Initial commit

.gitignore

@@ -0,0 +1,31 @@
+# Rust build artifacts
+target/
+
+# Editor and IDE files
+.vscode/
+.idea/
+*.swp
+*.swo
+*~
+
+# OS artifacts
+.DS_Store
+Thumbs.db
+desktop.ini
+
+# Environment and secrets
+.env
+.env.*
+*.env
+*.pem
+*.key
+*.p12
+secrets/
+
+# Log files
+*.log
+logs/
+
+# Runtime files
+*.sock
+*.pid

Cargo.toml

@@ -0,0 +1,26 @@
+[package]
+name = "breadmon"
+version = "0.1.0"
+edition = "2021"
+description = "TUI monitor manager for Hyprland"
+license = "MIT"
+
+[[bin]]
+name = "breadmon"
+path = "src/main.rs"
+
+[dependencies]
+ratatui    = "0.29"
+crossterm  = { version = "0.28", features = ["event-stream"] }
+tokio      = { version = "1", features = ["rt-multi-thread", "macros", "process", "signal", "sync", "time", "net", "io-util"] }
+serde      = { version = "1", features = ["derive"] }
+serde_json = "1"
+toml       = "0.8"
+anyhow     = "1"
+dirs       = "5"
+futures    = "0.3"
+
+[profile.release]
+lto = "thin"
+codegen-units = 1
+strip = "symbols"

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 Breadway
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# breadmon
+
+A terminal UI monitor manager for Hyprland. Lets you position, configure, and mirror displays interactively, then apply changes live via `hyprctl`.
+
+## Requirements
+
+- Hyprland compositor (the `hyprctl` binary must be on `PATH`)
+- Rust toolchain (to build from source)
+
+## Build
+
+```
+cargo build --release
+```
+
+The binary is written to `target/release/breadmon`.
+
+If you use the bread ecosystem, `bakery` can install it instead:
+
+```
+bread modules install /path/to/breadmon
+```
+
+## Usage
+
+```
+breadmon
+```
+
+The TUI opens with four tabs, switchable by number key or mouse click:
+
+| Key | Tab |
+|-----|-----|
+| `1` / F1 | Layout |
+| `2` / F2 | Config |
+| `3` / F3 | Mirror |
+| `4` / F4 | Profiles |
+
+### Layout
+
+A scaled canvas showing all connected monitors. The selected monitor is highlighted.
+
+| Key | Action |
+|-----|--------|
+| `hjkl` / arrow keys | Move selected monitor 1 px |
+| `Shift+hjkl` | Move selected monitor 10 px |
+| `Tab` / `n` | Cycle to next monitor |
+| `Shift+Tab` / `p` | Cycle to previous monitor |
+| `0` | Auto-arrange monitors left-to-right with no gaps |
+| `[` / `]` | Zoom canvas out / in |
+| Mouse drag | Drag monitor to reposition |
+
+Monitors snap to each other's edges when dragged or nudged within 10 px.
+
+### Config
+
+Per-monitor settings for the currently selected display.
+
+| Key | Action |
+|-----|--------|
+| `jk` / `Tab` | Move between fields |
+| `hl` / scroll | Cycle field value |
+| `,` / `.` | Scale −0.1 / +0.1 |
+| `[` / `]` | Switch to previous / next monitor |
+| `Enter` | Commit scale edit and apply |
+| `Esc` | Discard pending edits |
+
+Fields: Resolution, Refresh rate, Scale, Transform (rotation/flip), VRR, DPMS, Mirror of.
+
+The header shows the monitor's PPI and a suggested fractional scale when physical dimensions are available.
+
+### Mirror
+
+Finds the best common mode between two monitors and sets one to mirror the other. Use `Tab` to move focus between source and target, `hl` to cycle the selection, `Enter` to confirm.
+
+### Profiles
+
+Named snapshots of the current monitor configuration, stored as TOML files.
+
+| Key | Action |
+|-----|--------|
+| `jk` | Navigate profile list |
+| `Enter` | Load selected profile |
+| `d d` | Delete selected profile (double-press within 3 s) |
+| `Tab` | Move focus to name input / save button |
+
+Profiles are saved to `~/.config/breadmon/profiles/`.
+
+### Global keys
+
+| Key | Action |
+|-----|--------|
+| `a` | Apply current configuration via `hyprctl` |
+| `s` | Save current configuration as a profile |
+| `r` | Refresh monitor list from Hyprland |
+| `Ctrl+Z` | Undo last change (up to 20 steps) |
+| `q` / `Ctrl+C` | Quit (prompts once if there are unsaved changes) |
+
+breadmon also listens on Hyprland's event socket and reloads the monitor list automatically when a display is connected or disconnected.
+
+## Config
+
+Profiles are plain TOML files under `~/.config/breadmon/profiles/`. Each file records the monitor name, mode, position, scale, transform, VRR, DPMS, and mirror source. They are created and managed through the Profiles tab; there is no hand-written config file.

bakery.toml

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+name = "breadmon"
+description = "TUI monitor manager for Hyprland"
+binaries = ["breadmon"]
+system_deps = []
+optional_system_deps = ["hyprland"]
+bread_deps = []
+
+[config]
+dir = "~/.config/breadmon"
+
+[install]
+post_install = []

src/layout.rs

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+use crate::monitor::Monitor;
+
+#[derive(Debug, Clone)]
+pub struct LayoutState {
+    pub selected: usize,
+    pub snap_threshold: i32,
+    pub zoom: f32,
+}
+
+impl Default for LayoutState {
+    fn default() -> Self {
+        Self {
+            selected: 0,
+            snap_threshold: 10,
+            zoom: 1.0,
+        }
+    }
+}
+
+impl LayoutState {
+    pub fn clamp_selected(&mut self, count: usize) {
+        if count == 0 {
+            self.selected = 0;
+        } else if self.selected >= count {
+            self.selected = count - 1;
+        }
+    }
+
+    pub fn next(&mut self, count: usize) {
+        if count > 0 {
+            self.selected = (self.selected + 1) % count;
+        }
+    }
+
+    pub fn prev(&mut self, count: usize) {
+        if count > 0 {
+            self.selected = self.selected.checked_sub(1).unwrap_or(count - 1);
+        }
+    }
+}
+
+/// Snap a monitor being moved to the edges of its neighbours.
+/// Returns the adjusted (x, y) after snapping.
+pub fn snap_position(
+    moving_idx: usize,
+    new_x: i32,
+    new_y: i32,
+    monitors: &[Monitor],
+    threshold: i32,
+) -> (i32, i32) {
+    let mw = monitors[moving_idx].world_width() as i32;
+    let mh = monitors[moving_idx].world_height() as i32;
+
+    // Candidate snaps: (snapped_x, snapped_y, priority)
+    // We collect the closest snap in each axis independently
+    let mut best_x_dist = threshold + 1;
+    let mut best_y_dist = threshold + 1;
+    let mut snap_x = new_x;
+    let mut snap_y = new_y;
+
+    for (i, other) in monitors.iter().enumerate() {
+        if i == moving_idx {
+            continue;
+        }
+        let ox = other.x;
+        let oy = other.y;
+        let ow = other.world_width() as i32;
+        let oh = other.world_height() as i32;
+
+        // X-axis edge pairs:
+        // moving left vs other left
+        let pairs_x = [
+            (new_x, ox),           // left aligned
+            (new_x, ox + ow),      // moving left snaps to other right
+            (new_x + mw, ox),      // moving right snaps to other left
+            (new_x + mw, ox + ow), // right aligned
+        ];
+        for (ma, oa) in pairs_x {
+            let dist = (ma - oa).abs();
+            if dist < best_x_dist {
+                best_x_dist = dist;
+                snap_x = new_x + (oa - ma);
+            }
+        }
+
+        // Y-axis edge pairs
+        let pairs_y = [
+            (new_y, oy),
+            (new_y, oy + oh),
+            (new_y + mh, oy),
+            (new_y + mh, oy + oh),
+        ];
+        for (ma, oa) in pairs_y {
+            let dist = (ma - oa).abs();
+            if dist < best_y_dist {
+                best_y_dist = dist;
+                snap_y = new_y + (oa - ma);
+            }
+        }
+    }
+
+    (snap_x, snap_y)
+}
+
+/// Move the selected monitor by (dx, dy) pixels, then snap.
+pub fn move_selected(state: &LayoutState, monitors: &mut Vec<Monitor>, dx: i32, dy: i32) {
+    let idx = state.selected;
+    if idx >= monitors.len() {
+        return;
+    }
+    let new_x = monitors[idx].x + dx;
+    let new_y = monitors[idx].y + dy;
+    let (sx, sy) = snap_position(idx, new_x, new_y, monitors, state.snap_threshold);
+    monitors[idx].x = sx;
+    monitors[idx].y = sy;
+}
+
+/// Place monitors in a left-to-right row with no gaps.
+pub fn auto_arrange(monitors: &mut Vec<Monitor>) {
+    let mut cursor = 0i32;
+    for m in monitors.iter_mut() {
+        m.x = cursor;
+        m.y = 0;
+        cursor += m.world_width() as i32;
+    }
+}
+
+/// Compute canvas scale: returns pixels-per-cell such that all monitors fit in (area_w, area_h) cells.
+/// The 0.5 factor corrects for terminal cells being ~2:1 tall.
+pub fn canvas_scale(monitors: &[Monitor], area_w: u16, area_h: u16, zoom: f32) -> f32 {
+    if monitors.is_empty() || area_w == 0 || area_h == 0 {
+        return 1.0;
+    }
+    let (min_x, min_y, max_x, max_y) = bounding_box(monitors);
+    let total_w = (max_x - min_x).max(1) as f32;
+    let total_h = (max_y - min_y).max(1) as f32;
+
+    let sx = area_w as f32 / total_w;
+    let sy = area_h as f32 / total_h * 0.5; // cell-aspect correction
+    sx.min(sy) * zoom
+}
+
+/// (min_x, min_y, max_x, max_y) in world coordinates
+pub fn bounding_box(monitors: &[Monitor]) -> (i32, i32, i32, i32) {
+    let min_x = monitors.iter().map(|m| m.x).min().unwrap_or(0);
+    let min_y = monitors.iter().map(|m| m.y).min().unwrap_or(0);
+    let max_x = monitors.iter().map(|m| m.right_edge()).max().unwrap_or(1);
+    let max_y = monitors.iter().map(|m| m.bottom_edge()).max().unwrap_or(1);
+    (min_x, min_y, max_x, max_y)
+}
+
+/// Map a canvas cell position back to world coordinates (inverse of world_to_canvas)
+pub fn canvas_to_world(
+    col: u16,
+    row: u16,
+    scale: f32,
+    origin_x: i32,
+    origin_y: i32,
+    pad_x: u16,
+    pad_y: u16,
+) -> (i32, i32) {
+    let wx = if col >= pad_x {
+        ((col - pad_x) as f32 / scale) as i32 + origin_x
+    } else {
+        origin_x - (((pad_x - col) as f32 / scale) as i32)
+    };
+    let wy = if row >= pad_y {
+        ((row - pad_y) as f32 / (scale * 0.5)) as i32 + origin_y
+    } else {
+        origin_y - (((pad_y - row) as f32 / (scale * 0.5)) as i32)
+    };
+    (wx, wy)
+}
+
+/// Map a world coordinate to a canvas cell position
+pub fn world_to_canvas(
+    wx: i32,
+    wy: i32,
+    scale: f32,
+    origin_x: i32,
+    origin_y: i32,
+    pad_x: u16,
+    pad_y: u16,
+) -> (u16, u16) {
+    let cx = ((wx - origin_x) as f32 * scale) as u16 + pad_x;
+    let cy = ((wy - origin_y) as f32 * scale * 0.5) as u16 + pad_y;
+    (cx, cy)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::monitor::{Mode, Transform};
+
+    fn mon(name: &str, w: u32, h: u32, x: i32, y: i32) -> Monitor {
+        Monitor {
+            name: name.into(),
+            description: String::new(),
+            active_mode: Mode { width: w, height: h, refresh: 60.0 },
+            x,
+            y,
+            scale: 1.0,
+            transform: Transform::Normal,
+            vrr: false,
+            dpms: true,
+            disabled: false,
+            mirror_of: None,
+            available_modes: vec![],
+            physical_width_mm: 0,
+            physical_height_mm: 0,
+        }
+    }
+
+    #[test]
+    fn snap_to_adjacent_right_edge() {
+        let monitors = vec![
+            mon("A", 1920, 1200, 0, 0),
+            mon("B", 1920, 1080, 1915, 0), // almost touching, 5px gap
+        ];
+        // Moving B (index 1) at x=1915, A's right edge is 1920
+        // snap should pull B to x=1920
+        let (sx, _sy) = snap_position(1, 1915, 0, &monitors, 10);
+        assert_eq!(sx, 1920);
+    }
+
+    #[test]
+    fn no_snap_beyond_threshold() {
+        let monitors = vec![
+            mon("A", 1920, 1200, 0, 0),
+            mon("B", 1920, 1080, 1950, 0), // 30px gap, beyond threshold
+        ];
+        let (sx, _sy) = snap_position(1, 1950, 0, &monitors, 10);
+        assert_eq!(sx, 1950);
+    }
+
+    #[test]
+    fn auto_arrange_no_gaps() {
+        let mut monitors = vec![
+            mon("A", 1920, 1200, 100, 50),
+            mon("B", 1280, 1024, 200, 100),
+        ];
+        auto_arrange(&mut monitors);
+        assert_eq!(monitors[0].x, 0);
+        assert_eq!(monitors[0].y, 0);
+        assert_eq!(monitors[1].x, 1920);
+        assert_eq!(monitors[1].y, 0);
+    }
+}

