execution-client-hardening

execution-client-hardening is a skill for Claude Code, Codex from PlamenTSV/plamen. It costs 45 tokens per session (4,005 once invoked), scanned A, original, MIT.

A security review for blockchain execution engines—the software that runs smart-contract instructions and updates blockchain state. It covers Ethereum, Solana, Move, WebAssembly, and custom virtual machines.

In plain words
What is it for?
Use it to inspect instruction handling, gas accounting, state changes, and agreement between different implementations of a blockchain execution engine.
Why use it?
It helps detect bugs that could corrupt memory, charge the wrong amount of gas, interpret instructions incorrectly, or make different blockchain clients disagree.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/plamentsv/plamen/execution-client-hardening
Any agent
npx skills add PlamenTSV/plamen --skill execution-client-hardening
Clone the repo
git clone --depth 1 https://github.com/PlamenTSV/plamen

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 execution-client-hardening

README.md
[![agentmods](https://agentmods.dev/badge/skills/plamentsv/plamen/execution-client-hardening.svg)](https://agentmods.dev/skills/plamentsv/plamen/execution-client-hardening)
Your own site
<a href="https://agentmods.dev/skills/plamentsv/plamen/execution-client-hardening"><img src="https://agentmods.dev/badge/skills/plamentsv/plamen/execution-client-hardening.svg" alt="Measured on agentmods" height="20"></a>
Per session 45 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,005 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00045 $0.04005
Opus 5 $0.00023 $0.02003
Sonnet 5 $0.00009 $0.00801
Haiku 4.5 $0.00005 $0.00400

Measured 4d ago against content hash e4fccef4e6d7, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

execution-client-hardening 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 4d ago.

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.

agents/skills/injectable/l1/execution-client-hardening/SKILL.md · 269 lines

How it starts

The opening of the file, as written. The whole thing — 269 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Injectable Skill: Execution Client Hardening

L1 trigger: L1_PATTERN=true AND (core/vm/ OR revm OR interpreter OR opcodes.go OR evm-exec OR svm/ OR move-vm OR wasmi detected in recon subsystem map) Inject Into: depth-state-trace or depth-external Language: Go, Rust, occasionally C++ Finding prefix: [EX-N] Status: v0.1 draft, Round 4 exemplars pending

Orchestrator Decomposition Guide

  • Sections 1, 2: depth-state-trace (VM state transitions)
  • Sections 3, 4: depth-edge-case (opcode semantics)
  • Section 5: depth-external (gas metering)
  • Section 6: depth-consensus-invariant (cross-client consistency)

When This Skill Activates

Recon identifies a VM / execution engine. Covered VMs: EVM (all execution clients), SVM (Solana), Move VM (Aptos, Sui), WASM runtimes (NEAR, Polkadot), custom VMs. Client-vs-client divergence in VM behavior is Critical — historically several Ethereum consensus splits were VM implementation bugs.

1. Opcode Coverage Mapping

Enumerate every opcode / instruction the VM supports. For EVM, consult the latest Yellow Paper + EIPs. For others, the spec document.

Opcode Gas cost Stack delta State touched Notes

This mapping grounds later checks. A new client must implement every opcode; a fork client must not accidentally remove or reprice any opcode.

Tag: [OPCODE-COVERAGE:{missing-or-extra}]

2. Gas / Resource Metering

Every operation must be priced to cover its real cost. Historical bugs: Ethereum Shanghai attacks (2016) — EXTCODESIZE was too cheap relative to disk I/O.

Patterns to check

  • Disk-touching opcodes: SLOAD, SSTORE, EXTCODESIZE, EXTCODECOPY, EXTCODEHASH, BALANCE. Gas cost must reflect the (possibly cold) storage fetch.
  • Recursive opcodes: CALL, DELEGATECALL, CALLCODE, STATICCALL. Gas forwarding (63/64 rule) correctness.
  • Memory-expanding opcodes: MLOAD, MSTORE, RETURNDATACOPY, MCOPY. Memory expansion gas must be computed before the access.
  • Hashing: KECCAK256 cost proportional to input size.
  • Log emission: LOG0-LOG4 cost proportional to data size.

Read the full file on GitHub · 269 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. 4d ago First seen · 269 lines · 45 tokens per session scan A e4fccef4e6d7

Subscribe to this mod's changes

execution-client-hardening is a skill published in the GitHub repository PlamenTSV/plamen (281 stars, last pushed 1mo ago), licensed MIT. It adds 45 tokens to every session and 4,005 once invoked, about $0.0002 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 2026-08-30.

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