diff --git a/src/chart.rs b/src/chart.rs
new file mode 100644
index 0000000..255f5e2
--- /dev/null
+++ b/src/chart.rs
@@ -0,0 +1,220 @@
+//! The Jiggly hierarchical state machine: context, event enum, the
+//! `statechart!` definition itself, and the entry-action impls
+//! (the `during:` activities live in the `led` and `mouse` modules).
+
+use embassy_rp::{clocks::RoscRng, gpio::Output};
+use embassy_time::{Instant, Timer};
+use hsmc::statechart;
+
+use crate::config::{
+    BREATHE_PEAK, FLASH_DURATION, FLASH_PEAK, JIGGLE_PERIOD, KBD_PHASE_DURATION,
+    KBD_RELEASE_DEADLINE, KBD_WAKE_DEADLINE, MOUSE_PHASE_DURATION, MOUSE_WAKE_DEADLINE,
+    PIXEL_DWELL, QUIET_AFTER_ANIM, RUN_BEFORE_SHUTDOWN, SETTLING_DELAY, SHUTDOWN_FLASH_STEP,
+    WARN_5_AT, WARN_10_AT,
+};
+use crate::kbd::{KbdHid, send_kbd, wake_with_keyboard};
+use crate::led::{
+    Neo, blink_fast_red, boot_sweep, breathe_color, fade_to_green, paint, pulse_blue,
+    pulse_white,
+};
+use crate::mouse::{
+    MouseHid, animate_final_spiral, animate_spinner, animate_warning_5, animate_warning_10,
+    send_mouse, wake_with_mouse,
+};
+
+pub struct Ctx {
+    pub mouse: MouseHid,
+    pub kbd: KbdHid,
+    pub neo: Neo,
+    pub neo_pwr: Output<'static>,
+    pub active_start: Option<Instant>,
+}
+
+#[derive(Debug, Clone)]
+pub enum Ev {
+    BootDone,
+    SpinDone,
+    Jiggled,
+    WarnDone,
+    SpiralDone,
+}
+
+statechart! {
+Jiggly {
+    context: Ctx;
+    events: Ev;
+    default(Booting);
+
+    state Booting {
+        during: boot_sweep(neo, neo_pwr);
+        on(BootDone) => WakingHost;
+    }
+
+    // Wake the host using whichever input the host actually responds to.
+    // Keyboard first (more reliable on macOS), then a mouse shake as
+    // belt-and-suspenders. Each substate runs a oneshot entry action with
+    // its own internal deadline; the chart timer is what advances the
+    // chart. No durings, no events — purely entry + timer.
+    state WakingHost {
+        during: pulse_blue(neo);
+        default(WakingWithKeyboard);
+
+        state WakingWithKeyboard {
+            entry: keyboard_wake;
+            on(after KBD_PHASE_DURATION) => WakingWithMouse;
+        }
+
+        state WakingWithMouse {
+            entry: mouse_wake;
+            on(after MOUSE_PHASE_DURATION) => Settling;
+        }
+    }
+
+    // Quiet pause so the display has time to come out of sleep before the
+    // cursor starts drawing the spinner.
