Deprecate Classic Classes

text/1117-deprecate-classic-classes.md

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+---
+stage: accepted
+start-date: 2025-06-20T00:00:00.000Z
+release-date:
+release-versions:
+teams: # delete teams that aren't relevant
+  - cli
+  - data
+  - framework
+  - learning
+  - steering
+  - typescript
+prs:
+  accepted: https://github.com/emberjs/rfcs/pull/1117
+project-link:
+---
+
+# Deprecate Classic Classes
+
+## Summary
+
+Deprecate the Classic Class system.
+
+## Motivation
+
+For quite a while now, Ember has recommended the use of Native Classes over the Classic Class
+system. The one remaining sticking point has been Mixins. If we
+[Deprecate Mixins](https://github.com/emberjs/rfcs/pull/1116), then we can deprecate the Classic Class system.
+
+## Transition Path
+
+All uses of Classic Classes should be converted to Native Classes. Anything that cannot be converted will be deprecated first, such as [Mixins](https://github.com/emberjs/rfcs/pull/1116) and the [`observer` helper function](https://github.com/emberjs/rfcs/pull/1115).
+
+The `@classic` decorator (and any other APIs or patterns used to enable classic class interop) will also be deprecated as part of this transition. All code should migrate to native class syntax and patterns.
+
+## Exploration
+
+To validate this deprecation, I've tried removing all of the Classic Class system in this PR:
+https://github.com/emberjs/ember.js/pull/20923
+
+## How We Teach This
+
+We should remove all references from the guides.
+
+## Drawbacks
+
+Other than it being a lot of work, there are no drawbacks.
+
+## Alternatives
+
+None
+
+## Unresolved questions
+
+Should we keep `EmberObject` around as a home for some utility methods and sugar or remove it entirely?