spec-check

A skill that checks whether feature specifications still match the code that implements them. It reads the feature list and specifications, verifies source paths, and looks for differences or abandoned implementation files.

In plain words
What is it for?
Use it during maintenance or review to check one feature or all active and implemented features for specification drift.
Why use it?
It helps find outdated documentation, missing files, and mismatches between intended behavior and the current implementation.

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/schmidthole/serf/spec-check
Any agent
npx skills add schmidthole/serf --skill spec-check
Clone the repo
git clone --depth 1 https://github.com/schmidthole/serf

Made for: Claude Code, Codex.

Per session 22 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 520 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 $0.00022 $0.00520
Opus 5 $0.00011 $0.00260
Sonnet 5 $0.00004 $0.00104
Haiku 4.5 $0.00002 $0.00052

Measured 2d ago against content hash d33dfd69c83f, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

spec-check 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.

skills/spec-check/SKILL.md · 56 lines

How it starts

The opening of the file, as written. The whole thing — 56 lines — stays where its author put it; the contents beside it link to each section on GitHub.

reference

read development-workflow.md for the full conventions governing the specs directory structure, features, work items, and their formats.

instructions

check for drift between feature specs and their implementation. $ARGUMENTS is an optional feature name to check a single feature. if omitted, check all features.

follow these steps:

  1. locate features. read specs/features/features.md to get the list of features. if a specific feature was provided, filter to just that one.

  2. for each feature with status in-progress or implemented (skip features with status consolidated or retired):

    a. read the spec.md and extract the ## Source Paths section.

    b. if no source paths are listed, flag it as "missing source paths".

    c. for each source path listed, verify it exists in the codebase using glob. flag any paths that do not exist as "stale source path".

    d. read the spec's technical details (data structures, function signatures, config fields, behavior descriptions) and compare against the actual code at the source paths. flag any divergences as "spec drift".

  3. check for orphaned code. look for source files that implement feature-related logic but are not listed in any feature's source paths. this is a best-effort heuristic check, not exhaustive.

  4. output a report in this format:

## spec check results

### <feature-name> — <status>

- [x] source paths exist
- [ ] spec matches code — <brief description of drift>

### <feature-name> — <status>

- [ ] missing source paths

if everything is in sync, output a clean bill of health.

  1. offer to align. if any drift was detected, ask the user whether they would like to update the feature specs to match the current code. if approved:
    • update spec.md to reflect the actual implementation, preserving existing structure and writing style
    • add or remove source paths as needed
    • do not remove spec context that is still accurate
    • present each proposed change before making it

Read the full file on GitHub · 56 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. 2d ago First seen · 56 lines · 22 tokens per session scan A d33dfd69c83f

Subscribe to this mod's changes

spec-check is a skill published in the GitHub repository schmidthole/serf (2 stars, last pushed 5mo ago), licensed BSD-3-Clause. It adds 22 tokens to every session and 520 once invoked, about $0.0001 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.

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