derivation-basics SKILL.md skillA
derivation-basics from estuary/agent-skills is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add estuary/agent-skills/derivation-basics@git:20260707.6b608bfPins git:20260707.6b608bf in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- estuary/agent-skills
- Path
skills/derivation-basics/SKILL.md- Versions recorded
- 1
- Latest version
- git:20260707.6b608bf, committed Jul 7, 2026
- Size
- 19,820 bytes
- Repository stars
- 7
- License
- Apache-2.0
Foundation for writing Estuary derivations — what they are, language choice (SQL/TypeScript/Python), project layout, flowctl workflow, stateless vs stateful shuffling, and universal gotchas. Read this before any other derivation-* skill. Use when user says "write a derivation", "how do derivations work", "create a derivation", "derivation setup", or before starting any transformation work.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# derivation-basics Foundation for every Estuary derivation. Each `derivation-*` skill assumes you've read this and jumps straight to its specific use case. **Docs:** https://docs.estuary.dev/concepts/derivations/ — canonical concept page. This skill distills what you actually need to get started. ## What a derivation is A derivation is a collection produced by continuously transforming one or more source collections. It consists of: - An **output collection** with its own schema and key - A **catalog task** running one or more **transforms**. Each transform invokes a **lambda** — the user-written function that maps a source document to zero, one, or many output documents. In SQLite, the lambda is a block of SQL (written inline as `lambda:` or referenced from a `.sql` file). In TypeScript and Python, the lambda is a method on a class and the spec references the file via `module:` instead. - Optional **internal state**: SQLite tables declared in **migrations** (SQL statements run once at derivation startup to create the state tables), or reduction annotations in the output schema, used for aggregations, joins, and windowing …
Read the whole file at its exact version.
How to install
mdr add estuary/agent-skills/derivation-basics@sha256:2bdb4b0f9aab5a67The line at the top of this page pins the label git:20260707.6b608bf, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_tlsvdrh2e6so6ewf)
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Versions
The registry has recorded 1 version of this file, committed on Jul 7, 2026.
Audit of the latest version
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- pass: No instruction to send local credentials anywhere
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- pass: No curl or wget piped into a shell
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Source
estuary/agent-skills · 7 stars · license Apache-2.0 · pushed 2026-11-04 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_tlsvdrh2e6so6ewf GET https://markdownregistry.com/api/v1/resolve?ref=estuary/agent-skills/derivation-basics GET https://markdownregistry.com/api/v1/blob/2bdb4b0f9aab5a67a019eb320d6e4fa036773301e8e9145aaf0c5d4dbf693f9f
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.