check-impl-against-spec

check-impl-against-spec is a skill for Claude Code, Codex from Terry-Mao/AICodingFlow. It costs 44 tokens per session (506 once invoked), scanned A, a copy of check-impl-against-spec, MIT.

A review step that compares a pull request's code changes with an approved product or technical specification.

In plain words
What is it for?
It checks required behavior, files, constraints, migrations, and validation steps, then adds significant mismatches to the normal review results.
Why use it?
It reveals material differences between what was agreed and what was implemented.

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/terry-mao/aicodingflow/check-impl-against-spec
Any agent
npx skills add Terry-Mao/AICodingFlow --skill check-impl-against-spec
Clone the repo
git clone --depth 1 https://github.com/Terry-Mao/AICodingFlow

Made for: Claude Code, Codex.

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 check-impl-against-spec

README.md
[![agentmods](https://agentmods.dev/badge/skills/terry-mao/aicodingflow/check-impl-against-spec.svg)](https://agentmods.dev/skills/terry-mao/aicodingflow/check-impl-against-spec)
Your own site
<a href="https://agentmods.dev/skills/terry-mao/aicodingflow/check-impl-against-spec"><img src="https://agentmods.dev/badge/skills/terry-mao/aicodingflow/check-impl-against-spec.svg" alt="Measured on agentmods" height="20"></a>
Per session 44 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 506 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 94% copy Near-identical to another mod 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 $0.00044 $0.00506
Opus 5 $0.00022 $0.00253
Sonnet 5 $0.00009 $0.00101
Haiku 4.5 $0.00004 $0.00051

Measured 4d ago against content hash 1af02f995f30, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

check-impl-against-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.

Origin

This is a copy

94% identical to check-impl-against-spec — 6 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.github/skills/check-impl-against-spec/SKILL.md · 50 lines

How it starts

The opening of the file, as written. The whole thing — 50 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Check implementation against spec

Use this skill only when spec_context.md exists during PR review.

Goal

Determine whether the implementation in the checked-out PR materially matches the approved spec context. This is a supplement to the normal code review, not a separate output.

Inputs

  • spec_context.md contains the spec context to compare against. It may include both product spec content (intended behavior, acceptance criteria) and tech spec content (implementation details, file changes).
  • pr_diff.txt contains the annotated diff for the PR.
  • pr_description.txt may contain additional scope or rationale.
  • The working tree contains the PR branch contents.

How to evaluate spec alignment

  1. Read spec_context.md and extract the concrete commitments it makes:
    • required behaviors (from the product spec)
    • required files or subsystems to change (from the tech spec)
    • stated constraints
    • required follow-up steps, validation, or migrations
  2. Compare those commitments against the actual implementation in pr_diff.txt and the checked-out files.
  3. Treat small implementation-level adjustments as acceptable when they preserve the spec's intent. Do not flag harmless differences in naming, structure, or low-level technique.
  4. Flag a mismatch only when it is material, such as:
    • required behavior in the product spec is missing
    • the implementation contradicts a spec decision
    • the change introduces significant unplanned scope
    • a required validation, migration, or compatibility step from the tech spec is absent

How to report mismatches

  • Do not create a separate report file.
  • Fold spec-alignment findings into review.json.
  • Put broad spec-drift concerns in the review summary.
  • Add inline comments only when the mismatch can be tied to changed lines in the diff.
  • Treat material spec drift as at least an important concern.
  • If the implementation matches the spec closely enough, do not add comments just to mention alignment.

Read the full file on GitHub · 50 lines

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 · 50 lines · 44 tokens per session scan A 1af02f995f30

Subscribe to this mod's changes

check-impl-against-spec is a skill published in the GitHub repository Terry-Mao/AICodingFlow (165 stars, last pushed 6d ago), licensed MIT. It adds 44 tokens to every session and 506 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 94% identical to check-impl-against-spec, differing in 6 lines, and is treated as a copy.

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