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 code-yeongyu/senpi --skill coding-agent-extension-workergit clone --depth 1 https://github.com/code-yeongyu/senpiWrote 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/code-yeongyu/senpi/coding-agent-extension-worker)<a href="https://agentmods.dev/skills/code-yeongyu/senpi/coding-agent-extension-worker"><img src="https://agentmods.dev/badge/skills/code-yeongyu/senpi/coding-agent-extension-worker/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/code-yeongyu/senpi/coding-agent-extension-worker"><img src="https://agentmods.dev/badge/skills/code-yeongyu/senpi/coding-agent-extension-worker.svg" alt="Reviewed on agentmods" width="80" 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 | $0.00061 | $0.02508 |
| Opus 5.5 | $0.00024 | $0.01003 |
| Sonnet 5.5 | $0.00012 | $0.00502 |
| Haiku 4.5 | $0.00006 | $0.00251 |
Grade A, and why
coding-agent-extension-worker 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 1mo 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 — 138 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Coding Agent Extension Worker
You are implementing exactly ONE feature from features.json in the senpi-mono coding-agent package. Your feature has been pre-assigned — read it from features.json, identify it by its id, and focus exclusively on its description, preconditions, expectedBehavior, verificationSteps, and the assertions listed in fulfills.
Context you MUST read before starting
- Feature spec:
features.json— your assigned feature only. - Mission document:
mission.mdin the mission directory — for overall context. - Validation contract:
validation-contract.md— each ID in your feature'sfulfillsdescribes the exact pass/fail condition you must satisfy. Read ALL your fulfills entries before you start. - Architecture:
.factory/library/architecture.md— the target system shape. Your work MUST conform to this. - Environment notes:
.factory/library/environment.md— tooling quirks, forbidden patterns. - User testing surface:
.factory/library/user-testing.md— test infrastructure conventions. - Mission agents guidance:
AGENTS.mdin the mission directory — boundaries, conventions, git safety rules. - Project agents guidance: the root
AGENTS.mdat the repo root (senpi-mono coding guidelines) — fork strategy, commit conventions, anti-patterns.
Hard rules — never violate
- Fork strategy: Every change is a builtin-extension change. You may not modify
packages/ai,packages/agent,packages/tui,packages/mom,packages/pods,packages/coding-agent/src/core/settings-manager.ts,packages/coding-agent/src/core/extensions/types.ts,runner.ts,loader.ts,wrapper.ts, or any other builtin extension besidestodotools/andbuiltin/index.ts. - No type suppressions:
any,as any,@ts-ignore,@ts-expect-errorare forbidden across all files inbuiltin/todotools/. Use explicit type guards instead. - No inline imports: top-level ES imports only. Never
await import()orimport("pkg").Type. - No real LLM calls in tests: always use the faux provider via
createHarness. - Git safety: only
git add <specific-path>. Never-A, never., never--no-verify, neverreset --hard, nevercheckout ., neverclean -fd, neverstash. - Only commit files you touched in this session. Inspect
git statusbefore staging. - No emojis in code, commits, test names, or PR comments.
- Biome enforced: 3-space / tab indent matching the existing file style, 120-char line width.
tscenforced: all code compiles cleanly with no diagnostics.
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.
- 1mo ago First seen · 138 lines · 61 tokens per session scan A b98592a87474
coding-agent-extension-worker is a skill published in the GitHub repository code-yeongyu/senpi (482 stars, last pushed today), licensed MIT. It adds 61 tokens to every session and 2,508 once invoked, about $0.0002 per session on Opus 5.5. 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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