agent: wayland — evdev hotkey backend, download resume, SHA256 integrity

Add kon-hotkey crate with evdev-based global hotkey capture that works on
Wayland (and X11). Patterns from whisper-overlay: per-device async listeners,
inotify hotplug with udev permission retry, watch channel for live config
updates. Frontend detects Wayland at startup and selects evdev or
tauri-plugin-global-shortcut automatically.

Model downloads now support HTTP Range resume for interrupted downloads and
optional SHA256 integrity verification (incremental, no second pass).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

crates/core/src/model_registry.rs

@@ -40,6 +40,8 @@ pub struct ModelFile {
     pub filename: &'static str,
     pub url: &'static str,
     pub size: Megabytes,
+    /// SHA256 hex digest for integrity verification. None to skip check.
+    pub sha256: Option<&'static str>,
 }
 
 /// All metadata for a single downloadable model.
@@ -74,16 +76,19 @@ static ALL_MODELS: LazyLock<Vec<ModelEntry>> = LazyLock::new(|| {
                     filename: "encoder-model.onnx",
                     url: "https://huggingface.co/onnx-community/parakeet-ctc-0.6b-ONNX/resolve/main/onnx/model_int8.onnx",
                     size: Megabytes(1),
+                    sha256: None,
                 },
                 ModelFile {
                     filename: "model_int8.onnx_data",
                     url: "https://huggingface.co/onnx-community/parakeet-ctc-0.6b-ONNX/resolve/main/onnx/model_int8.onnx_data",
                     size: Megabytes(611),
+                    sha256: None,
                 },
                 ModelFile {
                     filename: "tokenizer.json",
                     url: "https://huggingface.co/onnx-community/parakeet-ctc-0.6b-ONNX/resolve/main/tokenizer.json",
                     size: Megabytes(1),
+                    sha256: None,
                 },
             ],
             description: "Fastest local model — near-instant transcription",
@@ -101,6 +106,7 @@ static ALL_MODELS: LazyLock<Vec<ModelEntry>> = LazyLock::new(|| {
                 filename: "ggml-tiny.en.bin",
                 url: "https://huggingface.co/ggerganov/whisper.cpp/resolve/main/ggml-tiny.en.bin",
                 size: Megabytes(75),
+                sha256: None,
             }],
             description: "Bundled with app — works instantly",
         },
@@ -117,6 +123,7 @@ static ALL_MODELS: LazyLock<Vec<ModelEntry>> = LazyLock::new(|| {
                 filename: "ggml-base.en.bin",
                 url: "https://huggingface.co/ggerganov/whisper.cpp/resolve/main/ggml-base.en.bin",
                 size: Megabytes(142),
+                sha256: None,
             }],
             description: "Good balance of speed and accuracy",
         },
@@ -133,6 +140,7 @@ static ALL_MODELS: LazyLock<Vec<ModelEntry>> = LazyLock::new(|| {
                 filename: "ggml-small.en.bin",
                 url: "https://huggingface.co/ggerganov/whisper.cpp/resolve/main/ggml-small.en.bin",
                 size: Megabytes(466),
+                sha256: None,
             }],
             description: "Accuracy-first English transcription",
         },
@@ -149,6 +157,7 @@ static ALL_MODELS: LazyLock<Vec<ModelEntry>> = LazyLock::new(|| {
                 filename: "ggml-medium.en.bin",
                 url: "https://huggingface.co/ggerganov/whisper.cpp/resolve/main/ggml-medium.en.bin",
                 size: Megabytes(1500),
+                sha256: None,
             }],
             description: "Best Whisper accuracy — needs 4+ GB RAM",
         },

crates/hotkey/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "kon-hotkey"
+version = "0.1.0"
+edition = "2021"
+description = "Wayland-compatible global hotkey listener for Kon — evdev backend with device hotplug"
+
+[dependencies]
+kon-core = { path = "../core" }
+tokio = { version = "1", features = ["rt", "sync", "macros", "time"] }
+serde = { version = "1", features = ["derive"] }
+log = "0.4"
+
+[target.'cfg(target_os = "linux")'.dependencies]
+evdev = { version = "0.12", features = ["tokio"] }
+notify = { version = "7", default-features = false, features = ["macos_fsevent"] }
+nix = { version = "0.29", features = ["fs"] }

