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parasite-eve-2-decomp: Skill for Claude Code

.grok/skills/match-function/SKILL.md

match-function is a skill for Claude Code, Codex from GabeRealB/parasite-eve-2-decomp. It costs 65 tokens per session (1,009 once invoked), scanned A, original, CC0-1.0.

A reverse-engineering workflow for matching one Parasite Eve 2 function so its compiled GCC 2.8.1 output for MIPS matches the target binary byte for byte.

In plain words
What is it for?
Bootstrapping a function-matching workspace, making minimal C changes, compiling attempts, and checking them against the target object file.
Why use it?
It provides a repeatable process for compiling, comparing, and verifying function attempts instead of guessing from assembly alone.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

This is GabeRealB/parasite-eve-2-decomp's own configuration. It tells Claude Code and Codex how to work on parasite-eve-2-decomp 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 parasite-eve-2-decomp configures →

Needs its repository: it runs a file that does not travel with it, so clone the repository first. The line is ./tools/match/claude --bootstrap-only <func>.

not rated 77repo +1 changed 25d ago A scan SkillSpector: pass 65 tokens original CC0-1.0
View source ↗ GabeRealB/parasite-eve-2-decomp
Reuse

Borrowing it

Nothing to install: this file belongs to GabeRealB/parasite-eve-2-decomp. 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/GabeRealB/parasite-eve-2-decomp/main/.grok/skills/match-function/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/GabeRealB/parasite-eve-2-decomp

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 match-function

README.md
[![agentmods](https://agentmods.dev/badge/skills/gaberealb/parasite-eve-2-decomp/match-function/github.svg)](https://agentmods.dev/skills/gaberealb/parasite-eve-2-decomp/match-function)
Your own site
<a href="https://agentmods.dev/skills/gaberealb/parasite-eve-2-decomp/match-function"><img src="https://agentmods.dev/badge/skills/gaberealb/parasite-eve-2-decomp/match-function/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 match-function

Your own site · 80×15
<a href="https://agentmods.dev/skills/gaberealb/parasite-eve-2-decomp/match-function"><img src="https://agentmods.dev/badge/skills/gaberealb/parasite-eve-2-decomp/match-function.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 65 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,009 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. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00065 $0.01009
Opus 5.5 $0.00026 $0.00404
Sonnet 5.5 $0.00013 $0.00202
Haiku 4.5 $0.00006 $0.00101

Measured 25d ago against content hash a6a5ae3367de, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

match-function 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 25d 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.

.grok/skills/match-function/SKILL.md · 40 lines

How it starts

The opening of the file, as written. The whole thing — 40 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Match one function

The matching loop (dumps, pins, permuter, verify) lives in tools/claude-decomp-env/MATCH_LOOP.md and is loaded as a Grok project rule (.grok/rules/match-loop.md). Follow it. Do not plan edits from asm-differ alone. Do not add register … asm("") because a saved register is wrong in the object dump.

Vacuum or ./tools/match/claude --bootstrap-only may already have created nonmatchings/<func>/ with base.c, target.o, and BRIEF.md. If that directory exists, do not re-run ./tools/match/claude.

If it does not exist, from the repo root:

./tools/match/claude --bootstrap-only <func>

That command resolves any overlay (asm/<ver>/<overlay>/…, including nested future units like stage1/101). Never search only asm/USA/main/. If tools/giveups/<func>/base.c exists, bootstrap copies that seed into base.c instead of m2c — start from it.

This session

  1. Read BRIEF.md in the scratch dir.
  2. cd there and run ./build.sh base.c with minimal edits so it compiles. Do not rewrite m2c/give-up C from the asm before the first score. If the seed is pinned, unpin as base_1.c and rescore.
  3. Put each attempt in base_N.c. Prefer already-matched siblings in the same TU over m2c control flow.
  4. After each ≥90% score, build.sh prints a NEXT: line. The next tool call is reading those dump files, then one C edit. Control-flow leftovers (branch/insert/delete ≠ 0) are not a pin/permuter job.
  5. Grep DECOMPILATION_LEARNINGS.md for the mismatch; do not read the whole file.
  6. Permuter only at ≥ 95% with branch=insert=delete=0, before pins. Vacuum also permutes after you exit if you leave a ≥95% unpinned base_N.c.
  7. Stop after ~10 attempts with no gain (or ~40 total). build.sh will also flag a stall.

Finish

  • 100%: replace INCLUDE_ASM in the host C file. New types go in this overlay's include/ (include/main/, include/gameplay/, include/<overlay>/). Not include/main/unknown_syms.h. Run ./tools/build-and-verify.sh and wait for ✅ BUILD SUCCEEDED. Commit matched <func> <attempts>.
  • Give up: append tools/match/difficult_functions as <func> <attempts> <best%>. Revert host C.
  • If vacuum launched you, leave the scratch dir (best unpinned base_N.c included). Vacuum archives it to tools/giveups/<func>/ then cleans the scratch. Otherwise delete the scratch after commit/give-up.
  • If the vacuum prompt says this is a disposable worktree (pe2-wt-<func>), commit only on this worktree. Do not git merge onto trunk and do not append tools/match/difficult_functions there; a later port agent on the original tree lands the result.
  • If the vacuum prompt says you are the port agent: rewrite the function onto current trunk. Never git merge / rebase / cherry-pick the worktree. Adapt to structs and TUs other agents already landed, then verify and commit on trunk.
  • Stale build/: worktrees copy existing binaries that still checksum from the INCLUDE_ASM version. sha256sum --check on build/USA/out/SLUS_010.42 is not a match. Only ./tools/build-and-verify.sh → ✅ BUILD SUCCEEDED counts. If python3 lacks splat/spimdisasm, use venv/bin/python3.

Read the full file on GitHub · 40 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. 25d ago Changed a6a5ae3367de
  2. 2mo ago First seen · 40 lines · 65 tokens per session scan A 99ab5f3bd0e7

Subscribe to this mod's changes

match-function is a skill published in the GitHub repository GabeRealB/parasite-eve-2-decomp (77 stars, last pushed 12d ago), licensed CC0-1.0. It adds 65 tokens to every session and 1,009 once invoked, about $0.0003 per session on Opus 5.5. 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.

Debugging
Related

match-function compared with skills from other repositories

match-function next to 6 skills from other repositories
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match-functionGabeRealB/parasite-eve-2-decompSkill7712d agoCC0-1.0A65Claude Code, Codex
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log-error-digestzebbern/claude-code-guideSkill4.7kyesterdayMITA71Claude Code, Codex
cwv-optimizeradobe/skillsSkill321todayApache-2.0A112Claude Code
ci-fixersipyourdrink-ltd/bernsteinSkill1.2ktodayApache-2.0A15Claude Code, Codex
incident-response-incident-responsermyndharis/antigravity-skillsSkill2.0kyesterdayMITA36Claude Code, Codex
diagnosing-missing-recordingsPostHog/posthogSkill41ktodaynoneA76Claude Code, Codex