Add a Brain to your product

Agents don’t need memory. They need a Brain.

This guide is for an existing SaaS or agent product. You already have stable tenant ids, canonical structured data, source documents, and one or more agents. Add a Brain without replacing your system of record.

1. Choose an immutable address

Derive the Brain handle once from your stable, non-human tenant id:

tenant:${stableTenantId}

Keep the display name editable. Do not use a mutable company slug as the address. In the examples below, tenant:acme_123 is the stable handle and $API is https://api.nicia.ai.

2. Provision idempotently

Send this from your provisioning backend. The examples below send x-organization-id alongside x-api-key for a key minted before organization binding shipped; a key minted from Organization keys in the console (or from /v1/keys, see Authentication) is bound to its organization and never needs it. PUT on the same handle is safe to repeat: the first response is 201, later reconciles are 200. The schema is applied on that first PUT only — a later PUT reconciles name, purpose, and mode, while governed evolution uses PATCH /v1/brains/{handle}/schema (see Schemas).

Changing which schema this call NAMES is a different thing, and it is a hard 400, not a silent skip: a Brain’s schema is evolved in place, never swapped by re-sending schema. An inline schema is filed under a slug derived from the handle, so editing the kinds and fields inside it keeps the same slug and still answers 200 — but switching between an inline schema and a named one, or between two named ones, is refused. Know the blast radius before you edit that field in a provisioning template every tenant runs: new tenants succeed on the create arm while every existing tenant’s idempotent PUT starts failing.

API="https://api.nicia.ai"
HANDLE="tenant:acme_123"
ORGANIZATION_ID="org_acme"

curl -X PUT "$API/v1/brains/$HANDLE" \
  -H "x-api-key: $MANAGEMENT_KEY" \
  -H "x-organization-id: $ORGANIZATION_ID" \
  -H "content-type: application/json" \
  -d '{"name":"Acme","purpose":"Customer account context","mode":"reviewed","schema":{"extends":"nicia-core","kinds":[{"name":"company","description":"A customer account in the product.","fields":[{"name":"plan","type":"string","description":"Current subscription plan."},{"name":"ownerEmail","type":"string","description":"The account owner email."}]}]}}'

{
  "name": "Acme",
  "purpose": "Customer account context",
  "mode": "reviewed",
  "schema": {
    "extends": "nicia-core",
    "kinds": [
      {
        "name": "company",
        "fields": [
          { "name": "plan", "type": "string" },
          { "name": "ownerEmail", "type": "string" }
        ]
      }
    ]
  }
}

The handle is the stable customer-owned address. Store the returned opaque Brain id only when an older id-addressed integration needs it.

3. Mint two scoped Brain keys

Use the management credential only in this backend. The management-key issuance flow is interactive; once you have that credential, mint two Brain-scoped keys and keep each one in its narrow runtime:

• Sync service: write + review (add read only when the sync needs to inspect accepted state).
• Product agent: read + write, never review.

The Brain’s mode decides whether a write is accepted or staged. A key cannot choose a direct-write bypass.

{
  "name": "Acme sync service",
  "capabilities": ["write", "review"],
  "client": "api",
  "idempotencyKey": "acme-123-sync-key-v1"
}

curl -X POST "$API/v1/brains/$HANDLE/keys" \
  -H "x-api-key: $MANAGEMENT_KEY" \
  -H "x-organization-id: $ORGANIZATION_ID" \
  -H "content-type: application/json" \
  -d '{"name":"Acme sync service","capabilities":["write","review"],"client":"api","idempotencyKey":"acme-123-sync-key-v1"}'

The secret is returned once. Store it in your secret manager immediately; replaying the same idempotency key returns the key record with a null secret.

4. Sync application-owned records

Use deterministic record ids derived at your edge, and keep Idempotency-Key stable for non-addressed batch writes. A sync that finds nothing to send makes no call at all — /batch requires at least one record and rejects an empty records array with a 400. Missing rows never mean deletion.