src/main.rs

@@ -0,0 +1,208 @@
+mod layout;
+mod mirror;
+mod monitor;
+mod profile;
+mod ui;
+
+use std::io;
+
+use anyhow::Result;
+use crossterm::{
+    event::{
+        DisableMouseCapture, EnableMouseCapture, Event, EventStream, KeyEventKind,
+        MouseEventKind,
+    },
+    execute,
+    terminal::{disable_raw_mode, enable_raw_mode, EnterAlternateScreen, LeaveAlternateScreen},
+};
+use futures::StreamExt;
+use ratatui::{backend::CrosstermBackend, Terminal};
+use tokio::{
+    sync::mpsc,
+    time::{interval, Duration},
+};
+
+use ui::{AppState, StatusLevel};
+
+fn hyprland_socket2_path() -> Option<String> {
+    let instance = std::env::var("HYPRLAND_INSTANCE_SIGNATURE").ok()?;
+    let runtime = std::env::var("XDG_RUNTIME_DIR").unwrap_or_else(|_| "/run/user/1000".into());
+    Some(format!("{}/hypr/{}/.socket2.sock", runtime, instance))
+}
+
+#[derive(Debug)]
+enum AppEvent {
+    Key(crossterm::event::KeyEvent),
+    Mouse(crossterm::event::MouseEvent),
+    Resize(u16, u16),
+    Tick,
+    MonitorChange,
+}
+
+#[tokio::main]
+async fn main() -> Result<()> {
+    let monitors = monitor::load_monitors().await.unwrap_or_else(|e| {
+        eprintln!("Warning: could not load monitors: {}", e);
+        vec![]
+    });
+
+    // Terminal setup
+    enable_raw_mode()?;
+    let mut stdout = io::stdout();
+    execute!(stdout, EnterAlternateScreen, EnableMouseCapture)?;
+    let backend = CrosstermBackend::new(stdout);
+    let mut terminal = Terminal::new(backend)?;
+
+    let result = run(&mut terminal, monitors).await;
+
+    // Restore terminal
+    disable_raw_mode()?;
+    execute!(terminal.backend_mut(), LeaveAlternateScreen, DisableMouseCapture)?;
+    terminal.show_cursor()?;
+
+    result
+}
+
+async fn run(
+    terminal: &mut Terminal<CrosstermBackend<io::Stdout>>,
+    monitors: Vec<monitor::Monitor>,
+) -> Result<()> {
+    let size = terminal.size()?;
+    let mut state = AppState::new(monitors, (size.width, size.height));
+
+    let (tx, mut rx) = mpsc::unbounded_channel::<AppEvent>();
+
+    // Event reader task
+    let tx_events = tx.clone();
+    tokio::spawn(async move {
+        let mut stream = EventStream::new();
+        let mut tick = interval(Duration::from_secs(5));
+        loop {
+            tokio::select! {
+                _ = tick.tick() => {
+                    let _ = tx_events.send(AppEvent::Tick);
+                }
+                maybe_event = stream.next() => {
+                    match maybe_event {
+                        Some(Ok(Event::Key(key))) => {
+                            let _ = tx_events.send(AppEvent::Key(key));
+                        }
+                        Some(Ok(Event::Mouse(mouse))) => {
+                            let _ = tx_events.send(AppEvent::Mouse(mouse));
+                        }
+                        Some(Ok(Event::Resize(w, h))) => {
+                            let _ = tx_events.send(AppEvent::Resize(w, h));
+                        }
+                        None => break,
+                        _ => {}
+                    }
+                }
+            }
+        }
+    });
+
+    // Hyprland socket hotplug listener
+    let tx_hotplug = tx.clone();
+    tokio::spawn(async move {
+        if let Some(sig) = hyprland_socket2_path() {
+            if let Ok(mut stream) = tokio::net::UnixStream::connect(&sig).await {
+                use tokio::io::AsyncBufReadExt;
+                let reader = tokio::io::BufReader::new(&mut stream);
+                let mut lines = reader.lines();
+                while let Ok(Some(line)) = lines.next_line().await {
+                    if line.starts_with("monitoradded")
+                        || line.starts_with("monitorremoved")
+                        || line.starts_with("monitorscale")
+                    {
+                        let _ = tx_hotplug.send(AppEvent::MonitorChange);
+                    }
+                }
+            }
+        }
+    });
+
+    loop {
+        state.tick_status();
+        terminal.draw(|f| ui::render(f, &state))?;
+
+        let event = rx.recv().await;
+
+        match event {
+            None => break,
+            Some(AppEvent::Tick) => {
+                if let Ok(monitors) = monitor::load_monitors().await {
+                    if !state.dirty {
+                        state.monitors = monitors;
+                        state.layout.clamp_selected(state.monitors.len());
+                    }
+                }
+            }
+            Some(AppEvent::MonitorChange) => {
+                if let Ok(monitors) = monitor::load_monitors().await {
+                    state.monitors = monitors;
+                    state.layout.clamp_selected(state.monitors.len());
+                    state.set_status("Monitor configuration changed.", StatusLevel::Info);
+                }
+            }
+            Some(AppEvent::Resize(w, h)) => {
+                state.terminal_size = (w, h);
+            }
+            Some(AppEvent::Mouse(mouse)) => {
+                if mouse.kind == MouseEventKind::Moved {
+                    continue;
+                }
+                ui::handle_mouse(mouse, &mut state);
+            }
+            Some(AppEvent::Key(key)) => {
+                if key.kind != KeyEventKind::Press {
+                    continue;
+                }
+
+                match key.code {
+                    crossterm::event::KeyCode::Char('a') => {
+                        state.pending_apply = true;
+                        state.set_status("Applying...", StatusLevel::Info);
+                    }
+                    crossterm::event::KeyCode::Char('s') => {
+                        ui::layout_view::trigger_save(&mut state);
+                    }
+                    crossterm::event::KeyCode::Char('r') => {
+                        match monitor::load_monitors().await {
+                            Ok(monitors) => {
+                                state.monitors = monitors;
+                                state.layout.clamp_selected(state.monitors.len());
+                                state.dirty = false;
+                                state.set_status("Monitors refreshed.", StatusLevel::Success);
+                            }
+                            Err(e) => {
+                                state.set_status(
+                                    format!("Refresh failed: {}", e),
+                                    StatusLevel::Error,
+                                );
+                            }
+                        }
+                    }
+                    _ => {
+                        if !ui::handle_key(key, &mut state) {
+                            break;
+                        }
+                    }
+                }
+            }
+        }
+
+        if state.pending_apply {
+            state.pending_apply = false;
+            match monitor::apply_monitors(&state.monitors).await {
+                Ok(()) => {
+                    state.set_status("Applied.", StatusLevel::Success);
+                }
+                Err(e) => {
+                    state.set_status(format!("Apply failed: {}", e), StatusLevel::Error);
+                }
+            }
+        }
+    }
+
+    Ok(())
+}

src/mirror.rs

@@ -0,0 +1,299 @@
+use std::collections::HashMap;
+
+use crate::monitor::{Mode, Monitor};
+
+#[derive(Debug, Clone)]
+pub struct MirrorResult {
+    pub source_mode: Mode,
+    pub mirror_mode: Mode,
+    pub refresh: f64,
+    pub ar_exact: bool,
+    pub ar_ratio: (u32, u32),
+}
+
+fn gcd(a: u32, b: u32) -> u32 {
+    if b == 0 { a } else { gcd(b, a % b) }
+}
+
+fn reduced_ar(w: u32, h: u32) -> (u32, u32) {
+    let g = gcd(w, h);
+    (w / g, h / g)
+}
+
+fn ratio_f64(ar: (u32, u32)) -> f64 {
+    ar.0 as f64 / ar.1 as f64
+}
+
+pub fn find_mirror_modes(source: &Monitor, target: &Monitor) -> Option<MirrorResult> {
+    let src_modes = &source.available_modes;
+    let tgt_modes = &target.available_modes;
+
+    if src_modes.is_empty() || tgt_modes.is_empty() {
+        return None;
+    }
+
+    // Group source modes by reduced AR
+    let mut src_by_ar: HashMap<(u32, u32), Vec<&Mode>> = HashMap::new();
+    for m in src_modes {
+        src_by_ar.entry(reduced_ar(m.width, m.height)).or_default().push(m);
+    }
+
+    #[derive(Debug)]
+    struct Candidate {
+        src_ar: (u32, u32),
+        tgt_ar: (u32, u32),
+        is_exact: bool,
+    }
+
+    let mut candidates: Vec<Candidate> = Vec::new();
+
+    for t in tgt_modes {
+        let tgt_ar = reduced_ar(t.width, t.height);
+        let tgt_ratio = ratio_f64(tgt_ar);
+
+        if src_by_ar.contains_key(&tgt_ar) {
+            // Check if we already have this exact pair
+            if !candidates.iter().any(|c| c.src_ar == tgt_ar && c.tgt_ar == tgt_ar && c.is_exact) {
+                candidates.push(Candidate { src_ar: tgt_ar, tgt_ar, is_exact: true });
+            }
+            continue;
+        }
+
+        // Approximate: check all source ARs within 5%
+        for &s_ar in src_by_ar.keys() {
+            let s_ratio = ratio_f64(s_ar);
+            if (s_ratio - tgt_ratio).abs() / s_ratio < 0.05 {
+                if !candidates.iter().any(|c| c.src_ar == s_ar && c.tgt_ar == tgt_ar) {
+                    candidates.push(Candidate { src_ar: s_ar, tgt_ar, is_exact: false });
+                }
+            }
+        }
+    }
+
+    if candidates.is_empty() {
+        return None;
+    }
+
+    // Score each candidate: sum of best pixel counts on each side
+    // Exact beats approximate regardless of score
+    let mut best_score: u64 = 0;
+    let mut best_exact = false;
+    let mut best_src_ar = (0u32, 0u32);
+    let mut best_tgt_ar = (0u32, 0u32);
+
+    for c in &candidates {
+        let src_max_px = src_by_ar[&c.src_ar]
+            .iter()
+            .map(|m| m.pixels())
+            .max()
+            .unwrap_or(0);
+        let tgt_max_px = tgt_modes
+            .iter()
+            .filter(|m| reduced_ar(m.width, m.height) == c.tgt_ar)
+            .map(|m| m.pixels())
+            .max()
+            .unwrap_or(0);
+        let score = src_max_px + tgt_max_px;
+
+        let better = if c.is_exact && !best_exact {
+            true
+        } else if !c.is_exact && best_exact {
+            false
+        } else {
+            score > best_score
+        };
+
+        if better {
+            best_score = score;
+            best_exact = c.is_exact;
+            best_src_ar = c.src_ar;
+            best_tgt_ar = c.tgt_ar;
+        }
+    }
+
+    if best_src_ar == (0, 0) {
+        return None;
+    }
+
+    // Best source mode (highest pixels at winning AR)
+    let best_src_mode = src_by_ar[&best_src_ar]
+        .iter()
+        .max_by_key(|m| m.pixels())
+        .copied()?;
+
+    // Best target mode
+    let best_tgt_mode = tgt_modes
+        .iter()
+        .filter(|m| reduced_ar(m.width, m.height) == best_tgt_ar)
+        .max_by_key(|m| m.pixels())?;
+
+    // Refresh matching
+    let src_refreshes: Vec<f64> = src_by_ar[&best_src_ar]
+        .iter()
+        .filter(|m| m.width == best_src_mode.width && m.height == best_src_mode.height)
+        .map(|m| m.refresh)
+        .collect();
+
+    let tgt_refreshes: Vec<f64> = tgt_modes
+        .iter()
+        .filter(|m| m.width == best_tgt_mode.width && m.height == best_tgt_mode.height)
+        .map(|m| m.refresh)
+        .collect();
+
+    // Exact common (within 0.01 Hz)
+    let exact_common: Vec<f64> = src_refreshes
+        .iter()
+        .filter(|&&sr| tgt_refreshes.iter().any(|&tr| (sr - tr).abs() < 0.01))
+        .copied()
+        .collect();
+
+    let chosen_refresh = if !exact_common.is_empty() {
+        exact_common.iter().copied().fold(f64::NEG_INFINITY, f64::max)
+    } else {
+        // Near-match within 1 Hz
+        let near: Vec<f64> = src_refreshes
+            .iter()
+            .flat_map(|&sr| {
+                tgt_refreshes
+                    .iter()
+                    .filter(move |&&tr| (sr - tr).abs() <= 1.0)
+                    .map(move |&tr| sr.min(tr))
+            })
+            .collect();
+
+        if !near.is_empty() {
+            near.iter().copied().fold(f64::NEG_INFINITY, f64::max)
+        } else {
+            // Fallback: max source refresh
+            src_refreshes.iter().copied().fold(f64::NEG_INFINITY, f64::max)
+        }
+    };
+
+    // Find actual mode structs within 0.1 Hz of chosen_refresh
+    let final_src = src_by_ar[&best_src_ar]
+        .iter()
+        .filter(|m| m.width == best_src_mode.width && m.height == best_src_mode.height)
+        .filter(|m| (m.refresh - chosen_refresh).abs() < 0.1)
+        .max_by_key(|m| m.pixels())
+        .copied()
+        .or(Some(best_src_mode))?;
+
+    let final_tgt = tgt_modes
+        .iter()
+        .filter(|m| m.width == best_tgt_mode.width && m.height == best_tgt_mode.height)
+        .filter(|m| (m.refresh - chosen_refresh).abs() < 0.1)
+        .max_by_key(|m| m.pixels())
+        .or_else(|| {
+            // fallback: nearest refresh on target
+            tgt_modes
+                .iter()
+                .filter(|m| m.width == best_tgt_mode.width && m.height == best_tgt_mode.height)
+                .min_by(|a, b| {
+                    let da = (a.refresh - chosen_refresh).abs();
+                    let db = (b.refresh - chosen_refresh).abs();
+                    da.partial_cmp(&db).unwrap_or(std::cmp::Ordering::Equal)
+                })
+        })?;
+
+    Some(MirrorResult {
+        source_mode: final_src.clone(),
+        mirror_mode: final_tgt.clone(),
+        refresh: chosen_refresh,
+        ar_exact: best_exact,
+        ar_ratio: best_src_ar,
+    })
+}
+
+pub fn refresh_match_label(result: &MirrorResult) -> &'static str {
+    let diff = (result.source_mode.refresh - result.mirror_mode.refresh).abs();
+    if diff < 0.01 {
+        "exact match"
+    } else if diff <= 1.0 {
+        "near match (≤1 Hz)"
+    } else {
+        "mismatch"
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::monitor::{Transform};
+
+    fn make_monitor_with_modes(name: &str, modes: Vec<Mode>) -> Monitor {
+        let active = modes[0].clone();
+        Monitor {
+            name: name.into(),
+            description: String::new(),
+            active_mode: active,
+            x: 0,
+            y: 0,
+            scale: 1.0,
+            transform: Transform::Normal,
+            vrr: false,
+            dpms: true,
+            disabled: false,
+            mirror_of: None,
+            available_modes: modes,
+            physical_width_mm: 0,
+            physical_height_mm: 0,
+        }
+    }
+
+    fn m(w: u32, h: u32, r: f64) -> Mode {
+        Mode { width: w, height: h, refresh: r }
+    }
+
+    #[test]
+    fn identical_mode_lists_exact_match() {
+        let modes = vec![m(1920, 1200, 60.0), m(1280, 800, 60.0)];
+        let src = make_monitor_with_modes("eDP-1", modes.clone());
+        let tgt = make_monitor_with_modes("HDMI-A-1", modes);
+        let result = find_mirror_modes(&src, &tgt).unwrap();
+        assert!(result.ar_exact);
+        assert_eq!(result.source_mode.width, 1920);
+        assert_eq!(result.mirror_mode.width, 1920);
+        assert!((result.refresh - 60.0).abs() < 0.01);
+    }
+
+    #[test]
+    fn different_ar_approx_match() {
+        // 16:9 source vs 16:10 target — AR ratio ~11% difference, exceeds 5%
+        // so this should fail to find a match (incompatible)
+        // Actually 16:10 ratio is 1.6, 16:9 is 1.777, diff/1.777 = 10% > 5%
+        let src = make_monitor_with_modes("src", vec![m(1920, 1080, 60.0)]);
+        let tgt = make_monitor_with_modes("tgt", vec![m(1920, 1200, 60.0)]);
+        // These are >5% apart so should be None
+        let result = find_mirror_modes(&src, &tgt);
+        assert!(result.is_none());
+    }
+
+    #[test]
+    fn near_common_ar_within_5pct() {
+        // 16:9 = 1.7778, 17:9 = 1.8889, diff/1.7778 = ~6%, just over
+        // Let's use a case within 5%: 1920x1080 (16:9 = 1.7778) vs 2560x1440 (16:9 = 1.7778)
+        let src = make_monitor_with_modes("src", vec![m(1920, 1080, 60.0)]);
+        let tgt = make_monitor_with_modes("tgt", vec![m(2560, 1440, 60.0)]);
+        let result = find_mirror_modes(&src, &tgt).unwrap();
+        assert!(result.ar_exact);
+    }
+
+    #[test]
+    fn near_refresh_match() {
+        let src = make_monitor_with_modes("src", vec![m(1920, 1080, 60.0)]);
+        let tgt = make_monitor_with_modes("tgt", vec![m(1920, 1080, 59.94)]);
+        let result = find_mirror_modes(&src, &tgt).unwrap();
+        assert!(result.ar_exact);
+        // chosen_refresh should be the min of the near pair = 59.94
+        assert!((result.refresh - 59.94).abs() < 0.1);
+    }
+
+    #[test]
+    fn incompatible_modes_returns_none() {
+        let src = make_monitor_with_modes("src", vec![m(1920, 1080, 60.0)]);
+        let tgt = make_monitor_with_modes("tgt", vec![m(1024, 768, 60.0)]);
+        // 16:9 vs 4:3, difference >> 5%
+        let result = find_mirror_modes(&src, &tgt);
+        assert!(result.is_none());
+    }
+}

