shape-spec

shape-spec is a skill for Claude Code, Codex from t1djani/servo. It costs 50 tokens per session (498 once invoked), scanned A, original, MIT.

A workflow skill for turning an agreed design into a self-checking written specification. It records what must not break and which reference sources will be used to judge the work.

In plain words
What is it for?
Use it after design decisions are settled and before making an implementation plan. It helps write the goal, approach, scope, exclusions, invariants, and judging sources into one specification.
Why use it?
It keeps important constraints from being forgotten as the work moves from design into planning and implementation. It also makes the specification easier to review against the project's intended scope and requirements.

Skill for Claude CodeCodex

Part of the servo plugin — 9 skills, 1 command shipped together

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/t1djani/servo/shape-spec
Any agent
npx skills add t1djani/servo --skill shape-spec
Clone the repo
git clone --depth 1 https://github.com/t1djani/servo

Made for: Claude Code, Codex.

Or install servo, the plugin that ships this one along with the rest of its 9 skills, 1 command.

Wrote 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.

agentmods badge for shape-spec

README.md
[![agentmods](https://agentmods.dev/badge/skills/t1djani/servo/shape-spec.svg)](https://agentmods.dev/skills/t1djani/servo/shape-spec)
Your own site
<a href="https://agentmods.dev/skills/t1djani/servo/shape-spec"><img src="https://agentmods.dev/badge/skills/t1djani/servo/shape-spec.svg" alt="Measured on agentmods" height="20"></a>
Per session 50 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 498 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 $0.00050 $0.00498
Opus 5 $0.00025 $0.00249
Sonnet 5 $0.00010 $0.00100
Haiku 4.5 $0.00005 $0.00050

Measured 4d ago against content hash b4c6b1e9f430, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

shape-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 4d 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.

skills/shape-spec/SKILL.md · 27 lines

What it actually says

shape-spec

Turn a decided design into a spec that the rest of the flow can trust. A good servo spec is not just a description; it carries the means to check itself. Two moves make that happen.

The two moves

  • Embed the invariants inline (constrain). Whatever the work must never break — pulled from the invariants oracle and the relevant experts — is written into the spec as an explicit list, not left implicit. A constraint that is physically present in the document cannot be silently forgotten downstream.

  • Name the oracles (point, do not freeze). The spec declares which sources it will be judged against — scope, invariants, acceptance, prior-art — by reference, so they stay fresh. (A plan, later, will snapshot its acceptance target instead; a spec evolves, so it points.)

Procedure

  1. Start from the context brief (gather-context) and the decided forks (expert-panel). Do not re-open settled decisions here.
  2. Write the spec. State the goal, the approach, and the scope — including what is explicitly out of scope.
  3. Add an Invariants section. List, inline, what must not break, each tagged with the oracle/expert it came from.
  4. Add an Oracles section. Name the manifest keys this spec will be gated against.
  5. Gate the spec. Run servo-gate on the spec, once per relevant oracle: against invariants (does it violate any?), scope (does it match the intent, no creep?), prior-art (does it ignore or contradict what exists?), footguns (does it walk into a known trap?). Fix what comes back FIX/STOP; do not proceed on an open finding.

Rule

The spec is the last place divergence is allowed. After it, the plan is pure convergence. If a real fork is still open, go back to expert-panel — do not bury the choice in the spec for the plan to trip over.

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. 4d ago First seen · 27 lines · 50 tokens per session scan A b4c6b1e9f430

Subscribe to this mod's changes

shape-spec is a skill published in the GitHub repository t1djani/servo (1 stars, last pushed 2mo ago), licensed MIT. It adds 50 tokens to every session and 498 once invoked, about $0.0003 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 2026-08-31.

Related

Other skills, from other repositories

quiz-me

Quiz the user on root cause and intended fix BEFORE writing any non-trivial code, then verify comprehension of every change after. Use when the user asks for a bug fix, refactor, or feature and wants to stay technically sharp instead of vibe-coding. Also use when the user says "quiz me", "don't let me vibe code", or…

emanzurv/quiz-me-skill · 82 tokens

website-deploy-builder

Plan what to build on Website Deploy (simple-host.app). Helps a user decide whether their idea fits the static + light-backend model, maps it to concrete patterns (shared JSON state with atomic ops, append-only collections, private/password-locked pages on a custom domain, drop-in comments/feedback widgets…

vineetu/simple-host · 114 tokens

connect-domain

Connect a user's own custom domain (subdomain e.g. recipes.brand.com via CNAME, or apex e.g. brand.com via A record) to a site already deployed on simple-host. Use when a user wants their site served from their own domain with automatic HTTPS, or wants a private/password-protected site (privacy is offered only on a…

vineetu/simple-host · 108 tokens

personal-voice-capture

Use when a user wants an agent to learn, encode, or improve their personal writing voice as a reusable skill through source-text ingestion and iterative calibration edits.

eranshir/personal-voice-capture · 37 tokens

demo-video-factory

Generate a custom 26s product-demo video from any SaaS URL — brand-matched scenes, a recreated product-UI "wow" scene, real screenshots, and a soundtrack. Use whenever the user wants a demo, promo, launch, or marketing video for a website or product.

jonny-1812/demo-video-factory · 63 tokens

website-deploy

Deploy static websites to simple-host.app. Use when an agent needs to guide a user through registration, build/validate a static site, deploy it (inline JSON files OR a tar.gz/zip archive), or wire up the per-site backend — shared JSON state with atomic ops, append-only collections, private (password-locked) pages on…

vineetu/simple-host · 87 tokens