crates/hotkey/src/lib.rs

@@ -0,0 +1,138 @@
+//! Wayland-compatible global hotkey listener for Kon.
+//!
+//! On Linux, reads `/dev/input/event*` devices via the `evdev` crate to capture
+//! global hotkeys without any display-server dependency. This works on both X11
+//! and Wayland, but requires the user to be in the `input` group (or have read
+//! access to `/dev/input/`).
+//!
+//! On non-Linux platforms, this crate is a no-op — the Tauri global-shortcut
+//! plugin handles hotkeys there.
+//!
+//! Architecture stolen from oddlama/whisper-overlay and adapted for Kon.
+
+#[cfg(target_os = "linux")]
+mod linux;
+
+#[cfg(target_os = "linux")]
+pub use linux::*;
+
+#[cfg(not(target_os = "linux"))]
+mod stub;
+
+#[cfg(not(target_os = "linux"))]
+pub use stub::*;
+
+use serde::{Deserialize, Serialize};
+
+/// A hotkey combination: one or more modifiers + a trigger key.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct HotkeyCombo {
+    pub ctrl: bool,
+    pub shift: bool,
+    pub alt: bool,
+    pub super_key: bool,
+    /// The evdev key code for the trigger key (e.g. KEY_R = 19).
+    /// On the frontend, this is mapped from the key name.
+    pub key_code: u16,
+    /// Human-readable label for display (e.g. "Ctrl+Shift+R").
+    pub label: String,
+}
+
+impl HotkeyCombo {
+    /// Parse a Tauri-style hotkey string like "Ctrl+Shift+R" into a HotkeyCombo.
+    /// Returns None if the string can't be parsed.
+    pub fn from_tauri_str(s: &str) -> Option<Self> {
+        let parts: Vec<&str> = s.split('+').map(|p| p.trim()).collect();
+        if parts.is_empty() {
+            return None;
+        }
+
+        let mut ctrl = false;
+        let mut shift = false;
+        let mut alt = false;
+        let mut super_key = false;
+        let mut trigger: Option<&str> = None;
+
+        for part in &parts {
+            match part.to_lowercase().as_str() {
+                "ctrl" | "control" => ctrl = true,
+                "shift" => shift = true,
+                "alt" => alt = true,
+                "super" | "meta" | "cmd" | "command" => super_key = true,
+                _ => trigger = Some(part),
+            }
+        }
+
+        let key_name = trigger?;
+        let key_code = key_name_to_evdev_code(key_name)?;
+
+        Some(Self {
+            ctrl,
+            shift,
+            alt,
+            super_key,
+            key_code,
+            label: s.to_string(),
+        })
+    }
+}
+
+/// Map a key name (from the frontend) to an evdev key code.
+/// Covers the keys likely to be used in hotkey combos.
+fn key_name_to_evdev_code(name: &str) -> Option<u16> {
+    // evdev key codes from linux/input-event-codes.h
+    Some(match name.to_uppercase().as_str() {
+        "A" => 30, "B" => 48, "C" => 46, "D" => 32, "E" => 18,
+        "F" => 33, "G" => 34, "H" => 35, "I" => 23, "J" => 36,
+        "K" => 37, "L" => 38, "M" => 50, "N" => 49, "O" => 24,
+        "P" => 25, "Q" => 16, "R" => 19, "S" => 31, "T" => 20,
+        "U" => 22, "V" => 47, "W" => 17, "X" => 45, "Y" => 21,
+        "Z" => 44,
+        "1" => 2, "2" => 3, "3" => 4, "4" => 5, "5" => 6,
+        "6" => 7, "7" => 8, "8" => 9, "9" => 10, "0" => 11,
+        "F1" => 59, "F2" => 60, "F3" => 61, "F4" => 62,
+        "F5" => 63, "F6" => 64, "F7" => 65, "F8" => 66,
+        "F9" => 67, "F10" => 68, "F11" => 87, "F12" => 88,
+        "SPACE" | " " => 57,
+        "ESCAPE" | "ESC" => 1,
+        "TAB" => 15,
+        "BACKSPACE" => 14,
+        "ENTER" | "RETURN" => 28,
+        "DELETE" => 111,
+        "HOME" => 102, "END" => 107,
+        "PAGEUP" => 104, "PAGEDOWN" => 109,
+        "UP" | "ARROWUP" => 103,
+        "DOWN" | "ARROWDOWN" => 108,
+        "LEFT" | "ARROWLEFT" => 105,
+        "RIGHT" | "ARROWRIGHT" => 106,
+        "INSERT" => 110,
+        "PAUSE" => 119,
+        "SCROLLLOCK" => 70,
+        "PRINTSCREEN" => 99,
+        "`" | "BACKQUOTE" => 41,
+        "-" | "MINUS" => 12,
+        "=" | "EQUAL" => 13,
+        "[" | "BRACKETLEFT" => 26,
+        "]" | "BRACKETRIGHT" => 27,
+        "\\" | "BACKSLASH" => 43,
+        ";" | "SEMICOLON" => 39,
+        "'" | "QUOTE" => 40,
+        "," | "COMMA" => 51,
+        "." | "PERIOD" => 52,
+        "/" | "SLASH" => 53,
+        _ => return None,
+    })
+}
+
+/// Check whether the current user can read evdev devices.
+/// Returns a diagnostic message if not.
+pub fn check_evdev_access() -> Result<(), String> {
+    #[cfg(target_os = "linux")]
+    {
+        linux::check_access()
+    }
+    #[cfg(not(target_os = "linux"))]
+    {
+        Err("evdev hotkeys are only supported on Linux".to_string())
+    }
+}