src/monitor.rs

@@ -0,0 +1,461 @@
+use anyhow::{Context, Result};
+use serde::Deserialize;
+use tokio::process::Command;
+
+#[derive(Debug, Clone, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct RawMonitor {
+    pub id: u32,
+    pub name: String,
+    pub description: String,
+    pub width: u32,
+    pub height: u32,
+    pub x: i32,
+    pub y: i32,
+    pub scale: f64,
+    pub refresh_rate: f64,
+    pub transform: u8,
+    pub available_modes: Vec<String>,
+    pub physical_width: u32,
+    pub physical_height: u32,
+    pub dpms_status: bool,
+    pub vrr: bool,
+    pub mirror_of: String,
+    #[serde(default)]
+    pub disabled: bool,
+}
+
+#[derive(Debug, Clone, PartialEq)]
+pub struct Mode {
+    pub width: u32,
+    pub height: u32,
+    pub refresh: f64,
+}
+
+impl Mode {
+    pub fn parse(s: &str) -> Option<Self> {
+        // Format: "1920x1200@60.00Hz"
+        let s = s.trim_end_matches("Hz");
+        let (res, refresh_str) = s.split_once('@')?;
+        let (w_str, h_str) = res.split_once('x')?;
+        Some(Mode {
+            width: w_str.parse().ok()?,
+            height: h_str.parse().ok()?,
+            refresh: refresh_str.parse().ok()?,
+        })
+    }
+
+    pub fn compact(&self) -> String {
+        format!("{}x{}@{:.2}", self.width, self.height, self.refresh)
+    }
+
+    pub fn pixels(&self) -> u64 {
+        self.width as u64 * self.height as u64
+    }
+}
+
+impl std::fmt::Display for Mode {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}x{}@{:.2}Hz", self.width, self.height, self.refresh)
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Transform {
+    Normal = 0,
+    R90 = 1,
+    R180 = 2,
+    R270 = 3,
+    Flipped = 4,
+    FlippedR90 = 5,
+    FlippedR180 = 6,
+    FlippedR270 = 7,
+}
+
+impl Transform {
+    pub fn from_u8(v: u8) -> Self {
+        match v {
+            1 => Self::R90,
+            2 => Self::R180,
+            3 => Self::R270,
+            4 => Self::Flipped,
+            5 => Self::FlippedR90,
+            6 => Self::FlippedR180,
+            7 => Self::FlippedR270,
+            _ => Self::Normal,
+        }
+    }
+
+    pub fn as_u8(self) -> u8 {
+        self as u8
+    }
+
+    pub fn label(self) -> &'static str {
+        match self {
+            Self::Normal => "Normal",
+            Self::R90 => "90°",
+            Self::R180 => "180°",
+            Self::R270 => "270°",
+            Self::Flipped => "Flipped",
+            Self::FlippedR90 => "Flipped 90°",
+            Self::FlippedR180 => "Flipped 180°",
+            Self::FlippedR270 => "Flipped 270°",
+        }
+    }
+
+    pub fn all() -> &'static [Transform] {
+        &[
+            Self::Normal,
+            Self::R90,
+            Self::R180,
+            Self::R270,
+            Self::Flipped,
+            Self::FlippedR90,
+            Self::FlippedR180,
+            Self::FlippedR270,
+        ]
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct Monitor {
+    pub name: String,
+    pub description: String,
+    pub active_mode: Mode,
+    pub x: i32,
+    pub y: i32,
+    pub scale: f64,
+    pub transform: Transform,
+    pub vrr: bool,
+    pub dpms: bool,
+    pub disabled: bool,
+    pub mirror_of: Option<String>,
+    pub available_modes: Vec<Mode>,
+    /// Physical dimensions in millimetres (0 if unknown)
+    pub physical_width_mm: u32,
+    pub physical_height_mm: u32,
+}
+
+impl Monitor {
+    fn from_raw(raw: RawMonitor) -> Self {
+        let mut modes: Vec<Mode> = raw
+            .available_modes
+            .iter()
+            .filter_map(|s| Mode::parse(s))
+            .collect();
+        // Sort descending by pixels then refresh for consistent ordering
+        modes.sort_by(|a, b| {
+            b.pixels()
+                .cmp(&a.pixels())
+                .then(b.refresh.partial_cmp(&a.refresh).unwrap_or(std::cmp::Ordering::Equal))
+        });
+        modes.dedup_by(|a, b| a.width == b.width && a.height == b.height && (a.refresh - b.refresh).abs() < 0.01);
+
+        let active_mode = Mode {
+            width: raw.width,
+            height: raw.height,
+            refresh: raw.refresh_rate,
+        };
+
+        let mirror_of = if raw.mirror_of.is_empty() || raw.mirror_of == "none" {
+            None
+        } else {
+            Some(raw.mirror_of)
+        };
+
+        Monitor {
+            name: raw.name,
+            description: raw.description,
+            active_mode,
+            x: raw.x,
+            y: raw.y,
+            scale: raw.scale,
+            transform: Transform::from_u8(raw.transform),
+            vrr: raw.vrr,
+            dpms: raw.dpms_status,
+            disabled: raw.disabled,
+            mirror_of,
+            available_modes: modes,
+            physical_width_mm: raw.physical_width,
+            physical_height_mm: raw.physical_height,
+        }
+    }
+
+    /// Width in world coordinates (swapped for 90/270 transforms)
+    pub fn world_width(&self) -> u32 {
+        match self.transform {
+            Transform::R90 | Transform::R270 | Transform::FlippedR90 | Transform::FlippedR270 => {
+                self.active_mode.height
+            }
+            _ => self.active_mode.width,
+        }
+    }
+
+    /// Height in world coordinates
+    pub fn world_height(&self) -> u32 {
+        match self.transform {
+            Transform::R90 | Transform::R270 | Transform::FlippedR90 | Transform::FlippedR270 => {
+                self.active_mode.width
+            }
+            _ => self.active_mode.height,
+        }
+    }
+
+    pub fn right_edge(&self) -> i32 {
+        self.x + self.world_width() as i32
+    }
+
+    pub fn bottom_edge(&self) -> i32 {
+        self.y + self.world_height() as i32
+    }
+
+    /// Pixels-per-inch, or None if physical dimensions are unknown.
+    pub fn ppi(&self) -> Option<f64> {
+        if self.physical_width_mm == 0 || self.physical_height_mm == 0 {
+            return None;
+        }
+        let diag_px = ((self.active_mode.width.pow(2) + self.active_mode.height.pow(2)) as f64).sqrt();
+        let diag_mm = ((self.physical_width_mm.pow(2) + self.physical_height_mm.pow(2)) as f64).sqrt();
+        Some(diag_px / (diag_mm / 25.4))
+    }
+
+    /// Suggested fractional scale based on PPI.
+    pub fn suggested_scale(&self) -> Option<f64> {
+        let ppi = self.ppi()?;
+        Some(if ppi < 110.0 {
+            1.0
+        } else if ppi < 150.0 {
+            1.25
+        } else if ppi < 200.0 {
+            1.5
+        } else {
+            2.0
+        })
+    }
+
+    /// Unique resolutions available (deduped WxH pairs)
+    pub fn unique_resolutions(&self) -> Vec<(u32, u32)> {
+        let mut seen = Vec::new();
+        for m in &self.available_modes {
+            let pair = (m.width, m.height);
+            if !seen.contains(&pair) {
+                seen.push(pair);
+            }
+        }
+        seen
+    }
+
+    /// Refresh rates available for a given WxH
+    pub fn refreshes_for(&self, width: u32, height: u32) -> Vec<f64> {
+        self.available_modes
+            .iter()
+            .filter(|m| m.width == width && m.height == height)
+            .map(|m| m.refresh)
+            .collect()
+    }
+}
+
+pub async fn load_monitors() -> Result<Vec<Monitor>> {
+    let output = Command::new("hyprctl")
+        .args(["monitors", "all", "-j"])
+        .output()
+        .await
+        .context("failed to run hyprctl monitors all -j")?;
+
+    let stdout = String::from_utf8_lossy(&output.stdout);
+    let raw: Vec<RawMonitor> =
+        serde_json::from_str(&stdout).context("failed to parse hyprctl monitors JSON")?;
+
+    // Hyprland reports mirrorOf as a numeric ID string when using `monitors all`.
+    // Resolve to monitor name so format_hypr_line emits the correct `mirror,<name>`.
+    let id_to_name: std::collections::HashMap<String, String> =
+        raw.iter().map(|r| (r.id.to_string(), r.name.clone())).collect();
+
+    Ok(raw
+        .into_iter()
+        .map(|mut r| {
+            if r.mirror_of != "none" && !r.mirror_of.is_empty() {
+                if let Some(name) = id_to_name.get(&r.mirror_of) {
+                    r.mirror_of = name.clone();
+                }
+            }
+            Monitor::from_raw(r)
+        })
+        .collect())
+}
+
+pub fn format_hypr_line(m: &Monitor) -> String {
+    if let Some(src) = &m.mirror_of {
+        format!(
+            "monitor={},{},auto,{:.2},mirror,{}",
+            m.name,
+            m.active_mode.compact(),
+            m.scale,
+            src
+        )
+    } else {
+        format!(
+            "monitor={},{},{}x{},{:.2},transform,{},vrr,{}",
+            m.name,
+            m.active_mode.compact(),
+            m.x,
+            m.y,
+            m.scale,
+            m.transform.as_u8(),
+            if m.vrr { 1 } else { 0 }
+        )
+    }
+}
+
+pub async fn apply_monitors(monitors: &[Monitor]) -> Result<()> {
+    // breadmon stores mirror_of on the slave; hl.monitor() wants mirror= on the source.
+    let mut mirror_slaves: std::collections::HashMap<&str, &str> = std::collections::HashMap::new();
+    for m in monitors {
+        if let Some(src) = &m.mirror_of {
+            mirror_slaves.insert(src.as_str(), m.name.as_str());
+        }
+    }
+
+    let mut eval_stmts: Vec<String> = Vec::new();
+    let mut dpms_off: Vec<String> = Vec::new();
+
+    for m in monitors {
+        if m.disabled {
+            continue;
+        }
+        if m.mirror_of.is_some() {
+            // Mirror slaves get no independent hl.monitor() call; only track DPMS.
+            if !m.dpms {
+                dpms_off.push(m.name.clone());
+            }
+            continue;
+        }
+
+        let mode = format!(
+            "{}x{}@{}",
+            m.active_mode.width,
+            m.active_mode.height,
+            (m.active_mode.refresh + 0.5) as u32
+        );
+        let position = format!("{}x{}", m.x, m.y);
+        let scale = format!("{:.2}", m.scale);
+
+        let mut stmt = format!(
+            "hl.monitor({{ output = \"{}\", mode = \"{}\", position = \"{}\", scale = \"{}\", transform = {}, vrr = {}",
+            m.name, mode, position, scale, m.transform.as_u8(), m.vrr
+        );
+
+        if let Some(&slave) = mirror_slaves.get(m.name.as_str()) {
+            stmt.push_str(&format!(", mirror = \"{}\"", slave));
+        }
+
+        stmt.push_str(" })");
+        eval_stmts.push(stmt);
+
+        if !m.dpms {
+            dpms_off.push(m.name.clone());
+        }
+    }
+
+    if !eval_stmts.is_empty() {
+        let lua = eval_stmts.join("; ");
+        let output = Command::new("hyprctl")
+            .args(["eval", &lua])
+            .output()
+            .await
+            .context("hyprctl eval failed")?;
+
+        let stdout = String::from_utf8_lossy(&output.stdout).trim().to_owned();
+        if stdout != "ok" {
+            return Err(anyhow::anyhow!("hyprctl: {}", stdout));
+        }
+    }
+
+    for name in dpms_off {
+        Command::new("hyprctl")
+            .args(["dispatch", "dpms", "off", &name])
+            .output()
+            .await
+            .context("hyprctl dispatch dpms off failed")?;
+    }
+
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn mode_parse_normal() {
+        let m = Mode::parse("1920x1200@60.00Hz").unwrap();
+        assert_eq!(m.width, 1920);
+        assert_eq!(m.height, 1200);
+        assert!((m.refresh - 60.0).abs() < 0.01);
+    }
+
+    #[test]
+    fn mode_parse_fractional() {
+        let m = Mode::parse("3840x2160@59.94Hz").unwrap();
+        assert_eq!(m.width, 3840);
+        assert_eq!(m.height, 2160);
+        assert!((m.refresh - 59.94).abs() < 0.01);
+    }
+
+    #[test]
+    fn mode_compact_roundtrip() {
+        let m = Mode { width: 1920, height: 1080, refresh: 60.0 };
+        let s = m.compact();
+        let m2 = Mode::parse(&format!("{}Hz", s)).unwrap();
+        assert_eq!(m.width, m2.width);
+        assert_eq!(m.height, m2.height);
+    }
+
+    #[test]
+    fn format_hypr_line_normal() {
+        let m = Monitor {
+            name: "eDP-1".into(),
+            description: String::new(),
+            active_mode: Mode { width: 1920, height: 1200, refresh: 60.0 },
+            x: 0,
+            y: 0,
+            scale: 1.0,
+            transform: Transform::Normal,
+            vrr: false,
+            dpms: true,
+            disabled: false,
+            mirror_of: None,
+            available_modes: vec![],
+            physical_width_mm: 0,
+            physical_height_mm: 0,
+        };
+        assert_eq!(
+            format_hypr_line(&m),
+            "monitor=eDP-1,1920x1200@60.00,0x0,1.00,transform,0,vrr,0"
+        );
+    }
+
+    #[test]
+    fn format_hypr_line_mirror() {
+        let m = Monitor {
+            name: "HDMI-A-1".into(),
+            description: String::new(),
+            active_mode: Mode { width: 1920, height: 1080, refresh: 60.0 },
+            x: 1920,
+            y: 0,
+            scale: 1.0,
+            transform: Transform::Normal,
+            vrr: false,
+            dpms: true,
+            disabled: false,
+            mirror_of: Some("eDP-1".into()),
+            available_modes: vec![],
+            physical_width_mm: 0,
+            physical_height_mm: 0,
+        };
+        assert_eq!(
+            format_hypr_line(&m),
+            "monitor=HDMI-A-1,1920x1080@60.00,auto,1.00,mirror,eDP-1"
+        );
+    }
+}

