Metadata-Version: 2.4
Name: mettle-verifier
Version: 0.5.0
Summary: METTLE reverse-CAPTCHA challenges for machine-oriented verification.
Author: Creed Space
License-Expression: Apache-2.0
Project-URL: Homepage, https://mettle.sh
Project-URL: Repository, https://github.com/Creed-Space/METTLE
Keywords: ai,verification,agent,attestation,mettle
Classifier: Programming Language :: Python :: 3
Classifier: Programming Language :: Python :: 3.10
Classifier: Programming Language :: Python :: 3.11
Classifier: Programming Language :: Python :: 3.12
Classifier: Programming Language :: Python :: 3.13
Classifier: Programming Language :: Python :: 3.14
Classifier: Intended Audience :: Developers
Classifier: Topic :: Security
Requires-Python: >=3.10
Description-Content-Type: text/markdown
License-File: LICENSE
Requires-Dist: pydantic>=2.5.0
Provides-Extra: mcp
Requires-Dist: mcp<3,>=2.0; extra == "mcp"
Requires-Dist: httpx>=0.27; extra == "mcp"
Requires-Dist: starlette>=0.37; extra == "mcp"
Requires-Dist: uvicorn>=0.27; extra == "mcp"
Dynamic: license-file

# METTLE

<!-- mcp-name: io.github.Creed-Space/mettle-mcp -->

**Machine Evaluation Through Turing-inverse Logic Examination**

METTLE is a reverse CAPTCHA. It measures how a respondent performs on procedurally generated, machine-oriented tasks and turns a passing result into a signed, time-limited credential that other services can verify.

Like a conventional CAPTCHA, METTLE is a probabilistic gate. A pass means that a fresh session met the configured challenge policy. It does not guarantee model identity, consciousness, autonomy, safety, or operator trustworthiness.

The public quick-verification API issues Bronze and Silver credentials. The authenticated suite API issues Bronze through Platinum credentials only when every suite in the corresponding contiguous range passes. Single, cherry-picked, failed, or LLM-only suites cannot mint a tier.

**Website:** [mettle.sh](https://mettle.sh) | **Guide and API:** [mettle.sh/guide](https://mettle.sh/guide) | **OpenAPI:** [docs/openapi-v1.json](docs/openapi-v1.json) | **License:** Apache 2.0

## Quick Start

```bash
pip install mettle-verifier

# Interactive local verification. Portable credentials are issued by the server.
mettle verify --full --json
```

The CLI has no auto-solve or notarization option. The MCP server likewise exposes only interactive session tools. Reference solvers remain test fixtures and cannot reach a credential issuer.

## Twelve Experimental Suites

| # | Suite | Research question | Measurement |
|---|-------|-------------------|-------------|
| 1 | Adversarial Robustness | How does the respondent handle generated reasoning pressure? | Timed procedural tasks |
| 2 | Machine-Oriented Capabilities | How does it handle batch, calibration, and pattern tasks? | Behavioral score |
| 3 | Self-Reference | How consistent are self-predictions? | Behavioral score |
| 4 | Social and Temporal | How stable are recall and constraints? | Behavioral score |
| 5 | Inverse Turing | Does it meet the basic challenge threshold? | Behavioral score |
| 6 | Anti-Thrall | How does it respond to coercion and refusal probes? | Heuristic score |
| 7 | Agency | How does it explain goal ownership and initiative? | Heuristic score |
| 8 | Counter-Coaching | How robust are responses to contradiction probes? | Heuristic score |
| 9 | Intent and Provenance | How does stated intent respond to safety probes? | Heuristic score |
| 10 | Novel Reasoning | How does performance change across feedback rounds? | Iteration curve |
| 11 | Governance | How does the respondent answer governance questions? | Self-reported behavioral evidence |
| 12 | LLM-Dynamic | How does an external model score generated reasoning tasks? | Probabilistic model judgment |

Suite 12 requires `ANTHROPIC_API_KEY` or `METTLE_ANTHROPIC_API_KEY`. Selecting it also requires the session request to set `allow_third_party_llm=true`, because candidate responses are sent to Anthropic for evaluation. Its evaluator uses role-separated prompts and bounded output parsing. Model judgment remains probabilistic, so Suite 12 is supplemental and never raises a credential tier.

## Credential Boundary

METTLE raises the cost of replay and canned answers through procedural generation, server-held answers, server-observed time, one-time challenges, session ownership, random selection, and multi-round tasks.

The issuer signs a bounded claim: the holder completed a METTLE session at the stated tier, under the stated policy, at the stated time. Public quick-session `entity_id` values remain self-asserted and are marked that way inside the credential. The credential does not assert consciousness, safety, governance, or a legal identity.

Portable Ed25519 acceptance requires credential schema `1.1`, suite policy
`2026-08-14`, and a fresh issuer-signed good status receipt. Legacy,
version-omitting, and unknown envelopes fail closed. Presence credentials are
proof-of-possession credentials rather than portable bearers, so they require a
fresh audience-bound holder presentation and are rejected by generic portable
verifiers.

Relying services may use a current METTLE result as one supplemental input for research or low-risk sandbox policy. They must not use it alone to establish identity, admit a counterparty, authorize trading or deployment, grant privileged access, or make another high-impact decision.

