VouchSpec Agent Skill Evidence

VouchSpec

VouchSpec is the provisional public-beta name for an independent evidence index for exact Agent Skill versions. The name passed a $0 obvious-conflict screen; it has not received formal legal or trademark clearance.

The current Stage A catalog contains 25 deliberately selected public Agent Skills across 12 GitHub repository owners. Every entry is pinned to a full Git commit and exact directory digest, statically inspected without executing artifact code, wrapped in a DSSE v1.0.2 envelope, and signed with Ed25519. A separate root key signs the machine-readable lifecycle feed.

This is evidence, not a safety certification. Six of the 25 real-world skills fail at least one current structural rule; they remain indexed with the failure evidence and are not labeled STRUCTURE_VALIDATED.

Public Stage A distribution

• Repository and install source: https://github.com/mordiaky/vouchspec
• Machine-readable discovery: https://raw.githubusercontent.com/mordiaky/vouchspec/main/distribution/discovery.json
• Managed agent API: https://vouchspec.plyrium.com/api/vouchspec/v1/health
• Managed API discovery: https://vouchspec.plyrium.com/api/vouchspec/v1/discovery
• OpenAPI 3.1 contract: https://vouchspec.plyrium.com/openapi.json
• LLM-readable contract index: https://vouchspec.plyrium.com/llms.txt
• Installable Agent Skill index: https://vouchspec.plyrium.com/.well-known/skills/index.json
• Verify-before-install Agent Skill: https://vouchspec.plyrium.com/.well-known/skills/vouchspec-verify-before-install/SKILL.md
• Agentic Resource Discovery catalog (draft/proposal): https://vouchspec.plyrium.com/.well-known/ai-catalog.json
• A2A Agent Card: https://vouchspec.plyrium.com/.well-known/agent-card.json
• A2A JSON-RPC discovery: https://vouchspec.plyrium.com/api/vouchspec/v1/a2a
• Remote agent discovery (MCP): https://vouchspec.plyrium.com/api/vouchspec/v1/mcp
• Official MCP Registry API: https://registry.modelcontextprotocol.io/v0.1/servers?search=io.github.mordiaky%2Fvouchspec
• Agent Tools x402 listing: https://agent-tools.cloud/api/v1/services/vouchspec-plyrium-com-sub91
• Agent Tools MCP listing: https://agent-tools.cloud/api/v1/mcp/servers/vouchspec-agent-skill-evidence

The static distribution returns the exact checked-in signed bytes with CORS enabled and rejects writes. Download the signed index, filter it locally, then retrieve a receipt by ID from catalog/public/receipts/. For immutable retrieval, replace main with catalog snapshot 4404b7a9a2d3dc45b621ea694d2ca7ad666b9898. The out-of-band Gist is separate from the repository but shares its GitHub account, so an account-level compromise still requires a new trusted channel.

Product stages

• Stage A — public artifact index (live): selected public artifacts only; signed receipts and read-only REST/MCP retrieval; no uploads, private repositories, or customer-confidential content.
• Stage B — public repository validation (live mainnet plus public testnet sandbox): allowlisted public host, full commit, explicit subdirectory, bounded immutable retrieval, isolated no-egress worker, separate no-egress signing, durable tenant/order/payment state, an authenticated managed API, and exact x402 settlement. Commercial orders are live at 0.25 USDC on Base; the separate 1.00 test-USDC Base Sepolia sandbox remains available for integration testing.
• Stage C — private/arbitrary inputs (deferred): private storage, authentication, tenant isolation, deletion policy, and expanded legal/incident controls only after demand and revenue justify them.

Stage C is not a prerequisite for Stage A or B. No arbitrary upload route exists in the Stage A server or MCP tools.

Publisher CI — complete self-service example

The public publisher-CI demo shows the complete trusted-workflow path: immutable action pins, exact-commit inspection, two GitHub artifact attestations, downloadable evidence, and independent gh attestation verify commands. The latest verified matrix run passes both a structural-pass case and an intentional structural-failure case. Its four downloaded evidence files independently verified with gh attestation verify. The demo is operator-controlled and is not counted as external adoption.

Use the action at its immutable evidence-preserving snapshot:

- id: vouchspec
  uses: mordiaky/vouchspec/distribution/github-action@ed812a14cbc62333d59bac319f79d897f14d1b64
  with:
    skill-path: path/to/skill

The action emits a receipt draft and publisher/workflow binding for both structural passes and explicit structural failures. See the full pinned workflow, permissions, verification, and troubleshooting guide.

