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 agentmods add skills/kunchenguid/firstmate/firstmate-coding-guidelinesnpx skills add kunchenguid/firstmate --skill firstmate-coding-guidelinesgit clone --depth 1 https://github.com/kunchenguid/firstmateWhat 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 | $0.00130 | $0.02329 |
| Opus 5 | $0.00065 | $0.01164 |
| Sonnet 5 | $0.00026 | $0.00466 |
| Haiku 4.5 | $0.00013 | $0.00233 |
Grade A, and why
firstmate-coding-guidelines 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 2d 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 — 128 lines — stays where its author put it; the contents beside it link to each section on GitHub.
firstmate-coding-guidelines
Load this before changing firstmate's shared, tracked material, as defined by AGENTS.md section 1.
It exists because AGENTS.md grew from 585 to 958 lines between its last two restructures, entirely from conditional detail added inline instead of routed to its right home.
Applying the rules below on every change is what keeps that from happening again.
Knowledge-placement decision tree
Before writing a new fact anywhere in this repo, ask where it belongs, in this order.
- Does the firstmate AGENT need this on every session or every turn to operate?
If yes:
AGENTS.md, inline. - Does the agent need it only in a nameable situation - a spawn, a recovery, a specific wake type, a specific lifecycle step?
If yes: an agent-only skill under
.agents/skills/, plus a one-line trigger pointer left inline inAGENTS.md(usually section 13). - Is it public product, setup, or user/operator reference?
If yes: the surface classified for that audience in
docs/documentation-audiences.md, limited to current behavior, setup, supported limits, stable invariants, concise rationale, and current verification entry points. - Is it contributor/maintainer architecture? If yes: the classified maintainer-architecture owner for stable ownership, extension points, mechanism boundaries, and safety rationale.
- Is it active reusable verification for a current guarantee? If yes: an explicitly classified maintainer-verification record may keep current dates, versions, exact commands, and exact output.
- Is it task or incident evidence - chronology, transcripts, branches, temporary paths, failed hypotheses, or delivery proof? If yes: keep it in the private task report or PR evidence by default, after distilling every unique current fact into its authoritative owner.
- Is it mechanics - exact flags, exact commands, exact paths?
If yes: the script's own header comment plus its
--helpoutput, not prose inAGENTS.md, a skill, or a second documentation owner.
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.
- 2d ago First seen · 128 lines · 130 tokens per session scan A ca7bd8f24f56
firstmate-coding-guidelines is a skill published in the GitHub repository kunchenguid/firstmate (4,623 stars, last pushed today), licensed MIT. It adds 130 tokens to every session and 2,329 once invoked, about $0.0006 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.
Other skills, from other repositories
systematic-debugging
Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes.
brainstorming
You MUST use this before any creative work - creating features, building components, adding functionality, or modifying behavior. Explores user intent, requirements and design before implementation.
chat-pet-sprite-creation
Use when creating or changing VS Code chat pet sprite art, sprite sheets, state animations, eye treatments, Stable/Insiders variants, or pet transitions under src/vs/workbench/contrib/chat/browser/widget/media/chatPet.
cpu-profile-analysis
Analyze V8/Chrome CPU profiles (.cpuprofile) and DevTools trace files (Trace-.json). Use when: profiling performance, investigating slow functions, comparing code paths, finding bottlenecks, analyzing timeToRequest, understanding call trees from sampling profiler data, analyzing layout/paint/rendering, investigating…
agent-host-chat-contributions
Build and review cross-cutting agent-host chat behavior through lifecycle contributions. Use when adding turn lifecycle side effects, prompt or context injection, restored-history transformation, protocol-action observation, or when reviewing changes that add code to AgentSideEffects or AgentService.
auto-perf-optimize
Run agent-driven VS Code performance or memory investigations. Use when asked to launch Code OSS, automate a VS Code scenario, run the Chat memory smoke runner, capture renderer heap snapshots, take workflow screenshots, compare run summaries, or drive a repeatable scenario before heap-snapshot analysis.