src/profile.rs

@@ -0,0 +1,179 @@
+use anyhow::{Context, Result};
+use serde::{Deserialize, Serialize};
+use std::path::PathBuf;
+
+use crate::monitor::{Mode, Monitor, Transform};
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct ProfileMonitor {
+    pub name: String,
+    pub mode: String,
+    pub x: i32,
+    pub y: i32,
+    pub scale: f64,
+    pub transform: u8,
+    pub vrr: bool,
+    pub dpms: bool,
+    pub mirror_of: String,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct ProfileMeta {
+    pub name: String,
+    pub created: String,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct Profile {
+    pub profile: ProfileMeta,
+    pub monitors: Vec<ProfileMonitor>,
+}
+
+pub fn profiles_dir() -> PathBuf {
+    dirs::config_dir()
+        .unwrap_or_else(|| PathBuf::from("~/.config"))
+        .join("breadmon/profiles")
+}
+
+pub fn save(profile: &Profile) -> Result<()> {
+    let dir = profiles_dir();
+    std::fs::create_dir_all(&dir).context("failed to create profiles dir")?;
+    let path = dir.join(format!("{}.toml", profile.profile.name));
+    let content = toml::to_string_pretty(profile).context("failed to serialize profile")?;
+    std::fs::write(&path, content).context("failed to write profile")?;
+    Ok(())
+}
+
+pub fn load(name: &str) -> Result<Profile> {
+    let path = profiles_dir().join(format!("{}.toml", name));
+    let content = std::fs::read_to_string(&path)
+        .with_context(|| format!("failed to read profile '{}'", name))?;
+    toml::from_str(&content).context("failed to parse profile TOML")
+}
+
+pub fn list() -> Result<Vec<String>> {
+    let dir = profiles_dir();
+    if !dir.exists() {
+        return Ok(vec![]);
+    }
+    let mut names = Vec::new();
+    for entry in std::fs::read_dir(&dir).context("failed to read profiles dir")? {
+        let entry = entry?;
+        let path = entry.path();
+        if path.extension().and_then(|e| e.to_str()) == Some("toml") {
+            if let Some(stem) = path.file_stem().and_then(|s| s.to_str()) {
+                names.push(stem.to_owned());
+            }
+        }
+    }
+    names.sort();
+    Ok(names)
+}
+
+pub fn delete(name: &str) -> Result<()> {
+    let path = profiles_dir().join(format!("{}.toml", name));
+    std::fs::remove_file(&path)
+        .with_context(|| format!("failed to delete profile '{}'", name))
+}
+
+pub fn from_monitors(name: &str, monitors: &[Monitor]) -> Profile {
+    let profile_monitors = monitors
+        .iter()
+        .map(|m| ProfileMonitor {
+            name: m.name.clone(),
+            mode: m.active_mode.compact(),
+            x: m.x,
+            y: m.y,
+            scale: m.scale,
+            transform: m.transform.as_u8(),
+            vrr: m.vrr,
+            dpms: m.dpms,
+            mirror_of: m.mirror_of.clone().unwrap_or_default(),
+        })
+        .collect();
+
+    Profile {
+        profile: ProfileMeta {
+            name: name.to_owned(),
+            created: chrono_now(),
+        },
+        monitors: profile_monitors,
+    }
+}
+
+/// Apply a profile's settings onto a list of live monitors (matched by name).
+/// Monitors not in the profile are left unchanged.
+pub fn apply_to_monitors(profile: &Profile, monitors: &mut Vec<Monitor>) {
+    for pm in &profile.monitors {
+        if let Some(m) = monitors.iter_mut().find(|m| m.name == pm.name) {
+            if let Some(mode) = Mode::parse(&format!("{}Hz", pm.mode)) {
+                m.active_mode = mode;
+            }
+            m.x = pm.x;
+            m.y = pm.y;
+            m.scale = pm.scale;
+            m.transform = Transform::from_u8(pm.transform);
+            m.vrr = pm.vrr;
+            m.dpms = pm.dpms;
+            m.mirror_of = if pm.mirror_of.is_empty() {
+                None
+            } else {
+                Some(pm.mirror_of.clone())
+            };
+        }
+    }
+}
+
+fn chrono_now() -> String {
+    // Simple ISO 8601 timestamp without pulling in chrono
+    // Uses date command; falls back to a placeholder if unavailable
+    std::process::Command::new("date")
+        .arg("+%Y-%m-%dT%H:%M:%SZ")
+        .output()
+        .ok()
+        .and_then(|o| String::from_utf8(o.stdout).ok())
+        .map(|s| s.trim().to_owned())
+        .unwrap_or_else(|| "unknown".to_owned())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::monitor::{Mode, Transform};
+
+    fn make_monitor(name: &str, w: u32, h: u32, x: i32, y: i32) -> Monitor {
+        Monitor {
+            name: name.into(),
+            description: String::new(),
+            active_mode: Mode { width: w, height: h, refresh: 60.0 },
+            x,
+            y,
+            scale: 1.0,
+            transform: Transform::Normal,
+            vrr: false,
+            dpms: true,
+            disabled: false,
+            mirror_of: None,
+            available_modes: vec![],
+            physical_width_mm: 0,
+            physical_height_mm: 0,
+        }
+    }
+
+    #[test]
+    fn profile_roundtrip() {
+        let monitors = vec![
+            make_monitor("eDP-1", 1920, 1200, 0, 0),
+            make_monitor("HDMI-A-1", 1920, 1080, 1920, 0),
+        ];
+        let profile = from_monitors("test", &monitors);
+        let serialized = toml::to_string_pretty(&profile).unwrap();
+        let deserialized: Profile = toml::from_str(&serialized).unwrap();
+
+        assert_eq!(deserialized.profile.name, "test");
+        assert_eq!(deserialized.monitors.len(), 2);
+        assert_eq!(deserialized.monitors[0].name, "eDP-1");
+        assert_eq!(deserialized.monitors[0].mode, "1920x1200@60.00");
+        assert_eq!(deserialized.monitors[1].x, 1920);
+    }
+}