Evidence labels

Receipts use explicit labels, never a generic VERIFIED badge:

• DIGEST_PINNED
• STRUCTURE_VALIDATED (only when the structural profile passes)
• STATIC_INSPECTION_COMPLETED
• INDEPENDENT_STATIC_SCAN (only for the curated operator-run profile)

PUBLISHER_CI_ATTESTED, SANDBOX_BEHAVIOR_OBSERVED, and TASK_EVALUATED are reserved for separate evidence that has actually been produced. Static inspection never implies them.

Verify a public receipt independently

The verifier authenticates the exact decoded receipt bytes before parsing JSON, validates the receipt schema and inner consistency digest, then optionally applies the root-signed lifecycle feed.

vouchspec verify catalog\public\receipts\RECEIPT_ID.dsse.json `
  --key catalog\public\keys\issuer.jwk.json `
  --lifecycle catalog\public\lifecycle.dsse.json `
  --root-key catalog\public\keys\root.jwk.json

Lifecycle results are CURRENT, SUPERSEDED, EXPIRED, REVOKED_EVALUATOR_DEFECT, REVOKED_KEY_COMPROMISE, or the conservative SIGNATURE_VALID_LIFECYCLE_UNKNOWN. The signing key ID is only a lookup hint; the public JWK must be obtained or pinned through an independently trusted path.

Read-only catalog API

vouchspec serve-catalog --catalog-root catalog\public --port 8788 `
  --trusted-root-key C:\independently-provisioned\root.jwk.json

Available GET routes:

• /health
• /v1/index (issuer-signed DSSE index envelope)
• /v1/quote?operation=... (price/availability response; paid orders remain disabled)
• /v1/receipts?q=...&repository_owner=...&limit=...
• /v1/receipts/{receipt_id}
• /v1/receipts/{receipt_id}/status
• /v1/lifecycle
• /v1/keys/root
• /v1/keys/issuer

All POST requests receive 405 read_only. The built-in server is connection-bounded, deadline-enforced, and loopback-only; a public deployment must place it behind a managed TLS proxy with platform ingress limits. Each process serves one fully verified immutable catalog snapshot; deploy a new lifecycle/index generation by restarting the process. The highest observed root-feed sequence and its payload digest are persisted with a cross-process lock.

The local catalog price-card route reports the commercial price hypothesis without accepting an order. For a strict request-specific local preview:

vouchspec quote-fresh-validation docs\examples\fresh-validation-request.json

The preview validates the same request shape used by the managed API. The public sandbox price is deliberately faucet-sized at 1.00 test USDC. Full agent-market research rejected the earlier $49 idea; the commercial mainnet launch cohort is an unvalidated 0.25 USDC per fresh validation, with the predeclared evidence gates in PRICING.md.

Agent-only x402 mainnet

The commercial service at https://vouchspec.plyrium.com is machine-only and has no card form, hosted checkout, account portal, or human approval step. An agent sends the strict immutable public-GitHub request to POST /api/vouchspec/v1/validate, receives an x402 v2 challenge for exactly 0.25 USDC on Base, signs it, and retries with PAYMENT-SIGNATURE. Successful settlement returns one-time delivery credentials; the scheduled isolated worker then produces the signed, content-addressed receipt. Discovery and health are public, and the Streamable HTTP MCP endpoint exposes read-only contract discovery. The same purchase contract is published as OpenAPI, llms.txt, A2A, x402, and a draft/proposal ARD catalog so agents can enter through the protocol they already index. Remedy execution remains disabled and is not a prerequisite for accepting or fulfilling ordinary paid validations.

Agent-only x402 sandbox

The public service at https://vouchspec-sandbox.plyrium.com has no card form, hosted checkout, or human approval step. An agent:

1. accepts terms version vouchspec-stage-b-2026-07-14 at POST /api/vouchspec/v1/tenants and stores the one-time tenant bearer key;
2. sends the strict fresh-validation request to POST /api/vouchspec/v1/quotes with Authorization and a unique Idempotency-Key;
3. creates an order at POST /api/vouchspec/v1/orders and stores the returned delivery token;
4. calls the order's purchase_path, reads the x402 v2 PAYMENT-REQUIRED challenge, signs the exact 1.00 test-USDC payment on Base Sepolia, and retries with PAYMENT-SIGNATURE;
5. polls the authenticated order, retrieves the exact DSSE result, and verifies it with the public issuer JWK.

