undo

undo is a skill for Claude Code from SienkLogic/plan-build-run. It costs 19 tokens per session (1,911 once invoked), scanned A, original, MIT.

A post-build quality check for a completed development phase. It looks for missing tests, failing tests, and verification steps that lack automated coverage.

In plain words
What is it for?
Use it to audit validation coverage, identify requirements without tests, and produce a validation report with any needed test work.
Why use it?
A feature may appear finished while important requirements remain untested. This helps expose those gaps and arrange additional tests before the phase is accepted.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter. Also seen: names the AskUserQuestion tool; mentions Claude Code.

Part of the pbr plugin — 44 skills, 71 commands, 18 agents, 3 hooks shipped together

Good fit Use it to audit validation coverage, identify requirements without tests, and produce a validation report with any needed test work.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/sienklogic/plan-build-run/undo
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 SienkLogic/plan-build-run --skill undo
Clone the repo
git clone --depth 1 https://github.com/SienkLogic/plan-build-run

Made for: Claude Code.

Or install pbr, the plugin that ships this one along with the rest of its 44 skills, 71 commands, 18 agents, 3 hooks.

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 undo

README.md
[![agentmods](https://agentmods.dev/badge/skills/sienklogic/plan-build-run/undo.svg)](https://agentmods.dev/skills/sienklogic/plan-build-run/undo)
Your own site
<a href="https://agentmods.dev/skills/sienklogic/plan-build-run/undo"><img src="https://agentmods.dev/badge/skills/sienklogic/plan-build-run/undo.svg" alt="Measured on agentmods" height="20"></a>
Per session 19 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,911 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 $0.00019 $0.01911
Opus 5 $0.00010 $0.00955
Sonnet 5 $0.00004 $0.00382
Haiku 4.5 $0.00002 $0.00191

Measured 4d ago against content hash 9d57dfeaec87, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

undo 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.

plugins/pbr/skills/undo/SKILL.md · 222 lines

How it starts

The opening of the file, as written. The whole thing — 222 lines — stays where its author put it; the contents beside it link to each section on GitHub.

STOP — DO NOT READ THIS FILE. You are already reading it. This prompt was injected into your context by Claude Code's plugin system. Begin executing Step 0 immediately.

Step 0 — Immediate Output

Before ANY tool calls, display this banner:

╔══════════════════════════════════════════════════════════════╗
║  PLAN-BUILD-RUN ► UNDO                                       ║
╚══════════════════════════════════════════════════════════════╝

Then proceed to Step 1.

/pbr:undo — Safe Commit Reversal

You are running the undo skill. Your job is to help the user safely revert recent PBR-generated commits using git revert (history-preserving), not git reset (destructive).

This skill runs inline (no Task delegation).


Step 1 — Gather PBR Commits

Run:

git log --oneline --no-merges -50

Filter lines matching the PBR commit pattern: ^[0-9a-f]+ (feat|fix|refactor|test|docs|chore|wip|revert)(\([a-zA-Z0-9._-]+\))?:

If no PBR commits found, display:

No PBR commits found in the last 50 commits.

Then exit.

Parse $ARGUMENTS for flags:

  • --last N: limit to N most recent PBR commits (default 20)
  • --phase NN: filter to commits for a specific phase number (e.g. --phase 55)
  • --plan NN-MM: filter to commits for a specific plan (e.g. --plan 55-02)
  • --range HASH..HASH: preselect a hash range for revert — if provided, skip to Step 5 with that range pre-filled

Phase manifest mode (--phase NN):

When --phase NN is specified, first check for a .phase-manifest.json in the phase directory:

  1. Resolve the phase directory: .planning/phases/{NN}-*/
  2. Check for .phase-manifest.json in that directory
  3. If manifest exists: use manifest.commits as the commit list (skip git log scan)
  4. If manifest missing (phases completed before manifest support): fall back to git log scan and filter by scope pattern

Phase manifests are written by completePhase(). Older phases may not have manifests.

Apply filters to the collected PBR commits before proceeding.

Read the full file on GitHub · 222 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 · 222 lines · 19 tokens per session scan A 9d57dfeaec87

Subscribe to this mod's changes

undo is a skill published in the GitHub repository SienkLogic/plan-build-run (17 stars, last pushed 5mo ago), licensed MIT. It adds 19 tokens to every session and 1,911 once invoked, about $0.0001 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 2026-09-03.