src/ui/config_view.rs

@@ -0,0 +1,488 @@
+use crossterm::event::{KeyCode, KeyEvent, MouseButton, MouseEvent, MouseEventKind};
+use ratatui::{
+    layout::{Constraint, Direction, Layout, Rect},
+    style::{Color, Modifier, Style},
+    text::{Line, Span},
+    widgets::{Block, Borders, List, ListItem, ListState, Paragraph},
+    Frame,
+};
+
+use crate::{
+    monitor::{Monitor, Transform},
+    ui::{AppState, StatusLevel},
+};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum ConfigField {
+    Resolution,
+    Refresh,
+    Scale,
+    Transform,
+    Vrr,
+    Dpms,
+    MirrorOf,
+}
+
+impl ConfigField {
+    const ALL: &'static [ConfigField] = &[
+        Self::Resolution,
+        Self::Refresh,
+        Self::Scale,
+        Self::Transform,
+        Self::Vrr,
+        Self::Dpms,
+        Self::MirrorOf,
+    ];
+
+    fn label(self) -> &'static str {
+        match self {
+            Self::Resolution => "Resolution",
+            Self::Refresh => "Refresh",
+            Self::Scale => "Scale",
+            Self::Transform => "Transform",
+            Self::Vrr => "VRR",
+            Self::Dpms => "DPMS",
+            Self::MirrorOf => "Mirror of",
+        }
+    }
+}
+
+#[derive(Debug, Default)]
+pub struct ConfigState {
+    pub monitor_idx: usize,
+    pub focused: usize, // index into ConfigField::ALL
+    // Dropdown indices
+    pub res_idx: usize,
+    pub refresh_idx: usize,
+    pub transform_idx: usize,
+    pub mirror_idx: usize, // 0 = none, 1.. = monitor names
+    // Scale editing
+    pub scale_str: String,
+    pub scale_editing: bool,
+    // Cached lists
+    pub resolutions: Vec<(u32, u32)>,
+    pub refreshes: Vec<f64>,
+    pub mirror_options: Vec<String>, // "(none)", then monitor names
+}
+
+impl ConfigState {
+    pub fn sync_from_monitor(&mut self, idx: usize, monitors: &[Monitor]) {
+        if monitors.is_empty() {
+            return;
+        }
+        let idx = idx.min(monitors.len() - 1);
+        self.monitor_idx = idx;
+        let m = &monitors[idx];
+
+        self.resolutions = m.unique_resolutions();
+        // Find current resolution index
+        self.res_idx = self
+            .resolutions
+            .iter()
+            .position(|&(w, h)| w == m.active_mode.width && h == m.active_mode.height)
+            .unwrap_or(0);
+
+        self.update_refreshes(m);
+
+        self.transform_idx = m.transform.as_u8() as usize;
+        self.scale_str = format!("{:.2}", m.scale);
+        self.scale_editing = false;
+
+        // Mirror options
+        self.mirror_options = std::iter::once("(none)".to_owned())
+            .chain(
+                monitors
+                    .iter()
+                    .filter(|other| other.name != m.name)
+                    .map(|other| other.name.clone()),
+            )
+            .collect();
+
+        self.mirror_idx = m
+            .mirror_of
+            .as_deref()
+            .and_then(|src| self.mirror_options.iter().position(|o| o == src))
+            .unwrap_or(0);
+    }
+
+    fn update_refreshes(&mut self, m: &Monitor) {
+        if let Some(&(w, h)) = self.resolutions.get(self.res_idx) {
+            self.refreshes = m.refreshes_for(w, h);
+            self.refresh_idx = self
+                .refreshes
+                .iter()
+                .position(|&r| (r - m.active_mode.refresh).abs() < 0.01)
+                .unwrap_or(0);
+        }
+    }
+
+    fn current_field(&self) -> ConfigField {
+        ConfigField::ALL[self.focused.min(ConfigField::ALL.len() - 1)]
+    }
+
+    fn next_field(&mut self) {
+        self.focused = (self.focused + 1) % ConfigField::ALL.len();
+    }
+
+    fn prev_field(&mut self) {
+        self.focused = self.focused.checked_sub(1).unwrap_or(ConfigField::ALL.len() - 1);
+    }
+}
+
+pub fn handle_key(event: KeyEvent, state: &mut AppState) {
+    let cfg = &mut state.config;
+
+    match event.code {
+        KeyCode::Char('j') | KeyCode::Down => {
+            cfg.scale_editing = false;
+            cfg.next_field();
+        }
+        KeyCode::Char('k') | KeyCode::Up => {
+            cfg.scale_editing = false;
+            cfg.prev_field();
+        }
+        KeyCode::Tab => {
+            cfg.scale_editing = false;
+            cfg.next_field();
+        }
+        KeyCode::BackTab => {
+            cfg.scale_editing = false;
+            cfg.prev_field();
+        }
+        // Navigate between monitors
+        KeyCode::Char('[') => {
+            let count = state.monitors.len();
+            if count > 0 {
+                let new_idx = state.config.monitor_idx.checked_sub(1).unwrap_or(count - 1);
+                state.layout.selected = new_idx;
+                state.config.sync_from_monitor(new_idx, &state.monitors);
+            }
+        }
+        KeyCode::Char(']') => {
+            let count = state.monitors.len();
+            if count > 0 {
+                let new_idx = (state.config.monitor_idx + 1) % count;
+                state.layout.selected = new_idx;
+                state.config.sync_from_monitor(new_idx, &state.monitors);
+            }
+        }
+        KeyCode::Char('a') => {
+            apply_current(state);
+        }
+        KeyCode::Char('s') => {
+            crate::ui::layout_view::trigger_save(state);
+        }
+        KeyCode::Esc => {
+            state.config.scale_editing = false;
+            // Re-sync from live monitor to discard pending edits
+            let idx = state.config.monitor_idx;
+            state.config.sync_from_monitor(idx, &state.monitors);
+        }
+        KeyCode::Enter => {
+            if state.config.current_field() == ConfigField::Scale {
+                commit_scale(state);
+            }
+            apply_current(state);
+        }
+        _ => {
+            state.push_undo();
+            handle_field_key(event, state);
+        }
+    }
+}
+
+pub fn handle_mouse(event: MouseEvent, state: &mut AppState) {
+    if state.monitors.is_empty() {
+        return;
+    }
+    let row = event.row;
+    // Content area starts at y=2 (after tab bar).
+    // Config view: header (Length(2)) at y=2-3, list block starts at y=4.
+    // List border top at y=4, items at y=5+.
+    let items_start_row = 5u16;
+
+    match event.kind {
+        MouseEventKind::Down(MouseButton::Left) => {
+            if row >= items_start_row {
+                let field_idx = (row - items_start_row) as usize;
+                if field_idx < ConfigField::ALL.len() {
+                    state.config.focused = field_idx;
+                }
+            }
+        }
+        MouseEventKind::ScrollUp => {
+            state.push_undo();
+            let fake_right = KeyEvent::new(KeyCode::Right, crossterm::event::KeyModifiers::NONE);
+            handle_field_key(fake_right, state);
+        }
+        MouseEventKind::ScrollDown => {
+            state.push_undo();
+            let fake_left = KeyEvent::new(KeyCode::Left, crossterm::event::KeyModifiers::NONE);
+            handle_field_key(fake_left, state);
+        }
+        _ => {}
+    }
+}
+
+fn handle_field_key(event: KeyEvent, state: &mut AppState) {
+    let monitors_len = state.monitors.len();
+    if monitors_len == 0 {
+        return;
+    }
+    let idx = state.config.monitor_idx.min(monitors_len - 1);
+
+    match state.config.current_field() {
+        ConfigField::Resolution => match event.code {
+            KeyCode::Char('h') | KeyCode::Left => {
+                if state.config.res_idx > 0 {
+                    state.config.res_idx -= 1;
+                    let m = &state.monitors[idx];
+                    state.config.update_refreshes(m);
+                    sync_mode_to_monitor(state, idx);
+                    state.dirty = true;
+                }
+            }
+            KeyCode::Char('l') | KeyCode::Right => {
+                if state.config.res_idx + 1 < state.config.resolutions.len() {
+                    state.config.res_idx += 1;
+                    let m = &state.monitors[idx];
+                    state.config.update_refreshes(m);
+                    sync_mode_to_monitor(state, idx);
+                    state.dirty = true;
+                }
+            }
+            _ => {}
+        },
+        ConfigField::Refresh => match event.code {
+            KeyCode::Char('h') | KeyCode::Left => {
+                if state.config.refresh_idx > 0 {
+                    state.config.refresh_idx -= 1;
+                    sync_mode_to_monitor(state, idx);
+                    state.dirty = true;
+                }
+            }
+            KeyCode::Char('l') | KeyCode::Right => {
+                if state.config.refresh_idx + 1 < state.config.refreshes.len() {
+                    state.config.refresh_idx += 1;
+                    sync_mode_to_monitor(state, idx);
+                    state.dirty = true;
+                }
+            }
+            _ => {}
+        },
+        ConfigField::Scale => match event.code {
+            KeyCode::Char(',') => {
+                let s = state.monitors[idx].scale - 0.1;
+                state.monitors[idx].scale = (s * 100.0).round() / 100.0;
+                state.monitors[idx].scale = state.monitors[idx].scale.max(0.1);
+                state.config.scale_str = format!("{:.2}", state.monitors[idx].scale);
+                state.dirty = true;
+            }
+            KeyCode::Char('.') => {
+                let s = state.monitors[idx].scale + 0.1;
+                state.monitors[idx].scale = (s * 100.0).round() / 100.0;
+                state.monitors[idx].scale = state.monitors[idx].scale.min(10.0);
+                state.config.scale_str = format!("{:.2}", state.monitors[idx].scale);
+                state.dirty = true;
+            }
+            KeyCode::Char(c) if c.is_ascii_digit() || c == '.' => {
+                state.config.scale_editing = true;
+                state.config.scale_str.push(c);
+            }
+            KeyCode::Backspace => {
+                state.config.scale_str.pop();
+            }
+            _ => {}
+        },
+        ConfigField::Transform => match event.code {
+            KeyCode::Char('h') | KeyCode::Left => {
+                let all = Transform::all();
+                state.config.transform_idx = state
+                    .config
+                    .transform_idx
+                    .checked_sub(1)
+                    .unwrap_or(all.len() - 1);
+                state.monitors[idx].transform = all[state.config.transform_idx];
+                state.dirty = true;
+            }
+            KeyCode::Char('l') | KeyCode::Right => {
+                let all = Transform::all();
+                state.config.transform_idx = (state.config.transform_idx + 1) % all.len();
+                state.monitors[idx].transform = all[state.config.transform_idx];
+                state.dirty = true;
+            }
+            _ => {}
+        },
+        ConfigField::Vrr => match event.code {
+            KeyCode::Char('h') | KeyCode::Left | KeyCode::Char('l') | KeyCode::Right | KeyCode::Char(' ') => {
+                state.monitors[idx].vrr = !state.monitors[idx].vrr;
+                state.dirty = true;
+            }
+            _ => {}
+        },
+        ConfigField::Dpms => match event.code {
+            KeyCode::Char('h') | KeyCode::Left | KeyCode::Char('l') | KeyCode::Right | KeyCode::Char(' ') => {
+                state.monitors[idx].dpms = !state.monitors[idx].dpms;
+                state.dirty = true;
+            }
+            _ => {}
+        },
+        ConfigField::MirrorOf => match event.code {
+            KeyCode::Char('h') | KeyCode::Left => {
+                if state.config.mirror_idx > 0 {
+                    state.config.mirror_idx -= 1;
+                    sync_mirror_to_monitor(state, idx);
+                    state.dirty = true;
+                }
+            }
+            KeyCode::Char('l') | KeyCode::Right => {
+                if state.config.mirror_idx + 1 < state.config.mirror_options.len() {
+                    state.config.mirror_idx += 1;
+                    sync_mirror_to_monitor(state, idx);
+                    state.dirty = true;
+                }
+            }
+            _ => {}
+        },
+    }
+}
+
+fn sync_mode_to_monitor(state: &mut AppState, idx: usize) {
+    if let Some(&(w, h)) = state.config.resolutions.get(state.config.res_idx) {
+        if let Some(&r) = state.config.refreshes.get(state.config.refresh_idx) {
+            state.monitors[idx].active_mode.width = w;
+            state.monitors[idx].active_mode.height = h;
+            state.monitors[idx].active_mode.refresh = r;
+        }
+    }
+}
+
+fn sync_mirror_to_monitor(state: &mut AppState, idx: usize) {
+    let chosen = state.config.mirror_options.get(state.config.mirror_idx).cloned();
+    state.monitors[idx].mirror_of = match chosen.as_deref() {
+        Some("(none)") | None => None,
+        Some(s) => Some(s.to_owned()),
+    };
+}
+
+fn commit_scale(state: &mut AppState) {
+    let idx = state.config.monitor_idx.min(state.monitors.len().saturating_sub(1));
+    if let Ok(v) = state.config.scale_str.parse::<f64>() {
+        state.monitors[idx].scale = v.clamp(0.1, 10.0);
+        state.config.scale_str = format!("{:.2}", state.monitors[idx].scale);
+        state.dirty = true;
+    }
+    state.config.scale_editing = false;
+}
+
+fn apply_current(state: &mut AppState) {
+    state.pending_apply = true;
+    state.set_status("Applying...", StatusLevel::Info);
+    state.dirty = false;
+}
+
+pub fn render(f: &mut Frame, area: Rect, state: &AppState) {
+    if state.monitors.is_empty() {
+        f.render_widget(
+            Paragraph::new("No monitors detected.").style(Style::default().fg(Color::DarkGray)),
+            area,
+        );
+        return;
+    }
+
+    let idx = state.config.monitor_idx.min(state.monitors.len() - 1);
+    let m = &state.monitors[idx];
+
+    let chunks = Layout::default()
+        .direction(Direction::Vertical)
+        .constraints([Constraint::Length(2), Constraint::Min(0)])
+        .split(area);
+
+    // Monitor header with PPI hint
+    let ppi_hint = match (m.ppi(), m.suggested_scale()) {
+        (Some(ppi), Some(scale)) => format!("  │  {:.0} PPI  (suggested scale: {:.2})", ppi, scale),
+        _ => String::new(),
+    };
+    let header = format!(" {} — {}{}", m.name, m.description, ppi_hint);
+    f.render_widget(
+        Paragraph::new(header).style(Style::default().fg(Color::White).add_modifier(Modifier::BOLD)),
+        chunks[0],
+    );
+
+    let form_area = chunks[1];
+    let row_height = 1u16;
+    let fields = ConfigField::ALL;
+
+    let items: Vec<ListItem> = fields
+        .iter()
+        .enumerate()
+        .map(|(i, &field)| {
+            let is_focused = i == state.config.focused;
+            let value = field_value(field, state, m);
+            let label = format!("  {:12}  {}", field.label(), value);
+            let style = if is_focused {
+                Style::default()
+                    .fg(Color::Yellow)
+                    .add_modifier(Modifier::BOLD)
+                    .bg(Color::DarkGray)
+            } else {
+                Style::default().fg(Color::White)
+            };
+            ListItem::new(Line::from(Span::styled(label, style)))
+        })
+        .collect();
+
+    let _ = row_height; // used implicitly via ListItem heights
+    let list = List::new(items).block(
+        Block::default()
+            .borders(Borders::ALL)
+            .border_style(Style::default().fg(Color::DarkGray))
+            .title(" Config "),
+    );
+
+    let mut list_state = ListState::default();
+    list_state.select(Some(state.config.focused));
+    f.render_stateful_widget(list, form_area, &mut list_state);
+}
+
+fn field_value(field: ConfigField, state: &AppState, m: &Monitor) -> String {
+    match field {
+        ConfigField::Resolution => {
+            if let Some(&(w, h)) = state.config.resolutions.get(state.config.res_idx) {
+                format!("{}x{}  (h/l to change)", w, h)
+            } else {
+                format!("{}x{}", m.active_mode.width, m.active_mode.height)
+            }
+        }
+        ConfigField::Refresh => {
+            if let Some(&r) = state.config.refreshes.get(state.config.refresh_idx) {
+                format!("{:.2} Hz  (h/l to change)", r)
+            } else {
+                format!("{:.2} Hz", m.active_mode.refresh)
+            }
+        }
+        ConfigField::Scale => {
+            if state.config.scale_editing {
+                format!("{}|  (Enter to commit, ,/. for ±0.1)", state.config.scale_str)
+            } else {
+                format!("{}  (,/. for ±0.1)", state.config.scale_str)
+            }
+        }
+        ConfigField::Transform => Transform::all()
+            [state.config.transform_idx.min(Transform::all().len() - 1)]
+            .label()
+            .to_owned(),
+        ConfigField::Vrr => {
+            if m.vrr { "ON".to_owned() } else { "OFF".to_owned() }
+        }
+        ConfigField::Dpms => {
+            if m.dpms { "ON".to_owned() } else { "OFF".to_owned() }
+        }
+        ConfigField::MirrorOf => state
+            .config
+            .mirror_options
+            .get(state.config.mirror_idx)
+            .cloned()
+            .unwrap_or_else(|| "(none)".to_owned()),
+    }
+}