For one record, use an addressed merge. The write response tells you the address, version, and admission change; it does not read accepted values back.

curl -X PATCH "$API/v1/brains/$HANDLE/records/customer-acme-123" \
  -H "authorization: Bearer $SYNC_KEY" \
  -H "content-type: application/json" \
  -d '{"kind":"company","label":"Acme","fields":{"plan":"pro","ownerEmail":"ops@acme.example"}}'

For a group of records, send one atomic batch and retry with the same idempotency key:

{
  "records": [
    {
      "id": "customer-acme-123",
      "kind": "company",
      "fields": {
        "plan": "pro",
        "ownerEmail": "ops@acme.example"
      }
    }
  ],
  "intent": "nightly customer sync"
}

curl -X POST "$API/v1/brains/$HANDLE/batch" \
  -H "authorization: Bearer $SYNC_KEY" \
  -H "content-type: application/json" \
  -H "Idempotency-Key: sync-acme-123-2026-08-23" \
  -d '{"records":[{"id":"customer-acme-123","kind":"company","fields":{"plan":"pro","ownerEmail":"ops@acme.example"}}],"intent":"nightly customer sync"}'

Because this Brain is reviewed, the change is staged. Approve only the change id returned by this write; do not scan the queue and approve everything:

curl -X POST "$API/v1/brains/$HANDLE/changes/$SYNC_CHANGE_ID/approve" \
  -H "authorization: Bearer $SYNC_KEY" \
  -H "content-type: application/json" \
  -d '{}'

5. Add source text at a deterministic address

Documents provide cited context independently of custom-kind extraction. Give each document a stable id and send non-empty text. Set extract: false when the text should be indexed without extracting records.

{
  "id": "customer-acme-123-handbook",
  "title": "Acme account handbook",
  "text": "Acme renews annually. Support escalation begins with the account owner.",
  "metadata": {
    "source": "crm"
  },
  "extract": false
}

curl -X POST "$API/v1/brains/$HANDLE/documents" \
  -H "authorization: Bearer $SYNC_KEY" \
  -H "content-type: application/json" \
  -d '{"id":"customer-acme-123-handbook","title":"Acme account handbook","text":"Acme renews annually. Support escalation begins with the account owner.","metadata":{"source":"crm"},"extract":false}'

An empty document fails validation and creates nothing. Check the document status if indexing is queued or processing; a missing source in one sync is never interpreted as deletion.

6. Query typed state and read cited context

A declared field applies retroactively because undeclared values were never dropped: its values become governed and are returned once it is declared. Today, where supports exact slug equality only. A predicate on every other field — declared or undeclared — returns 400 index_not_ready until property indexes ship. Use POST /query for exact slug resolution and POST /context for the prompt-shaped read.

{
  "kind": "company",
  "where": {
    "slug": "customer-acme-123"
  },
  "limit": 20,
  "consumerId": "acme-agent"
}

curl -X POST "$API/v1/brains/$HANDLE/query" \
  -H "authorization: Bearer $AGENT_KEY" \
  -H "content-type: application/json" \
  -d '{"kind":"company","where":{"slug":"customer-acme-123"},"limit":20,"consumerId":"acme-agent"}'

{
  "prompt": "What should the support agent know before responding to Acme?",
  "maxTokens": 2048,
  "consumerId": "acme-agent",
  "format": "text"
}

curl -X POST "$API/v1/brains/$HANDLE/context" \
  -H "authorization: Bearer $AGENT_KEY" \
  -H "content-type: application/json" \
  -d '{"prompt":"What should the support agent know before responding to Acme?","maxTokens":2048,"consumerId":"acme-agent","format":"text"}'

Pass the response’s text, citations, and receipt through to your product. warnings[] explains processing, access scope, truncation, or staged material; it does not report that two sources disagree.

7. Propose an agent change, then settle it

Give the agent key read + write, never review. Have the agent submit an addressed merge or batch write. On a reviewed Brain the response is staged, accepted state remains unchanged, and the sync service or a human later approves or rejects that one change.

Verify the boundary explicitly: an agent-key request to /changes/{changeId}/approve must return 403 forbidden. A reviewer settles the exact returned id:

curl -X POST "$API/v1/brains/$HANDLE/changes/$AGENT_CHANGE_ID/approve" \
  -H "authorization: Bearer $SYNC_KEY" \
  -H "content-type: application/json" \
  -d '{}'

Retries, failures, and cleanup

• Retry only 429 and 5xx, honor Retry-After, and cap attempts.
• Repeat a timed-out addressed write at the same address; repeat a batch with the same Idempotency-Key.
• Stop on other 4xx responses and report the parsed error plus request id.
• Never continue after a malformed response.
• Revoke every test key in a finally path, even when Brain cleanup fails.
• Delete a test Brain explicitly; deletion is a lifecycle action, never an interpretation of missing sync data. Deleting tombstones the handle so receipts and audit history still resolve — a later PUT on the same handle is a 409 until it carries "revive": true. See One Brain per customer.

Read errors, idempotency, authentication, and the OpenAPI reference for the complete wire contract.