crates/hotkey/src/linux.rs

@@ -0,0 +1,333 @@
+//! Linux evdev-based global hotkey listener.
+//!
+//! Reads raw input events from `/dev/input/event*` devices. Works on both
+//! X11 and Wayland because it operates at the kernel level, bypassing the
+//! display server entirely.
+//!
+//! Key patterns stolen from oddlama/whisper-overlay:
+//! - Device hotplug via `notify` watching `/dev/input/`
+//! - Retry loop for udev permission propagation on new devices
+//! - Per-device async event streams
+
+use std::collections::HashSet;
+use std::path::{Path, PathBuf};
+use std::sync::Arc;
+
+use evdev::{Device, InputEventKind, Key};
+use notify::{recommended_watcher, EventKind, RecursiveMode, Watcher};
+use tokio::sync::{mpsc, watch, Mutex};
+
+use crate::HotkeyCombo;
+
+/// Events emitted by the hotkey listener.
+#[derive(Debug, Clone)]
+pub enum HotkeyEvent {
+    /// The configured hotkey was pressed.
+    Pressed,
+    /// The configured hotkey was released (useful for push-to-talk).
+    Released,
+}
+
+/// Manages evdev device listeners and hotplug detection.
+pub struct EvdevHotkeyListener {
+    /// Send a new hotkey config to all listener tasks.
+    hotkey_tx: watch::Sender<Option<HotkeyCombo>>,
+    /// Signals all tasks to shut down.
+    shutdown_tx: mpsc::Sender<()>,
+}
+
+impl EvdevHotkeyListener {
+    /// Start the hotkey listener. Returns the listener handle and a receiver
+    /// for hotkey events.
+    ///
+    /// The listener spawns:
+    /// 1. One async task per input device that has the target key
+    /// 2. A watcher task that detects new devices via inotify on `/dev/input/`
+    pub fn start(
+        combo: HotkeyCombo,
+        event_tx: mpsc::Sender<HotkeyEvent>,
+    ) -> Self {
+        let (hotkey_tx, hotkey_rx) = watch::channel(Some(combo));
+        let (shutdown_tx, mut shutdown_rx) = mpsc::channel::<()>(1);
+
+        let tracked = Arc::new(Mutex::new(HashSet::<PathBuf>::new()));
+
+        // Spawn initial device listeners
+        let hotkey_rx_clone = hotkey_rx.clone();
+        let event_tx_clone = event_tx.clone();
+        let tracked_clone = tracked.clone();
+        tokio::spawn(async move {
+            scan_and_attach(
+                &hotkey_rx_clone,
+                &event_tx_clone,
+                &tracked_clone,
+            )
+            .await;
+        });
+
+        // Spawn hotplug watcher
+        let hotkey_rx_hotplug = hotkey_rx.clone();
+        let event_tx_hotplug = event_tx.clone();
+        let tracked_hotplug = tracked.clone();
+        tokio::spawn(async move {
+            let (notify_tx, mut notify_rx) = mpsc::channel::<PathBuf>(32);
+
+            // notify watcher runs on a blocking thread internally
+            let _watcher = {
+                let notify_tx = notify_tx.clone();
+                let mut w = recommended_watcher(move |res: Result<notify::Event, _>| {
+                    if let Ok(event) = res {
+                        if matches!(event.kind, EventKind::Create(_)) {
+                            for path in event.paths {
+                                if is_event_device(&path) {
+                                    let _ = notify_tx.blocking_send(path);
+                                }
+                            }
+                        }
+                    }
+                })
+                .expect("failed to create inotify watcher");
+                w.watch(Path::new("/dev/input"), RecursiveMode::NonRecursive)
+                    .expect("failed to watch /dev/input");
+                w
+            };
+
+            loop {
+                tokio::select! {
+                    Some(path) = notify_rx.recv() => {
+                        // Retry opening with backoff — udev permissions propagate
+                        // asynchronously after device creation (whisper-overlay pattern)
+                        let hotkey_rx = hotkey_rx_hotplug.clone();
+                        let event_tx = event_tx_hotplug.clone();
+                        let tracked = tracked_hotplug.clone();
+                        tokio::spawn(async move {
+                            for attempt in 0..5 {
+                                if attempt > 0 {
+                                    tokio::time::sleep(
+                                        std::time::Duration::from_secs(1)
+                                    ).await;
+                                }
+                                if try_attach_device(
+                                    &path, &hotkey_rx, &event_tx, &tracked,
+                                ).await {
+                                    break;
+                                }
+                            }
+                        });
+                    }
+                    _ = shutdown_rx.recv() => break,
+                }
+            }
+        });
+
+        Self {
+            hotkey_tx,
+            shutdown_tx,
+        }
+    }
+
+    /// Update the hotkey combination. All device listeners pick up the
+    /// change via the watch channel.
+    pub fn set_hotkey(&self, combo: HotkeyCombo) {
+        let _ = self.hotkey_tx.send(Some(combo));
+    }
+
+    /// Stop all listeners and clean up.
+    pub async fn stop(&self) {
+        let _ = self.hotkey_tx.send(None);
+        let _ = self.shutdown_tx.send(()).await;
+    }
+}
+
+/// Check whether the user has access to evdev devices.
+pub fn check_access() -> Result<(), String> {
+    let input_dir = Path::new("/dev/input");
+    if !input_dir.exists() {
+        return Err("/dev/input does not exist".to_string());
+    }
+
+    // Try to open any event device
+    let entries = std::fs::read_dir(input_dir)
+        .map_err(|e| format!("Cannot read /dev/input: {e}"))?;
+
+    for entry in entries.flatten() {
+        let path = entry.path();
+        if is_event_device(&path) {
+            match Device::open(&path) {
+                Ok(_) => return Ok(()),
+                Err(e) => {
+                    if e.kind() == std::io::ErrorKind::PermissionDenied {
