cratis-chronicle-reducer SKILL.md skillA
cratis-chronicle-reducer 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-chronicle-reducer@git:20261016.b081bc9Pins git:20261016.b081bc9 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-chronicle-reducer/SKILL.md- Versions recorded
- 5
- Latest version
- git:20261016.b081bc9, committed Oct 16, 2026
- First version recorded
- Oct 14, 2026
- Size
- 15,950 bytes
- Repository stars
- 4
- License
- MIT
Write a Chronicle IReducerFor reducer when model-bound projection attributes and the fluent IProjectionFor builder cannot express a read-model state transition. Covers the admission test, the exact accepted method signatures, the nullable-current requirement, deletion, passivity and event filtering. Use only after the projection options are genuinely exhausted; do not use for ordinary event-to-property mapping.
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
# Chronicle reducers A reducer builds a read model as "current state plus event produces next state", with real C# control flow. Start with model-bound attributes, use fluent `IProjectionFor<T>` when mappings need structure, and choose a reducer when branching on prior state, calculations or guards read better as code. A reducer is a normal choice, not a last resort. For the application-code ladder and PDL's outside-code role, read [choosing a style](../cratis-chronicle-read-model/SKILL.md#step-3--choose-a-projection-or-a-reducer). Requires Chronicle 19.58.0 for self-reducing read models. For new .NET reducers, default to **self-reducing read models**: public static `Reduce` methods beside the state, discovered by shape without a marker. Use a separate `IReducerFor<T>` for fold-time DI, replay-time instance state or useful separation; nominate a plain class only when its assembly cannot reference Chronicle. Self reduction is .NET-only; other SDKs retain their own contracts. This guidance does not claim Stage renders the self form. ## Verified product sources Sources: …
Read the whole file at its exact version.
How to install
mdr add cratis/ai/cratis-chronicle-reducer@sha256:95108af46cf77587The line at the top of this page pins the label git:20261016.b081bc9, 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_japc7zowcamkzmrp)
2 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 5 versions of this file, between Oct 14, 2026 and Oct 16, 2026, more than one a day.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20261016.b081bc9 latest | 2026-10-16 | b081bc9 | 15,950 B | A | view · diff |
| git:20261014.8b817dc | 2026-10-14 | 8b817dc | 15,679 B | A | view · diff |
| git:20261014.97fa750 | 2026-10-14 | 97fa750 | 15,625 B | A | view · diff |
| git:20261014.c40f070 | 2026-10-14 | c40f070 | 15,952 B | A | view · diff |
| git:20261014.e378299 | 2026-10-14 | e378299 | 19,461 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 (15950 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_japc7zowcamkzmrp GET https://markdownregistry.com/api/v1/resolve?ref=cratis/ai/cratis-chronicle-reducer GET https://markdownregistry.com/api/v1/blob/95108af46cf77587f3311690b460df510a8034a8ed7ac3c9ceca5f7498d1979e
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.