spec-executor

spec-executor is a skill for Claude Code, Codex from tt-a1i/matt-skills-with-to-goal. It costs 96 tokens per session (1,149 once invoked), scanned A, original, MIT.

A workflow for implementing an already approved software specification in a separate coding session. A specification is a written description of what should be built and how success will be checked.

In plain words
What is it for?
Use it to implement, test, review, and report on one approved specification when the work fits in a single session.
Why use it?
It keeps planning decisions separate from implementation and prevents the agent from guessing which draft or requirement is authoritative.

Skill for Claude CodeCodex

Written for Claude Code and Codex: shipped in a Claude Code plugin, but also agents/openai.yaml present.

Part of the matt-skills-with-to-goal plugin — 40 skills shipped together

Good fit Use it to implement, test, review, and report on one approved specification when the work fits in a single session.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/tt-a1i/matt-skills-with-to-goal/spec-executor
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.

Any agent
npx skills add tt-a1i/matt-skills-with-to-goal --skill spec-executor
Clone the repo
git clone --depth 1 https://github.com/tt-a1i/matt-skills-with-to-goal

Made for: Claude Code, Codex.

Or install matt-skills-with-to-goal, the plugin that ships this one along with the rest of its 40 skills.

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 spec-executor

README.md
[![agentmods](https://agentmods.dev/badge/skills/tt-a1i/matt-skills-with-to-goal/spec-executor/github.svg)](https://agentmods.dev/skills/tt-a1i/matt-skills-with-to-goal/spec-executor)
Your own site
<a href="https://agentmods.dev/skills/tt-a1i/matt-skills-with-to-goal/spec-executor"><img src="https://agentmods.dev/badge/skills/tt-a1i/matt-skills-with-to-goal/spec-executor/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.

agentmods 80×15 button for spec-executor

Your own site · 80×15
<a href="https://agentmods.dev/skills/tt-a1i/matt-skills-with-to-goal/spec-executor"><img src="https://agentmods.dev/badge/skills/tt-a1i/matt-skills-with-to-goal/spec-executor.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 96 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,149 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 5.1 $0.00096 $0.01149
Opus 5 $0.00048 $0.00575
Sonnet 5 $0.00019 $0.00230
Haiku 4.5 $0.00010 $0.00115

Measured 12d ago against content hash 46b32e61914f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

spec-executor 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 12d 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/engineering/spec-executor/SKILL.md · 87 lines

How it starts

The opening of the file, as written. The whole thing — 87 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Spec Executor

Implement one approved spec in the forked execution thread. Treat the planning thread as the source of product decisions, keep implementation detail here, and return a compact receipt that can be pasted back.

Resolve the execution contract

  1. Find the latest SPEC READY block in inherited conversation history. Later user corrections override it; older conflicting requirements do not.
  2. Read the complete spec artifact referenced by that block, including tracker comments or directly linked decisions. Do not reconstruct a second long goal.
  3. Require the route to say that the spec is suitable for forked execution. If it says to-tickets, contains unresolved product decisions, or cannot fit one implementation context, stop and explain the routing problem.
  4. If no SPEC READY block exists, proceed only when the user explicitly identifies an approved spec and asks for its implementation. Otherwise ask for the final source rather than guessing which draft won.
  5. Extract and preserve:
    • repository and starting baseline;
    • user-visible outcome and acceptance criteria;
    • agreed test seam;
    • explicit non-goals and workspace boundaries;
    • authorization for commit, push, review request, deployment, tracker edits, data changes, and other external effects.

Do not reopen settled product questions. Pause only when the final spec is internally contradictory, conflicts materially with the repository, lacks a required external contract, or requires new authority.

Lock scope before editing

Inspect repository instructions, branch, HEAD, worktree status, recent relevant history, and the current implementation at the agreed seam. Record the actual pre-implementation HEAD as the review fixed point.

Send a short execution lock before substantive edits:

Executing: <one-sentence outcome>
Source: <spec issue, file, or final SPEC READY block>
In scope: <compact list>
Out of scope: <compact list>
Validation: <primary seam and required gates>
External authority: <what is and is not authorized>

Read the full file on GitHub · 87 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. 12d ago First seen · 87 lines · 96 tokens per session scan A 46b32e61914f

Subscribe to this mod's changes

spec-executor is a skill published in the GitHub repository tt-a1i/matt-skills-with-to-goal (160 stars, last pushed 15d ago), licensed MIT. It adds 96 tokens to every session and 1,149 once invoked, about $0.0005 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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