+                        return Err(format!(
+                            "Permission denied reading {}. \
+                             Add your user to the 'input' group: \
+                             sudo usermod -aG input $USER \
+                             (then log out and back in)",
+                            path.display()
+                        ));
+                    }
+                }
+            }
+        }
+    }
+
+    Err("No input devices found in /dev/input".to_string())
+}
+
+/// Scan all `/dev/input/event*` devices and attach listeners to any
+/// that support the target key.
+async fn scan_and_attach(
+    hotkey_rx: &watch::Receiver<Option<HotkeyCombo>>,
+    event_tx: &mpsc::Sender<HotkeyEvent>,
+    tracked: &Arc<Mutex<HashSet<PathBuf>>>,
+) {
+    let input_dir = Path::new("/dev/input");
+    let entries = match std::fs::read_dir(input_dir) {
+        Ok(e) => e,
+        Err(e) => {
+            log::error!("Cannot read /dev/input: {e}");
+            return;
+        }
+    };
+
+    for entry in entries.flatten() {
+        let path = entry.path();
+        if is_event_device(&path) {
+            try_attach_device(&path, hotkey_rx, event_tx, tracked).await;
+        }
+    }
+}
+
+/// Try to open a device and start listening if it supports the target key.
+/// Returns true if the device was successfully attached.
+async fn try_attach_device(
+    path: &Path,
+    hotkey_rx: &watch::Receiver<Option<HotkeyCombo>>,
+    event_tx: &mpsc::Sender<HotkeyEvent>,
+    tracked: &Arc<Mutex<HashSet<PathBuf>>>,
+) -> bool {
+    let mut tracked_set = tracked.lock().await;
+    if tracked_set.contains(path) {
+        return true;
+    }
+
+    let device = match Device::open(path) {
+        Ok(d) => d,
+        Err(e) => {
+            log::debug!("Cannot open {}: {e}", path.display());
+            return false;
+        }
+    };
+
+    // Check if this device has the keys we need
+    let supported = device.supported_keys();
+    let has_keys = supported.map_or(false, |keys| {
+        // Must support at least some keyboard keys
+        keys.contains(Key::KEY_A) || keys.contains(Key::KEY_R)
+    });
+
+    if !has_keys {
+        return false;
+    }
+
+    let device_name = device
+        .name()
+        .unwrap_or("unknown")
+        .to_string();
+    log::info!("Attached hotkey listener to: {} ({})", device_name, path.display());
+
+    tracked_set.insert(path.to_path_buf());
+    drop(tracked_set);
+
+    // Spawn a listener task for this device
+    let hotkey_rx = hotkey_rx.clone();
+    let event_tx = event_tx.clone();
+    let path_owned = path.to_path_buf();
+    let tracked = tracked.clone();
+
+    tokio::spawn(async move {
+        if let Err(e) = device_listener(device, hotkey_rx, event_tx).await {
+            log::warn!("Device listener for {} ended: {e}", path_owned.display());
+        }
+        // Remove from tracked set so hotplug can re-attach if reconnected
+        tracked.lock().await.remove(&path_owned);
+    });
+
+    true
+}
+
+/// Listen for events on a single device. Tracks modifier state and fires
+/// hotkey events when the combo matches.
+async fn device_listener(
+    device: Device,
+    mut hotkey_rx: watch::Receiver<Option<HotkeyCombo>>,
+    event_tx: mpsc::Sender<HotkeyEvent>,
+) -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
+    let mut stream = device.into_event_stream()?;
+
+    // Track modifier state
+    let mut ctrl_held = false;
+    let mut shift_held = false;
+    let mut alt_held = false;
+    let mut super_held = false;
+
+    loop {
+        tokio::select! {
+            result = stream.next_event() => {
+                let event = result?;
+
+                if let InputEventKind::Key(key) = event.kind() {
+                    let pressed = event.value() == 1; // 1 = press, 0 = release, 2 = repeat
+                    let released = event.value() == 0;
+
+                    // Update modifier state
+                    match key {
+                        Key::KEY_LEFTCTRL | Key::KEY_RIGHTCTRL => {
+                            ctrl_held = pressed || (!released && ctrl_held);
+                        }
+                        Key::KEY_LEFTSHIFT | Key::KEY_RIGHTSHIFT => {
+                            shift_held = pressed || (!released && shift_held);
+                        }
+                        Key::KEY_LEFTALT | Key::KEY_RIGHTALT => {
+                            alt_held = pressed || (!released && alt_held);
+                        }
+                        Key::KEY_LEFTMETA | Key::KEY_RIGHTMETA => {
+                            super_held = pressed || (!released && super_held);
+                        }
+                        trigger_key => {
+                            let combo = hotkey_rx.borrow().clone();
+                            if let Some(ref combo) = combo {
+                                let code = trigger_key.code();
+                                if code == combo.key_code
+                                    && ctrl_held == combo.ctrl
+                                    && shift_held == combo.shift
+                                    && alt_held == combo.alt
+                                    && super_held == combo.super_key
+                                {
+                                    if pressed {
+                                        let _ = event_tx.send(HotkeyEvent::Pressed).await;
+                                    } else if released {
+                                        let _ = event_tx.send(HotkeyEvent::Released).await;
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+            _ = hotkey_rx.changed() => {
+                // Hotkey config changed — if set to None, shut down
+                if hotkey_rx.borrow().is_none() {
+                    break;
+                }
+            }
+        }
+    }
+
+    Ok(())
+}
+
+fn is_event_device(path: &Path) -> bool {
+    path.file_name()
+        .and_then(|n| n.to_str())
+        .map_or(false, |n| n.starts_with("event"))
+}