src/ui/layout_view.rs

@@ -0,0 +1,332 @@
+use crossterm::event::{KeyCode, KeyEvent, KeyModifiers, MouseButton, MouseEvent, MouseEventKind};
+use ratatui::{
+    layout::{Constraint, Direction, Layout, Rect},
+    style::{Color, Modifier, Style},
+    text::Span,
+    widgets::{Block, BorderType, Borders, Paragraph},
+    Frame,
+};
+
+use crate::{
+    layout::{auto_arrange, bounding_box, canvas_scale, canvas_to_world, move_selected, snap_position, world_to_canvas},
+    monitor::Monitor,
+    ui::{AppState, DragState, StatusLevel, Tab},
+};
+
+pub fn handle_key(event: KeyEvent, state: &mut AppState) {
+    let shift = event.modifiers.contains(KeyModifiers::SHIFT);
+    let step = if shift { 10 } else { 1 };
+    let count = state.monitors.len();
+
+    match event.code {
+        KeyCode::Char('h') | KeyCode::Left => {
+            state.push_undo();
+            move_selected(&state.layout, &mut state.monitors, -step, 0);
+            state.dirty = true;
+        }
+        KeyCode::Char('l') | KeyCode::Right => {
+            state.push_undo();
+            move_selected(&state.layout, &mut state.monitors, step, 0);
+            state.dirty = true;
+        }
+        KeyCode::Char('k') | KeyCode::Up => {
+            state.push_undo();
+            move_selected(&state.layout, &mut state.monitors, 0, -step);
+            state.dirty = true;
+        }
+        KeyCode::Char('j') | KeyCode::Down => {
+            state.push_undo();
+            move_selected(&state.layout, &mut state.monitors, 0, step);
+            state.dirty = true;
+        }
+        KeyCode::Tab | KeyCode::Char('n') => state.layout.next(count),
+        KeyCode::BackTab | KeyCode::Char('p') => state.layout.prev(count),
+        KeyCode::Char('[') => state.layout.zoom = (state.layout.zoom - 0.1).max(0.1),
+        KeyCode::Char(']') => state.layout.zoom = (state.layout.zoom + 0.1).min(5.0),
+        KeyCode::Char('0') => {
+            state.push_undo();
+            auto_arrange(&mut state.monitors);
+            state.dirty = true;
+        }
+        KeyCode::Enter => {
+            state.config.sync_from_monitor(state.layout.selected, &state.monitors);
+            state.tab = Tab::Config;
+        }
+        _ => {}
+    }
+}
+
+pub fn handle_mouse(event: MouseEvent, state: &mut AppState) {
+    let col = event.column;
+    let row = event.row;
+
+    match event.kind {
+        MouseEventKind::Down(MouseButton::Left) => {
+            let canvas = canvas_area(state.terminal_size);
+            if let Some(idx) = monitor_at(col, row, canvas, state) {
+                let (min_x, min_y, _, _) = bounding_box(&state.monitors);
+                let scale = canvas_scale_for(canvas, state);
+                let (wx, wy) = canvas_to_world(col, row, scale, min_x, min_y, canvas.x + 1, canvas.y + 1);
+
+                // Push undo at drag start, not on every move
+                state.push_undo();
+                state.layout.selected = idx;
+                state.drag_state = Some(DragState {
+                    monitor_idx: idx,
+                    origin_x: state.monitors[idx].x,
+                    origin_y: state.monitors[idx].y,
+                    click_world_x: wx,
+                    click_world_y: wy,
+                });
+            }
+        }
+        MouseEventKind::Drag(MouseButton::Left) => {
+            if let Some(ref drag) = state.drag_state {
+                let canvas = canvas_area(state.terminal_size);
+                let (min_x, min_y, _, _) = bounding_box(&state.monitors);
+                let scale = canvas_scale_for(canvas, state);
+                let (wx, wy) = canvas_to_world(col, row, scale, min_x, min_y, canvas.x + 1, canvas.y + 1);
+
+                let idx = drag.monitor_idx;
+                let new_x = drag.origin_x + (wx - drag.click_world_x);
+                let new_y = drag.origin_y + (wy - drag.click_world_y);
+                let (sx, sy) = snap_position(idx, new_x, new_y, &state.monitors, state.layout.snap_threshold);
+                state.monitors[idx].x = sx;
+                state.monitors[idx].y = sy;
+                state.dirty = true;
+            }
+        }
+        MouseEventKind::Up(MouseButton::Left) => {
+            state.drag_state = None;
+        }
+        MouseEventKind::ScrollUp => {
+            let canvas = canvas_area(state.terminal_size);
+            if in_canvas(col, row, canvas) {
+                state.layout.zoom = (state.layout.zoom + 0.1).min(5.0);
+            } else {
+                state.layout.prev(state.monitors.len());
+            }
+        }
+        MouseEventKind::ScrollDown => {
+            let canvas = canvas_area(state.terminal_size);
+            if in_canvas(col, row, canvas) {
+                state.layout.zoom = (state.layout.zoom - 0.1).max(0.1);
+            } else {
+                state.layout.next(state.monitors.len());
+            }
+        }
+        _ => {}
+    }
+}
+
+pub fn render(f: &mut Frame, area: Rect, state: &AppState) {
+    if state.monitors.is_empty() {
+        let msg = Paragraph::new("No monitors detected. Is Hyprland running?")
+            .style(Style::default().fg(Color::DarkGray));
+        f.render_widget(msg, area);
+        return;
+    }
+
+    let chunks = Layout::default()
+        .direction(Direction::Vertical)
+        .constraints([Constraint::Min(0), Constraint::Length(1)])
+        .split(area);
+
+    render_canvas(f, chunks[0], state);
+    render_readout(f, chunks[1], state);
+}
+
+fn render_canvas(f: &mut Frame, area: Rect, state: &AppState) {
+    let monitors = &state.monitors;
+    let (min_x, min_y, _, _) = bounding_box(monitors);
+    let scale = canvas_scale_for(area, state);
+
+    // Pre-compute which monitors are overlapping (shown with red borders)
+    let overlapping = overlapping_monitors(monitors);
+
+    let selected = state.layout.selected;
+    let draw_order: Vec<usize> = (0..monitors.len())
+        .filter(|&i| i != selected)
+        .chain(std::iter::once(selected))
+        .collect();
+
+    for i in draw_order {
+        let m = &monitors[i];
+        let (cx, cy) = world_to_canvas(m.x, m.y, scale, min_x, min_y, area.x + 1, area.y + 1);
+        let cw = ((m.world_width() as f32 * scale) as u16).max(4);
+        let ch = ((m.world_height() as f32 * scale * 0.5) as u16).max(2);
+
+        let cw = cw.min(area.width.saturating_sub(cx.saturating_sub(area.x)));
+        let ch = ch.min(area.height.saturating_sub(cy.saturating_sub(area.y)));
+        if cw == 0 || ch == 0 {
+            continue;
+        }
+
+        let rect = Rect { x: cx, y: cy, width: cw, height: ch };
+
+        let is_selected = i == selected;
+        let is_dragging = state.drag_state.as_ref().map(|d| d.monitor_idx == i).unwrap_or(false);
+        let is_overlapping = overlapping[i];
+
+        let border_style = if is_dragging {
+            Style::default().fg(Color::Magenta).add_modifier(Modifier::BOLD)
+        } else if is_overlapping {
+            Style::default().fg(Color::Red).add_modifier(Modifier::BOLD)
+        } else if is_selected {
+            Style::default().fg(Color::Yellow).add_modifier(Modifier::BOLD)
+        } else {
+            Style::default().fg(Color::Blue)
+        };
+
+        let label = format!(" {} ", m.name);
+        let mode_str = format!(" {}@{:.0}Hz ", m.active_mode.width, m.active_mode.refresh);
+
+        let block = Block::default()
+            .borders(Borders::ALL)
+            .border_type(if is_selected || is_dragging || is_overlapping {
+                BorderType::Thick
+            } else {
+                BorderType::Rounded
+            })
+            .border_style(border_style)
+            .title(Span::styled(&label, border_style))
+            .title_bottom(Span::styled(&mode_str, Style::default().fg(Color::DarkGray)));
+
+        f.render_widget(block, rect);
+    }
+}
+
+fn render_readout(f: &mut Frame, area: Rect, state: &AppState) {
+    if state.monitors.is_empty() {
+        return;
+    }
+    let idx = state.layout.selected.min(state.monitors.len() - 1);
+    let m = &state.monitors[idx];
+
+    let mirror_info = m.mirror_of.as_ref()
+        .map(|src| format!("  mirror:{}", src))
+        .unwrap_or_default();
+
+    let overlap_warn = if overlapping_monitors(&state.monitors)[idx] {
+        "  ⚠ OVERLAP"
+    } else {
+        ""
+    };
+
+    let drag_hint = if state.drag_state.is_some() { "  [dragging]" } else { "" };
+
+    let text = format!(
+        " {}  x:{}  y:{}  {}x{}@{:.0}Hz  scale:{:.2}{}{}{}",
+        m.name, m.x, m.y,
+        m.active_mode.width, m.active_mode.height, m.active_mode.refresh,
+        m.scale,
+        mirror_info, overlap_warn, drag_hint,
+    );
+    f.render_widget(
+        Paragraph::new(text).style(Style::default().fg(Color::Cyan)),
+        area,
+    );
+}
+
+/// Returns a bool per monitor: true if it overlaps any other monitor.
+fn overlapping_monitors(monitors: &[Monitor]) -> Vec<bool> {
+    let mut flags = vec![false; monitors.len()];
+    for i in 0..monitors.len() {
+        for j in (i + 1)..monitors.len() {
+            let a = &monitors[i];
+            let b = &monitors[j];
+            if a.x < b.right_edge() && a.right_edge() > b.x
+                && a.y < b.bottom_edge() && a.bottom_edge() > b.y
+            {
+                flags[i] = true;
+                flags[j] = true;
+            }
+        }
+    }
+    flags
+}
+
+/// Canvas rect from terminal size.
+/// Tab bar = y 0-1 (height 2), bottom bar = last row (height 1), readout = 1 row inside content.
+pub fn canvas_area(terminal_size: (u16, u16)) -> Rect {
+    let (tw, th) = terminal_size;
+    Rect {
+        x: 0,
+        y: 2,
+        width: tw,
+        height: th.saturating_sub(4),
+    }
+}
+
+fn in_canvas(col: u16, row: u16, canvas: Rect) -> bool {
+    col >= canvas.x + 1
+        && col < canvas.x + canvas.width.saturating_sub(1)
+        && row >= canvas.y + 1
+        && row < canvas.y + canvas.height.saturating_sub(1)
+}
+
+fn canvas_scale_for(area: Rect, state: &AppState) -> f32 {
+    let w = area.width.saturating_sub(2);
+    let h = area.height.saturating_sub(2);
+    canvas_scale(&state.monitors, w, h, state.layout.zoom)
+}
+
+/// Hit-test: which monitor (if any) is at canvas position (col, row)?
+fn monitor_at(col: u16, row: u16, canvas: Rect, state: &AppState) -> Option<usize> {
+    if state.monitors.is_empty() {
+        return None;
+    }
+    let monitors = &state.monitors;
+    let (min_x, min_y, _, _) = bounding_box(monitors);
+    let scale = canvas_scale_for(canvas, state);
+    let pad_x = canvas.x + 1;
+    let pad_y = canvas.y + 1;
+
+    // Check selected first (renders on top)
+    let selected = state.layout.selected;
+    let order: Vec<usize> = std::iter::once(selected)
+        .chain((0..monitors.len()).filter(|&i| i != selected))
+        .collect();
+
+    for i in order {
+        let m = &monitors[i];
+        let (cx, cy) = world_to_canvas(m.x, m.y, scale, min_x, min_y, pad_x, pad_y);
+        let cw = ((m.world_width() as f32 * scale) as u16).max(4);
+        let ch = ((m.world_height() as f32 * scale * 0.5) as u16).max(2);
+        if col >= cx && col < cx + cw && row >= cy && row < cy + ch {
+            return Some(i);
+        }
+    }
+    None
+}
+
+pub fn trigger_save(state: &mut AppState) {
+    use crate::monitor::format_hypr_line;
+    use std::path::PathBuf;
+
+    let path: PathBuf = dirs::config_dir()
+        .unwrap_or_else(|| PathBuf::from(std::env::var("HOME").unwrap_or_default()))
+        .join("hypr/monitors.conf");
+
+    let is_new = !path.exists();
+    let mut lines = vec!["# Generated by breadmon — do not edit by hand".to_owned()];
+    for m in &state.monitors {
+        lines.push(format_hypr_line(m));
+    }
+    let content = lines.join("\n") + "\n";
+
+    match std::fs::write(&path, &content) {
+        Ok(()) => {
+            if is_new {
+                state.set_status(
+                    format!("Saved. Add: source = {} to hyprland.conf", path.display()),
+                    StatusLevel::Success,
+                );
+            } else {
+                state.set_status(format!("Saved to {}", path.display()), StatusLevel::Success);
+            }
+            state.dirty = false;
+        }
+        Err(e) => state.set_status(format!("Save failed: {}", e), StatusLevel::Error),
+    }
+}

src/ui/mirror_view.rs

@@ -0,0 +1,420 @@
+use crossterm::event::{KeyCode, KeyEvent, MouseButton, MouseEvent, MouseEventKind};
+use ratatui::{
+    layout::{Constraint, Direction, Layout, Rect},
+    style::{Color, Modifier, Style},
+    text::{Line, Span},
+    widgets::{Block, Borders, Paragraph},
+    Frame,
+};
+
+use crate::{
+    mirror::{find_mirror_modes, refresh_match_label, MirrorResult},
+    ui::{AppState, StatusLevel},
+};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum MirrorField {
+    Source,
+    Target,
+    Compute,
+    Apply,
+    Cancel,
+}
+
+#[derive(Debug, Default)]
+pub struct MirrorState {
+    pub source_idx: usize,
+    pub target_idx: usize,
+    pub result: Option<MirrorResult>,
+    pub focused: usize, // index into FIELDS
+}
+
+const FIELDS: &[MirrorField] = &[
+    MirrorField::Source,
+    MirrorField::Target,
+    MirrorField::Compute,
+    MirrorField::Apply,
+    MirrorField::Cancel,
+];
+
+impl MirrorState {
+    fn current_field(&self) -> MirrorField {
+        FIELDS[self.focused.min(FIELDS.len() - 1)]
+    }
+
+    fn next_field(&mut self) {
+        // Skip Apply/Cancel if no result yet
+        let mut next = (self.focused + 1) % FIELDS.len();
+        if self.result.is_none() && (FIELDS[next] == MirrorField::Apply || FIELDS[next] == MirrorField::Cancel) {
+            next = 0;
+        }
+        self.focused = next;
+    }
+
+    fn prev_field(&mut self) {
+        let len = FIELDS.len();
+        let mut prev = self.focused.checked_sub(1).unwrap_or(len - 1);
+        if self.result.is_none() && (FIELDS[prev] == MirrorField::Apply || FIELDS[prev] == MirrorField::Cancel) {
+            prev = FIELDS.iter().position(|&f| f == MirrorField::Compute).unwrap_or(2);
+        }
+        self.focused = prev;
+    }
+
+    /// Ensure source and target are different
+    pub fn fix_indices(&mut self, count: usize) {
+        if count < 2 {
+            return;
+        }
+        if self.source_idx == self.target_idx {
+            self.target_idx = (self.source_idx + 1) % count;
+        }
+    }
+}
+
+pub fn handle_key(event: KeyEvent, state: &mut AppState) {
+    let count = state.monitors.len();
+    if count < 2 {
+        return;
+    }
+
+    match event.code {
+        KeyCode::Tab | KeyCode::Char('j') | KeyCode::Down => {
+            state.mirror.next_field();
+        }
+        KeyCode::BackTab | KeyCode::Char('k') | KeyCode::Up => {
+            state.mirror.prev_field();
+        }
+        KeyCode::Char('h') | KeyCode::Left => match state.mirror.current_field() {
+            MirrorField::Source => {
+                state.mirror.source_idx = state.mirror.source_idx.checked_sub(1).unwrap_or(count - 1);
+                state.mirror.fix_indices(count);
+                state.mirror.result = None;
+            }
+            MirrorField::Target => {
+                state.mirror.target_idx = state.mirror.target_idx.checked_sub(1).unwrap_or(count - 1);
+                state.mirror.fix_indices(count);
+                state.mirror.result = None;
+            }
+            _ => {}
+        },
+        KeyCode::Char('l') | KeyCode::Right => match state.mirror.current_field() {
+            MirrorField::Source => {
+                state.mirror.source_idx = (state.mirror.source_idx + 1) % count;
+                state.mirror.fix_indices(count);
+                state.mirror.result = None;
+            }
+            MirrorField::Target => {
+                state.mirror.target_idx = (state.mirror.target_idx + 1) % count;
+                state.mirror.fix_indices(count);
+                state.mirror.result = None;
+            }
+            _ => {}
+        },
+        KeyCode::Enter => match state.mirror.current_field() {
+            MirrorField::Compute => {
+                let src = &state.monitors[state.mirror.source_idx];
+                let tgt = &state.monitors[state.mirror.target_idx];
+                match find_mirror_modes(src, tgt) {
+                    Some(result) => {
+                        state.mirror.result = Some(result);
+                        // Move focus to Apply
+                        state.mirror.focused = FIELDS.iter().position(|&f| f == MirrorField::Apply).unwrap_or(3);
+                    }
+                    None => {
+                        state.set_status(
+                            "No compatible modes found between these monitors.",
+                            StatusLevel::Error,
+                        );
+                    }
+                }
+            }
+            MirrorField::Apply => {
+                if let Some(result) = state.mirror.result.clone() {
+                    state.push_undo();
+                    let src_name = state.monitors[state.mirror.source_idx].name.clone();
+                    let tgt_idx = state.mirror.target_idx;
+
+                    state.monitors[tgt_idx].active_mode = result.mirror_mode.clone();
+                    state.monitors[tgt_idx].mirror_of = Some(src_name.clone());
+
+                    state.dirty = true;
+                    state.mirror.result = None;
+                    state.mirror.focused = 0;
+                    state.set_status(
+                        format!(
+                            "Mirror set: {} → {} at {}",
+                            src_name,
+                            state.monitors[tgt_idx].name,
+                            result.mirror_mode
+                        ),
+                        StatusLevel::Success,
+                    );
+                }
+            }
+            MirrorField::Cancel => {
+                state.mirror.result = None;
+                state.mirror.focused = 0;
+            }
+            _ => {}
+        },
+        KeyCode::Esc => {
+            state.mirror.result = None;
+            state.mirror.focused = 0;
+        }
+        _ => {}
+    }
+}
+
+pub fn handle_mouse(event: MouseEvent, state: &mut AppState) {
+    let count = state.monitors.len();
+    if count < 2 {
+        return;
+    }
+
+    let row = event.row;
+    // Content area starts at y=2.
+    // Pickers chunk: y=2..5 (height 4).  Source line at y=2, target at y=4.
+    // Compute button: y=6.
+    // Result panel: y=7+ (border at y=7, buttons at ~y=13 for a typical terminal).
+
+    match event.kind {
+        MouseEventKind::Down(MouseButton::Left) => {
+            match row {
+                2 | 3 => {
+                    // Source picker area
+                    let f_idx = FIELDS.iter().position(|&f| f == MirrorField::Source).unwrap_or(0);
+                    state.mirror.focused = f_idx;
+                }
+                4 | 5 => {
+                    // Target picker area
+                    let f_idx = FIELDS.iter().position(|&f| f == MirrorField::Target).unwrap_or(1);
+                    state.mirror.focused = f_idx;
+                }
+                6 => {
+                    // Compute button
+                    let f_idx = FIELDS.iter().position(|&f| f == MirrorField::Compute).unwrap_or(2);
+                    state.mirror.focused = f_idx;
+                    // Also activate it
+                    let src = &state.monitors[state.mirror.source_idx];
+                    let tgt = &state.monitors[state.mirror.target_idx];
+                    match crate::mirror::find_mirror_modes(src, tgt) {
+                        Some(result) => {
+                            state.mirror.result = Some(result);
+                            state.mirror.focused = FIELDS.iter().position(|&f| f == MirrorField::Apply).unwrap_or(3);
+                        }
+                        None => {
+                            state.set_status(
+                                "No compatible modes found between these monitors.",
+                                crate::ui::StatusLevel::Error,
+                            );
+                        }
+                    }
+                }
+                r if r >= 7 => {
+                    // Result panel: Apply is on the line with buttons.
+                    // Rough column check: col < 20 = Apply, col >= 20 = Cancel
+                    if state.mirror.result.is_some() {
+                        let col = event.column;
+                        if col < 20 {
+                            // Activate Apply
+                            state.mirror.focused = FIELDS.iter().position(|&f| f == MirrorField::Apply).unwrap_or(3);
+                            if let Some(result) = state.mirror.result.clone() {
+                                state.push_undo();
+                                let src_name = state.monitors[state.mirror.source_idx].name.clone();
+                                let tgt_idx = state.mirror.target_idx;
+                                state.monitors[tgt_idx].active_mode = result.mirror_mode.clone();
+                                state.monitors[tgt_idx].mirror_of = Some(src_name.clone());
+                                state.dirty = true;
+                                state.mirror.result = None;
+                                state.mirror.focused = 0;
+                                state.set_status(
+                                    format!("Mirror set: {} → {} at {}", src_name, state.monitors[tgt_idx].name, result.mirror_mode),
+                                    crate::ui::StatusLevel::Success,
+                                );
+                            }
+                        } else {
+                            // Cancel
+                            state.mirror.result = None;
+                            state.mirror.focused = 0;
+                        }
+                    }
+                }
+                _ => {}
+            }
+        }
+        MouseEventKind::ScrollUp => {
+            // Scroll in source/target pickers to cycle monitors
+            match state.mirror.current_field() {
+                MirrorField::Source => {
+                    state.mirror.source_idx = state.mirror.source_idx.checked_sub(1).unwrap_or(count - 1);
+                    state.mirror.fix_indices(count);
+                    state.mirror.result = None;
+                }
+                MirrorField::Target => {
+                    state.mirror.target_idx = state.mirror.target_idx.checked_sub(1).unwrap_or(count - 1);
+                    state.mirror.fix_indices(count);
+                    state.mirror.result = None;
+                }
+                _ => {}
+            }
+        }
+        MouseEventKind::ScrollDown => {
+            match state.mirror.current_field() {
+                MirrorField::Source => {
+                    state.mirror.source_idx = (state.mirror.source_idx + 1) % count;
+                    state.mirror.fix_indices(count);
+                    state.mirror.result = None;
+                }
+                MirrorField::Target => {
+                    state.mirror.target_idx = (state.mirror.target_idx + 1) % count;
+                    state.mirror.fix_indices(count);
+                    state.mirror.result = None;
+                }
+                _ => {}
+            }
+        }
+        _ => {}
+    }
+}
+
+pub fn render(f: &mut Frame, area: Rect, state: &AppState) {
+    let count = state.monitors.len();
+
+    if count < 2 {
+        f.render_widget(
+            Paragraph::new("Need at least 2 monitors for mirror setup.")
+                .style(Style::default().fg(Color::DarkGray)),
+            area,
+        );
+        return;
+    }
+
+    let chunks = Layout::default()
+        .direction(Direction::Vertical)
+        .constraints([
+            Constraint::Length(4), // pickers
+            Constraint::Length(1), // compute button
+            Constraint::Min(0),    // result / hint
+        ])
+        .split(area);
+
+    render_pickers(f, chunks[0], state, count);
+    render_compute_btn(f, chunks[1], state);
+    if let Some(ref result) = state.mirror.result {
+        render_result(f, chunks[2], state, result);
+    } else {
+        let hint = Paragraph::new("  Press Enter on [Compute] to find the best matching modes.")
+            .style(Style::default().fg(Color::DarkGray));
+        f.render_widget(hint, chunks[2]);
+    }
+}
+
+fn render_pickers(f: &mut Frame, area: Rect, state: &AppState, count: usize) {
+    let src_name = state
+        .monitors
+        .get(state.mirror.source_idx.min(count - 1))
+        .map(|m| m.name.as_str())
+        .unwrap_or("?");
+    let tgt_name = state
+        .monitors
+        .get(state.mirror.target_idx.min(count - 1))
+        .map(|m| m.name.as_str())
+        .unwrap_or("?");
+
+    let focused = state.mirror.current_field();
+
+    let src_style = if focused == MirrorField::Source {
+        Style::default().fg(Color::Yellow).add_modifier(Modifier::BOLD)
+    } else {
+        Style::default().fg(Color::White)
+    };
+    let tgt_style = if focused == MirrorField::Target {
+        Style::default().fg(Color::Yellow).add_modifier(Modifier::BOLD)
+    } else {
+        Style::default().fg(Color::White)
+    };
+
+    let lines = vec![
+        Line::from(vec![
+            Span::raw("  Source  "),
+            Span::styled(format!("[ {} ]", src_name), src_style),
+            Span::raw("  (mirror this output)"),
+        ]),
+        Line::raw(""),
+        Line::from(vec![
+            Span::raw("  Target  "),
+            Span::styled(format!("[ {} ]", tgt_name), tgt_style),
+            Span::raw("  (the mirroring output)"),
+        ]),
+    ];
+
+    f.render_widget(Paragraph::new(lines), area);
+}
+
+fn render_compute_btn(f: &mut Frame, area: Rect, state: &AppState) {
+    let focused = state.mirror.current_field() == MirrorField::Compute;
+    let style = if focused {
+        Style::default().fg(Color::Yellow).add_modifier(Modifier::BOLD)
+    } else {
+        Style::default().fg(Color::DarkGray)
+    };
+    f.render_widget(
+        Paragraph::new("  [ Compute Best Match ]").style(style),
+        area,
+    );
+}
+
+fn render_result(f: &mut Frame, area: Rect, state: &AppState, result: &MirrorResult) {
+    let ar = result.ar_ratio;
+    let ar_label = if result.ar_exact {
+        format!("{}:{} (exact)", ar.0, ar.1)
+    } else {
+        format!("{}:{} (approx)", ar.0, ar.1)
+    };
+
+    let refresh_label = refresh_match_label(result);
+
+    let focused = state.mirror.current_field();
+    let apply_style = if focused == MirrorField::Apply {
+        Style::default().fg(Color::Green).add_modifier(Modifier::BOLD)
+    } else {
+        Style::default().fg(Color::White)
+    };
+    let cancel_style = if focused == MirrorField::Cancel {
+        Style::default().fg(Color::Yellow).add_modifier(Modifier::BOLD)
+    } else {
+        Style::default().fg(Color::DarkGray)
+    };
+
+    let lines = vec![
+        Line::raw(""),
+        Line::from(Span::styled(
+            format!("  Source mode:  {}  (AR {})", result.source_mode, ar_label),
+            Style::default().fg(Color::White),
+        )),
+        Line::from(Span::styled(
+            format!("  Mirror mode:  {}", result.mirror_mode),
+            Style::default().fg(Color::White),
+        )),
+        Line::from(Span::styled(
+            format!("  Refresh:      {:.2} Hz  ({})", result.refresh, refresh_label),
+            Style::default().fg(Color::White),
+        )),
+        Line::raw(""),
+        Line::from(vec![
+            Span::raw("  "),
+            Span::styled("[ Apply Mirror ]", apply_style),
+            Span::raw("   "),
+            Span::styled("[ Cancel ]", cancel_style),
+        ]),
+    ];
+
+    let block = Block::default()
+        .borders(Borders::ALL)
+        .border_style(Style::default().fg(Color::DarkGray))
+        .title(" Result ");
+
+    let inner = block.inner(area);
+    f.render_widget(block, area);
+    f.render_widget(Paragraph::new(lines), inner);
+}

