## I have read the
[CONTRIBUTING.md](https://github.com/supabase/supabase/blob/master/CONTRIBUTING.md)
file.
YES
## What kind of change does this PR introduce?
Feature / chore: hide assistant model selection in the UI and default
chats to GPT-5.6 Luna.
## What is the current behavior?
The assistant composer exposes a model picker. Paid orgs default to
`gpt-5.3-codex`; everyone else defaults to `gpt-5.4-nano`.
## What is the new behavior?
- The model picker is hidden in the assistant composer and Explorer
home.
- Chats default to `gpt-5.6-luna` with `reasoningEffort: medium`.
- Model selection plumbing is kept (registry, entitlements, `setModel`,
generate-v4 request body) so a requested model can still be honored when
provided.
- Other completion endpoints still use `gpt-5.4-nano`.
## Additional context
Model selector UI can be re-enabled by passing `selectedModel` /
`onSelectModel` to `AssistantChatForm`.
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **New Features**
* Added support for the GPT-5.6 Luna model with medium reasoning
capability.
* Made GPT-5.6 Luna the default assistant model.
* **Improvements**
* Simplified assistant chat by removing model selection from the primary
chat experience.
* Updated model fallback behavior to use the standard assistant model.
* Chat forms can now optionally display model selection when configured.
* **Tests**
* Updated model coverage and assistant chat tests for the new defaults
and behavior.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
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Co-authored-by: Cursor <cursoragent@cursor.com>
