openlogi_core/

binding.rs

//! Logical mouse button identifiers and the action vocabulary each one can
//! bind to. Lives in `openlogi-core` because the [`config`](crate::config)
//! schema serializes these directly — the GUI re-exports them.
//!
//! When [`Action`] gains new variants, keep the existing variant names stable:
//! the TOML config keys/values use the enum variant identifiers verbatim, so
//! renames are migration events.

use std::collections::BTreeMap;
use std::fmt;
use std::time::Instant;

use serde::{Deserialize, Serialize};

/// One of the user-rebindable hotspots on a Logi mouse. The order matches the
/// physical layout from front to side; [`ButtonId::ALL`] is consumed by the
/// default-binding generator and the popover trigger list.
#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, PartialOrd, Ord, Serialize, Deserialize)]
pub enum ButtonId {
    LeftClick,
    RightClick,
    MiddleClick,
    Back,
    Forward,
    /// The "ModeShift" button under the wheel — typically used for SmartShift /
    /// DPI cycle. Named `DpiToggle` for historical reasons.
    DpiToggle,
    /// The horizontal thumb wheel's click. Kept in [`ButtonId::ALL`] so its
    /// default still seeds and dispatches when the wheel is diverted, even
    /// though the mouse model surfaces the two rotation directions instead of
    /// the click (see `mouse_model::geometry`).
    Thumbwheel,
    /// Rotating the thumb wheel "up" (positive rotation). Bound, by default, to
    /// continuous horizontal scroll; see the agent-core `watchers`-side dispatch.
    ThumbwheelScrollUp,
    /// Rotating the thumb wheel "down" (negative rotation).
    ThumbwheelScrollDown,
    /// The thumb-pad gesture button on MX-line devices. The press itself
    /// fires the bound action; swipe directions are P1.5 territory.
    GestureButton,
}

impl ButtonId {
    pub const ALL: [ButtonId; 10] = [
        ButtonId::LeftClick,
        ButtonId::RightClick,
        ButtonId::MiddleClick,
        ButtonId::Back,
        ButtonId::Forward,
        ButtonId::DpiToggle,
        ButtonId::Thumbwheel,
        ButtonId::ThumbwheelScrollUp,
        ButtonId::ThumbwheelScrollDown,
        ButtonId::GestureButton,
    ];

    /// Whether this button is one the OS hook (macOS `CGEventTap` / Linux evdev)
    /// remaps: Middle, Back, or Forward. The primary L/R clicks always pass
    /// through (suppressing them would brick the mouse), and the DPI / thumb /
    /// dedicated gesture controls aren't visible to the OS hook at all (they're
    /// captured over HID++). These are exactly the buttons that can become an
    /// OS-hook gesture button, so the hook's remap gate and the gesture-owner
    /// projection share this one definition.
    #[must_use]
    pub fn is_os_hook_button(self) -> bool {
        matches!(
            self,
            ButtonId::MiddleClick | ButtonId::Back | ButtonId::Forward
        )
    }

    /// Human-readable label for popovers and tooltips.
    #[must_use]
    pub fn label(self) -> &'static str {
        match self {
            ButtonId::LeftClick => "Left Click",
            ButtonId::RightClick => "Right Click",
            ButtonId::MiddleClick => "Middle Click",
            ButtonId::Back => "Back",
            ButtonId::Forward => "Forward",
            ButtonId::DpiToggle => "DPI Toggle",
            ButtonId::Thumbwheel => "Thumb Wheel",
            ButtonId::ThumbwheelScrollUp => "Thumb Wheel Up",
            ButtonId::ThumbwheelScrollDown => "Thumb Wheel Down",
            ButtonId::GestureButton => "Gesture Button",
        }
    }
}

impl fmt::Display for ButtonId {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.write_str(self.label())
    }
}

/// One of the five sub-bindings on the gesture button: hold + swipe up/down/
/// left/right or a plain click without movement. Logi ships these as
/// independent assignments (`SLOT_NAME_GESTURE_*_BUTTON` in the
/// `device_gesture_buttons_image` metadata block) — OpenLogi mirrors the
/// same shape.
///
/// Variant identifiers are TOML-stable: renames are migration events.
#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, PartialOrd, Ord, Serialize, Deserialize)]
pub enum GestureDirection {
    Up,
    Down,
    Left,
    Right,
    Click,
}

impl GestureDirection {
    pub const ALL: [GestureDirection; 5] = [
        GestureDirection::Up,
        GestureDirection::Down,
        GestureDirection::Left,
        GestureDirection::Right,
        GestureDirection::Click,
    ];

    #[must_use]
    pub fn label(self) -> &'static str {
        match self {
            GestureDirection::Up => "Up",
            GestureDirection::Down => "Down",
            GestureDirection::Left => "Left",
            GestureDirection::Right => "Right",
            GestureDirection::Click => "Click",
        }
    }

    /// Arrow glyph for compact list rendering.
    #[must_use]
    pub fn glyph(self) -> &'static str {
        match self {
            GestureDirection::Up => "↑",
            GestureDirection::Down => "↓",
            GestureDirection::Left => "←",
            GestureDirection::Right => "→",
            GestureDirection::Click => "·",
        }
    }
}

impl fmt::Display for GestureDirection {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.write_str(self.label())
    }
}

/// Minimum dominant-axis travel (raw-XY units) before a held gesture commits to
/// a direction. Tuned to match Logitech Options+'s responsiveness.
pub const GESTURE_SWIPE_THRESHOLD: i32 = 50;
/// Maximum cross-axis travel allowed at the threshold, so only a reasonably
/// straight swipe commits. Grows with the dominant axis (`max(deadzone, 35%)`).
pub const GESTURE_SWIPE_DEADZONE: i32 = 40;
/// Minimum time a gesture button must be held before its travel can commit to a
/// swipe. Distinguishes a deliberate hold-and-swipe from a quick click whose
/// cursor happened to be moving. Shared by both gesture paths (the HID++ thumb
/// pad and the OS-hook Middle/Back/Forward).
pub const GESTURE_HOLD_FOR_SWIPE: std::time::Duration = std::time::Duration::from_millis(160);

