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 romiluz13/pi-agent-skills --skill pi-extension-authoringgit clone --depth 1 https://github.com/romiluz13/pi-agent-skillsWrote 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/romiluz13/pi-agent-skills/pi-extension-authoring)<a href="https://agentmods.dev/skills/romiluz13/pi-agent-skills/pi-extension-authoring"><img src="https://agentmods.dev/badge/skills/romiluz13/pi-agent-skills/pi-extension-authoring/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.
<a href="https://agentmods.dev/skills/romiluz13/pi-agent-skills/pi-extension-authoring"><img src="https://agentmods.dev/badge/skills/romiluz13/pi-agent-skills/pi-extension-authoring.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00104 | $0.00620 |
| Opus 5 | $0.00052 | $0.00310 |
| Sonnet 5 | $0.00021 | $0.00124 |
| Haiku 4.5 | $0.00010 | $0.00062 |
Grade A, and why
pi-extension-authoring 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.
How it starts
The opening of the file, as written. The whole thing — 35 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Pi extension authoring
Ground every answer in pi-mono/ files below.
Grounding
pi-mono/packages/coding-agent/docs/extensions.md— capabilities, lifecycle, patterns.pi-mono/packages/coding-agent/examples/extensions/README.md— runnable examples index.pi-mono/packages/coding-agent/src/core/resource-loader.ts—extendResources()appends paths viamergePathsafter existinglastSkillPaths(late paths lose name collisions to earlier ones unless names differ).pi-mono/packages/coding-agent/src/core/agent-session.ts— extension commands vs queued prompts; skill expansion hooks.pi-mono/packages/coding-agent/docs/tui.md— extension TUI component integration with@mariozechner/pi-tui:Componentrendering contract, overlay patterns, input handling in extension context.pi-mono/packages/coding-agent/docs/custom-provider.md—registerProvider()for proxies, OAuth/SSO, custom APIs, and custom model definitions.
Invariants
- Extensions can register tools, commands, themes, prompts, and extra skill paths; exact API surface is defined in docs and example modules — start from
docs/extensions.md, not memory. - Dynamic resource discovery patterns live under
pi-mono/packages/coding-agent/examples/extensions/(e.g.dynamic-resources/listing in examples README).
Workflows
- New extension: Read
docs/extensions.md, clone the closestexamples/extensions/template, then align with projectAGENTS.mdif working insidepi-mono. - Skills from extensions: Trace
extendResources+mergePathsinresource-loader.tsto explain ordering with user/project/package skills. - Extension TUI: Read
docs/tui.mdfor theComponentrendering contract in extension context; combine withpi-tuiskill for library-level APIs. - Custom providers via extension: See
pi-mono/packages/coding-agent/docs/custom-provider.mdforregisterProvider()OAuth flows and proxy patterns (grounded inpi-cli-workspace).
Anti-patterns
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.
- 11d ago First seen · 35 lines · 104 tokens per session scan A f190a4570dad
pi-extension-authoring is a skill published in the GitHub repository romiluz13/pi-agent-skills (18 stars, last pushed 5mo ago), licensed MIT. It adds 104 tokens to every session and 620 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.
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