pi-parity-review

pi-parity-review is a skill for Claude Code from sky-valley/pi. It costs 54 tokens per session (1,448 once invoked), scanned A, original, MIT.

A review guide for checking whether a ported change faithfully matches the original Pi implementation, using its TypeScript source and published npm build.

In plain words
What is it for?
Comparing source and diffs, reviewing uncommitted changes, and validating a port without modifying the working tree.
Why use it?
It helps uncover differences that tests written by the person doing the port may miss.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

Good fit Comparing source and diffs, reviewing uncommitted changes, and validating a port without modifying the working tree.

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Install with agentmods
npx agentmods add skills/sky-valley/pi/pi-parity-review
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 sky-valley/pi --skill pi-parity-review
Clone the repo
git clone --depth 1 https://github.com/sky-valley/pi

Made for: Claude Code.

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 pi-parity-review

README.md
[![agentmods](https://agentmods.dev/badge/skills/sky-valley/pi/pi-parity-review/github.svg)](https://agentmods.dev/skills/sky-valley/pi/pi-parity-review)
Your own site
<a href="https://agentmods.dev/skills/sky-valley/pi/pi-parity-review"><img src="https://agentmods.dev/badge/skills/sky-valley/pi/pi-parity-review/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 pi-parity-review

Your own site · 80×15
<a href="https://agentmods.dev/skills/sky-valley/pi/pi-parity-review"><img src="https://agentmods.dev/badge/skills/sky-valley/pi/pi-parity-review.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 54 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,448 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 $0.00054 $0.01448
Opus 5 $0.00027 $0.00724
Sonnet 5 $0.00011 $0.00290
Haiku 4.5 $0.00005 $0.00145

Measured 11d ago against content hash e2933de526a8, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

pi-parity-review 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 11d 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.

.claude/skills/pi-parity-review/SKILL.md · 95 lines

How it starts

The opening of the file, as written. The whole thing — 95 lines — stays where its author put it; the contents beside it link to each section on GitHub.

pi-parity-review — is the port true to pi?

Input: the upstream change (sha in the upstream clone) and our ported diff. You are independent of the porter: assume the port is wrong until the diff proves otherwise. Self-authored tests are circular — they pin what the porter believed, not what pi does. Every sweep of this project found real bugs ONLY via comparison against real pi.

Working-tree safety (hard rule)

You are reviewing the UNCOMMITTED working tree — it is the only copy of the port. NEVER mutate it: no git checkout/restore/reset/stash/clean, no edits to ported files. To mutation-test (disable a fix and confirm its test fails), copy the file to a scratch path, mutate the COPY in a throwaway dir (or git worktree add a detached checkout), run tests there, and discard it — never touch the live file. If you ever do dirty the tree, restore it exactly and say so loudly in your report.

References

  • Upstream TS: $PI_UPSTREAM_DIR (default ~/.cache/pi-upstream). Never read its working tree — always name a sha: git -C dir show <sha>:<path>, git -C dir diff <sha>^1..<sha>, git -C dir grep <pattern> <sha> -- <path>. The checkout is whatever was last checked out and is nobody's contract; during the 2026-08-11 cycle it sat at a 2026-06-07 commit, ~2 months behind, so a plain grep of it reported the OPPOSITE of what the pin contained and read as though upstream had reverted the change under review. /pi-sync now fast-forwards it during preflight, which makes that failure less likely but not impossible — and even a correct tree is at origin/main, which mid-cycle is AHEAD of the pin and so is still not what you are reviewing.
  • Published npm build: install/refresh @earendil-works/pi-ai + pi-coding-agent at the matching release into a scratch dir. When the TS source and the shipped build disagree, the BUILD wins — it's what real pi runs and what all goldens come from.
  • Goldens in-repo: coding/testdata/sessparity/, coding/testdata/imgparity/, the default-system-prompt golden, and the tool output-string tests.

Read the full file on GitHub · 95 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. 11d ago First seen · 95 lines · 54 tokens per session scan A e2933de526a8

Subscribe to this mod's changes

pi-parity-review is a skill published in the GitHub repository sky-valley/pi (48 stars, last pushed today), licensed MIT. It adds 54 tokens to every session and 1,448 once invoked, about $0.0003 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.