ↓
[ Ledger ]         deterministic extractor produces structured records
   ↓
[ Wiki ]           entity resolution, narrative summarization, embeddings
   ↓
[ Policy ]         action evaluated against active policy version
   ↓
[ Agent ]          execution dispatched to off-chain rail or on-chain account
   ↓
[ Audit ]          every step hashed, Merkle root anchored on Base

Control Flow

Control flows down. Higher layers gate lower ones.

Layer Above	Gates	Layer Below
Audit	requires hash links from	every other layer
Agent	requires verdict from	Policy
Policy	reads from	Ledger only (never Wiki)
Wiki	rebuilds from	Ledger
Ledger	replays from	Raw
Raw	sources from	the tenant's connected systems

Off-Chain and on-Chain Split

Most logic is off-chain by design. On-chain contracts exist to anchor state, register identity, enforce session-key scope/limits, and route agent execution.

Tier	What Lives Here
Off-chain	Raw artifacts (Azure Blob), Ledger records (Postgres), Wiki graph (Postgres + pgvector), Policy compiler, Agent runtime
On-chain (Base L2)	BrainAuditAnchor, BrainPolicyRegistry, BrainSmartAccount, BrainMCPAgentRegistry

→ Smart contract reference

What's Next

📥 Raw and Ledger

How evidence becomes deterministic structure.

Raw and Ledger

🧠 The Wiki

The memory graph per tenant.

The Wiki

📋 Policy and Permissioning

Plain-English rules to deterministic guards.

Policy and Permissioning