What is reengineering-vibe-code?

A process for turning an existing prototype into a more reliable application. It examines the running app, records its current behaviour in tests, separates business rules, and moves work in independently checked slices.

Use it to rescue a quickly built local app, document its requirements, test its existing behaviour, and identify changes that need human approval.

It provides a safety net for changing a prototype without silently changing what it already does.

reengineering-vibe-code — Skill for Claude Code by richfrem

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.

Any agent

npx skills add richfrem/agent-plugins-skills --skill reengineering-vibe-code

Clone the repo

git clone --depth 1 https://github.com/richfrem/agent-plugins-skills

Made for: Claude Code.

Or install agent-exploration-cycle, the plugin that ships this one along with the rest of its 5 skills, 4 agents.

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/richfrem/agent-plugins-skills/reengineering-vibe-code/github.svg)](https://agentmods.dev/skills/richfrem/agent-plugins-skills/reengineering-vibe-code)

Your own site

<a href="https://agentmods.dev/skills/richfrem/agent-plugins-skills/reengineering-vibe-code"><img src="https://agentmods.dev/badge/skills/richfrem/agent-plugins-skills/reengineering-vibe-code/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/richfrem/agent-plugins-skills/reengineering-vibe-code"><img src="https://agentmods.dev/badge/skills/richfrem/agent-plugins-skills/reengineering-vibe-code.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 124 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 999 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.

Model	Per session	Once invoked
Fable 5.1	$0.00124	$0.00999
Opus 5.5	$0.00050	$0.00400
Sonnet 5.5	$0.00025	$0.00200
Haiku 4.5	$0.00012	$0.00100

Measured 2d ago against content hash 9d9e14a09814, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

reengineering-vibe-code 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 2d 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.

plugins/agent-exploration-cycle/.apm/skills/reengineering-vibe-code/SKILL.md · 53 lines

How it starts

The opening of the file, as written. The whole thing — 53 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Reengineering Vibe Code

Path 2: vibe-reengineering.mmd. Router: vibe-orchestrator-agent.md.

Constraints • Quick start • Workflow • Verification • References

Constraints

Truth order: specs/REQS.md > tests/characterization/ > /domain > derived specs > prototype code (rules). A conflict is HUMAN_REQUIRED.
Never autonomously rewrite auth, billing, cryptography or compliance logging; they need a hash-bound human-approval.json.
Characterization tests assert legacy behavior verbatim; fixtures contain no absolute paths or secrets.
Only the four independent agents decide: domain-purity-auditor, semantic-drift-auditor, certification-verifier (sole authority for slice-certified) and business-rule-audit-agent. After two rejections for the same issue, escalate to the user.
Do destructive work in an isolated workspace (os-control-worktree skill). Register the task through os-control-intake only when the user runs a control plane.
Ask the five architecture questions one at a time. Pick runtime and model through the cli-agent skill.

Quick start

test -f exploration/captures/DISCOVERY_REPORT.md || echo "start at phase 1"
ls specs/REQS.md tests/characterization 2>/dev/null

Workflow

Seven phases (guide): browser audit, safety net, five questions, REQS and risk gate (full architecture package optional), domain extraction with purity audit, target scaffolding (ADR, ports, session memory), slice migration with drift audit and certification. Finish by handing to handing-off-to-engineering.

Verification

Run the characterization suite (100 percent parity), the purity and drift reports, and the certification report in temp/.

Acceptance criteria: acceptance-criteria.md.

Read the full file on GitHub · 53 lines

Files

What ships with it

25 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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.

2d ago First seen · 53 lines · 124 tokens per session scan A 9d9e14a09814

Subscribe to this mod's changes

reengineering-vibe-code is a skill published in the GitHub repository richfrem/agent-plugins-skills (7 stars, last pushed yesterday), licensed MIT. It adds 124 tokens to every session and 999 once invoked, about $0.0005 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 2026-10-24.

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