+    state Settling {
+        during: pulse_white(neo);
+        on(after SETTLING_DELAY) => Spinning;
+    }
+
+    state Spinning {
+        during: animate_spinner(mouse);
+        during: fade_to_green(neo);
+        on(SpinDone) => Active;
+    }
+
+    state Active {
+        entry: capture_active_start;
+        on(every JIGGLE_PERIOD) => jiggle_pair;
+        on(after WARN_10_AT) => Warning10;
+        on(after WARN_5_AT) => Warning5;
+        on(after RUN_BEFORE_SHUTDOWN) => Ending;
+        default(Breathing);
+
+        state Breathing {
+            during: breathe_color(neo, active_start);
+            on(Jiggled) => Flashing;
+        }
+
+        state Flashing {
+            entry: paint_white;
+            on(after FLASH_DURATION) => Breathing;
+        }
+
+        state Warning10 {
+            during: animate_warning_10(mouse);
+            on(WarnDone) => Breathing;
+        }
+
+        state Warning5 {
+            during: animate_warning_5(mouse);
+            on(WarnDone) => Breathing;
+        }
+    }
+
+    state Ending {
+        during: blink_fast_red(neo);
+        default(Spiraling);
+
+        state Spiraling {
+            during: animate_final_spiral(mouse);
+            on(SpiralDone) => Quiet;
+        }
+
+        state Quiet {
+            on(after QUIET_AFTER_ANIM) => PoweringDown;
+        }
+    }
+
+    state PoweringDown {
+        entry: shutdown_flashes;
+        entry: power_off_neo;
+    }
+}
+}
+
+impl JigglyActions for JigglyActionContext<'_> {
+    async fn capture_active_start(&mut self) {
+        self.active_start = Some(Instant::now());
+    }
+
+    async fn keyboard_wake(&mut self) {
+        let result = embassy_futures::select::select(
+            wake_with_keyboard(&mut self.kbd),
+            Timer::after(KBD_WAKE_DEADLINE),
+        )
+        .await;
+        #[cfg(feature = "defmt")]
+        match result {
+            embassy_futures::select::Either::First(_) => defmt::info!("kbd wake: completed"),
+            embassy_futures::select::Either::Second(_) => {
+                defmt::warn!(
+                    "kbd wake: deadline hit ({} ms)",
+                    KBD_WAKE_DEADLINE.as_millis()
+                )
+            }
+        }
+        #[cfg(not(feature = "defmt"))]
+        let _ = result;
+        // Belt-and-suspenders: always send an all-keys-released report,
+        // even if the deadline preempted the loop *between* a key-down
+        // and its key-up. Without this, a stuck modifier (Shift!) or key
+        // on the host side could persist until the user unplugs the
+        // device. Bounded by KBD_RELEASE_DEADLINE so a misbehaving
+        // endpoint can't pin the chart.
+        let _ = embassy_futures::select::select(
+            send_kbd(&mut self.kbd, 0, [0; 6]),
+            Timer::after(KBD_RELEASE_DEADLINE),
+        )
+        .await;
+    }
+
+    async fn mouse_wake(&mut self) {
+        let result = embassy_futures::select::select(
+            wake_with_mouse(&mut self.mouse),
+            Timer::after(MOUSE_WAKE_DEADLINE),
+        )
+        .await;
+        #[cfg(feature = "defmt")]
+        match result {
+            embassy_futures::select::Either::First(_) => defmt::info!("mouse wake: completed"),
+            embassy_futures::select::Either::Second(_) => defmt::warn!(
+                "mouse wake: deadline hit ({} ms)",
+                MOUSE_WAKE_DEADLINE.as_millis()
+            ),
+        }
+        #[cfg(not(feature = "defmt"))]
+        let _ = result;
+    }
+
+    async fn jiggle_pair(&mut self) {
+        let (dx, dy): (i8, i8) = if (RoscRng::next_u8() & 1) == 0 {
+            (1, 0)
+        } else {
+            (0, 1)
+        };
+        #[cfg(feature = "defmt")]
+        defmt::info!("jiggle: dx={} dy={}", dx, dy);
+        send_mouse(&mut self.mouse, dx, dy).await;
+        Timer::after(PIXEL_DWELL).await;
+        send_mouse(&mut self.mouse, -dx, -dy).await;
+        let _ = self.emit(Ev::Jiggled);
+    }
+
+    async fn paint_white(&mut self) {
+        paint(&mut self.neo, FLASH_PEAK, FLASH_PEAK, FLASH_PEAK).await;
+    }
+
+    async fn shutdown_flashes(&mut self) {
+        for _ in 0..3 {
+            paint(&mut self.neo, 0, BREATHE_PEAK, 0).await;
+            Timer::after(SHUTDOWN_FLASH_STEP).await;
+            paint(&mut self.neo, 0, 0, 0).await;
+            Timer::after(SHUTDOWN_FLASH_STEP).await;
+        }
+    }
+
+    async fn power_off_neo(&mut self) {
+        self.neo_pwr.set_low();
+    }
+}
diff --git a/src/config.rs b/src/config.rs
new file mode 100644
index 0000000..b476af9
--- /dev/null
+++ b/src/config.rs
@@ -0,0 +1,152 @@
+//! Compile-time tuning constants — timing, geometry, brightness.
+//!