crates/hotkey/src/stub.rs

@@ -0,0 +1,32 @@
+//! No-op stub for non-Linux platforms.
+//!
+//! On macOS and Windows, Tauri's global-shortcut plugin handles hotkeys
+//! natively. This stub exists so the crate compiles on all platforms.
+
+use tokio::sync::mpsc;
+
+use crate::HotkeyCombo;
+
+/// Events emitted by the hotkey listener.
+#[derive(Debug, Clone)]
+pub enum HotkeyEvent {
+    Pressed,
+    Released,
+}
+
+/// Stub listener that does nothing on non-Linux platforms.
+pub struct EvdevHotkeyListener;
+
+impl EvdevHotkeyListener {
+    pub fn start(
+        _combo: HotkeyCombo,
+        _event_tx: mpsc::Sender<HotkeyEvent>,
+    ) -> Self {
+        log::info!("evdev hotkey listener is a no-op on this platform");
+        Self
+    }
+
+    pub fn set_hotkey(&self, _combo: HotkeyCombo) {}
+
+    pub async fn stop(&self) {}
+}

crates/transcription/Cargo.toml

@@ -16,3 +16,6 @@ tokio = { version = "1", features = ["rt", "sync"] }
 # Model downloads
 reqwest = { version = "0.12", features = ["stream"] }
 futures-util = "0.3"
+
+# Download integrity verification
+sha2 = "0.10"

crates/transcription/src/model_manager.rs

@@ -76,6 +76,11 @@ pub async fn download(
     Ok(())
 }
 
+/// Download a single file with HTTP Range resume and optional SHA256 verification.
+///
+/// Resume pattern from Buzz (chidiwilliams/buzz): if a .part file exists,
+/// send a Range header to resume from where we left off. SHA256 is checked
+/// incrementally during download — no second pass over the file.
 async fn download_file(
     file: &ModelFile,
     dest: &Path,
@@ -83,6 +88,7 @@ async fn download_file(
     progress: &(impl Fn(DownloadProgress) + Send),
 ) -> Result<()> {
     use futures_util::StreamExt;
+    use sha2::{Digest, Sha256};
 
     let part_path = dest.with_extension(
         dest.extension()
@@ -95,23 +101,72 @@ async fn download_file(
         .build()
         .map_err(|e| KonError::DownloadFailed(e.to_string()))?;
 
