cratis-arc-query-kotlin SKILL.md skillA
cratis-arc-query-kotlin from cratis/ai is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add cratis/ai/cratis-arc-query-kotlin@git:20261012.0af903aPins git:20261012.0af903a in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- cratis/ai
- Path
.cratis/ai/skills/cratis-arc-query-kotlin/SKILL.md- Versions recorded
- 2
- Latest version
- git:20261012.0af903a, committed Oct 12, 2026
- First version recorded
- Sep 17, 2026
- Size
- 11,418 bytes
- Repository stars
- 4
- License
- MIT
Add a query to a Cratis Arc @ReadModel in Kotlin or Java — companion-object or static query methods, GET vs RFC QUERY, and observable queries returning Kotlin Flow, JDK Flow.Publisher, or RxJava 3 Observable over SSE and WebSocket. Use when exposing read-model data from a Kotlin or Java Arc application. Do not use for the .NET Arc query shape, for command definition, or for how events populate the read model (Chronicle projections/reducers).
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
# Add a query to an Arc read model in Kotlin or Java
A `@ReadModel` is a plain Kotlin or Java type whose companion-object (Kotlin) or
static (Java) methods are queries. KSP generates a reflection-free
`QueryPerformer` per method; there is no controller to write.
## Verified product sources
Verified against `Arc.Kotlin` at tag **`v7.7.0`**: JDK 17, Gradle 8.14.4,
Kotlin 2.4.20, KSP 2.3.12, Spring Boot 4.1.1, JUnit Jupiter 6.1.3. `io.cratis:arc` supplies
`io.cratis.arc.artifacts.ReadModel`, `io.cratis.arc.queries.Path`,
`@QueryHttpMethod`, `@QueryTransport`, `ObservableState<T>`. The optional
`arc-rxjava3` artifact adds RxJava 3 `Observable` support at runtime. The
`queries/QueryPage.kt`, `QueryRendererFor.kt` and the observable pipeline
verify the paging and transport contracts below.
## Declare a one-shot query
```kotlin
@ReadModel
@AllowAnonymous
data class TaskView(val id: String, val title: String) {
companion object {
@JvmStatic
@Path("/api/tasks/by-id")
suspend fun byId(id: String, @FromServices repository: TaskRepository): TaskView? =
repository.byId(id)
@JvmStatic
@Path("/api/tasks")
…Read the whole file at its exact version.
How to install
mdr add cratis/ai/cratis-arc-query-kotlin@sha256:b59f61e8c0bdbc2fThe line at the top of this page pins the label git:20261012.0af903a, 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_c4mqjkrlxo4evhsg)
2 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 2 versions of this file, between Sep 17, 2026 and Oct 12, 2026, about one every 25 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20261012.0af903a latest | 2026-10-12 | 0af903a | 11,418 B | A | view · diff |
| git:20260917.fb593b8 | 2026-09-17 | fb593b8 | 10,179 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 (11418 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
cratis/ai · 4 stars · license MIT · pushed 2026-11-04 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_c4mqjkrlxo4evhsg GET https://markdownregistry.com/api/v1/resolve?ref=cratis/ai/cratis-arc-query-kotlin GET https://markdownregistry.com/api/v1/blob/b59f61e8c0bdbc2f9de248ec837256476666ddcb34c02f935e198d901969c0e7
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.