spec

A specification workflow that turns a rough feature idea into an ordered set of product, design, security, performance, testing, and implementation documents.

In plain words
What is it for?
Use it to create linked specifications, a glossary, decision records, a delivery roadmap, and an engineer-facing build plan.
Why use it?
It reduces missing decisions and disagreements between the people defining a feature and the engineers building it.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/tyrchen/rust-lib-template/spec
Any agent
npx skills add tyrchen/rust-lib-template --skill spec
Clone the repo
git clone --depth 1 https://github.com/tyrchen/rust-lib-template

Made for: Claude Code, Codex.

Per session 173 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,728 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00173 $0.05728
Opus 5 $0.00086 $0.02864
Sonnet 5 $0.00035 $0.01146
Haiku 4.5 $0.00017 $0.00573

Measured 2d ago against content hash 83ee07c17955, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

spec 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.

.agents/skills/spec/SKILL.md · 400 lines

How it starts

The opening of the file, as written. The whole thing — 400 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Spec

Turn requirements into a load-bearing spec set: numbered, cross-linked, dependency-ordered, with a stakeholder-facing roadmap and an engineer-facing implementation plan that pair 1:1. The spec set is the contract between intent and code; if it is wrong or incoherent, every downstream phase pays for it.

When this fires

  • "write the spec / PRD / design / impl plan / roadmap for X"
  • "restructure the specs so it can be built incrementally"
  • "review the design and add the missing specs"
  • "phase this delivery — what lands when?"
  • The user describes a system non-trivial enough that ad-hoc coding will produce drift, missing invariants, or unbounded scope
  • The research skill has produced memos and the next move is to commit decisions to a spec

Output shape

A directory of numbered Markdown files under ./specs/. The numbering is the build order — reading top-to-bottom matches the milestone progression in the roadmap. Update ./specs/index.md so a fresh reader can navigate.

Diagram expectation

Use fenced ASCII-style diagrams (```text) whenever they materially improve understanding of high-level architecture, data flow, processing flow, component/subsystem relationships, lifecycle/state transitions, or build/dependency order. Diagrams are part of the spec contract: keep labels precise, show directionality, and put the diagram near the decision it clarifies. Prefer terminal-safe text diagrams over Mermaid so the spec remains readable in terminals, code review, and plain Markdown renderers. Unicode box-drawing characters (┌─┐│└┘, , ) are encouraged when they make the structure clearer. Do not add decorative diagrams that merely restate simple prose.

For non-trivial systems, the diagram must be structurally rich enough to review: use nested boxes, lanes, or grouped boundaries rather than a bare A -> B -> C chain. Show component ownership, trust/runtime boundaries, queues/channels, storage, external services, error paths, and fan-in/fan-out where they matter. A simple arrow chain is acceptable only for a short linear ordering with no meaningful boundary or alternative path.

Read the full file on GitHub · 400 lines

Files

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.

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. 2d ago First seen · 400 lines · 173 tokens per session scan A 83ee07c17955

Subscribe to this mod's changes

spec is a skill published in the GitHub repository tyrchen/rust-lib-template (51 stars, last pushed 3mo ago), licensed MIT. It adds 173 tokens to every session and 5,728 once invoked, about $0.0009 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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