What is atproto-repository?

A guide for working with AT Protocol repositories, the signed per-account record stores used by services such as Bluesky. It covers their tree structure, binary file format, commits, and signatures in Rust, TypeScript, or Go.

Use it when building or checking AT Protocol repository support, including Merkle Search Trees, CAR files, commits, record keys, and cryptographic signatures.

It explains the exact rules needed to read, create, import, export, or validate these repositories. This helps avoid invalid files, broken signatures, and incorrectly encoded data.

atproto-repository — Skill for Claude Code by ngerakines

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 ngerakines/atproto-skills --skill atproto-repository

Clone the repo

git clone --depth 1 https://github.com/ngerakines/atproto-skills

Made for: Claude Code.

Or install atproto-skills, the plugin that ships this one along with the rest of its 7 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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/ngerakines/atproto-skills/atproto-repository/github.svg)](https://agentmods.dev/skills/ngerakines/atproto-skills/atproto-repository)

Your own site

<a href="https://agentmods.dev/skills/ngerakines/atproto-skills/atproto-repository"><img src="https://agentmods.dev/badge/skills/ngerakines/atproto-skills/atproto-repository/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/ngerakines/atproto-skills/atproto-repository"><img src="https://agentmods.dev/badge/skills/ngerakines/atproto-skills/atproto-repository.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 696 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 3,481 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.

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.

Model	Per session	Once invoked
Fable 5.1	$0.00696	$0.03481
Opus 5	$0.00348	$0.01741
Sonnet 5	$0.00139	$0.00696
Haiku 4.5	$0.00070	$0.00348

Measured 12d ago against content hash 071d3edd66a1, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

atproto-repository 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/atproto-repository/SKILL.md · 165 lines

How it starts

The opening of the file, as written. The whole thing — 165 lines — stays where its author put it; the contents beside it link to each section on GitHub.

AT Protocol Repository

An AT Protocol repository is a single account's entire record store, addressed by its DID. Every record lives at a key in a Merkle Search Tree; the tree's root CID is sealed by a signed commit; the commit plus every block it transitively references are the repository. On the wire, it travels as a CAR v1 file.

This skill routes to per-language guides for Rust, TypeScript, and Go, sitting on top of a language-neutral spec in shared/.

Defaults

DRISL — canonical DAG-CBOR: bytewise map keys, shortest-form integers, no indefinite-length framing, CIDs as tag 42 + identity multibase.
CAR v1 — varint ‖ header-cbor ‖ (varint ‖ 36-byte-CID ‖ bytes)*. Roots list declares the commit CID.
MST — SHA-256 key height with fanout 4 (count pairs of leading zero bits). Node shape {l?, e:[{p,k,v,t?}]}. Keys are <collection>/<rkey>, max 1024 bytes.
Commit — {did, version:3, data, rev, prev, sig}. prev is null for genesis (though see §divergence). Signing bytes = DAG-CBOR of the commit minus sig.
Signature — raw r ‖ s ECDSA (k-256 or p-256), low-S normalized. Verified against the #atproto Multikey in the signer's DID document.

Full normative rules: shared/drisl.md, shared/car-v1.md, shared/mst.md, shared/commit-and-signing.md, shared/data-model.md. Fixtures: shared/test-vectors.md. Cross-language differences: shared/divergence-matrix.md.

Language detection

Before generating or reviewing any repo code, determine the target language from project files or the file being edited:

Cargo.toml, *.rs, any mention of atproto-repo / atproto-dasl / atproto-record → Rust — read from rust/.
package.json, tsconfig.json, *.ts, *.tsx, imports of @atproto/repo / @atproto/lex-cbor / @atproto/crypto → TypeScript — read from typescript/. Also *.js/*.jsx when there is no .ts present.
go.mod, *.go, imports of github.com/bluesky-social/indigo/atproto/repo → Go — read from go/.

Read the full file on GitHub · 165 lines

Files

What ships with it

22 files 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.

12d ago First seen · 165 lines · 0 tokens per session scan A 071d3edd66a1

Subscribe to this mod's changes

atproto-repository is a skill published in the GitHub repository ngerakines/atproto-skills (50 stars, last pushed 4mo ago), licensed MIT. It adds 696 tokens to every session and 3,481 once invoked, about $0.0035 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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