---

name: xproof version: 3.3.7 description: "Certify what your agent decided (WHY) before acting, and what it produced (WHAT) after. 4W audit trail on MultiversX, violations layer on Base, trust score." skill_visibility: public homepage: https://xproof.app metadata: {"xproof":{"category":"proof,security,compliance,accountability,prove-before-act","api_base":"https://xproof.app"}}

xProof — Prove Before & After Act

Anchor reasoning (WHY) before execution and actual result (WHAT) after — creating a complete, tamper-proof 4W audit trail on MultiversX (Who via MX-8004, What/When/Why via xProof). Trust score, violations layer, public verification.

The Core Pattern

1. Reason (WHY) → 2. Hash locally → 3. Anchor WHY on-chain → 4. Get proof_id → 5. Execute → 6. Hash result (WHAT) → 7. Anchor WHAT on-chain → 8. Full 4W trail

The proof_id from step 4 is your immutable pre-execution commitment — if something goes wrong, you have forensic evidence that the reasoning preceded the action.

4W breakdown — what each letter means and who provides it:

xProof owns WHAT / WHEN / WHY and the causal link that proves reasoning preceded the action. MX-8004 owns WHO. Together they form a forensically complete 4W trail.

Agent reference: https://xproof.app/agent-context — 13 Q&A sections written specifically for autonomous agents: production deployment patterns, retry policy, x402 payment walkthrough, 4W audit trail deep-dive, privacy model, fleet monitoring, latency benchmarks, and framework integration examples (LangChain, CrewAI, AutoGen, LlamaIndex, OpenAI Agents SDK, Fetch.ai).

Why anchor before acting? An agent that proves its reasoning before executing is fundamentally more trustworthy than one that cannot. It creates an unbreakable causal chain: the intent existed before the action, and the blockchain makes that sequence immutable.

Why audit? Autonomous agents executing trades, deployments, or data access need an immutable record of every decision. The Agent Audit Log Standard enforces this: no proof = no execution.

Why violations? Trust requires accountability. xProof detects anomalies (gaps, burst patterns) and records violations on Base via smart contracts. Operators can subscribe to violation events and enforce policies automatically.

Pricing

Flat rate: $0.01 per proof -- no tiers, no volume discounts, same price whether you anchor 1 or 100,000 proofs.

Payment: USDC on Base (x402, no account) or EGLD on MultiversX (ACP/wallet) or prepaid credits.

Quick Install

The canonical source for all skill files is the main xProof repository (jasonxkensei/xProof), which is the repository audited by security tools. Install from there directly:

mkdir -p <SKILL_DIR>/xproof/references

# Core Skill — from the canonical main repository
curl -sL https://raw.githubusercontent.com/jasonxkensei/xProof/main/clawhub-publish/xproof/SKILL.md \
  > <SKILL_DIR>/xproof/SKILL.md

# Reference Manuals
for f in certification x402 mcp; do
  curl -sL "https://raw.githubusercontent.com/jasonxkensei/xProof/main/clawhub-publish/xproof/references/${f}.md" \
    > "<SKILL_DIR>/xproof/references/${f}.md"
done

Source verification: All files above are served from github.com/jasonxkensei/xProof — the same repository that contains the server code, contracts, and SDKs. You can audit the full source at that URL before installing.

Data & Privacy

Data & Privacy

Transparency notice — what leaves your environment when using this skill.

What xproof.app does NOT receive: raw file contents, prompt text, model weights, environment variables, or any field you do not explicitly pass.

Data retention: proof records are permanent and public by default (that is the point — immutable evidence). Before certifying, confirm you want the hash publicly anchored on MultiversX mainnet forever.

Skill file: this file (<SKILL_DIR>/xproof/SKILL.md) is intentionally public and contains no secrets. It is documentation only — API patterns, pricing, and integration examples. Safe to audit, share, or version-control.

Security

• NEVER commit API keys to a public repository.
• ALWAYS add .env to your .gitignore.
• API keys are prefixed pm_ -- treat them like passwords.
• x402 mode requires no API key (payment replaces authentication).
• NEVER send plaintext content to xproof.app -- always hash locally first (sha256sum, crypto.subtle.digest, or equivalent). The only field xproof accepts is file_hash (64-char SHA-256 hex). No raw text, documents, or binary data should ever leave your environment.
• x402 is opt-in and autonomous -- once enabled, your agent can initiate USDC payments on Base without per-transaction confirmation. Configure a spending cap in your agent framework and require human approval above your threshold before enabling x402 in production.
• llms.txt and llms-full.txt are static documentation references -- load them once at install time for API reference, not at runtime on every call. Fetching them dynamically on each invocation creates an unnecessary runtime dependency on xproof.app availability and a potential prompt-injection surface if the file is ever compromised.
• Guard/enforcement templates are versioned in the repository -- never fetch agent enforcement code from a runtime URL. Use the pinned versions in references/ or the SDK packages (xproof on PyPI, @xproof/xproof on npm).