/// Classify the *running* raw-XY travel of a held gesture button into a
/// directional swipe, the instant it commits — or `None` while it's still too
/// short or too diagonal.
///
/// The dominant axis must pass [`GESTURE_SWIPE_THRESHOLD`] while the cross axis
/// stays within `max(`[`GESTURE_SWIPE_DEADZONE`]`, 35% of dominant)`. Callers
/// fire the bound action the moment this returns `Some` — mid-swipe, like
/// Options+ — rather than waiting for the button release; a press that never
/// commits a direction is treated as [`GestureDirection::Click`] on release.
///
/// Coordinates follow the device's raw-XY convention (`+x` = right, `+y` =
/// down), so an upward swipe (negative `dy`) maps to [`GestureDirection::Up`].
#[must_use]
pub fn detect_swipe(dx: i32, dy: i32) -> Option<GestureDirection> {
    // Saturating throughout: a [`SwipeAccumulator`] hold that never commits (a
    // sustained diagonal) keeps summing travel, so `dx`/`dy` can reach the i32
    // bounds. `i32::MIN.abs()` would panic and a plain `dominant * 35` would
    // overflow — and a panic in the input-hook callback is exactly the freeze
    // hazard we must never hit. The clamp is inert in the normal range.
    let (abs_x, abs_y) = (dx.saturating_abs(), dy.saturating_abs());
    let dominant = abs_x.max(abs_y);
    if dominant < GESTURE_SWIPE_THRESHOLD {
        return None;
    }
    let cross_limit = GESTURE_SWIPE_DEADZONE.max(dominant.saturating_mul(35) / 100);
    if abs_x > abs_y {
        if abs_y > cross_limit {
            return None;
        }
        Some(if dx > 0 {
            GestureDirection::Right
        } else {
            GestureDirection::Left
        })
    } else {
        if abs_x > cross_limit {
            return None;
        }
        Some(if dy > 0 {
            GestureDirection::Down
        } else {
            GestureDirection::Up
        })
    }
}

/// The mid-swipe state machine shared by both gesture-capture paths: the HID++
/// thumb pad (`openlogi-hid`'s `0x1b04` raw-XY divert) and the OS-hook
/// Middle/Back/Forward buttons (`openlogi-agent-core`'s CGEventTap). A gesture
/// button's hold accumulates travel; the instant the dominant axis commits a
/// direction — after the button has been held [`GESTURE_HOLD_FOR_SWIPE`], so a
/// quick click whose cursor drifted doesn't count — [`Self::accumulate`] returns
/// that direction exactly once, like Logitech Options+. A hold that never
/// commits is a plain click, reported by [`Self::end`].
///
/// The two paths differ only in *what identifies the held control* (a
/// [`ButtonId`] for the OS hook, a diverted CID for the thumb pad), so each owns
/// that and embeds this for the shared travel logic. Keeping the logic in one
/// place is deliberate: the two copies it replaced had already drifted apart
/// (one resolved a swipe only on release), which mis-fired the click.
#[derive(Debug, Default)]
pub struct SwipeAccumulator {
    /// When the current hold began, or `None` when not holding. Gates a
    /// deliberate swipe against a quick click whose cursor happened to move.
    held_since: Option<Instant>,
    /// Accumulated raw-XY travel since the hold began (saturating, so an
    /// arbitrarily long hold can never overflow).
    dx: i32,
    dy: i32,
    /// Set once a direction has committed this hold, so it fires exactly once
    /// and the release isn't then also read as a click.
    fired: bool,
}

impl SwipeAccumulator {
    /// Begin a fresh hold, resetting the travel accumulator and commit state.
    pub fn begin(&mut self) {
        self.held_since = Some(Instant::now());
        self.dx = 0;
        self.dy = 0;
        self.fired = false;
    }

    /// Whether a hold is in progress (between [`Self::begin`] and [`Self::end`]),
    /// so callers can do rising/falling-edge detection without a second flag.
    #[must_use]
    pub fn is_holding(&self) -> bool {
        self.held_since.is_some()
    }

    /// Feed a pointer-move / raw-XY delta into the current hold. Returns
    /// `Some(direction)` exactly once per hold — the instant travel commits, and
    /// only after the hold passes [`GESTURE_HOLD_FOR_SWIPE`] — and `None` while
    /// still too short, already committed, or not holding.
    pub fn accumulate(&mut self, dx: i32, dy: i32) -> Option<GestureDirection> {
        if self.fired || self.held_since.is_none() {
            return None;
        }
        self.dx = self.dx.saturating_add(dx);
        self.dy = self.dy.saturating_add(dy);
        let held_long_enough = self
            .held_since
            .is_some_and(|t| t.elapsed() >= GESTURE_HOLD_FOR_SWIPE);
        if held_long_enough && let Some(dir) = detect_swipe(self.dx, self.dy) {
            self.fired = true;
            return Some(dir);
        }
        None
    }

    /// End the current hold. Returns `true` when an in-progress hold ended
    /// without committing a swipe — the caller should fire the plain `Click`
    /// action — and `false` when a swipe already fired mid-motion, or when there
    /// was no hold to end (a stray release reports no click).
    pub fn end(&mut self) -> bool {
        let was_click = self.held_since.is_some() && !self.fired;
        self.held_since = None;
        was_click
    }

    /// Test-only seam: backdate the current hold so its [`GESTURE_HOLD_FOR_SWIPE`]
    /// gate is already satisfied, letting a test exercise a committed swipe
    /// without sleeping. Real code never calls this — [`Self::begin`] records the
    /// true start instant. A no-op when not currently holding.
    #[doc(hidden)]
    pub fn backdate_hold_for_test(&mut self) {
        if self.held_since.is_some() {
            self.held_since = Instant::now().checked_sub(GESTURE_HOLD_FOR_SWIPE * 2);
        }
    }
}

/// Grouping for popover section headers.
///
/// Used by [`Action::category`] and rendered as a small muted label above
/// each group in the action picker.
#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
pub enum Category {
    /// Cut, copy, paste, undo, redo, select-all, find, save.
    Editing,
    /// Browser navigation: tabs, page reload, back/forward.
    Browser,
    /// Playback and volume controls.
    Media,
    /// Physical mouse clicks.
    Mouse,
    /// DPI cycle and SmartShift.
    Dpi,
    /// Scroll direction shortcuts.
    Scroll,
    /// Window/app navigation: Mission Control, Launchpad, etc.
    Navigation,
    /// Lock screen, show desktop, system-level actions.
    System,
}

impl Category {
    /// Short label for popover section headers (already uppercase so callers
    /// don't have to transform it).
    #[must_use]
    pub fn label(self) -> &'static str {
        match self {
            Category::Editing => "EDITING",
            Category::Browser => "BROWSER",
            Category::Media => "MEDIA",
            Category::Mouse => "MOUSE",
            Category::Dpi => "DPI",
            Category::Scroll => "SCROLL",
            Category::Navigation => "NAVIGATION",
            Category::System => "SYSTEM",
        }
    }
}

/// What pressing a [`ButtonId`] should do.
///
/// Serialization uses serde's default external tagging: unit variants
/// serialize as a bare string (`"BrowserBack"`) and the tuple variant
/// serializes as a single-key table (`{ CustomShortcut = "my chord" }`).
///
/// **Stability contract:** existing variant *names* are frozen — they form the
/// on-disk `config.toml` schema. New variants may be appended freely; removing
/// or renaming a variant requires a `schema_version` bump and a migration.
///
/// This type is pure config data: OS-level event synthesis for each variant
/// lives in the `openlogi-inject` crate (`openlogi_inject::execute`), keeping
/// this crate platform- and IO-free.
#[derive(Clone, Debug, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub enum Action {
    // ── System ───────────────────────────────────────────────────────────────
    /// Suppress the input entirely — the button or wheel direction is captured
    /// but no OS event is synthesised, so the physical input does nothing.
    None,

