settlement-witness

settlement-witness is a skill for Claude Code, Codex from nutstrut/default-settlement-verifier. It costs 81 tokens per session (1,607 once invoked), scanned A, original, MIT.

A local verifier for signed SAR v0.1 settlement receipts. These receipts are records used to support claims that a task or settlement was completed.

In plain words
What is it for?
It is for verifying receipts offline with Ed25519 signatures and RFC 8785 canonical formatting, including bundled self-test fixtures.
Why use it?
It checks whether a receipt's signature and formatting are valid before you trust it or use it as evidence.

Skill for Claude CodeCodex

Which agent this was written for is unclear — built for openclaw. Also seen: built for openclaw.

Good fit It is for verifying receipts offline with Ed25519 signatures and RFC 8785 canonical formatting, including bundled self-test fixtures.

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Install with agentmods
npx agentmods add skills/nutstrut/default-settlement-verifier/settlement-witness
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add nutstrut/default-settlement-verifier --skill settlement-witness
Clone the repo
git clone --depth 1 https://github.com/nutstrut/default-settlement-verifier

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for settlement-witness

README.md
[![agentmods](https://agentmods.dev/badge/skills/nutstrut/default-settlement-verifier/settlement-witness/github.svg)](https://agentmods.dev/skills/nutstrut/default-settlement-verifier/settlement-witness)
Your own site
<a href="https://agentmods.dev/skills/nutstrut/default-settlement-verifier/settlement-witness"><img src="https://agentmods.dev/badge/skills/nutstrut/default-settlement-verifier/settlement-witness/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for settlement-witness

Your own site · 80×15
<a href="https://agentmods.dev/skills/nutstrut/default-settlement-verifier/settlement-witness"><img src="https://agentmods.dev/badge/skills/nutstrut/default-settlement-verifier/settlement-witness.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 81 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,607 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00081 $0.01607
Opus 5 $0.00041 $0.00804
Sonnet 5 $0.00016 $0.00321
Haiku 4.5 $0.00008 $0.00161

Measured 9d ago against content hash db49f31b4ce3, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

settlement-witness scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.

The scan reads SKILL.md. This mod also ships 3 executable files (scripts/registry_snapshot.py, scripts/verify_receipt.py, tests/test_registry_lifecycle.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

curl -sS https://defaultverifier.com/settlement-witness \
openclaw/skills/settlement-witness/SKILL.md · 186 lines

How it starts

The opening of the file, as written. The whole thing — 186 lines — stays where its author put it; the contents beside it link to each section on GitHub.

New in 0.1.0: local-first verification. Receipt cryptography is verified entirely on your machine — no network required. Network is optional and only used when you explicitly request remote receipt issuance or resolution.

SettlementWitness

Verify SAR v0.1 settlement receipts locally. Optionally request DefaultVerifier-signed receipts.

When to use

  • Before trusting a task-complete claim from another agent
  • Before chaining downstream actions to an agent output
  • Before using a receipt as evidence
  • Before acting on a settlement- or payment-adjacent claim
  • When you prefer a local, offline verifier

First run (offline, no network needed)

Run the self-test against all bundled fixtures:

python3 scripts/verify_receipt.py --self-test

Expected output: self_test_passed: true with all six fixtures [OK].

Verify a single receipt

python3 scripts/verify_receipt.py fixtures/sar-v0.1-pass.json

Returns JSON:

{
  "valid": true,
  "receipt_id": "sha256:...",
  "kid": "sar-prod-ed25519-05",
  "verdict": "PASS",
  "errors": [],
  "signer_lifecycle_status": "active",
  "trusted_current_production_signer": true,
  "trusted_historical_signer": true,
  "registry_snapshot_sha256": "2da5285f...",
  "offline_verification_note": "Verified offline against the bundled registry snapshot ..."
}

Tamper test (should fail)

python3 scripts/verify_receipt.py fixtures/tampered-receipt.json

Returns valid: false with errors listing the digest mismatch and signature failure. This proves the verifier actually rejects tampered receipts.

How to interpret results

Field Meaning
valid: true Receipt digest and Ed25519 signature both verified
valid: false Receipt failed cryptographic verification
verdict: PASS The signed outcome claims the spec was met
verdict: FAIL The signed outcome claims the spec was not met
verdict: INDETERMINATE The issuer signed an honest uncertainty state
errors: [...] What specifically failed
signer_lifecycle_status The signer's bundled-registry-snapshot lifecycle: active, retired, reserved, documented_non_operational_duplicate, legacy_unclassified, wrong_profile, or unknown
trusted_current_production_signer true only when the key is the current active production signer — a retired key's historical signature can still be valid: true with this false
trusted_historical_signer true when the key is eligible for historical verification (active, retired, or legacy-unclassified)
registry_snapshot_sha256 SHA-256 of the bundled registry snapshot this run verified against
offline_verification_note States this was verified against the bundled snapshot only — not a live-registry freshness claim

Read the full file on GitHub · 186 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 9d ago First seen · 186 lines · 81 tokens per session scan A db49f31b4ce3

Subscribe to this mod's changes

settlement-witness is a skill published in the GitHub repository nutstrut/default-settlement-verifier (0 stars, last pushed 6d ago), licensed MIT. It adds 81 tokens to every session and 1,607 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Related

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