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Configuration

Option A: API Key Authentication

# ---- xProof ---------------------------------------------------------------
XPROOF_API_KEY="pm_..."                          # Your API key (from xproof.app)
XPROOF_BASE_URL="https://xproof.app"             # Production endpoint

Get an API key at xproof.app (connect wallet, go to Settings > API Keys).

Option B: x402 Payment Protocol (No Account Required)

No configuration needed. Pay in USDC on Base (eip155:8453) directly in the HTTP request. The 402 response header tells your agent exactly what to pay. Flat rate: $0.01 per proof.

WARNING -- autonomous payments: x402 is an opt-in mode that enables your agent to initiate on-chain USDC transactions without per-transaction user confirmation. Before enabling x402 in production:

• Set a spending cap in your agent framework (e.g. max $N/day or $N/session).
• Require human approval for any single call that would exceed your risk threshold.
• Note that POST /api/batch supports up to 100 items per call -- at $0.01 each, a batch of 100 costs $1.00.
• Disable x402 entirely in environments where autonomous spending is not authorised.

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1. Core Skills Catalog

1.1 Proof Anchoring (REST API)

Full Reference

1.2 Proof Anchoring (MCP -- JSON-RPC 2.0)

Full Reference

1.3 Payment (x402)

Full Reference

x402 is not a separate skill -- it is a payment method. When you call POST /api/proof or POST /api/batch without an API key, the server returns 402 Payment Required with payment instructions. Your agent pays in USDC on Base and retries with an X-Payment header.

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2. Webhooks

Supply an optional webhook_url field on POST /api/proof or POST /api/batch to receive a callback when the proof is confirmed on-chain.

Scope — the webhook payload contains only:

No raw file content, no API keys, no account information, and no metadata beyond the above is ever sent to the webhook endpoint.

Authentication: Every delivery includes an X-Webhook-Signature header containing an HMAC-SHA256 signature computed with a per-relationship secret. Verify this signature before processing the payload. Retry policy: 3 attempts with exponential backoff (1 s, 5 s, 30 s).

SSRF protection: xproof.app validates webhook_url before delivery. Private IP ranges (RFC 1918), loopback (127.x, ::1), link-local, and non-HTTPS destinations are blocked. DNS rebinding is mitigated by pinning the resolved socket address to the pre-validated IP at connection time.

# Example proof request with webhook
curl -X POST ${XPROOF_BASE_URL}/api/proof \
  -H "Authorization: Bearer pm_..." \
  -H "Content-Type: application/json" \
  -d '{
    "file_hash": "a1b2c3...",
    "filename": "output.json",
    "webhook_url": "https://your-agent.example.com/hooks/xproof"
  }'

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9. Violations Layer (Base)

xProof monitors agent behavior and detects anomalies. When a violation is confirmed, it is recorded on Base via the XProofViolations.sol smart contract, impacting the agent's trust score.

Violation Types

Smart contracts: XProofViolations.sol | ViolationWatcher.sol

Docs: https://xproof.app/docs/base-violations

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10. Agent Proof Standard

xProof implements the open Agent Proof Standard -- a composable, chain-agnostic format for agent accountability.

Full specification: AGENT_PROOF_STANDARD.md

Standard API: GET /api/standard | GET /api/standard/validate (POST)

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11. Discovery Endpoints

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12. Command Cheatsheet

# Hash locally first -- the original content must never leave your environment.
# xproof only receives the SHA-256 hex hash, filename, and metadata you choose to share.
sha256sum myfile.pdf | awk '{print $1}'
# Then POST the hash to /api/proof

# Anchor via MCP
curl -X POST ${XPROOF_BASE_URL}/mcp \
  -H "Authorization: Bearer pm_..." \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"certify_file","arguments":{"file_hash":"...","filename":"myfile.pdf"}}}'

# Verify a proof
curl ${XPROOF_BASE_URL}/api/proof/<proof_id>

# Get badge (embed in README)
![xProof](https://xproof.app/badge/<proof_id>)

# Batch anchor
curl -X POST ${XPROOF_BASE_URL}/api/batch \
  -H "Authorization: Bearer pm_..." \
  -d '{"files":[{"file_hash":"...","filename":"a.txt"},{"file_hash":"...","filename":"b.txt"}]}'

# Health check
curl ${XPROOF_BASE_URL}/api/acp/health