[BUG] [v0.1.0] load_session_at_index() appends loaded messages to existing conversation instead of replacing them

[climax-dev-1]

Bug Description

load_session_at_index() in cortex-tui/src/runner/event_loop/mouse.rs loads a session from history but never clears the existing messages in app_state.messages before appending the loaded session's messages. This causes messages from the previous session to remain visible, with the newly loaded session's messages appended after them.

Location

src/cortex-tui/src/runner/event_loop/mouse.rs, lines 361–384

Root Cause

The function calls self.app_state.load_session(session_id) which only sets the session ID and switches to AppView::Session — it does not clear self.app_state.messages. Then the loop on line 368 calls self.app_state.add_message(message) for each message in the loaded session, appending them to whatever messages were already present.

fn load_session_at_index(&mut self, idx: usize) -> Result<()> {
    if let Some(session) = self.app_state.session_history.get(idx) {
        let session_id = session.id;
        self.app_state.load_session(session_id);  // does NOT clear messages

        let session_id_str = session_id.to_string();
        if let Ok(loaded_session) = CortexSession::load(&session_id_str) {
            for msg in loaded_session.messages() {
                // Appends on top of existing messages!
                self.app_state.add_message(message);
            }
            self.cortex_session = Some(loaded_session);
        }
    }
    Ok(())
}

Reproduction Steps

1. Start a conversation and exchange several messages with the AI
2. Click on a different session in the session history sidebar
3. Observe that the UI now shows the old conversation's messages followed by the loaded session's messages

Expected Behavior

When loading a session from history, the existing messages should be cleared first so only the loaded session's messages are displayed.

Fix

Add self.app_state.clear_messages() (or equivalent) before the message loading loop:

fn load_session_at_index(&mut self, idx: usize) -> Result<()> {
    if let Some(session) = self.app_state.session_history.get(idx) {
        let session_id = session.id;
        self.app_state.load_session(session_id);

        let session_id_str = session_id.to_string();
        if let Ok(loaded_session) = CortexSession::load(&session_id_str) {
            self.app_state.clear_messages();  // Clear before loading
            for msg in loaded_session.messages() {
                // ...
            }
        }
    }
    Ok(())
}

Impact

Users who click on sessions in the sidebar will see a corrupted conversation view with messages from multiple sessions mixed together. This makes session history navigation unreliable.

Version

v0.1.0