+//! Every magic number lives here so the rest of the firmware reads as
+//! pure behaviour. Several values are joint-tuned by `scripts/tune_runtime.py`
+//! — see the README's "Why four hours…" section for the rationale.
+
+use embassy_time::Duration as EDuration;
+use hsmc::Duration;
+
+// ── Lifecycle timing (statechart Durations) ────────────────────────
+// 4h00m: optimum from the 4-D Monte Carlo (RUN_DURATION × YELLOW_AT ×
+// RED_AT × FAST_RED_AT) over a typical office workday distribution
+// with a per-minute press-on-warning user model. Lands the screen-sleep
+// in the 12:15–12:45 sweet spot on ~52 % of days and somewhere in
+// lunch on ~74 %. See the README's "Why four hours…" section and
+// `scripts/tune_runtime.py` for the simulation.
+pub(crate) const RUN_DURATION: Duration = Duration::from_hours(4);
+pub(crate) const SHUTDOWN_LEAD: Duration = Duration::from_secs(30);
+pub(crate) const RUN_BEFORE_SHUTDOWN: Duration = RUN_DURATION.saturating_sub(SHUTDOWN_LEAD);
+pub(crate) const SHUTDOWN_ANIM_BUDGET: Duration = Duration::from_secs(5);
+pub(crate) const QUIET_AFTER_ANIM: Duration = SHUTDOWN_LEAD.saturating_sub(SHUTDOWN_ANIM_BUDGET);
+pub(crate) const JIGGLE_PERIOD: Duration = Duration::from_secs(270);
+pub(crate) const FLASH_DURATION: Duration = Duration::from_millis(100);
+
+// Phase boundaries — compared against time *remaining* in Active.
+// Joint optimum from `scripts/tune_runtime.py`. Yellow and red are
+// kept deliberately short (5 min each); the long phase is fast-red.
+// See the README's "Why four hours…" section for the rationale.
+pub(crate) const YELLOW_AT: EDuration = EDuration::from_secs(30 * 60);
+pub(crate) const RED_AT: EDuration = EDuration::from_secs(25 * 60);
+pub(crate) const FAST_RED_AT: EDuration = EDuration::from_secs(20 * 60);
+
+// LED breathing math
+pub(crate) const LED_TICK: EDuration = EDuration::from_millis(20);
+pub(crate) const SLOW_GREEN_PERIOD: EDuration = EDuration::from_secs(4);
+pub(crate) const YELLOW_PERIOD: EDuration = EDuration::from_secs(3);
+pub(crate) const RED_PERIOD: EDuration = EDuration::from_secs(2);
+pub(crate) const FAST_RED_PERIOD: EDuration = EDuration::from_millis(500);
+
+// Wake-up LED feedback periods. Blue on WakingHost (kbd+mouse), white on
+// Settling, then a linear white→green fade across the Spinning duration so
+// the LED hands off cleanly to Active's green breathing.
+pub(crate) const WAKING_PULSE_PERIOD: EDuration = EDuration::from_millis(800);
+pub(crate) const SETTLING_PULSE_PERIOD: EDuration = EDuration::from_millis(1200);
+pub(crate) const SPINNER_FADE_DURATION: EDuration = EDuration::from_millis(600);
+
+// LED brightness (raw WS2812 PWM, 0..=255).
+pub(crate) const BREATHE_FLOOR: u8 = 1;
+pub(crate) const BREATHE_PEAK: u8 = 16;
+pub(crate) const FLASH_PEAK: u8 = 160;
+
+// ── Animation parameters ───────────────────────────────────────────
+// 8ms frames + HID poll_ms=8 means each frame's report actually reaches the
+// host instead of being coalesced — at 16ms frames against a 60ms poll the
+// shake looked sluggish because three reports out of four were dropped on the
+// floor.
+pub(crate) const ANIM_FRAME: EDuration = EDuration::from_millis(8);
+
+// Frantic side-to-side, the gesture a person makes to wake a sleeping display.
+// 10 full oscillations × 8 frames of full period = 80 frames × 8 ms = 640 ms,
+// which works out to a ~12 Hz alternation — visibly "shaking", not "sweeping".
