Fix model name display in TUI sidebar for all model types

[dgageot]

The sidebar flickered because AgentInfoEvent was emitted multiple times per LLM turn (before and after the call) and never showed the actual model for rule-based routing.

Three changes fix all issues:

1. sidebar.SetAgentInfo: early-return when agent name, model, and description are all unchanged. This is the single dedup point that prevents redundant re-renders from any emission source.

2. loop.go: move the per-iteration AgentInfo emission from stream start to right before the LLM call. Remove the post-call revert branch that caused the original flickering. Fallback models are handled via a dedicated post-call emission.

3. rulebased/client.go: wrap the stream returned by the selected sub-provider to override response.Model with the sub-provider's ID (the YAML-configured name). streaming.go emits AgentInfo as soon as the first chunk reveals a model different from the one already shown, so the sidebar updates immediately when a routed model starts responding.

Assisted-By: docker-agent

[docker-agent]

Review Summary

Assessment: 🟢 APPROVE

Summary

This PR successfully fixes the sidebar flickering issue through three well-coordinated changes:

1. Deduplication in sidebar.go: The SetAgentInfo method now properly checks all three fields (agent name, model ID, and description) before early-returning, preventing redundant re-renders.

2. Event timing in loop.go: Moving the AgentInfo emission to just before the LLM call (instead of at loop start) and removing the post-call revert logic eliminates the flickering caused by multiple emissions per turn.

3. Rule-based routing support: The rulebased.Client now tracks and exposes the selected sub-provider ID via LastSelectedModelID(), which is properly consumed in fallback.go to emit the correct model name for routed calls.

The changes are clean, well-commented, and include comprehensive test updates. The code correctly handles:

• Type assertions with ok checks (fallback.go:289)
• All three fields in the deduplication check (sidebar.go:274)
• Proper state tracking without race conditions

Findings

No issues found. The implementation is correct and addresses the stated problem effectively.