-    let response = client
-        .get(file.url)
+    // Check for existing partial download (resume support)
+    let existing_bytes = if part_path.exists() {
+        std::fs::metadata(&part_path)
+            .map(|m| m.len())
+            .unwrap_or(0)
+    } else {
+        0
+    };
+
+    let mut request = client.get(file.url);
+
+    // If we have a partial file and no SHA256 to verify (can't verify partial),
+    // request a range resume. If SHA256 is set, we restart to ensure integrity.
+    let resuming = existing_bytes > 0 && file.sha256.is_none();
+    if resuming {
+        request = request.header("Range", format!("bytes={existing_bytes}-"));
+    }
+
+    let response = request
         .send()
         .await
         .map_err(|e| KonError::DownloadFailed(e.to_string()))?;
 
-    let total_bytes = response.content_length().unwrap_or(0);
+    // Check if server supports range (206 Partial Content) or gave full file (200)
+    let actually_resuming = resuming && response.status().as_u16() == 206;
+
+    let total_bytes = if actually_resuming {
+        // Content-Range: bytes START-END/TOTAL — extract TOTAL
+        response
+            .headers()
+            .get("content-range")
+            .and_then(|v| v.to_str().ok())
+            .and_then(|s| s.rsplit('/').next())
+            .and_then(|s| s.parse::<u64>().ok())
+            .unwrap_or(0)
+    } else {
+        response.content_length().unwrap_or(0)
+    };
+
     let mut stream = response.bytes_stream();
-    let mut downloaded: u64 = 0;
+    let mut downloaded: u64 = if actually_resuming { existing_bytes } else { 0 };
     let mut last_percent: u8 = 0;
 
-    let mut out = std::fs::File::create(&part_path)?;
+    // Open file for append (resume) or create (fresh start)
+    let mut out = if actually_resuming {
+        std::fs::OpenOptions::new()
+            .append(true)
+            .open(&part_path)?
+    } else {
+        std::fs::File::create(&part_path)?
+    };
+
+    // Incremental SHA256 — only when a checksum is provided
+    let mut hasher = file.sha256.map(|_| Sha256::new());
+
+    // If resuming without SHA256, we can't hash the already-downloaded portion,
+    // but we also don't need to — we only hash when sha256 is set, and we
+    // restart from scratch in that case.
 
     while let Some(chunk) = stream.next().await {
         let chunk = chunk
             .map_err(|e| KonError::DownloadFailed(e.to_string()))?;
         std::io::Write::write_all(&mut out, &chunk)?;
+        if let Some(ref mut h) = hasher {
+            h.update(&chunk);
+        }
         downloaded += chunk.len() as u64;
 
         let percent = if total_bytes > 0 {
@@ -133,6 +188,21 @@ async fn download_file(
     }
 
     drop(out);
+
+    // Verify SHA256 if provided
+    if let (Some(expected), Some(hasher)) = (file.sha256, hasher) {
+        let actual = format!("{:x}", hasher.finalize());
+        if actual != expected {
+            // Delete corrupt file so next attempt starts fresh
+            let _ = std::fs::remove_file(&part_path);
+            return Err(KonError::DownloadFailed(format!(
+                "SHA256 mismatch for {}: expected {}, got {}",
+                file.filename, expected, actual
+            )));
+        }
+    }
+
+    // Atomic rename — file is complete and verified
     std::fs::rename(&part_path, dest)?;
 
     Ok(())

src-tauri/Cargo.toml

@@ -20,6 +20,7 @@ kon-transcription = { path = "../crates/transcription" }
 kon-ai-formatting = { path = "../crates/ai-formatting" }
 kon-storage = { path = "../crates/storage" }
 kon-cloud-providers = { path = "../crates/cloud-providers" }
+kon-hotkey = { path = "../crates/hotkey" }
 