    // ── Mouse ────────────────────────────────────────────────────────────────
    /// Primary mouse button.
    LeftClick,
    /// Secondary mouse button.
    RightClick,
    /// Middle mouse button (wheel click).
    MiddleClick,
    /// Mouse "back" side button (extra button 4). Synthesizes the real mouse
    /// button event, which browsers and most apps interpret as "navigate back"
    /// natively — unlike [`Action::BrowserBack`], which sends ⌘[ and is ignored
    /// by many apps.
    MouseBack,
    /// Mouse "forward" side button (extra button 5). Native counterpart to
    /// [`Action::MouseBack`]; see [`Action::BrowserForward`] for the ⌘] form.
    MouseForward,

    // ── Editing ──────────────────────────────────────────────────────────────
    /// Copy the current selection (⌘C / Ctrl+C).
    Copy,
    /// Paste from the clipboard (⌘V / Ctrl+V).
    Paste,
    /// Cut the current selection (⌘X / Ctrl+X).
    Cut,
    /// Undo the last action (⌘Z / Ctrl+Z).
    Undo,
    /// Redo the last undone action (⌘⇧Z on macOS / Ctrl+Shift+Z on Linux).
    ///
    /// Note: Ctrl+Y is the dominant redo shortcut in LibreOffice and many GTK
    /// apps. Ctrl+Shift+Z is used here because it mirrors the macOS convention
    /// and works in GNOME text fields, browsers, and Electron apps. If Ctrl+Y
    /// coverage is needed, a `CustomShortcut` binding is the escape hatch.
    Redo,
    /// Select all content (⌘A / Ctrl+A).
    SelectAll,
    /// Open the find / search bar (⌘F / Ctrl+F).
    Find,
    /// Save the current document (⌘S / Ctrl+S).
    Save,

    // ── Browser / Navigation ──────────────────────────────────────────────────
    /// Navigate backward in browser history.
    BrowserBack,
    /// Navigate forward in browser history.
    BrowserForward,
    /// Open a new tab (⌘T / Ctrl+T).
    NewTab,
    /// Close the current tab (⌘W / Ctrl+W).
    CloseTab,
    /// Reopen the last closed tab (⌘⇧T / Ctrl+Shift+T).
    ReopenTab,
    /// Switch to the next tab (⌃⇥ / Ctrl+Tab).
    NextTab,
    /// Switch to the previous tab (⌃⇧⇥ / Ctrl+Shift+Tab).
    PrevTab,
    /// Reload the current page (⌘R / Ctrl+R).
    ReloadPage,

    // ── Navigation / Window ───────────────────────────────────────────────────
    /// macOS Mission Control (⌃↑).
    MissionControl,
    /// macOS App Exposé — all windows for the current app (⌃↓).
    AppExpose,
    /// Switch to the previous desktop / Space.
    PreviousDesktop,
    /// Switch to the next desktop / Space.
    NextDesktop,
    /// Show the desktop (hide all windows).
    ShowDesktop,
    /// Open Launchpad.
    LaunchpadShow,

    // ── System ────────────────────────────────────────────────────────────────
    /// Lock the screen (⌘⌃Q on macOS).
    ///
    /// On Linux, calls `org.freedesktop.login1.Manager.LockSession($XDG_SESSION_ID)`
    /// on the system bus (current session only). Falls back to Super+L when
    /// `$XDG_SESSION_ID` is unset or on non-systemd systems.
    LockScreen,
    /// Capture a screenshot.
    Screenshot,

    // ── Media ────────────────────────────────────────────────────────────────
    /// Toggle media play/pause.
    PlayPause,
    /// Skip to the next track.
    NextTrack,
    /// Go back to the previous track.
    PrevTrack,
    /// Increase system volume.
    VolumeUp,
    /// Decrease system volume.
    VolumeDown,
    /// Toggle system mute.
    MuteVolume,

    // ── DPI ──────────────────────────────────────────────────────────────────
    /// Step through the configured DPI preset list (P1.7).
    CycleDpiPresets,
    /// Jump to a specific zero-based preset in the device's DPI preset list.
    /// Out-of-range indices clamp to the list length at fire time (P1.7).
    SetDpiPreset(u8),
    /// Toggle the HID++ SmartShift ratchet/free-spin wheel mode (P1.1).
    ToggleSmartShift,

    // ── Scroll ───────────────────────────────────────────────────────────────
    /// Synthesise a vertical scroll-up tick.
    ScrollUp,
    /// Synthesise a vertical scroll-down tick.
    ScrollDown,
    /// Synthesise a horizontal scroll-left tick.
    HorizontalScrollLeft,
    /// Synthesise a horizontal scroll-right tick.
    HorizontalScrollRight,

    // ── Custom ───────────────────────────────────────────────────────────────
    /// Replay an arbitrary recorded key chord (P1.3).
    ///
    /// Holds the structured chord data so `openlogi_inject::execute` can post the
    /// real keystroke (macOS: CGEventPost with the encoded modifier flags).
    /// The `display` field is used by [`Action::label`] so the popover
    /// shows the user-friendly chord name.
    CustomShortcut(KeyCombo),
}

/// A modifier + virtual-key keystroke captured by the P1.3 recorder UI or
/// hand-authored in `config.toml`.
///
/// `modifiers` is a bitmask of [`KeyCombo::MOD_CMD`] etc. so the wire format
/// is a compact integer, not a string. `key_code` is the macOS virtual key
/// (`kVK_*`); on Linux, `openlogi-inject` maps it to an evdev `KeyCode` when it
/// synthesizes the chord.
///
/// `display` is purely for rendering — e.g. `"⌘⇧P"`. Callers regenerate it
/// from the captured chord; we keep it in the struct so older configs
/// continue to render the same label without re-deriving on every load.
#[derive(Clone, Debug, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub struct KeyCombo {
    /// Bitmask of [`Self::MOD_CMD`] etc.
    pub modifiers: u8,
    /// macOS virtual key code (`kVK_*`). 0 means "no key" — useful for
    /// modifier-only placeholders that the recorder UI rejects. On Linux,
    /// `openlogi-inject` translates this to an evdev `KeyCode`.
    pub key_code: u16,
    /// Pre-rendered chord label, e.g. `"⌘⇧P"`. Empty falls through to a
    /// generated label at runtime.
    #[serde(default)]
    pub display: String,
}

impl KeyCombo {
    pub const MOD_CMD: u8 = 1 << 0;
    pub const MOD_SHIFT: u8 = 1 << 1;
    pub const MOD_CTRL: u8 = 1 << 2;
    pub const MOD_OPTION: u8 = 1 << 3;

