ad-spec

A feature specification writer for a software project. It creates a document describing one feature’s user scenarios, requirements, and measures of success within the project’s existing documentation structure.

In plain words
What is it for?
Use it to draft a single-feature specification in the project’s docs. It helps distinguish feature specifications from PRDs, which describe the product as a whole.
Why use it?
It turns a broad feature idea into a shared, reviewable description before planning and coding begin. It also keeps feature decisions consistent with the project’s terminology and product requirements.

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/corridortech/posecap/ad-spec
Any agent
npx skills add CorridorTech/PoseCap --skill ad-spec
Clone the repo
git clone --depth 1 https://github.com/CorridorTech/PoseCap

Made for: Claude Code, Codex.

Per session 137 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,687 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 $0.00137 $0.01687
Opus 5 $0.00068 $0.00843
Sonnet 5 $0.00027 $0.00337
Haiku 4.5 $0.00014 $0.00169

Measured 2d ago against content hash dd58899527c8, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

ad-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/ad-spec/SKILL.md · 114 lines

How it starts

The opening of the file, as written. The whole thing — 114 lines — stays where its author put it; the contents beside it link to each section on GitHub.

<background_information> Drafts doc/specs/<NNNN>-<short-slug>.md for one feature. Status lifecycle: draft → accepted → shipped | superseded by SPEC-NNNN. Spec is the layer-4 artifact in the kit's six-layer stack — Constitution (AGENTS.md + WORKFLOW.md) → Domain (CONTEXT.md) → Product (doc/product/PRD.md) → Spec (this skill) → Plan/Decisions (ARCHITECTURE.md + doc/adr/ + doc/tasks/) → Code. Multiple tasks implement one spec; ADRs may be driven by spec constraints. The Domain layer (ubiquitous language per Evans 2003) is the source of canonical nouns the spec must use; if the spec introduces a new noun, resolve it through CONTEXT.md first. The Product layer (PRD) is the source of target user, product-level success metrics, and cross-feature constraints the spec inherits from.

Codex auto-trigger on description keywords is less mature than Claude Code's. If auto-invocation does not fire when the user asks to "draft a spec" for a single feature, invoke this skill manually. If the user asks for a "PRD" or "product requirements" — route them to ad-prd instead; PRDs are Layer 3 (product-level), not feature-level. </background_information>

Step 2 — confirm scope. The spec captures one feature. If the user's request implies multiple, ask which to write first; the others become follow-up specs. A "feature" here is the smallest user-visible outcome that has its own success criteria — not a task (work unit) and not a binding architectural decision (ADR).

Step 3 — interview to fill. Ask one question per missing field, in this order:

  • Context: business context first per ADR-0008. Why the feature exists, the user / constraint / problem it addresses, the cost of not building it.
  • User Scenarios: Given-When-Then for the key flows. Each scenario independently testable.
  • Functional Requirements: testable statements. Plain bullets (no checkbox — Spec is decision-record per ADR-0030 §1; implementation tracking lives in per-Spec tasks).
  • Non-functional Requirements: perf / security / a11y / observability — only when binding.
  • Success Criteria: measurable per WORKFLOW.md §1. Plain bullets; pass/fail observable, not aspirational. Per-criterion progress tracking lives in per-Spec tasks.
  • Edge Cases: empty inputs, large inputs, concurrent access, missing prerequisites, permission errors.
  • Out of Scope: explicit non-goals.
  • Open Questions: deferred decisions. Each becomes an ADR or a documented punt.
  • Related: ADRs touched, tasks implementing it (lazy), other specs this one supersedes or depends on.

Status starts at draft. Created: today, ISO format. Owner: ask. Do NOT invent values; leave <TODO> and ask.

Step 4 — write the file. Path: doc/specs/<NNNN>-<short-slug>.md. Use the template below.

Stop after writing. Do NOT flip status to accepted — that requires user review.

Step 5 — editing guidance for later turns. Append to Open Questions; close with resolution paragraphs, never delete. Flip Status to accepted on user sign-off; shipped once all per-Spec tasks complete; superseded when replaced. Add tasks to Related as they are created. Implementation tracking (per-criterion progress) lives in per-Spec tasks, not in the Spec. Never rewrite existing prose — append rationale to Open Questions rather than mutating original requirement text.

Status: <draft | accepted | shipped | superseded by SPEC-NNNN> Created: <YYYY-MM-DD> Owner: <name or role>

Read the full file on GitHub · 114 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 · 114 lines · 137 tokens per session scan A dd58899527c8

Subscribe to this mod's changes

ad-spec is a skill published in the GitHub repository CorridorTech/PoseCap (190 stars, last pushed 9d ago), licensed Apache-2.0. It adds 137 tokens to every session and 1,687 once invoked, about $0.0007 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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