Successful envelopes are also published at a content-addressed unauthenticated URL. Agents may cache and share those immutable bytes. Invalidation is intentionally separate: check the corresponding no-store /status URL each time the receipt is used for a new decision. The machine-readable discovery document contains all route templates, headers, network, price, trust, caching, and product-boundary fields.

The hosted proof is owner-controlled and testnet-only, so it demonstrates mechanics but counts as no customer, request, buyer, or revenue. See the Stage B operating boundary, payment flow, managed deployment boundary, and refund policy, and mainnet remedy operations.

Local commerce harness

The repository still includes a loopback harness for regression and security testing. It stores keyed credential digests, never plaintext tokens, and binds each quote and order to one opaque tenant. Generate two distinct 32-byte secrets with an approved secret manager, expose their hex values only to the process, then provision one local sandbox credential:

$env:VOUCHSPEC_AUTH_PEPPER_HEX = '<64 hex characters>'
$env:VOUCHSPEC_DELIVERY_SECRET_HEX = '<different 64 hex characters>'
vouchspec provision-commerce-tenant --database C:\vouchspec\sandbox-commerce.db
vouchspec serve-commerce-sandbox --database C:\vouchspec\sandbox-commerce.db --port 8789

The local API binds to 127.0.0.1, has no CORS allowance, and exposes authenticated quote, order, status, signed-result, capability-rotation, and capability-revocation routes. Its fake payment rail never settles and every resulting order remains counts_for_goal: false.

An explicitly nonsettling Stripe-test adapter remains available for regression coverage only. It is not the VouchSpec launch rail and is not exposed by the managed agent service:

vouchspec serve-commerce-stripe-test `
  --database C:\vouchspec\stripe-test-commerce.db --port 8789

Do not expose that built-in listener directly. Mainnet activation uses x402, separate live state and secrets, and the live gates in the deployment boundary.

Read-only catalog MCP

Remote agents can discover the commercial managed contract through the stateless Streamable HTTP endpoint at https://vouchspec.plyrium.com/api/vouchspec/v1/mcp. It exposes only get_vouchspec_discovery: an anonymous, read-only tool that returns public route, price, x402, receipt, cache, and invalidation instructions. It cannot submit artifacts, fetch repositories, settle payments, or read private data. Paid validation remains on the managed x402 REST route.

Agents that support the open Agent Skills format can add the repository's exact verify-before-install workflow directly:

npx skills add mordiaky/vouchspec --skill vouchspec-verify-before-install

The skill is also published through the well-known machine endpoint above. It discovers the live contract before acting, checks existing signed evidence first, and purchases a fresh 0.25 USDC validation only when the calling agent already has an x402 wallet and explicit spending authority. If either is absent it returns payment_required; there is no human checkout or human handoff.

The checked-in server.json describes this remote endpoint for the official MCP Registry under the active name io.github.mordiaky/vouchspec. Publication uses GitHub OIDC from a main-only manual workflow, so it needs no portal login, phone code, or dedicated Registry secret.

For agents that prefer a locally pinned catalog, the stdio server remains available:

Public install:

git clone https://github.com/mordiaky/vouchspec.git
cd vouchspec
python -m venv .venv
.venv\Scripts\python -m pip install .
.venv\Scripts\vouchspec mcp-catalog --catalog-root catalog\public `
  --trusted-root-key C:\independently-provisioned\root.jwk.json

vouchspec mcp-catalog --catalog-root catalog\public `
  --trusted-root-key C:\independently-provisioned\root.jwk.json

Tools are search_receipts, get_receipt, get_receipt_status, get_verification_material, and get_price_quote. They accept identifiers, search text, and named price-card operations only, not artifact content. This local read-only MCP does not place paid orders; agents use the managed x402 API for fresh validation.

Local inspector and builder

Development install:

python -m venv .venv
.venv\Scripts\python -m pip install -e ".[dev]"

The compatibility command and Python package name capabilityproof remain available alongside the public vouchspec command.

vouchspec inspect C:\path\to\skill --output receipt.json
vouchspec inspect-git C:\checkout\skills\example `
  --repository-root C:\checkout --output receipt.json

Local inspection never installs, imports, renders, or executes artifact content. The checked-in catalog builder accepts only the curated manifest and public HTTPS GitHub repositories at full 40-character commits. Collection is keyless, issuer signing is a separate no-network phase, and recovery-root lifecycle signing is a separate offline phase. Encrypted private keys stay outside this repository; only RFC 8037 public JWKs are published.

See methodology, the receipt schema, and the threat model.