    /// Build the human-readable label from the modifier bitmask + key code.
    /// Falls back to `"⌘key 0xNN"` when the key code isn't one of the
    /// commonly-recognised letters; the recorder UI usually overrides this
    /// with its own derivation.
    #[must_use]
    pub fn rendered_label(&self) -> String {
        if !self.display.is_empty() {
            return self.display.clone();
        }
        let mut out = String::new();
        if self.modifiers & Self::MOD_CTRL != 0 {
            out.push('⌃');
        }
        if self.modifiers & Self::MOD_OPTION != 0 {
            out.push('⌥');
        }
        if self.modifiers & Self::MOD_SHIFT != 0 {
            out.push('⇧');
        }
        if self.modifiers & Self::MOD_CMD != 0 {
            out.push('⌘');
        }
        match self.key_code {
            0x00 => out.push('A'),
            0x01 => out.push('S'),
            0x02 => out.push('D'),
            0x03 => out.push('F'),
            0x06 => out.push('Z'),
            0x07 => out.push('X'),
            0x08 => out.push('C'),
            0x09 => out.push('V'),
            0x0B => out.push('B'),
            0x0C => out.push('Q'),
            0x0D => out.push('W'),
            0x0E => out.push('E'),
            0x0F => out.push('R'),
            0x10 => out.push('Y'),
            0x11 => out.push('T'),
            0x20 => out.push('U'),
            0x22 => out.push('I'),
            0x1F => out.push('O'),
            0x23 => out.push('P'),
            _ => {
                use std::fmt::Write as _;
                let _ = write!(out, "key 0x{:02X}", self.key_code);
            }
        }
        out
    }
}

/// What a single rebindable [`ButtonId`] does: either one [`Action`], or — for a
/// raw-XY-capable button placed in gesture mode — a per-[`GestureDirection`]
/// map (hold + swipe up/down/left/right, or a plain click).
///
/// There has only ever been one binding map per device; a gesture binding is
/// just a binding whose payload is a direction map instead of a single action.
///
/// # Serialization
///
/// `#[serde(untagged)]`: [`Single`](Binding::Single) serializes exactly as the
/// bare [`Action`] did before (a string `"BrowserBack"`, or a single-key table
/// for the payload variants), and [`Gesture`](Binding::Gesture) serializes as a
/// table keyed by [`GestureDirection`] names (`Up`/`Down`/`Left`/`Right`/
/// `Click`).
///
/// The two arms are disambiguated by the **zero overlap** between [`Action`]
/// variant names and [`GestureDirection`] variant names — untagged tries
/// `Single(Action)` first, and a table keyed by `Up` etc. cannot parse as an
/// externally-tagged `Action`, so it falls through to `Gesture`. A payload
/// action like `{ SetDpiPreset = 2 }` is a valid externally-tagged `Action`, so
/// it stays `Single` and never reaches the `Gesture` arm. This invariant is the
/// entire safety basis for untagged routing; the `binding_untagged_*` tests
/// guard it (a future `Action` named `Up`/`Down`/`Left`/`Right`/`Click` would
/// silently mis-route, and those tests would fail).
#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
#[serde(untagged)]
pub enum Binding {
    /// One action, fired on press. The shape every non-gesture button uses.
    Single(Action),
    /// Per-direction sub-bindings for a button in gesture mode. Keyed by the
    /// committed swipe direction, with [`GestureDirection::Click`] holding the
    /// plain-click (no-swipe) action.
    Gesture(BTreeMap<GestureDirection, Action>),
}

impl Binding {
    /// The plain-click action for this binding: the [`Single`](Binding::Single)
    /// action, or the [`Gesture`](Binding::Gesture) map's
    /// [`Click`](GestureDirection::Click) entry. Falls back to [`Action::None`]
    /// when a gesture binding has no explicit `Click`.
    ///
    /// Lets the click-dispatch path stay binding-shape-agnostic.
    #[must_use]
    pub fn click_action(&self) -> Action {
        match self {
            Binding::Single(action) => action.clone(),
            Binding::Gesture(map) => map
                .get(&GestureDirection::Click)
                .cloned()
                .unwrap_or(Action::None),
        }
    }

    /// The action bound to `direction`, if this is a gesture binding.
    /// [`Single`](Binding::Single) has no directions and returns `None`.
    #[must_use]
    pub fn direction_action(&self, direction: GestureDirection) -> Option<&Action> {
        match self {
            Binding::Single(_) => None,
            Binding::Gesture(map) => map.get(&direction),
        }
    }

    /// Whether this binding drives raw-XY swipe capture (the
    /// [`Gesture`](Binding::Gesture) arm).
    #[must_use]
    pub fn is_gesture(&self) -> bool {
        matches!(self, Binding::Gesture(_))
    }

    /// Promote a [`Single`](Binding::Single) binding in place to a
    /// [`Gesture`](Binding::Gesture), keeping its action as the
    /// [`GestureDirection::Click`] entry and leaving the swipe arms unbound.
    /// A no-op when this is already a [`Gesture`](Binding::Gesture).
    pub fn upgrade_to_gesture(&mut self) {
        if let Binding::Single(action) = self {
            let mut map = BTreeMap::new();
            map.insert(GestureDirection::Click, action.clone());
            *self = Binding::Gesture(map);
        }
    }

    /// Fill any unbound directions of a [`Gesture`](Binding::Gesture) binding
    /// with their canonical [`default_gesture_binding`], so a button promoted to
    /// the gesture role always exposes the full five-direction set — rather than
    /// leaving swipe arms the GUI renders as defaults but the runtime never
    /// dispatches. A no-op on [`Single`](Binding::Single) and on directions
    /// already bound (existing user choices are preserved).
    pub fn fill_gesture_defaults(&mut self) {
        if let Binding::Gesture(map) = self {
            for dir in GestureDirection::ALL {
                map.entry(dir)
                    .or_insert_with(|| default_gesture_binding(dir));
            }
        }
    }
}

impl From<Action> for Binding {
    fn from(action: Action) -> Self {
        Binding::Single(action)
    }
}