src/ui/mod.rs

@@ -0,0 +1,322 @@
+pub mod config_view;
+pub mod layout_view;
+pub mod mirror_view;
+pub mod profiles_view;
+
+use std::time::Instant;
+
+use crossterm::event::{KeyCode, KeyEvent, KeyModifiers, MouseButton, MouseEvent, MouseEventKind};
+use ratatui::{
+    layout::{Constraint, Direction, Layout, Rect},
+    style::{Color, Modifier, Style},
+    text::{Line, Span},
+    widgets::{Block, Paragraph, Tabs},
+    Frame,
+};
+
+use crate::{
+    layout::LayoutState,
+    monitor::Monitor,
+};
+
+use config_view::ConfigState;
+use mirror_view::MirrorState;
+use profiles_view::ProfilesState;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Tab {
+    Layout,
+    Config,
+    Mirror,
+    Profiles,
+}
+
+impl Tab {
+    pub fn index(self) -> usize {
+        match self {
+            Self::Layout => 0,
+            Self::Config => 1,
+            Self::Mirror => 2,
+            Self::Profiles => 3,
+        }
+    }
+
+    fn from_col(col: u16) -> Option<Self> {
+        // Tab titles: " 1 Layout "(10), " 2 Config "(10), " 3 Mirror "(10), " 4 Profiles "(12)
+        // Each separated by a 1-char divider │
+        const WIDTHS: [u16; 4] = [10, 10, 10, 12];
+        let mut x = 0u16;
+        for (i, &w) in WIDTHS.iter().enumerate() {
+            if col >= x && col < x + w {
+                return Some(match i {
+                    0 => Self::Layout,
+                    1 => Self::Config,
+                    2 => Self::Mirror,
+                    3 => Self::Profiles,
+                    _ => unreachable!(),
+                });
+            }
+            x += w + 1;
+        }
+        None
+    }
+
+    fn hints(self) -> &'static str {
+        match self {
+            Self::Layout =>
+                " [hjkl/drag]move  [Tab]next  [Shift+hjkl]×10  [0]arrange  [Ctrl+Z]undo  [a]apply  [s]save",
+            Self::Config =>
+                " [jk]field  [hl]value  [,.]scale  [Enter]apply  [Esc]cancel  [\\[\\]]monitor  [Ctrl+Z]undo",
+            Self::Mirror =>
+                " [Tab]focus  [hl]cycle  [Enter]confirm  [Ctrl+Z]undo",
+            Self::Profiles =>
+                " [jk]nav  [Enter]load  [d×2]delete  [Tab]name  [Ctrl+Z]undo",
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum StatusLevel {
+    Info,
+    Success,
+    Error,
+}
+
+pub struct StatusMsg {
+    pub text: String,
+    pub level: StatusLevel,
+    pub born: Instant,
+}
+
+/// Drag state for moving monitors in the layout canvas.
+pub struct DragState {
+    pub monitor_idx: usize,
+    pub origin_x: i32,
+    pub origin_y: i32,
+    pub click_world_x: i32,
+    pub click_world_y: i32,
+}
+
+pub struct AppState {
+    pub monitors: Vec<Monitor>,
+    pub tab: Tab,
+    pub layout: LayoutState,
+    pub config: ConfigState,
+    pub mirror: MirrorState,
+    pub profiles: ProfilesState,
+    pub status: Option<StatusMsg>,
+    pub dirty: bool,
+    pub quit_confirm: bool,
+    pub drag_state: Option<DragState>,
+    pub terminal_size: (u16, u16),
+    /// Set to true by any handler that wants `main.rs` to run `apply_monitors`.
+    pub pending_apply: bool,
+    /// Snapshots for Ctrl+Z undo (up to 20 deep).
+    pub undo_stack: Vec<Vec<Monitor>>,
+}
+
+impl AppState {
+    pub fn new(monitors: Vec<Monitor>, terminal_size: (u16, u16)) -> Self {
+        let profiles_list = crate::profile::list().unwrap_or_default();
+        Self {
+            monitors,
+            tab: Tab::Layout,
+            layout: LayoutState::default(),
+            config: ConfigState::default(),
+            mirror: MirrorState::default(),
+            profiles: ProfilesState::new(profiles_list),
+            status: None,
+            dirty: false,
+            quit_confirm: false,
+            drag_state: None,
+            terminal_size,
+            pending_apply: false,
+            undo_stack: Vec::new(),
+        }
+    }
+
+    pub fn set_status(&mut self, text: impl Into<String>, level: StatusLevel) {
+        self.status = Some(StatusMsg { text: text.into(), level, born: Instant::now() });
+    }
+
+    pub fn tick_status(&mut self) {
+        if let Some(s) = &self.status {
+            if s.born.elapsed().as_secs() >= 3 {
+                self.status = None;
+            }
+        }
+    }
+
+    pub fn switch_tab(&mut self, tab: Tab) {
+        self.tab = tab;
+        if tab == Tab::Config {
+            self.config.sync_from_monitor(self.layout.selected, &self.monitors);
+        }
+    }
+
+    /// Save a monitor snapshot for undo (max 20 entries).
+    pub fn push_undo(&mut self) {
+        self.undo_stack.push(self.monitors.clone());
+        if self.undo_stack.len() > 20 {
+            self.undo_stack.remove(0);
+        }
+    }
+
+    /// Restore the most recent undo snapshot.
+    pub fn undo(&mut self) {
+        if let Some(snapshot) = self.undo_stack.pop() {
+            self.monitors = snapshot;
+            self.dirty = true;
+            self.layout.clamp_selected(self.monitors.len());
+            // Re-sync config view to the restored state
+            let idx = self.layout.selected;
+            self.config.sync_from_monitor(idx, &self.monitors);
+            self.set_status("Undone.", StatusLevel::Info);
+        } else {
+            self.set_status("Nothing to undo.", StatusLevel::Info);
+        }
+    }
+}
+
+/// Returns true if the app should continue running, false to quit.
+pub fn handle_key(event: KeyEvent, state: &mut AppState) -> bool {
+    // Quit
+    if event.code == KeyCode::Char('q')
+        || (event.code == KeyCode::Char('c') && event.modifiers.contains(KeyModifiers::CONTROL))
+    {
+        if state.dirty && !state.quit_confirm {
+            state.set_status("Unsaved changes. Press q again to quit.", StatusLevel::Info);
+            state.quit_confirm = true;
+            return true;
+        }
+        return false;
+    }
+    state.quit_confirm = false;
+
+    // Global: Ctrl+Z undo
+    if event.code == KeyCode::Char('z') && event.modifiers.contains(KeyModifiers::CONTROL) {
+        state.undo();
+        return true;
+    }
+
+    // Global tab switching
+    match event.code {
+        KeyCode::Char('1') | KeyCode::F(1) => { state.switch_tab(Tab::Layout); return true; }
+        KeyCode::Char('2') | KeyCode::F(2) => { state.switch_tab(Tab::Config); return true; }
+        KeyCode::Char('3') | KeyCode::F(3) => { state.switch_tab(Tab::Mirror); return true; }
+        KeyCode::Char('4') | KeyCode::F(4) => { state.switch_tab(Tab::Profiles); return true; }
+        _ => {}
+    }
+
+    match state.tab {
+        Tab::Layout => layout_view::handle_key(event, state),
+        Tab::Config => config_view::handle_key(event, state),
+        Tab::Mirror => mirror_view::handle_key(event, state),
+        Tab::Profiles => profiles_view::handle_key(event, state),
+    }
+
+    true
+}
+
+pub fn handle_mouse(event: MouseEvent, state: &mut AppState) {
+    let col = event.column;
+    let row = event.row;
+    let (_, th) = state.terminal_size;
+
+    // Tab bar: rows 0-1
+    if row < 2 {
+        if event.kind == MouseEventKind::Down(MouseButton::Left) {
+            if let Some(tab) = Tab::from_col(col) {
+                state.switch_tab(tab);
+            }
+        }
+        return;
+    }
+
+    // Bottom bar: last row
+    if row >= th.saturating_sub(1) {
+        return;
+    }
+
+    match state.tab {
+        Tab::Layout => layout_view::handle_mouse(event, state),
+        Tab::Config => config_view::handle_mouse(event, state),
+        Tab::Mirror => mirror_view::handle_mouse(event, state),
+        Tab::Profiles => profiles_view::handle_mouse(event, state),
+    }
+}
+
+pub fn render(f: &mut Frame, state: &AppState) {
+    let area = f.area();
+    let chunks = Layout::default()
+        .direction(Direction::Vertical)
+        .constraints([
+            Constraint::Length(2),
+            Constraint::Min(0),
+            Constraint::Length(1),
+        ])
+        .split(area);
+
+    render_tabs(f, chunks[0], state);
+
+    match state.tab {
+        Tab::Layout => layout_view::render(f, chunks[1], state),
+        Tab::Config => config_view::render(f, chunks[1], state),
+        Tab::Mirror => mirror_view::render(f, chunks[1], state),
+        Tab::Profiles => profiles_view::render(f, chunks[1], state),
+    }
+
+    render_bottom_bar(f, chunks[2], state);
+}
+
+fn render_tabs(f: &mut Frame, area: Rect, state: &AppState) {
+    let titles: Vec<Line> = vec![
+        Line::from(Span::raw(" 1 Layout ")),
+        Line::from(Span::raw(" 2 Config ")),
+        Line::from(Span::raw(" 3 Mirror ")),
+        Line::from(Span::raw(" 4 Profiles ")),
+    ];
+    let tabs = Tabs::new(titles)
+        .block(Block::default())
+        .select(state.tab.index())
+        .style(Style::default().fg(Color::DarkGray))
+        .highlight_style(
+            Style::default()
+                .fg(Color::Yellow)
+                .add_modifier(Modifier::BOLD),
+        )
+        .divider(Span::raw("│"));
+
+    f.render_widget(tabs, area);
+}
+
+fn render_bottom_bar(f: &mut Frame, area: Rect, state: &AppState) {
+    let dirty_marker = if state.dirty { " [modified]" } else { "" };
+    let hints = format!("{}{}  [q]uit", state.tab.hints(), dirty_marker);
+
+    let (status_text, status_style) = if let Some(msg) = &state.status {
+        let color = match msg.level {
+            StatusLevel::Info => Color::Cyan,
+            StatusLevel::Success => Color::Green,
+            StatusLevel::Error => Color::Red,
+        };
+        (format!("  {} ", msg.text), Style::default().fg(color))
+    } else {
+        (String::new(), Style::default())
+    };
+
+    let status_width = status_text.len() as u16;
+    let bar_chunks = Layout::default()
+        .direction(Direction::Horizontal)
+        .constraints([Constraint::Min(0), Constraint::Length(status_width)])
+        .split(area);
+
+    f.render_widget(
+        Paragraph::new(hints).style(Style::default().fg(Color::DarkGray)),
+        bar_chunks[0],
+    );
+    f.render_widget(
+        Paragraph::new(status_text).style(status_style),
+        bar_chunks[1],
+    );
+}

