# `MishkaCmsCore.Runtime.Resources.Validations.CodeChange`
[🔗](https://github.com/mishka-group/mishka_cms_core/blob/v0.0.1/lib/mishka_cms_core/runtime/resources/__validations/code_change.ex#L5)

Refuses code written by hand when this deployment has turned it off, and Elixir from a write that
names no actor.

Who may write a document, its code included, is the resource's policy: the document's own runtime
area or `admin:<surface>:code`. What this enforces at the action boundary is the deployment switch
of `MishkaCmsCore.Runtime.PageBuilder.CodeAccess` — `config :mishka_cms_core, :page_code, :off`
stops code the server runs for everybody, master included. A form, the admin JSON:API, a script
and the builder all pass through here.

## What counts as code

  * **Elixir** — `events`, `infos` and `helpers`, whichever the resource declares. Code has to
    APPEAR to count: a create sets these to `[]`, and removing code is always allowed.
  * **HEEx typed by hand** — `template`, `root_layout_template`, and each template of an error
    page's `error_pages` entries. A template that changed counts, except an empty document's
    starter markup (`MishkaCmsCore.Runtime.PageBuilder.PageStarter.blank/1`).

## Who is writing, read from the changeset context

  * `page_code: :package` — a package installing what it ships (a UI kit, starter content, an
    extension's sample pages, the dev generator). Nothing is checked.
  * `page_code: :publish` — a draft being published onto its live record. Nothing is checked: the
    draft was checked when it was written.
  * `page_code: :fork` — the builder writing a draft: its source's Elixir, copied unchanged, and
    the template the builder generated. Nothing is checked.
  * `page_code: :builder` — the builder writing the template it generated from its tree. The
    template is not typed; Elixir still counts.
  * `page_code: :copy` — a record copied whole. Its template is not typed; Elixir still counts.

A write with no actor is the system's own — a seed, a fixture, a background job. Its templates are
let through, and its Elixir is refused.

---

*Consult [api-reference.md](api-reference.md) for complete listing*