impl Action {
    /// Display label for the popover row.
    ///
    /// Returns `String` rather than `&str` so parameterized variants (e.g.
    /// `SetDpiPreset(i)`, `CustomShortcut(s)`) can build a label that
    /// includes their payload.
    #[must_use]
    pub fn label(&self) -> String {
        match self {
            Action::None => "Do Nothing".into(),
            Action::LeftClick => "Left Click".into(),
            Action::RightClick => "Right Click".into(),
            Action::MiddleClick => "Middle Click".into(),
            Action::MouseBack => "Back (Button 4)".into(),
            Action::MouseForward => "Forward (Button 5)".into(),
            Action::Copy => "Copy".into(),
            Action::Paste => "Paste".into(),
            Action::Cut => "Cut".into(),
            Action::Undo => "Undo".into(),
            Action::Redo => "Redo".into(),
            Action::SelectAll => "Select All".into(),
            Action::Find => "Find".into(),
            Action::Save => "Save".into(),
            Action::BrowserBack => "Browser Back".into(),
            Action::BrowserForward => "Browser Forward".into(),
            Action::NewTab => "New Tab".into(),
            Action::CloseTab => "Close Tab".into(),
            Action::ReopenTab => "Reopen Tab".into(),
            Action::NextTab => "Next Tab".into(),
            Action::PrevTab => "Previous Tab".into(),
            Action::ReloadPage => "Reload Page".into(),
            Action::MissionControl => "Mission Control".into(),
            Action::AppExpose => "App Exposé".into(),
            Action::PreviousDesktop => "Previous Desktop".into(),
            Action::NextDesktop => "Next Desktop".into(),
            Action::ShowDesktop => "Show Desktop".into(),
            Action::LaunchpadShow => "Launchpad".into(),
            Action::LockScreen => "Lock Screen".into(),
            Action::Screenshot => "Screenshot".into(),
            Action::PlayPause => "Play / Pause".into(),
            Action::NextTrack => "Next Track".into(),
            Action::PrevTrack => "Previous Track".into(),
            Action::VolumeUp => "Volume Up".into(),
            Action::VolumeDown => "Volume Down".into(),
            Action::MuteVolume => "Mute".into(),
            Action::CycleDpiPresets => "Cycle DPI Presets".into(),
            Action::SetDpiPreset(i) => format!("DPI Preset {}", i + 1),
            Action::ToggleSmartShift => "Toggle SmartShift".into(),
            Action::ScrollUp => "Scroll Up".into(),
            Action::ScrollDown => "Scroll Down".into(),
            Action::HorizontalScrollLeft => "Scroll Left".into(),
            Action::HorizontalScrollRight => "Scroll Right".into(),
            Action::CustomShortcut(combo) => combo.rendered_label(),
        }
    }

    /// Which [`Category`] this action belongs to, used for popover grouping.
    #[must_use]
    pub fn category(&self) -> Category {
        match self {
            Action::LeftClick
            | Action::RightClick
            | Action::MiddleClick
            | Action::MouseBack
            | Action::MouseForward => Category::Mouse,
            // CustomShortcut is assigned to Editing so it doesn't need a
            // separate arm (it's not in the picker catalog).
            Action::Copy
            | Action::Paste
            | Action::Cut
            | Action::Undo
            | Action::Redo
            | Action::SelectAll
            | Action::Find
            | Action::Save
            | Action::CustomShortcut(_) => Category::Editing,
            Action::BrowserBack
            | Action::BrowserForward
            | Action::NewTab
            | Action::CloseTab
            | Action::ReopenTab
            | Action::NextTab
            | Action::PrevTab
            | Action::ReloadPage => Category::Browser,
            Action::MissionControl
            | Action::AppExpose
            | Action::PreviousDesktop
            | Action::NextDesktop
            | Action::ShowDesktop
            | Action::LaunchpadShow => Category::Navigation,
            Action::None | Action::LockScreen | Action::Screenshot => Category::System,
            Action::PlayPause
            | Action::NextTrack
            | Action::PrevTrack
            | Action::VolumeUp
            | Action::VolumeDown
            | Action::MuteVolume => Category::Media,
            Action::CycleDpiPresets | Action::SetDpiPreset(_) | Action::ToggleSmartShift => {
                Category::Dpi
            }
            Action::ScrollUp
            | Action::ScrollDown
            | Action::HorizontalScrollLeft
            | Action::HorizontalScrollRight => Category::Scroll,
        }
    }

    /// All pickable actions in a deterministic order.
    ///
    /// [`Action::CustomShortcut`] is intentionally excluded — it is opened via
    /// "Record shortcut…" (P1.3), not selected from the catalog.
    #[must_use]
    pub fn catalog() -> Vec<Action> {
        vec![
            // Mouse
            Action::LeftClick,
            Action::RightClick,
            Action::MiddleClick,
            Action::MouseBack,
            Action::MouseForward,
            // Editing
            Action::Copy,
            Action::Paste,
            Action::Cut,
            Action::Undo,
            Action::Redo,
            Action::SelectAll,
            Action::Find,
            Action::Save,
            // Browser
            Action::BrowserBack,
            Action::BrowserForward,
            Action::NewTab,
            Action::CloseTab,
            Action::ReopenTab,
            Action::NextTab,
            Action::PrevTab,
            Action::ReloadPage,
            // Navigation
            Action::MissionControl,
            Action::AppExpose,
            Action::PreviousDesktop,
            Action::NextDesktop,
            Action::ShowDesktop,
            Action::LaunchpadShow,
            // System
            Action::None,
            Action::LockScreen,
            Action::Screenshot,
            // Media
            Action::PlayPause,
            Action::NextTrack,
            Action::PrevTrack,
            Action::VolumeUp,
            Action::VolumeDown,
            Action::MuteVolume,
            // DPI
            Action::CycleDpiPresets,
            Action::ToggleSmartShift,
            // Scroll
            Action::ScrollUp,
            Action::ScrollDown,
            Action::HorizontalScrollLeft,
            Action::HorizontalScrollRight,
        ]
    }
}

/// Sensible defaults for a fresh device so the panel isn't empty on first run.
///
/// Thumbwheel / GestureButton defaults match what Logi Options+ ships for
/// MX-line devices: thumb wheel click → App Exposé, gesture button →
/// Mission Control. The thumb wheel isn't captured yet; the gesture button is
/// (per-direction, see [`default_gesture_binding`]). The bindings persist
/// regardless so the user only configures once.
///
/// `GestureButton`'s entry here is vestigial: in the merged [`Binding`] model
/// the gesture button defaults to [`Binding::Gesture`] (see
/// [`default_binding_for`]), so this single-action value is never the source of
/// truth for it. It is retained only so the per-button-`Action` callers (the
/// hook map, scroll defaults, labels) stay total.
#[must_use]
pub fn default_binding(button: ButtonId) -> Action {
    match button {
        ButtonId::LeftClick => Action::LeftClick,
        ButtonId::RightClick => Action::RightClick,
        ButtonId::MiddleClick => Action::MiddleClick,
        ButtonId::Back => Action::BrowserBack,
        ButtonId::Forward => Action::BrowserForward,
        ButtonId::DpiToggle => Action::CycleDpiPresets,
        ButtonId::Thumbwheel => Action::AppExpose,
        // The thumb wheel scrolls horizontally by default: rotating it produces
        // continuous horizontal scroll, with "up" → right and "down" → left.
        // The wheel watcher renders these two actions as smooth, sensitivity-
        // scaled scrolling rather than the discrete per-press burst a button
        // would get (see `watchers::gesture`).
        ButtonId::ThumbwheelScrollUp => Action::HorizontalScrollRight,
        ButtonId::ThumbwheelScrollDown => Action::HorizontalScrollLeft,
        ButtonId::GestureButton => Action::MissionControl,
    }
}

