pierre-guard

A set of checks for maintaining Plannotator's connection to Pierre, an open-source renderer for showing code differences in a review interface. It focuses on the integration's component API, Shadow DOM selectors, and styling variables.

In plain words
What is it for?
Use it when changing DiffViewer.tsx, upgrading @pierre/diffs, changing its CSS injection, adding FileDiff properties, or modifying related Shadow DOM styling.
Why use it?
The integration depends on internal details that can break when the renderer or review UI changes. The checks direct developers to verify those details against current source or type definitions.

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/backnotprop/plannotator/pierre-guard
Any agent
npx skills add backnotprop/plannotator --skill pierre-guard
Clone the repo
git clone --depth 1 https://github.com/backnotprop/plannotator

Made for: Claude Code, Codex.

Per session 103 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,735 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 $0.00103 $0.01735
Opus 5 $0.00051 $0.00868
Sonnet 5 $0.00021 $0.00347
Haiku 4.5 $0.00010 $0.00173

Measured 3d ago against content hash a12d94354893, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

pierre-guard 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 3d 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/pierre-guard/SKILL.md · 138 lines

How it starts

The opening of the file, as written. The whole thing — 138 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Pierre Integration Guard

Plannotator's code review UI wraps @pierre/diffs — an open-source diff renderer that uses Shadow DOM. The integration is concentrated in a single file but relies on undocumented internals (shadow DOM selectors, CSS variable names, grid layout assumptions). This skill helps verify changes don't break that contract.

Source of Truth

Always verify against the upstream repo or local .d.ts files — don't rely on memory of the API shape.

What We Import

import { FileDiff } from '@pierre/diffs/react';
import { getSingularPatch, processFile } from '@pierre/diffs';

These are the only three imports. DiffViewer.tsx is the only file that touches Pierre.

API Surface to Guard

1. Component Props (FileDiff)

Read the current prop types from node_modules/@pierre/diffs/dist/react/index.d.ts or the upstream source. The props we use:

Prop Type Notes
fileDiff FileDiffMetadata From getSingularPatch() or processFile()
options FileDiffOptions<T> See options table below
lineAnnotations DiffLineAnnotation<T>[] { side, lineNumber, metadata }
selectedLines SelectedLineRange | null { start, end, side }
renderAnnotation (ann) => ReactNode Custom inline annotation renderer
renderHoverUtility (getHoveredLine) => ReactNode The + button on hover (deprecated upstream — watch for removal)

2. Options Object

Option Value We Pass Risk
themeType 'dark' | 'light' Low — standard enum
unsafeCSS CSS string High — targets internal selectors
diffStyle 'split' | 'unified' Low — standard enum
diffIndicators 'bars' Low
hunkSeparators 'line-info' Low
enableLineSelection true Low
enableHoverUtility true Medium — deprecated prop
onLineSelectionEnd callback Medium — signature could change

Read the full file on GitHub · 138 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. 3d ago First seen · 138 lines · 103 tokens per session scan A a12d94354893

Subscribe to this mod's changes

pierre-guard is a skill published in the GitHub repository backnotprop/plannotator (8,341 stars, last pushed yesterday), licensed Apache-2.0. It adds 103 tokens to every session and 1,735 once invoked, about $0.0005 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.