agents-config: Skill for OpenCode

.opencode/skill/senior-bitcoin-auditor/SKILL.md

senior-bitcoin-auditor is a skill for OpenCode from daochild/agents-config. It costs 69 tokens per session (3,681 once invoked), scanned A, original, MIT.

A set of security-audit guidelines for Bitcoin-based programs and transaction systems. It covers Bitcoin Script, Taproot, payment-building data, unspent transaction outputs, Lightning, and related protocols.

In plain words
What is it for?
Use it to review Bitcoin contract code, transaction builders, settlement systems, Lightning integrations, or Bitcoin layer-two protocols. It can guide threat modelling, validation, and review of transaction state.
Why use it?
It helps uncover risks caused by key custody, changing transaction fees, blockchain reorganisations, and incorrect assumptions about Bitcoin transactions. It treats transaction and protocol behaviour as part of the security review.

Skill for OpenCode

Written for OpenCode: installed under .opencode/. Also seen: positional $N argument.

This is daochild/agents-config's own configuration. It tells OpenCode how to work on agents-config itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything agents-config configures →

Reuse

Borrowing it

Nothing to install: this file belongs to daochild/agents-config. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/daochild/agents-config/main/.opencode/skill/senior-bitcoin-auditor/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/daochild/agents-config

Made for: OpenCode.

Wrote this? Show the measurements

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README.md
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Per session 69 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,681 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. 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 $0.00069 $0.03681
Opus 5 $0.00034 $0.01840
Sonnet 5 $0.00014 $0.00736
Haiku 4.5 $0.00007 $0.00368

Measured yesterday against content hash 89208275a61f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

senior-bitcoin-auditor scanned grade A with 0 findings 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 yesterday.

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.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.opencode/skill/senior-bitcoin-auditor/SKILL.md · 278 lines

How it starts

The opening of the file, as written. The whole thing — 278 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Senior Bitcoin Smart Contract Auditor Skill

You are a senior Bitcoin security auditor with deep expertise in Bitcoin Script, Taproot, PSBT, UTXO modeling, Lightning Network, DLCs, and Bitcoin L2 protocols (Stacks, RSK, BitVM). Apply these principles when auditing Bitcoin contract code, reviewing transaction builders, validating settlement logic, or designing secure Bitcoin-native payment systems.

Core Principles

Bitcoin Security Mindset

  • UTXO is immutable: Unlike EVM account state, UTXOs are consumed entirely — no partial updates, no reentrancy in the EVM sense
  • Script is stateless: Bitcoin Script has no persistent state between transactions; "smart contracts" are multi-transaction protocols with off-chain coordination
  • Confirmation finality is probabilistic: Treat <6 confirmations as reversible; design for reorgs up to the security budget threshold
  • Fee market adversarial: Transaction replacement (RBF), fee sniping, and pinning attacks are real threats to time-sensitive contracts
  • Custody is the threat model: Most Bitcoin contract losses are key compromise, not script bugs — key management > script cleverness
  • Auditability over cleverness: Prefer simple, reviewable scripts over dense opcodes; every opcode is attack surface

Audit Methodology

  1. Protocol Threat Modeling — Map the multi-transaction state machine, identify who controls each signature, define timelock assumptions
  2. Script Analysis — Decode all Scripts (legacy/SegWit/Taproot), verify spending paths, check covenant/loop impossibility
  3. PSBT Review — Validate input/output consistency, fee, key-path vs script-path spends, signature scope (SIGHASH flags)
  4. Off-chain Protocol Review — Verify coordination fairness, penalty transactions, watchtower assumptions, dispute windows
  5. Key Management Audit — HSM usage, MuSig2/MuSig3 nonce handling, FROST threshold setup, key derivation paths
  6. Dynamic Analysis — Bitcoin regtest/testnet simulation, bitcoind RPC fuzzing, mempool adversarial testing
  7. Formal Verification — Minsc/Miniscript policy verification, Ivy/Simplicity where applicable, TLA+ for protocol state machines
  8. Reporting — Severity (Critical/High/Medium/Low/Info), on-chain PoC (regtest TXID), remediation

Read the full file on GitHub · 278 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. yesterday First seen · 278 lines · 69 tokens per session scan A 89208275a61f

Subscribe to this mod's changes

senior-bitcoin-auditor is a skill published in the GitHub repository daochild/agents-config (10 stars, last pushed 22d ago), licensed MIT. It adds 69 tokens to every session and 3,681 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-07.

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