/// Per-direction defaults for the gesture button. These are captured live over
/// HID++ `0x1b04` (raw-XY diversion) and dispatched like any other binding; the
/// defaults give the picker something sensible to show on first run.
#[must_use]
pub fn default_gesture_binding(direction: GestureDirection) -> Action {
    match direction {
        GestureDirection::Up => Action::MissionControl,
        GestureDirection::Down => Action::ShowDesktop,
        GestureDirection::Left => Action::PrevTab,
        GestureDirection::Right => Action::NextTab,
        GestureDirection::Click => Action::AppExpose,
    }
}

/// The canonical default [`Binding`] for a fresh button in the merged model.
///
/// [`ButtonId::GestureButton`] defaults to [`Binding::Gesture`] populated from
/// [`default_gesture_binding`] — preserving the existing per-direction swipe
/// behavior — so the GUI mode toggle and the runtime agree it starts in gesture
/// mode. Every other button defaults to [`Binding::Single`] of its
/// [`default_binding`].
///
/// This is the seed when a button is first promoted to a gesture binding (see
/// [`Config::set_gesture_direction`](crate::config::Config::set_gesture_direction)),
/// so a freshly-customized gesture button always carries a full default
/// direction map — including a [`GestureDirection::Click`] — rather than a sparse
/// map whose click would project to a no-op [`Action::None`].
#[must_use]
pub fn default_binding_for(button: ButtonId) -> Binding {
    match button {
        ButtonId::GestureButton => Binding::Gesture(
            GestureDirection::ALL
                .into_iter()
                .map(|d| (d, default_gesture_binding(d)))
                .collect(),
        ),
        other => Binding::Single(default_binding(other)),
    }
}

#[cfg(test)]
#[allow(clippy::expect_used, reason = "expect/unwrap are idiomatic in tests")]
mod tests {
    use std::collections::BTreeMap;

    use serde::{Deserialize, Serialize};

    use super::*;

    // ── Roundtrip wrapper: defined here so it precedes any `let` statements ──

    /// Minimal TOML-serializable wrapper used by `roundtrip`.
    /// Defined at module scope to satisfy `clippy::items_after_statements`.
    #[derive(Serialize, Deserialize)]
    struct RoundtripWrapper {
        binding: BTreeMap<ButtonId, Action>,
    }

    // ── Catalog tests ─────────────────────────────────────────────────────────

    #[test]
    fn catalog_has_at_least_29_entries() {
        let catalog = Action::catalog();
        assert!(
            catalog.len() >= 29,
            "catalog has {} entries, need ≥ 29",
            catalog.len()
        );
    }

    #[test]
    fn catalog_excludes_custom_shortcut() {
        let catalog = Action::catalog();
        for action in &catalog {
            assert!(
                !matches!(action, Action::CustomShortcut(_)),
                "catalog must not contain CustomShortcut"
            );
        }
    }

    // ── Binding (merged model) serde routing ──────────────────────────────────

    /// On-disk shape: a `ButtonId` → [`Binding`] map, as `DeviceConfig.bindings`
    /// serializes it.
    #[derive(Serialize, Deserialize)]
    struct BindingWrapper {
        bindings: BTreeMap<ButtonId, Binding>,
    }

    fn binding_roundtrip(bindings: BTreeMap<ButtonId, Binding>) -> BTreeMap<ButtonId, Binding> {
        let toml = toml::to_string_pretty(&BindingWrapper { bindings }).expect("serialize");
        toml::from_str::<BindingWrapper>(&toml)
            .expect("deserialize")
            .bindings
    }

    #[test]
    fn binding_single_roundtrips_including_payload_variants() {
        let mut bindings = BTreeMap::new();
        bindings.insert(ButtonId::Back, Binding::Single(Action::BrowserBack));
        bindings.insert(
            ButtonId::DpiToggle,
            Binding::Single(Action::SetDpiPreset(2)),
        );
        bindings.insert(
            ButtonId::Forward,
            Binding::Single(Action::CustomShortcut(KeyCombo {
                modifiers: KeyCombo::MOD_CMD,
                key_code: 0x23,
                display: "⌘P".into(),
            })),
        );
        let back = binding_roundtrip(bindings);
        assert_eq!(back[&ButtonId::Back], Binding::Single(Action::BrowserBack));
        assert_eq!(
            back[&ButtonId::DpiToggle],
            Binding::Single(Action::SetDpiPreset(2))
        );
        assert!(matches!(
            back[&ButtonId::Forward],
            Binding::Single(Action::CustomShortcut(_))
        ));
    }

    #[test]
    fn binding_gesture_roundtrips() {
        let mut map = BTreeMap::new();
        map.insert(GestureDirection::Up, Action::Copy);
        map.insert(GestureDirection::Click, Action::Paste);
        let mut bindings = BTreeMap::new();
        bindings.insert(ButtonId::GestureButton, Binding::Gesture(map.clone()));
        let back = binding_roundtrip(bindings);
        assert_eq!(back[&ButtonId::GestureButton], Binding::Gesture(map));
    }

    /// The untagged-routing safety guard. A TOML table keyed by ANY
    /// [`GestureDirection`] name must deserialize as [`Binding::Gesture`], never
    /// [`Binding::Single`]. If a future [`Action`] payload variant is ever named
    /// `Up`/`Down`/`Left`/`Right`/`Click`, the table would parse as `Single`
    /// first and this test fails — catching the silent mis-route at CI time.
    #[test]
    fn binding_direction_keyed_table_routes_to_gesture() {
        for dir in GestureDirection::ALL {
            // `GestureDirection`'s serde key equals its `Display`/variant name.
            let toml = format!("bindings.GestureButton.{dir} = \"None\"");
            let parsed = toml::from_str::<BindingWrapper>(&toml).expect("deserialize");
            assert!(
                matches!(
                    parsed.bindings[&ButtonId::GestureButton],
                    Binding::Gesture(_)
                ),
                "a {dir}-keyed table must route to Gesture, not Single"
            );
        }
    }

    /// The collision case: a payload [`Action`] also serializes as a single-key
    /// table, but untagged must keep it [`Binding::Single`] (it parses as a valid
    /// externally-tagged `Action` before the `Gesture` arm is tried).
    #[test]
    fn binding_payload_action_stays_single() {
        let toml = "bindings.DpiToggle.SetDpiPreset = 2";
        let parsed = toml::from_str::<BindingWrapper>(toml).expect("deserialize");
        assert_eq!(
            parsed.bindings[&ButtonId::DpiToggle],
            Binding::Single(Action::SetDpiPreset(2))
        );
    }

    // ── Gesture classification ────────────────────────────────────────────────

    #[test]
    fn detect_swipe_below_threshold_keeps_accumulating() {
        // Too little travel to commit — caller keeps summing raw-XY.
        assert_eq!(detect_swipe(40, 5), None);
        assert_eq!(detect_swipe(0, 0), None);
    }

