sdk-seam

sdk-seam is a skill for Claude Code, Codex from gridaco/nothing. It costs 142 tokens per session (4,362 once invoked), scanned A, a copy of sdk-seam, Apache-2.0.

Design guidance for keeping the boundary between two software development kits or contract sides clean, as if they communicated through a network protocol or foreign-function interface. It focuses on stable public data rather than shared internal details.

In plain words
What is it for?
Use it when designing APIs, package boundaries, inter-process communication, foreign-function interfaces, or any producer-and-consumer contract that must evolve independently.
Why use it?
It prevents tightly coupled contracts that only work because one author controls both sides and can change them together.

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/gridaco/nothing/sdk-seam
Any agent
npx skills add gridaco/nothing --skill sdk-seam
Clone the repo
git clone --depth 1 https://github.com/gridaco/nothing

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 sdk-seam

README.md
[![agentmods](https://agentmods.dev/badge/skills/gridaco/nothing/sdk-seam.svg)](https://agentmods.dev/skills/gridaco/nothing/sdk-seam)
Your own site
<a href="https://agentmods.dev/skills/gridaco/nothing/sdk-seam"><img src="https://agentmods.dev/badge/skills/gridaco/nothing/sdk-seam.svg" alt="Measured on agentmods" height="20"></a>
Per session 142 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,362 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 100% 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 $0.00142 $0.04362
Opus 5 $0.00071 $0.02181
Sonnet 5 $0.00028 $0.00872
Haiku 4.5 $0.00014 $0.00436

Measured 4d ago against content hash 4c9ef6b6605a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

sdk-seam 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

100% identical to sdk-seam — 0 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.

.agents/skills/sdk-seam/SKILL.md · 350 lines

How it starts

The opening of the file, as written. The whole thing — 350 lines — stays where its author put it; the contents beside it link to each section on GitHub.

sdk-seam

Companion to sdk-design. Read that first; its deciding table and disciplines are the foundation this skill builds on. Where sdk-design is about a single SDK's surface, this skill is about the seam — the joint between two SDKs (or two sides of one contract) — and what it takes to keep that joint clean when the same author writes both sides.

The failure mode

When you control both sides of a boundary, you produce dirty contracts — simply because you can. A field gets added on the producer side because the consumer needs it; the consumer reaches into the producer's internal shape because no public view exposes the slice; a one-off helper crosses the boundary because "we're going to refactor it later." Six months later the contract is unrecoverable, and the two sides can only be deployed together.

The honest test: if we couldn't shotgun-edit both sides at once, this design wouldn't be possible. That's not a virtue. It's a warning.

If the contract had been an IPC channel, an FFI ABI, a network protocol, or a published-versus-consumed package boundary from the start, the design would have been clean from the beginning, and it would have evolved cleanly. Cross-boundary work inside one repo, one workspace, or one mono-language project doesn't get that discipline for free — you have to manufacture it.

This applies to:

  • Two packages/grida-* packages where one consumes the other.
  • A package and its host application (a crates/* crate + a binary that links it; an npm package + a Next.js app).
  • A Rust crate and its WASM/FFI bindings (where one party can change generated code on the other side at will).
  • Two services sharing a wire format you control on both ends.
  • Two modules within one package that genuinely should be on opposite sides of a contract (because one is "core logic" and the other is "shell" — see $sdk-design D2).

The exercise

Before editing, restate the work as if you only owned one side.

Read the full file on GitHub · 350 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 · 350 lines · 142 tokens per session scan A 4c9ef6b6605a

Subscribe to this mod's changes

sdk-seam is a skill published in the GitHub repository gridaco/nothing (43 stars, last pushed 4d ago), licensed Apache-2.0. It adds 142 tokens to every session and 4,362 once invoked, about $0.0007 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to sdk-seam, differing in 0 lines, and is treated as a copy.

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