 # Tauri
 tauri = { version = "2", features = ["tray-icon"] }

src-tauri/src/commands/hotkey.rs

@@ -0,0 +1,107 @@
+use std::sync::Arc;
+
+use tauri::Emitter;
+use tokio::sync::{mpsc, Mutex};
+
+use kon_hotkey::{EvdevHotkeyListener, HotkeyCombo, HotkeyEvent};
+
+/// Managed state for the evdev hotkey listener.
+pub struct HotkeyState {
+    listener: Arc<Mutex<Option<EvdevHotkeyListener>>>,
+}
+
+impl HotkeyState {
+    pub fn new() -> Self {
+        Self {
+            listener: Arc::new(Mutex::new(None)),
+        }
+    }
+}
+
+/// Check whether the current session is running on Wayland.
+#[tauri::command]
+pub fn is_wayland_session() -> bool {
+    std::env::var("WAYLAND_DISPLAY").is_ok()
+        || std::env::var("XDG_SESSION_TYPE")
+            .map(|v| v == "wayland")
+            .unwrap_or(false)
+}
+
+/// Check whether evdev hotkey capture is available (user in `input` group, etc.).
+#[tauri::command]
+pub fn check_hotkey_access() -> Result<(), String> {
+    kon_hotkey::check_evdev_access()
+}
+
+/// Start the evdev global hotkey listener. Emits "kon:hotkey-pressed" and
+/// "kon:hotkey-released" events to the frontend.
+///
+/// If a listener is already running, it is stopped first.
+#[tauri::command]
+pub async fn start_evdev_hotkey(
+    app: tauri::AppHandle,
+    state: tauri::State<'_, HotkeyState>,
+    hotkey: String,
+) -> Result<(), String> {
+    let combo = HotkeyCombo::from_tauri_str(&hotkey)
+        .ok_or_else(|| format!("Cannot parse hotkey: {hotkey}"))?;
+
+    // Stop existing listener if any
+    let mut guard = state.listener.lock().await;
+    if let Some(existing) = guard.take() {
+        existing.stop().await;
+    }
+
+    let (event_tx, mut event_rx) = mpsc::channel::<HotkeyEvent>(64);
+    let listener = EvdevHotkeyListener::start(combo, event_tx);
+
+    *guard = Some(listener);
+    drop(guard);
+
+    // Forward evdev events to Tauri event bus
+    let app_clone = app.clone();
+    tokio::spawn(async move {
+        while let Some(event) = event_rx.recv().await {
+            match event {
+                HotkeyEvent::Pressed => {
+                    let _ = app_clone.emit("kon:hotkey-pressed", ());
+                }
+                HotkeyEvent::Released => {
+                    let _ = app_clone.emit("kon:hotkey-released", ());
+                }
+            }
+        }
+    });
+
+    Ok(())
+}
+
+/// Update the hotkey combo on a running listener.
+#[tauri::command]
+pub async fn update_evdev_hotkey(
+    state: tauri::State<'_, HotkeyState>,
+    hotkey: String,
+) -> Result<(), String> {
+    let combo = HotkeyCombo::from_tauri_str(&hotkey)
+        .ok_or_else(|| format!("Cannot parse hotkey: {hotkey}"))?;
+
+    let guard = state.listener.lock().await;
+    if let Some(ref listener) = *guard {
+        listener.set_hotkey(combo);
+        Ok(())
+    } else {
+        Err("Hotkey listener not running".to_string())
+    }
+}
+
+/// Stop the evdev hotkey listener.
+#[tauri::command]
+pub async fn stop_evdev_hotkey(
+    state: tauri::State<'_, HotkeyState>,
+) -> Result<(), String> {
+    let mut guard = state.listener.lock().await;
+    if let Some(listener) = guard.take() {
+        listener.stop().await;
+    }
+    Ok(())
+}

src-tauri/src/commands/mod.rs

@@ -1,6 +1,7 @@
 pub mod audio;
 pub mod clipboard;
 pub mod hardware;
+pub mod hotkey;
 pub mod models;
 pub mod transcription;
 pub mod windows;

src-tauri/src/lib.rs

@@ -107,6 +107,8 @@ pub fn run() {
             // Store init script for secondary windows (float, viewer)
             app.manage(PreferencesScript(init_script));
 
+            app.manage(commands::hotkey::HotkeyState::new());
+
             app.manage(AppState {
                 whisper_engine: Arc::new(LocalEngine::new(
                     EngineName::new("whisper"),
@@ -152,6 +154,12 @@ pub fn run() {
             // Hardware
             commands::hardware::probe_system,
             commands::hardware::rank_models,
+            // Hotkey (evdev — Wayland-compatible)
+            commands::hotkey::is_wayland_session,
+            commands::hotkey::check_hotkey_access,
+            commands::hotkey::start_evdev_hotkey,
+            commands::hotkey::update_evdev_hotkey,
+            commands::hotkey::stop_evdev_hotkey,
         ])
         .run(tauri::generate_context!())
         .expect("error while running Kon");

src/routes/+layout.svelte

@@ -41,29 +41,89 @@
     }
   });
 
