Linked built-in agents discard provider/model edits and return to “needs configuration”

[Audacity88]

Describe the bug

Provider and model selections made through Edit Agent are not persisted for linked built-in agents such as Honey and Bumble. After restarting Buzz, the agents return to “needs configuration” and ask for both fields again.

Steps to reproduce

1. Add or start a built-in agent such as Honey or Bumble using buzz-agent.
2. Open Edit Agent.
3. Select a provider and model.
4. Save the changes.
5. Restart Buzz or restart the agent.
6. Send the agent a message.

The agent reports that its provider and model are not configured.

Expected behavior

The provider and model selected in Edit Agent should remain effective after saving and restarting.

Version and platform

• Buzz version: 0.5.3
• OS: macOS 26.5.1

Logs / additional context

The linked agent instances resolve provider and model from their persona definitions, but the edit dialog omits both fields from its update whenever linkedPersona != null:

https://github.com/block/buzz/blob/desktop-v0.5.3/desktop/src/features/agents/ui/AgentInstanceEditDialog.tsx#L681-L710

Effective configuration then reads those fields from the linked definition:

https://github.com/block/buzz/blob/desktop-v0.5.3/desktop/src-tauri/src/managed_agents/effective_config/mod.rs#L74-L96

Because the built-in definitions have no provider or model defaults, the visible selections become a no-op. The dialog should either update the linked definition or direct the user to a definition-level configuration surface.

[iroiro147]

Fixed in PR #4268.

Root cause: For linked built-in personas, AgentInstanceEditDialog.handleSubmit sends provider: undefined and model: undefined, deferring to the persona definition. Built-in personas (Honey, Bumble) ship with both unset, so your edits were silently dropped and the agent fell back to global defaults — surfacing as "needs configuration" after restart.

Fix: When a linked persona's provider or model is edited in the dialog, the value is now propagated to the persona definition itself via updatePersona, so the configuration survives restart. Unlinked instances are unaffected.