diff --git a/CLAUDE.md b/CLAUDE.md
index 39fc92d..c53c74a 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -4,8 +4,7 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 
 ## Project Overview
 
-This is a Rust terminal user interface (TUI) application built with Ratatui.
-It will evolve to become a tui mail client
+**Skim** is a TUI email client built with Rust and Ratatui. It connects to IMAP servers (including Gmail) and displays inbox messages with a split-pane interface: email list on top, message preview on the bottom.
 
 ## Build and Run Commands
 
@@ -44,27 +43,34 @@ docker exec -it mailserver setup email add test@example.com password123
 docker-compose down
 ```
 
-Connection details: localhost:143 (IMAP) or localhost:993 (IMAPS). See `MAIL_SERVER_SETUP.md` for detailed usage.
+Connection details: localhost:143 (IMAP) or localhost:993 (IMAPS). See `MAIL_SERVER_SETUP.md` for detailed usage including Gmail configuration.
 
 ## Architecture
 
-This is a single-file application (`src/main.rs`) following the standard terminal application lifecycle:
+- **`src/main.rs`** — Terminal setup/teardown, delegates to `lib::main`
+- **`src/lib.rs`** — Main event loop, UI rendering, worker thread coordination
+- **`src/inbox.rs`** — IMAP inbox operations (refresh, fetch older, fetch body)
+- **`src/connect.rs`** — IMAP connection handling (plain TCP and TLS)
+- **`src/config.rs`** — Configuration loading from `config.toml`
 
-1. **Terminal Setup**: Enable raw mode and enter alternate screen
-2. **Event Loop**:
-   - Render UI using Ratatui's declarative widget system
-   - Poll for keyboard events (200ms timeout)
-   - Exit on 'q' or Escape key
-3. **Cleanup**: Disable raw mode, leave alternate screen, restore cursor
+### Key patterns
+
+- IMAP operations run in a **background worker thread** communicating via `mpsc` channels, keeping the UI responsive
+- Emails are loaded in **batches of 50**, with lazy loading when scrolling past the end
+- **Tab** switches focus between inbox list and preview pane
+- Selection is **preserved across refreshes** by matching IMAP sequence numbers
 
 ## Key Dependencies
 
-- **ratatui (0.29)**: TUI framework providing widgets, layouts, and rendering
-- **crossterm (0.28)**: Cross-platform terminal manipulation (raw mode, events, alternate screen)
+- **ratatui (0.30)**: TUI framework providing widgets, layouts, and rendering
+- **crossterm (0.29)**: Cross-platform terminal manipulation (raw mode, events, alternate screen)
+- **imap (2.4)**: IMAP protocol client
+- **native-tls (0.2)**: TLS support for secure IMAP connections (Gmail)
+- **chrono (0.4)**: Date parsing and timezone conversion
 
 ## Development Notes
 
 - Uses Rust edition 2024
-- The application uses a constraint-based layout system to center content
 - Terminal is set to raw mode to capture individual key presses
 - The alternate screen prevents terminal history pollution
+- `config.toml` contains credentials and is gitignored — see `config.toml.example` for the format