-  // Global hotkey registration
+  // Global hotkey registration — dual backend
+  // Wayland: evdev via kon-hotkey crate (works without display server)
+  // X11/macOS/Windows: tauri-plugin-global-shortcut (native)
   let registeredHotkey = null;
+  let hotkeyBackend = $state("unknown"); // "evdev" | "tauri" | "unavailable"
+
+  async function initHotkeyBackend() {
+    try {
+      const isWayland = await invoke("is_wayland_session");
+      if (isWayland) {
+        // Try evdev backend first (Wayland-compatible)
+        try {
+          await invoke("check_hotkey_access");
+          hotkeyBackend = "evdev";
+          console.log("Hotkey backend: evdev (Wayland)");
+        } catch (err) {
+          console.warn("evdev hotkey access denied:", err);
+          console.warn("Add your user to the 'input' group for global hotkeys on Wayland");
+          hotkeyBackend = "unavailable";
+        }
+      } else {
+        hotkeyBackend = "tauri";
+        console.log("Hotkey backend: tauri-plugin-global-shortcut (X11)");
+      }
+    } catch {
+      // Fallback to tauri plugin if detection fails
+      hotkeyBackend = "tauri";
+    }
+  }
 
   async function registerGlobalHotkey(hotkey) {
+    if (hotkeyBackend === "unknown") return; // not yet initialised
+
     try {
-      const mod = await import("@tauri-apps/plugin-global-shortcut");
-      if (registeredHotkey) {
-        await mod.unregister(registeredHotkey).catch(() => {});
-      }
-      await mod.register(hotkey, () => {
-        if (page.current !== "dictation") page.current = "dictation";
-        requestAnimationFrame(() => {
-          window.dispatchEvent(new CustomEvent("kon:toggle-recording"));
+      if (hotkeyBackend === "evdev") {
+        // evdev backend: start or update the Rust-side listener
+        if (registeredHotkey) {
+          await invoke("update_evdev_hotkey", { hotkey });
+        } else {
+          await invoke("start_evdev_hotkey", { hotkey });
+        }
+        registeredHotkey = hotkey;
+      } else if (hotkeyBackend === "tauri") {
+        // Tauri plugin backend (X11/macOS/Windows)
+        const mod = await import("@tauri-apps/plugin-global-shortcut");
+        if (registeredHotkey) {
+          await mod.unregister(registeredHotkey).catch(() => {});
+        }
+        await mod.register(hotkey, () => {
+          if (page.current !== "dictation") page.current = "dictation";
+          requestAnimationFrame(() => {
+            window.dispatchEvent(new CustomEvent("kon:toggle-recording"));
+          });
         });
-      });
-      registeredHotkey = hotkey;
+        registeredHotkey = hotkey;
+      }
     } catch (err) {
       console.error("Hotkey registration failed:", err);
     }
   }
 
+  // Listen for evdev hotkey events from the Rust backend
+  let unlistenEvdev = null;
+  async function setupEvdevListener() {
+    const { listen } = await import("@tauri-apps/api/event");
+    unlistenEvdev = await listen("kon:hotkey-pressed", () => {
+      if (page.current !== "dictation") page.current = "dictation";
+      requestAnimationFrame(() => {
+        window.dispatchEvent(new CustomEvent("kon:toggle-recording"));
+      });
+    });
+  }
+
   $effect(() => {
-    registerGlobalHotkey(settings.globalHotkey);
+    if (hotkeyBackend === "evdev" && !unlistenEvdev) {
+      setupEvdevListener();
+    }
+  });
+
+  $effect(() => {
+    if (hotkeyBackend !== "unknown") {
+      registerGlobalHotkey(settings.globalHotkey);
+    }
   });
 
   // Apply font size setting as CSS variable (legacy — kept for backwards compat)
@@ -100,6 +160,9 @@
     handleResize();
     window.addEventListener("resize", handleResize);
 
+    // Detect and initialise the correct hotkey backend
+    await initHotkeyBackend();
+
     try {
       const whisper = await invoke("list_models");
       const parakeet = await invoke("list_parakeet_models");
@@ -113,11 +176,16 @@
 
   onDestroy(() => {
     window.removeEventListener("resize", handleResize);
-    if (registeredHotkey) {
+    if (hotkeyBackend === "evdev") {
+      invoke("stop_evdev_hotkey").catch(() => {});
+    } else if (hotkeyBackend === "tauri" && registeredHotkey) {
       import("@tauri-apps/plugin-global-shortcut")
         .then((mod) => mod.unregister(registeredHotkey))
         .catch(() => {});
     }
+    if (unlistenEvdev) {
+      unlistenEvdev();
+    }
   });
 </script>