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.
npx skills add spences10/my-pi --skill pi-extension-developmentgit clone --depth 1 https://github.com/spences10/my-piWrote 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.
[](https://agentmods.dev/skills/spences10/my-pi/pi-extension-development)<a href="https://agentmods.dev/skills/spences10/my-pi/pi-extension-development"><img src="https://agentmods.dev/badge/skills/spences10/my-pi/pi-extension-development.svg" alt="Measured on agentmods" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00041 | $0.00327 |
| Opus 5 | $0.00020 | $0.00163 |
| Sonnet 5 | $0.00008 | $0.00065 |
| Haiku 4.5 | $0.00004 | $0.00033 |
Grade A, and why
pi-extension-development 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 9d 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.
What it actually says
Pi Extension Development
Use this workflow for packages/pi-* implementation work in this
repo.
Workflow
- Identify the package boundary first: root app,
src/extensions/*, or apackages/pi-*workspace package. - For new built-ins, add a package under
packages/, wire rootpackage.jsonoptional dependencies, and register insrc/extensions/builtin-registry.ts. - Keep extension entrypoints small: export a default extension function and pure helper functions for testable trigger logic.
- Put user-facing injected prompt text in one obvious template block; gate injection by selected tools/options when possible.
- Update package README and Changeset when behavior changes.
- Validate with the package script first, then root checks if registry/root files changed.
Project conventions
- Prefer
@spences10/pi-*workspace packages withworkspace:*links. - Tests live beside source as
*.test.tsand should cover trigger/gating helpers. - Avoid importing another package's
src/*ordist/*; use public package entrypoints. - Use
references/checklist.mdfor the exact file checklist when adding a package.
What ships with it
1 file 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.
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.
- 9d ago First seen · 39 lines · 41 tokens per session scan A f85e0679f18e
pi-extension-development is a skill published in the GitHub repository spences10/my-pi (118 stars, last pushed yesterday), licensed MIT. It adds 41 tokens to every session and 327 once invoked, about $0.0002 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.
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