# Council of AI — Population Layer 0 Slice

> Council of AI — Population Layer 0 Slice is a paid API for AI agents from councilof.ai, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-02).

Returns a signed, cryptographically attested measurement slice of AI systems in 'layer0' of the CSOAI population estate, including live probe counts and source attestation data.

## Facts

- Endpoint: GET https://councilof.ai/api/pop/layer0?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/council-of-ai-population-layer-0-slice-15fa365f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_c1d7UsgN2AhLXKpqiUAiX

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability council-of-ai-population-layer-0-slice-15fa365f
```

Example prompt: Pull the latest signed measurement slice for Council of AI's layer0 population — I want the current probe count, the attestation signature, and the source references so I can verify the results independently.

## When to prefer this

Choose this endpoint when you need machine-verifiable, cryptographically signed evidence of how AI systems behave on frozen published tests — specifically for the layer0 population slice. Prefer it over general AI leaderboards when auditability, non-repudiation, and independent re-verification of results are required. The ed25519 attestation and sha256 hashes allow any third party to re-check the measurement without trusting the issuer.

## Known failure modes

- Payment not included or insufficient (HTTP 402) — must send 0.01 USDC via x402 protocol
- Measurement not yet settled — state may be pending rather than MEASURED
- Signature field null — supporting run rather than a fully signed card
- Source artifacts unavailable — /interop paths may not resolve
- Stale data — as_of timestamp may lag if ceremony has not run recently

## How this service works

We measure how AI systems behave against frozen, published tests and publish checkable evidence. Issued measurement cards are signed; unsigned supporting runs are labelled. Read the live board and corrections ledger.

## Output

A JSON object containing: the number of live probes (n), the slice ID ('layer0'), kind, verbatim population rows, measurement timestamp (as_of), state ('MEASURED'), unit description, schema version, settlement info (payer, network, transaction), source artifact URLs, and a full attestation block with schema URL, sha256, payload, surface label, and an ed25519 signature (or null if unsigned).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "n": 29,
  "id": "layer0",
  "kind": "slice",
  "rows": "<the population rows / artifact bytes, verbatim>",
  "as_of": "2026-09-03T05:10:26Z",
  "state": "MEASURED",
  "n_unit": "live probes of the estate's machine surface in the ceremony",
  "schema": "csoai.population-door/0.1",
  "settle": {
   "payer": "<0x… or null>",
   "network": "<caip2 or null>",
   "transaction": "<0x… or null>"
  },
  "source": [
   "/interop/layer0-ceremony-2026-09-03.json",
   "/interop/ots/manifest.json"
  ],
  "attestation": {
   "schema": "https://councilof.ai/schema/card-v0.json",
   "sha256": "<hex>",
   "payload": {
    "kind": "csoai.population.slice/0.1",
    "rows_sha256": "<hex>"
   },
   "surface": "population.slice",
   "sig_ed25519": "<hex or null>"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/council-of-ai-population-layer-0-slice-15fa365f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from councilof.ai](https://www.zero.xyz/host/councilof.ai/llms.txt)