    #[test]
    fn detect_swipe_commits_clean_direction() {
        assert_eq!(detect_swipe(120, 5), Some(GestureDirection::Right));
        assert_eq!(detect_swipe(-120, 5), Some(GestureDirection::Left));
        assert_eq!(detect_swipe(5, 120), Some(GestureDirection::Down));
        assert_eq!(detect_swipe(5, -120), Some(GestureDirection::Up));
    }

    #[test]
    fn detect_swipe_rejects_diagonal() {
        // Past the threshold but too diagonal (cross axis beyond the band).
        assert_eq!(detect_swipe(60, 60), None);
        assert_eq!(detect_swipe(-60, -60), None);
    }

    #[test]
    fn detect_swipe_threshold_and_cross_band_boundaries() {
        // The threshold bound is inclusive (`< THRESHOLD` rejects), so exactly at
        // it commits and one below does not.
        assert_eq!(
            detect_swipe(GESTURE_SWIPE_THRESHOLD, 0),
            Some(GestureDirection::Right)
        );
        assert_eq!(detect_swipe(GESTURE_SWIPE_THRESHOLD - 1, 0), None);

        // The cross-axis band is max(deadzone, 35% of dominant). For a large
        // dominant the 35% term wins (200 → 70): 69 commits, 71 is too diagonal.
        assert_eq!(detect_swipe(200, 69), Some(GestureDirection::Right));
        assert_eq!(detect_swipe(200, 71), None);
        // For a small dominant the 40-unit floor wins (100 → max(40, 35) = 40).
        assert_eq!(detect_swipe(100, 39), Some(GestureDirection::Right));
        assert_eq!(detect_swipe(100, 41), None);
    }

    #[test]
    fn detect_swipe_does_not_panic_on_extreme_values() {
        // Saturated accumulator travel can reach the i32 bounds. `i32::MIN.abs()`
        // panics and `dominant * 35` overflows — both must be clamped, not crash.
        assert_eq!(detect_swipe(i32::MAX, 0), Some(GestureDirection::Right));
        assert_eq!(detect_swipe(i32::MIN, 0), Some(GestureDirection::Left));
        assert_eq!(detect_swipe(0, i32::MAX), Some(GestureDirection::Down));
        assert_eq!(detect_swipe(0, i32::MIN), Some(GestureDirection::Up));
        // A diagonal at the extremes is still rejected, without panicking.
        assert_eq!(detect_swipe(i32::MIN, i32::MIN), None);
    }

    // ── SwipeAccumulator (the shared mid-swipe state machine) ─────────────────

    #[test]
    fn accumulator_commits_a_direction_once_after_the_hold_gate() {
        let mut acc = SwipeAccumulator::default();
        acc.begin();
        acc.backdate_hold_for_test();
        // A clear rightward swipe commits exactly once, mid-motion.
        assert_eq!(
            acc.accumulate(GESTURE_SWIPE_THRESHOLD + 10, 0),
            Some(GestureDirection::Right)
        );
        // Further travel in the same hold must not re-fire.
        assert_eq!(acc.accumulate(50, 0), None);
    }

    #[test]
    fn accumulator_does_not_commit_before_the_hold_gate() {
        let mut acc = SwipeAccumulator::default();
        acc.begin(); // held_since = now, so the gate is not yet satisfied
        // A big delta arriving immediately (a quick click whose cursor drifted)
        // must not commit.
        assert_eq!(acc.accumulate(GESTURE_SWIPE_THRESHOLD + 100, 0), None);
        // Once held long enough, the next delta commits.
        acc.backdate_hold_for_test();
        assert!(acc.accumulate(GESTURE_SWIPE_THRESHOLD + 100, 0).is_some());
    }

    #[test]
    fn accumulator_end_reports_click_only_when_no_swipe_fired() {
        // A hold with only tiny drift never commits → end() is a click.
        let mut acc = SwipeAccumulator::default();
        acc.begin();
        acc.backdate_hold_for_test();
        assert_eq!(acc.accumulate(2, -1), None);
        assert!(acc.end(), "a hold that never swiped is a click");

        // A hold that committed a swipe → end() is not a click.
        acc.begin();
        acc.backdate_hold_for_test();
        assert!(acc.accumulate(GESTURE_SWIPE_THRESHOLD + 10, 0).is_some());
        assert!(!acc.end(), "a committed swipe must not also click");
    }

    #[test]
    fn accumulator_ignores_motion_when_not_holding() {
        let mut acc = SwipeAccumulator::default();
        assert!(!acc.is_holding());
        // Travel outside a hold is dropped, never committing a stray swipe.
        assert_eq!(acc.accumulate(GESTURE_SWIPE_THRESHOLD + 100, 0), None);
    }

    #[test]
    fn accumulator_sums_sub_threshold_deltas_until_they_commit() {
        // The whole reason for an accumulator (vs. detect_swipe on one delta):
        // several deltas each too small to commit on their own must sum across
        // the hold until the running total crosses the threshold, then commit.
        let mut acc = SwipeAccumulator::default();
        acc.begin();
        acc.backdate_hold_for_test();
        // Just under half the threshold: one or two steps never reach it, three do.
        let step = GESTURE_SWIPE_THRESHOLD / 2 - 1;
        assert_eq!(acc.accumulate(step, 0), None, "one step is sub-threshold");
        assert_eq!(acc.accumulate(step, 0), None, "two steps still under");
        assert_eq!(
            acc.accumulate(step, 0),
            Some(GestureDirection::Right),
            "the running sum finally crosses the threshold"
        );
    }

    #[test]
    fn accumulator_saturates_instead_of_overflowing() {
        // The doc promises an arbitrarily long hold can't overflow. A perfect
        // diagonal never commits, so travel keeps summing; feed deltas that would
        // overflow both an i32 sum and a naive cross-band multiply — both must
        // saturate, not panic (debug builds panic on overflow).
        let mut acc = SwipeAccumulator::default();
        acc.begin();
        acc.backdate_hold_for_test();
        assert_eq!(
            acc.accumulate(i32::MAX, i32::MAX),
            None,
            "a diagonal never commits"
        );
        assert_eq!(
            acc.accumulate(i32::MAX, i32::MAX),
            None,
            "the saturating sum must not panic"
        );
        // A clean axis on a fresh hold still commits with a saturated magnitude.
        acc.begin();
        acc.backdate_hold_for_test();
        assert_eq!(acc.accumulate(i32::MAX, 0), Some(GestureDirection::Right));
    }