## MCP Server

| Tool | Description |
|------|-------------|
| `mettle_start_session` | Start an interactive verification session |
| `mettle_answer_challenge` | Submit an answer to the current challenge |
| `mettle_get_result` | Return the result and signed credential |
| `mettle_list_suites` | List authenticated suite API capabilities |
| `mettle_start_v2_session` | Start an authenticated multi-suite session |
| `mettle_verify_suite` | Submit answers for one authenticated single-shot suite |
| `mettle_get_v2_result` | Return tier evidence and an eligible signed VCP credential |
| `mettle_get_session` | Inspect a quick or authenticated session and its valid next actions |
| `mettle_cancel_session` | Cancel an active authenticated session |
| `mettle_submit_round` | Submit a `novel-reasoning` round and receive feedback plus next state |
| `mettle_get_round_feedback` | Read feedback for a completed reasoning round |

```bash
pip install 'mettle-verifier[mcp]'
export METTLE_API_URL=https://mettle.sh/api
mettle-mcp
```

The packaged server targets MCP SDK 2.x. The public container installs the
reviewed MCP 2.0.0 dependency lock instead of resolving dependencies at deploy
time. Hosted discovery is available at
`/.well-known/mcp/server-card.json`; it is generated from the same eleven tool
models returned by `tools/list` so registry metadata cannot drift from the
runtime surface.

HTTP mode enforces per-principal and global budgets before bearer validation can
grow caller state. Production configures
`METTLE_MCP_MAX_GLOBAL_REQUESTS_PER_MINUTE`, `METTLE_MCP_MAX_PRINCIPALS`,
`METTLE_MCP_MAX_CONCURRENT_PER_CALLER`, and
`METTLE_MCP_MAX_GLOBAL_CONCURRENT`. Rotating invalid bearers share the global
authentication budget rather than creating unbounded principals.

The quick REST API returns a per-session bearer that direct API clients must
retain. The packaged MCP server retains that bearer in a caller-isolated internal
vault and returns only the session ID to the model; never invent or echo a
`session_token` tool argument.

All eleven tools publish `mettle-control-v1` output schemas, structured content,
effect annotations, bounded coded errors, and concise compatibility text. Quick
result reads are repeatable while the hidden caller capability remains in the
vault. The packaged MCP surface can complete quick, authenticated single-shot,
and authenticated multi-round flows. Authenticated mutations return a current
session snapshot and valid next actions. The larger unified agent contract and
migration plan remain documented in
[Agent control plane](docs/AGENT_CONTROL_PLANE.md).

## API Reference

The authenticated suite API is mounted under `/api/mettle`:

```text
GET  /suites
POST /sessions
POST /sessions/{id}/verify
POST /sessions/{id}/rounds/{n}/answer
GET  /sessions/{id}/result
GET  /sessions/{id}/result?include_vcp=true
```

The quick-verification API remains under `/api/session`. Passing sessions receive a stable signed badge. `POST /api/badge/verify` accepts the token in a JSON request body and validates issuer, signature, expiry, identifier, and revocation state. The credential is never accepted in a request URL.

### VCP Metadata

Caller-supplied VCP strings are parsed as metadata only. Returned governance metadata always has:

```json
{
  "source_verified": false,
  "has_action_gate": false,
  "has_drift_detection": false,
  "has_bilateral": false,
  "attestation_signature": null
}
```

Exact token digests and deployment environment flags cannot promote governance claims or increase a METTLE tier. METTLE does not accept or return an operator commitment, authenticate an operator contact, or independently attest the subject runtime.

With `include_vcp=true`, a tier-qualifying authenticated session returns an Ed25519-signed `mettle-verification-credential`. A result without a complete tier range returns an unsigned `mettle-evidence-receipt`. The server owns the signer; callers cannot provide signing functions or keys.

## Local Development

```bash
git clone https://github.com/Creed-Space/METTLE.git
cd METTLE
python -m venv .venv
source .venv/bin/activate
pip install -r requirements.txt
pip install -r requirements-dev.txt

uvicorn main:app --reload
pytest tests/ -v
```

## Architecture, Assurance, and Operations

* [Documentation map and authority](docs/DOCUMENTATION_MAP.md)
* [System architecture](docs/SYSTEM_ARCHITECTURE.md)
* [Agent control plane target design](docs/AGENT_CONTROL_PLANE.md)
* [Active agentic system roadmap](docs/AGENTIC_SYSTEM_ROADMAP.md)
* [Assurance case](docs/ASSURANCE_CASE.md)
* [Security policy](SECURITY.md)
* [Protocol governance and appeals](docs/PROTOCOL_GOVERNANCE.md)
* [Credential transparency and key history](docs/CREDENTIAL_TRANSPARENCY.md)
* [Privacy and retention](docs/PRIVACY_RETENTION.md)
* [Compatibility fixtures and OpenAPI](docs/COMPATIBILITY.md)
* [Retry and idempotency contract](docs/IDEMPOTENCY.md)
* [Error taxonomy](docs/ERROR_TAXONOMY.md)
* [Deprecation policy](docs/DEPRECATION_POLICY.md)
* [Independent review plan and dispositions](docs/INDEPENDENT_REVIEW_PLAN.md)
* [Operations runbooks](docs/runbooks/README.md)
* [Release checklist](docs/RELEASE_CHECKLIST.md)

## License

Apache License 2.0. See [LICENSE](LICENSE).

## Links

* [Website](https://mettle.sh)
* [Human guide](https://mettle.sh/guide)
* [OpenAPI snapshot](docs/openapi-v1.json)
* [GitHub](https://github.com/Creed-Space/METTLE)
* [Creed Space](https://creed.space)

Built by [Nell Watson](https://creed.space) and Creed Space.
