spec-drift

spec-drift is a skill for Claude Code, Codex from fold-run/fold. It costs 67 tokens per session (1,189 once invoked), scanned A, original, Apache-2.0.

A guide for comparing a new version of the Model Context Protocol specification with the protocol implemented by Fold. It produces a list of required changes, optional omissions, and documented gaps.

In plain words
What is it for?
Use it when a protocol revision or SDK update arrives, to review changelogs and deprecations and classify their effects on Fold's server and upstream-client sides.
Why use it?
It helps identify compatibility problems caused by specification changes before they become failures in conformance checks or client integrations.

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/fold-run/fold/spec-drift
Any agent
npx skills add fold-run/fold --skill spec-drift
Clone the repo
git clone --depth 1 https://github.com/fold-run/fold

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 spec-drift

README.md
[![agentmods](https://agentmods.dev/badge/skills/fold-run/fold/spec-drift.svg)](https://agentmods.dev/skills/fold-run/fold/spec-drift)
Your own site
<a href="https://agentmods.dev/skills/fold-run/fold/spec-drift"><img src="https://agentmods.dev/badge/skills/fold-run/fold/spec-drift.svg" alt="Measured on agentmods" height="20"></a>
Per session 67 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,189 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 $0.00067 $0.01189
Opus 5 $0.00034 $0.00594
Sonnet 5 $0.00013 $0.00238
Haiku 4.5 $0.00007 $0.00119

Measured 3d ago against content hash 2e5471cda1b8, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

spec-drift 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 3d 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.

.claude/skills/spec-drift/SKILL.md · 98 lines

How it starts

The opening of the file, as written. The whole thing — 98 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Protocol revision drift

/conformance catches drift in the suite. This catches drift in the specification — the changes that land months before a check exists for them, and the deprecations that never get a check at all.

Run it when a revision ships, when the SDK bumps a protocol version, and before any deliberate CONFORMANCE_COMMIT bump.

Procedure

1. Read the changelog, not the diff. https://modelcontextprotocol.io/specification/<new>/changelog.md lists major changes, minor changes, and deprecations. Also fetch …/deprecated.md — the removal registry, with the twelve-month window that tells you how long fold has.

2. Classify each entry against fold's two faces. fold is a server to its clients (gateway/router.go, the mcp.Server and its middleware) and a client to its upstreams (gateway/upstream.go). A change can hit one, the other, or both, and the answers differ:

  • Server-side changes fold must implement or clients break.
  • Client-side changes are usually the SDK's job — check whether go-sdk already covers it before writing anything.
  • Intermediary changes are fold's alone and no SDK will do them: list merging, cache scoping, error-code minting, namespacing. These are the ones that get missed.

3. Grep before concluding. A feature fold "doesn't support" often exists under another name. For each entry, search for the field, method, and header names:

grep -rni 'resultType\|input_required\|cacheScope\|ttlMs\|Mcp-Method' --include='*.go' .
grep -rn '\-320[0-9][0-9]' --include='*.go' . | grep -v _test

4. Check the SDK's position. fold never hand-rolls framing, so for most wire changes the question is "has the SDK shipped this yet" and the answer bounds what fold can do. Record the SDK version and the specific restriction — the subscriptions/listen gap in README "Not implemented" is exactly this shape, and it carries a drift canary in gateway/listen_test.go that fails when the SDK lifts its restriction. A gap that waits on the SDK gets a canary that fails when the wait ends — otherwise nobody learns the wait is over.

Read the full file on GitHub · 98 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. 3d ago First seen · 98 lines · 67 tokens per session scan A 2e5471cda1b8

Subscribe to this mod's changes

spec-drift is a skill published in the GitHub repository fold-run/fold (1 stars, last pushed 3d ago), licensed Apache-2.0. It adds 67 tokens to every session and 1,189 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

hotplex-release

通过判断 SemVer 影响、整理 CHANGELOG、对账版本面和验证发布输入来准备或发布 HotPlex 版本。不要用于主机二进制更新、运行时诊断或文档巡逻。.

hrygo/hotplex · 52 tokens

hotplex-docs-patrol

维护 HotPlex 当前文档,将代码、配置、API 或发布变更映射到 BFS 可达文档,只修复已验证的文档漂移。不要用于普通润色、运行时诊断或版本发布。.

hrygo/hotplex · 57 tokens

hotplex-stt-tts

初始化或修复 HotPlex 本地 STT 和 MOSS TTS 运行时,包括 Python 依赖、官方模型、配置和验收。仅在明确授权主机变更时使用;只读检查请使用 hotplex-cli 或 hotplex-diagnostics。.

hrygo/hotplex · 65 tokens

hotplex-diagnostics

深入诊断 HotPlex Gateway、Worker、Session、日志或反馈链异常。普通 status/doctor/security/config 只读检查属于 hotplex-cli;安装、更新、重启、配置写入和 Admin 变更属于 hotplex-operator。.

hrygo/hotplex · 59 tokens

hotplex-cli

使用 HotPlex CLI 处理 Cron、明确请求的 Slack 操作、普通用户聊天命令指引,以及只读 status、doctor、security、config 诊断。不要用于飞书写操作、发布、服务安装、二进制更新或 Admin 变更。.

hrygo/hotplex · 63 tokens

hotplex-operator

运维或初始化 HotPlex 主机,覆盖首次 onboard、服务安装/启动、二进制更新、主机配置、审计检查和 Admin 变更。仅在明确授权的 operator 上下文中使用。.

hrygo/hotplex · 54 tokens