author-composition SKILL.md skillA
author-composition from upbound/skills is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add upbound/skills/author-composition@git:20261012.20c120ePins git:20261012.20c120e in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- upbound/skills
- Path
skills/author-composition/SKILL.md- Versions recorded
- 2
- Latest version
- git:20261012.20c120e, committed Oct 12, 2026
- First version recorded
- Oct 8, 2026
- Size
- 13,086 bytes
- Repository stars
- 4
- License
- Apache-2.0
Use this skill when the user asks to create, extend, modify, or debug a Crossplane composition function in a control-plane project — in any language (KCL, Python, TypeScript, Go). Detects the function language and applies the matching reference. Also use when asked about Crossplane v2 composition patterns, model/type import paths, namespaced `.m.` APIs, or why a composition renders green but the resource never reconciles. For authoring the tests themselves use author-tests; for XRD design use…
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
# Composition Authoring Author and modify Crossplane composition functions, in any language `up function generate` supports, test first. ## Before you start A composition's *meaning* is language-agnostic; only its *syntax* differs. Read three layers: the charter (the rules), [patterns.md](references/patterns.md) (what each pattern means), and your language's file under `control-plane-project-charter/references/languages/` (the syntax). - **Reviewing function code:** the checks are in `control-plane-project-charter/references/charter/review.md`. **A test passes but the resource misbehaves on a control plane:** [patterns.md](references/patterns.md#a-green-test-with-a-misbehaving-resource). - Tests → `author-tests`; XRD design and scaffolding → `author-configuration-package`; the gate and deploying → `verify-configuration`; live cloud runs → `e2e-test-configuration`; migrating a function to v2 → `plan-v2-migration` (the function-side points: [patterns.md](references/patterns.md#migrating-a-function-to-v2)). ## Binding rules — they hold even if you open nothing else Load `control-plane-project-charter` first, or read its `SKILL.md` beside this skill's …
Read the whole file at its exact version.
How to install
mdr add upbound/skills/author-composition@sha256:365896cd18e0665aThe line at the top of this page pins the label git:20261012.20c120e, 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_6lif6hkew7dnsjyi)
2 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 2 versions of this file, between Oct 8, 2026 and Oct 12, 2026, about one every 4 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20261012.20c120e latest | 2026-10-12 | 20c120e | 13,086 B | A | view · diff |
| git:20261008.17a6e1f | 2026-10-08 | 17a6e1f | 12,968 B | A | view |
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (13086 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
upbound/skills · 4 stars · license Apache-2.0 · pushed 2026-10-12 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_6lif6hkew7dnsjyi GET https://markdownregistry.com/api/v1/resolve?ref=upbound/skills/author-composition GET https://markdownregistry.com/api/v1/blob/365896cd18e0665a294c59d25a635e3b0287a99a8df08515b94d2fc34b5e4a8e
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.