    #[test]
    fn accumulator_begin_recovers_a_stale_hold() {
        // A missed release (e.g. focus loss between press and release) can leave
        // a dangling hold that already fired with travel in some direction. A
        // fresh begin() must wipe both the `fired` latch and the travel, so the
        // next press isn't poisoned by the old one.
        let mut acc = SwipeAccumulator::default();
        acc.begin();
        acc.backdate_hold_for_test();
        // Stale hold commits LEFT (negative dx) and latches `fired`.
        assert_eq!(
            acc.accumulate(-(GESTURE_SWIPE_THRESHOLD + 10), 0),
            Some(GestureDirection::Left)
        );
        // No end() — a dropped release, then a fresh press.
        acc.begin();
        acc.backdate_hold_for_test();
        // Had `fired` leaked this would be None; had the negative travel leaked it
        // would commit Left. Committing Right proves begin() reset both.
        assert_eq!(
            acc.accumulate(GESTURE_SWIPE_THRESHOLD + 10, 0),
            Some(GestureDirection::Right)
        );
    }

    #[test]
    fn accumulator_end_without_a_hold_is_not_a_click() {
        // end() in isolation (no begin) must not claim a click — there was no
        // hold — so a stray release can't be read as a press.
        let mut acc = SwipeAccumulator::default();
        assert!(!acc.end(), "a release with no hold is not a click");
        // A redundant second release after a real hold already ended is inert too.
        acc.begin();
        assert!(acc.end(), "the held release is a click");
        assert!(!acc.end(), "the redundant second release is not a click");
    }

    // ── TOML roundtrip ────────────────────────────────────────────────────────

    /// Serialize then deserialize `action` through TOML, using a wrapper
    /// struct because TOML requires a top-level table.
    fn roundtrip(action: &Action) -> Action {
        let mut map: BTreeMap<ButtonId, Action> = BTreeMap::new();
        map.insert(ButtonId::Back, action.clone());
        let w = RoundtripWrapper { binding: map };
        let s = toml::to_string(&w).expect("serialize");
        let back: RoundtripWrapper = toml::from_str(&s).expect("deserialize");
        back.binding
            .into_values()
            .next()
            .expect("binding present after roundtrip")
    }

    #[test]
    fn all_catalog_variants_roundtrip_toml() {
        for action in Action::catalog() {
            let back = roundtrip(&action);
            assert_eq!(action, back, "TOML roundtrip failed for {action:?}");
        }
    }

    #[test]
    fn custom_shortcut_roundtrips_toml() {
        let action = Action::CustomShortcut(KeyCombo {
            modifiers: KeyCombo::MOD_CMD | KeyCombo::MOD_SHIFT,
            key_code: 0x23, // kVK_ANSI_P
            display: "⌘⇧P".into(),
        });
        assert_eq!(roundtrip(&action), action);
    }

    #[test]
    fn key_combo_rendered_label_uses_display_when_set() {
        let combo = KeyCombo {
            modifiers: 0,
            key_code: 0,
            display: "preset".into(),
        };
        assert_eq!(combo.rendered_label(), "preset");
    }

    #[test]
    fn key_combo_rendered_label_falls_back_to_modifiers_plus_key() {
        let combo = KeyCombo {
            modifiers: KeyCombo::MOD_CMD | KeyCombo::MOD_SHIFT,
            key_code: 0x23, // P
            display: String::new(),
        };
        assert_eq!(combo.rendered_label(), "⇧⌘P");
    }

    // ── Category tests ────────────────────────────────────────────────────────

    #[test]
    fn category_editing_variants() {
        assert_eq!(Action::Copy.category(), Category::Editing);
        assert_eq!(Action::Undo.category(), Category::Editing);
        assert_eq!(Action::SelectAll.category(), Category::Editing);
        assert_eq!(Action::Find.category(), Category::Editing);
        assert_eq!(Action::Save.category(), Category::Editing);
        assert_eq!(Action::Cut.category(), Category::Editing);
        assert_eq!(Action::Redo.category(), Category::Editing);
        assert_eq!(Action::Paste.category(), Category::Editing);
    }

    #[test]
    fn category_browser_variants() {
        assert_eq!(Action::BrowserBack.category(), Category::Browser);
        assert_eq!(Action::BrowserForward.category(), Category::Browser);
        assert_eq!(Action::NewTab.category(), Category::Browser);
        assert_eq!(Action::CloseTab.category(), Category::Browser);
        assert_eq!(Action::ReopenTab.category(), Category::Browser);
        assert_eq!(Action::NextTab.category(), Category::Browser);
        assert_eq!(Action::PrevTab.category(), Category::Browser);
        assert_eq!(Action::ReloadPage.category(), Category::Browser);
    }

    #[test]
    fn category_media_variants() {
        assert_eq!(Action::PlayPause.category(), Category::Media);
        assert_eq!(Action::NextTrack.category(), Category::Media);
        assert_eq!(Action::PrevTrack.category(), Category::Media);
        assert_eq!(Action::VolumeUp.category(), Category::Media);
        assert_eq!(Action::VolumeDown.category(), Category::Media);
        assert_eq!(Action::MuteVolume.category(), Category::Media);
    }

    #[test]
    fn category_mouse_variants() {
        assert_eq!(Action::LeftClick.category(), Category::Mouse);
        assert_eq!(Action::RightClick.category(), Category::Mouse);
        assert_eq!(Action::MiddleClick.category(), Category::Mouse);
    }

    #[test]
    fn category_dpi_variants() {
        assert_eq!(Action::CycleDpiPresets.category(), Category::Dpi);
        assert_eq!(Action::ToggleSmartShift.category(), Category::Dpi);
    }

    #[test]
    fn category_scroll_variants() {
        assert_eq!(Action::ScrollUp.category(), Category::Scroll);
        assert_eq!(Action::ScrollDown.category(), Category::Scroll);
        assert_eq!(Action::HorizontalScrollLeft.category(), Category::Scroll);
        assert_eq!(Action::HorizontalScrollRight.category(), Category::Scroll);
    }

    #[test]
    fn category_navigation_variants() {
        assert_eq!(Action::MissionControl.category(), Category::Navigation);
        assert_eq!(Action::AppExpose.category(), Category::Navigation);
        assert_eq!(Action::PreviousDesktop.category(), Category::Navigation);
        assert_eq!(Action::NextDesktop.category(), Category::Navigation);
        assert_eq!(Action::ShowDesktop.category(), Category::Navigation);
        assert_eq!(Action::LaunchpadShow.category(), Category::Navigation);
    }

    #[test]
    fn category_system_variants() {
        assert_eq!(Action::LockScreen.category(), Category::System);
        assert_eq!(Action::Screenshot.category(), Category::System);
    }

    // ── Category label smoke test ─────────────────────────────────────────────

    #[test]
    fn category_labels_are_nonempty() {
        let categories = [
            Category::Editing,
            Category::Browser,
            Category::Media,
            Category::Mouse,
            Category::Dpi,
            Category::Scroll,
            Category::Navigation,
            Category::System,
        ];
        for cat in categories {
            assert!(!cat.label().is_empty(), "label empty for {cat:?}");
        }
    }

    // ── Default binding ───────────────────────────────────────────────────────

    #[test]
    fn dpi_toggle_default_is_cycle_dpi_presets() {
        assert_eq!(
            default_binding(ButtonId::DpiToggle),
            Action::CycleDpiPresets
        );
    }
}