streamling-udf-plugin SKILL.md skillA
streamling-udf-plugin from goldsky-io/streamling is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add goldsky-io/streamling/streamling-udf-plugin@git:20260625.ecf56acPins git:20260625.ecf56ac in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- goldsky-io/streamling
- Path
skills/streamling-udf-plugin/SKILL.md- Versions recorded
- 1
- Latest version
- git:20260625.ecf56ac, committed Jun 25, 2026
- Size
- 12,165 bytes
- Repository stars
- 107
- License
- a license file GitHub does not identify
Use when implementing a streamling DataFusion scalar UDF — a custom function callable from pipeline SQL (SELECT my_func(col) FROM ...). Covers the ScalarUDFImpl trait, the modern invoke_with_args / ScalarFunctionArgs API, argument validation and downcasting, null propagation, return_type vs return_field_from_args, volatility, both registration macros, and the create_udf legacy path. Assumes streamling-plugin-basics.
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
# streamling UDF plugin — Agent Skill A **UDF** (user-defined function) is a DataFusion scalar function your plugin exposes, so pipeline SQL can call it: `SELECT truncate(body, 280) FROM stream`. It is the lightest way to add a derived column — no batch pipeline of your own, no `process_batch`. DataFusion calls your function inside its plan. **Prerequisites:** [`streamling-plugin-basics`](skill://streamling-plugin-basics) (crate setup, registration). To *use* the UDF once registered, see [`sql-transform`](skill://sql-transform). **API version:** these skills target DataFusion **49** / Arrow **55** (the `invoke_with_args` + `ScalarFunctionArgs` era). If your `Cargo.toml` pins an older DataFusion, the method may be `invoke(&self, args: Vec<ColumnarValue>)` instead — adapt accordingly. ## Two ways to author a UDF | Form | Register with | When | |---|---|---| | `struct MyFunc impl ScalarUDFImpl` (+ `Default`) | `register_plugin_udf!(MyFunc)` | Default — type-safe, structured, the modern recommendation | | closure via `create_udf(..)` returning a `ScalarUDF` | `register_plugin_udf_fn!(create_my_func)` | Legacy / quick — a `fn() -> ScalarUDF` factory | …
Read the whole file at its exact version.
How to install
mdr add goldsky-io/streamling/streamling-udf-plugin@sha256:d921dfb21b039d93The line at the top of this page pins the label git:20260625.ecf56ac, 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_gqrkrlhqctktppdz)
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Versions
The registry has recorded 1 version of this file, committed on Jun 25, 2026.
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 (12165 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
goldsky-io/streamling · 107 stars · license a license file GitHub does not identify · pushed 2026-11-06 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_gqrkrlhqctktppdz GET https://markdownregistry.com/api/v1/resolve?ref=goldsky-io/streamling/streamling-udf-plugin GET https://markdownregistry.com/api/v1/blob/d921dfb21b039d93549f987677bd2ae50b8a04f26d04dd49cc4b5c0e042c71c8
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.