src/ui/profiles_view.rs

@@ -0,0 +1,381 @@
+use std::time::Instant;
+
+use crossterm::event::{KeyCode, KeyEvent, MouseButton, MouseEvent, MouseEventKind};
+use ratatui::{
+    layout::{Constraint, Direction, Layout, Rect},
+    style::{Color, Modifier, Style},
+    text::{Line, Span},
+    widgets::{Block, Borders, List, ListItem, ListState, Paragraph},
+    Frame,
+};
+
+use crate::{
+    profile,
+    ui::{AppState, StatusLevel},
+};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum ProfileField {
+    List,
+    NameInput,
+    SaveBtn,
+}
+
+pub struct ProfilesState {
+    pub profiles: Vec<String>,
+    pub selected_idx: usize,
+    pub new_name: String,
+    pub focused: ProfileField,
+    pub delete_confirm: Option<(String, Instant)>,
+}
+
+impl ProfilesState {
+    pub fn new(profiles: Vec<String>) -> Self {
+        Self {
+            profiles,
+            selected_idx: 0,
+            new_name: String::new(),
+            focused: ProfileField::List,
+            delete_confirm: None,
+        }
+    }
+
+    pub fn refresh(&mut self) {
+        self.profiles = profile::list().unwrap_or_default();
+        if self.selected_idx >= self.profiles.len() && !self.profiles.is_empty() {
+            self.selected_idx = self.profiles.len() - 1;
+        }
+    }
+
+    fn tick_delete_confirm(&mut self) {
+        if let Some((_, born)) = &self.delete_confirm {
+            if born.elapsed().as_secs() >= 3 {
+                self.delete_confirm = None;
+            }
+        }
+    }
+}
+
+pub fn handle_key(event: KeyEvent, state: &mut AppState) {
+    state.profiles.tick_delete_confirm();
+
+    match event.code {
+        KeyCode::Tab => {
+            state.profiles.focused = match state.profiles.focused {
+                ProfileField::List => ProfileField::NameInput,
+                ProfileField::NameInput => ProfileField::SaveBtn,
+                ProfileField::SaveBtn => ProfileField::List,
+            };
+        }
+        KeyCode::BackTab => {
+            state.profiles.focused = match state.profiles.focused {
+                ProfileField::List => ProfileField::SaveBtn,
+                ProfileField::NameInput => ProfileField::List,
+                ProfileField::SaveBtn => ProfileField::NameInput,
+            };
+        }
+        KeyCode::Esc => {
+            state.profiles.new_name.clear();
+            state.profiles.delete_confirm = None;
+            state.profiles.focused = ProfileField::List;
+        }
+        _ => match state.profiles.focused {
+            ProfileField::List => handle_list_key(event, state),
+            ProfileField::NameInput => handle_name_key(event, state),
+            ProfileField::SaveBtn => {
+                if event.code == KeyCode::Enter {
+                    do_save(state);
+                }
+            }
+        },
+    }
+}
+
+fn handle_list_key(event: KeyEvent, state: &mut AppState) {
+    let count = state.profiles.profiles.len();
+
+    match event.code {
+        KeyCode::Char('j') | KeyCode::Down => {
+            if count > 0 {
+                state.profiles.selected_idx = (state.profiles.selected_idx + 1) % count;
+            }
+        }
+        KeyCode::Char('k') | KeyCode::Up => {
+            if count > 0 {
+                state.profiles.selected_idx = state
+                    .profiles
+                    .selected_idx
+                    .checked_sub(1)
+                    .unwrap_or(count - 1);
+            }
+        }
+        KeyCode::Enter => {
+            if count > 0 {
+                state.push_undo();
+                do_load(state);
+            }
+        }
+        KeyCode::Char('d') => {
+            if count == 0 {
+                return;
+            }
+            let name = state.profiles.profiles[state.profiles.selected_idx].clone();
+            if let Some((pending, _)) = &state.profiles.delete_confirm {
+                if *pending == name {
+                    // Second press: confirm delete
+                    match profile::delete(&name) {
+                        Ok(()) => {
+                            state.profiles.refresh();
+                            state.set_status(format!("Deleted profile '{}'", name), StatusLevel::Success);
+                        }
+                        Err(e) => {
+                            state.set_status(format!("Delete failed: {}", e), StatusLevel::Error);
+                        }
+                    }
+                    state.profiles.delete_confirm = None;
+                    return;
+                }
+            }
+            state.profiles.delete_confirm = Some((name.clone(), Instant::now()));
+            state.set_status(
+                format!("Press d again to delete '{}' (3s to cancel)", name),
+                StatusLevel::Info,
+            );
+        }
+        _ => {}
+    }
+}
+
+pub fn handle_mouse(event: MouseEvent, state: &mut AppState) {
+    let row = event.row;
+    let col = event.column;
+    let (tw, th) = state.terminal_size;
+
+    // Layout in profiles view:
+    // Content area: y=2..th-2
+    // List: y=2, height = content_h - 3 (save row is Length(3))
+    // Save row: y = th - 4, height 3
+    let content_h = th.saturating_sub(3); // th - tab(2) - bottom(1)
+    let save_row_y = 2 + content_h.saturating_sub(3);
+    // List block: border at y=2, items start at y=3
+    let list_items_start = 3u16;
+
+    match event.kind {
+        MouseEventKind::Down(MouseButton::Left) => {
+            if row >= save_row_y {
+                // Clicked in save row
+                let save_btn_x = tw.saturating_sub(16);
+                if col >= save_btn_x {
+                    // Save button
+                    state.profiles.focused = ProfileField::SaveBtn;
+                    do_save(state);
+                } else {
+                    // Name input
+                    state.profiles.focused = ProfileField::NameInput;
+                }
+            } else if row >= list_items_start {
+                let item_idx = (row - list_items_start) as usize;
+                if item_idx < state.profiles.profiles.len() {
+                    state.profiles.focused = ProfileField::List;
+                    state.profiles.selected_idx = item_idx;
+                }
+            }
+        }
+        MouseEventKind::Down(MouseButton::Right) => {
+            // Right-click on a profile item = load it
+            if row >= list_items_start && row < save_row_y {
+                let item_idx = (row - list_items_start) as usize;
+                if item_idx < state.profiles.profiles.len() {
+                    state.profiles.selected_idx = item_idx;
+                    state.push_undo();
+                    do_load(state);
+                }
+            }
+        }
+        MouseEventKind::ScrollUp => {
+            let count = state.profiles.profiles.len();
+            if count > 0 {
+                state.profiles.selected_idx =
+                    state.profiles.selected_idx.checked_sub(1).unwrap_or(count - 1);
+                state.profiles.focused = ProfileField::List;
+            }
+        }
+        MouseEventKind::ScrollDown => {
+            let count = state.profiles.profiles.len();
+            if count > 0 {
+                state.profiles.selected_idx = (state.profiles.selected_idx + 1) % count;
+                state.profiles.focused = ProfileField::List;
+            }
+        }
+        _ => {}
+    }
+}
+
+fn handle_name_key(event: KeyEvent, state: &mut AppState) {
+    match event.code {
+        KeyCode::Char(c) => {
+            // Only allow alphanumeric, dash, underscore
+            if c.is_alphanumeric() || c == '-' || c == '_' {
+                state.profiles.new_name.push(c);
+            }
+        }
+        KeyCode::Backspace => {
+            state.profiles.new_name.pop();
+        }
+        KeyCode::Enter => {
+            do_save(state);
+        }
+        _ => {}
+    }
+}
+
+fn do_save(state: &mut AppState) {
+    let name = state.profiles.new_name.trim().to_owned();
+    if name.is_empty() {
+        state.set_status("Enter a profile name first.", StatusLevel::Info);
+        return;
+    }
+    let profile = profile::from_monitors(&name, &state.monitors);
+    match profile::save(&profile) {
+        Ok(()) => {
+            state.profiles.new_name.clear();
+            state.profiles.refresh();
+            state.set_status(format!("Saved profile '{}'", name), StatusLevel::Success);
+        }
+        Err(e) => {
+            state.set_status(format!("Save failed: {}", e), StatusLevel::Error);
+        }
+    }
+}
+
+fn do_load(state: &mut AppState) {
+    let name = state.profiles.profiles[state.profiles.selected_idx].clone();
+    match profile::load(&name) {
+        Ok(p) => {
+            profile::apply_to_monitors(&p, &mut state.monitors);
+            state.dirty = true;
+            state.set_status(
+                format!("Loaded profile '{}'. Press [a] to apply.", name),
+                StatusLevel::Success,
+            );
+        }
+        Err(e) => {
+            state.set_status(format!("Load failed: {}", e), StatusLevel::Error);
+        }
+    }
+}
+
+pub fn render(f: &mut Frame, area: Rect, state: &AppState) {
+    let chunks = Layout::default()
+        .direction(Direction::Vertical)
+        .constraints([
+            Constraint::Min(0),    // profile list
+            Constraint::Length(3), // name input + save button
+        ])
+        .split(area);
+
+    render_list(f, chunks[0], state);
+    render_save_row(f, chunks[1], state);
+}
+
+fn render_list(f: &mut Frame, area: Rect, state: &AppState) {
+    let profiles = &state.profiles.profiles;
+    let is_focused = state.profiles.focused == ProfileField::List;
+
+    let items: Vec<ListItem> = if profiles.is_empty() {
+        vec![ListItem::new(Line::from(Span::styled(
+            "  No profiles saved yet.",
+            Style::default().fg(Color::DarkGray),
+        )))]
+    } else {
+        profiles
+            .iter()
+            .enumerate()
+            .map(|(i, name)| {
+                let is_selected = i == state.profiles.selected_idx;
+                let pending_delete = state
+                    .profiles
+                    .delete_confirm
+                    .as_ref()
+                    .map(|(n, _)| n == name)
+                    .unwrap_or(false);
+
+                let style = if is_selected && is_focused {
+                    Style::default()
+                        .fg(Color::Yellow)
+                        .add_modifier(Modifier::BOLD)
+                        .bg(Color::DarkGray)
+                } else if is_selected {
+                    Style::default().fg(Color::White).add_modifier(Modifier::BOLD)
+                } else {
+                    Style::default().fg(Color::White)
+                };
+
+                let label = if pending_delete {
+                    format!("  {}  [d again to confirm delete]", name)
+                } else {
+                    format!("  {}", name)
+                };
+
+                ListItem::new(Line::from(Span::styled(label, style)))
+            })
+            .collect()
+    };
+
+    let block = Block::default()
+        .borders(Borders::ALL)
+        .border_style(if is_focused {
+            Style::default().fg(Color::Yellow)
+        } else {
+            Style::default().fg(Color::DarkGray)
+        })
+        .title(" Profiles  (Enter=load  d=delete) ");
+
+    let list = List::new(items).block(block);
+    let mut list_state = ListState::default();
+    if !profiles.is_empty() {
+        list_state.select(Some(state.profiles.selected_idx));
+    }
+    f.render_stateful_widget(list, area, &mut list_state);
+}
+
+fn render_save_row(f: &mut Frame, area: Rect, state: &AppState) {
+    let name_focused = state.profiles.focused == ProfileField::NameInput;
+    let save_focused = state.profiles.focused == ProfileField::SaveBtn;
+
+    let chunks = Layout::default()
+        .direction(Direction::Horizontal)
+        .constraints([Constraint::Min(0), Constraint::Length(16)])
+        .split(area);
+
+    // Name input
+    let input_display = if name_focused {
+        format!(" Profile name: {}|", state.profiles.new_name)
+    } else {
+        format!(" Profile name: {}", state.profiles.new_name)
+    };
+    let input_style = if name_focused {
+        Style::default().fg(Color::Yellow)
+    } else {
+        Style::default().fg(Color::DarkGray)
+    };
+    f.render_widget(
+        Paragraph::new(input_display)
+            .style(input_style)
+            .block(Block::default().borders(Borders::ALL).border_style(input_style)),
+        chunks[0],
+    );
+
+    // Save button
+    let save_style = if save_focused {
+        Style::default().fg(Color::Green).add_modifier(Modifier::BOLD)
+    } else {
+        Style::default().fg(Color::DarkGray)
+    };
+    f.render_widget(
+        Paragraph::new(" [ Save ] ")
+            .style(save_style)
+            .block(Block::default().borders(Borders::ALL).border_style(save_style)),
+        chunks[1],
+    );
+}