---
# claudbg-nq36
title: 'TUI: app state model and screen enum'
status: completed
type: task
priority: normal
created_at: 2026-03-30T04:45:19Z
updated_at: 2026-03-30T16:40:31Z
parent: claudbg-i6l2
blocked_by:
    - claudbg-78xt
---

Define the central `AppState` struct and `Screen` enum that drive the entire TUI.

## Types to define (`src/tui/state.rs` or `src/commands/tui/state.rs`)

```rust
pub enum Screen {
    SessionList,
    Transcript { session_id: String },
    SubagentTranscript { parent_session_id: String, agent_id: String },
}

pub enum Focus {
    ChatLog,
    SubagentsPanel,
}

pub struct AppState {
    pub screen: Screen,
    // Session list
    pub sessions: Vec<SessionListItem>,   // loaded once
    pub list_selected: usize,
    // Transcript
    pub transcript_entries: Vec<RawEntry>,
    pub transcript_scroll: usize,         // vertical scroll offset
    pub transcript_h_scroll: usize,       // horizontal scroll offset
    pub subagents: Vec<AgentRef>,
    pub subagent_selected: usize,
    pub focus: Focus,
    // Modals
    pub show_quit_dialog: bool,
    pub show_help: bool,
}
```

## Notes

- `SessionListItem` is a lightweight struct with the display fields (short_id, date, project, model, msg_count, agent_count).
- State transitions: `AppState::enter_transcript(session_id)` loads entries + subagents. `AppState::go_back()` pops the screen stack (or just switches back to `SessionList`).
- Keep all data loading in state transitions so the render function is pure.

## Blocked by

- ratatui dependency task (claudbg-78xt)

## Summary of Changes\n\nCreated src/tui/mod.rs and src/tui/state.rs with Screen enum, Focus enum, AppState struct, SessionListItem, and AgentRef types. Added state transition methods: new(), enter_transcript(), enter_subagent_transcript(), go_back(). Reuses existing RawEntry and AgentRef types. 11 unit tests all pass. Wired into lib.rs via pub mod tui.