+pub(crate) const WAKE_OSCILLATIONS: u32 = 10;
+pub(crate) const WAKE_FRAMES_PER_HALF: u32 = 4;
+pub(crate) const WAKE_AMPLITUDE: f32 = 60.0;
+pub(crate) const WAKE_JITTER: f32 = 1.0;
+
+// 2 s pause after the shake so the display has time to actually wake before
+// we draw the spinner. The user wants this delay to live *here*, not before
+// the shake.
+pub(crate) const SETTLING_DELAY: Duration = Duration::from_secs(2);
+
+// ── Keyboard wake (host-wake first pass) ───────────────────────────
+// macOS often won't wake from raw HID mouse motion alone, but reliably wakes
+// from any keyboard event. We tap **F13** four times before the mouse shake.
+// F13–F24 are intentionally unmapped on every mainstream OS, so even in the
+// nightmare scenario where the deadline preempts the loop *between* a key-
+// down and key-up report and the host ends up holding F13 forever, nothing
+// visible happens — unlike with Shift, which would silently capitalise every
+// keystroke from the user's real keyboard until they unplug the device.
+// Earlier versions used Left Shift; that turned out to be exactly that
+// nightmare scenario in practice.
+pub(crate) const KBD_WAKE_TAPS: u32 = 4;
+pub(crate) const KBD_TAP_HOLD: EDuration = EDuration::from_millis(30);
+pub(crate) const KBD_TAP_GAP: EDuration = EDuration::from_millis(50);
+// Hard internal deadline on the keyboard-wake entry action. The taps total
+// ~320 ms so they finish well before this; the deadline only kicks in if a
+// USB write blocks (e.g. the host hasn't bound the keyboard endpoint yet).
+pub(crate) const KBD_WAKE_DEADLINE: EDuration = EDuration::from_millis(500);
+// Statechart timer for the WakingWithKeyboard state — chosen above the
+// internal deadline so the chart timer is what drives the transition out.
+pub(crate) const KBD_PHASE_DURATION: Duration = Duration::from_millis(550);
+// HID Keyboard usage page keycode for F13.
+pub(crate) const KBD_KEY_F13: u8 = 0x68;
+// Final-cleanup deadline — the all-keys-released report we send after the
+// main work loop is bounded by this so a misbehaving endpoint can't pin
+// the chart. Best-effort; if it doesn't land we tried.
+pub(crate) const KBD_RELEASE_DEADLINE: EDuration = EDuration::from_millis(100);
+
+// ── Mouse wake (host-wake second pass) ─────────────────────────────
+// Internal deadline on the mouse-shake entry action — the shake itself takes
+// ~640 ms; the cap exists so a misbehaving USB endpoint can't pin the chart.
+pub(crate) const MOUSE_WAKE_DEADLINE: EDuration = EDuration::from_millis(1000);
+pub(crate) const MOUSE_PHASE_DURATION: Duration = Duration::from_millis(1050);
+
+// Three quick clockwise circles read more clearly as "spinner / running"
+// than one slow lap. 25 frames per circle × 3 × 8 ms = 600 ms total.
+pub(crate) const RUN_RADIUS: f32 = 40.0;
+pub(crate) const RUN_FRAMES_PER_CIRCLE: u32 = 25;
+pub(crate) const RUN_CIRCLES: u32 = 3;
+
+// Shared "spin-down" spiral. Both radius and angle are driven by an eased phase
+// u(t) = t^EASE_POW with EASE_POW > 1 — slow at the start, ~EASE_POW× the
+// average rate at the finish. Because radius and angle share u, the inward
+// spiral and the rotation accelerate together: a coin/Euler-disk feel.
+pub(crate) const EASE_POW: f32 = 2.5;
+pub(crate) const SPIRAL_RADIUS_END: f32 = 2.0;
+
+// Final spiral — the dramatic full version, 30 s before USB goes silent.
+pub(crate) const FINAL_SPIRAL_RADIUS_START: f32 = 80.0;
+pub(crate) const FINAL_SPIRAL_TURNS: f32 = 5.0;
+pub(crate) const FINAL_SPIRAL_FRAMES: u32 = 625; // 5.0 s @ 8 ms/frame
+
+// 5-min warning — medium escalation.
+pub(crate) const WARN5_RADIUS_START: f32 = 50.0;
+pub(crate) const WARN5_TURNS: f32 = 3.0;
+pub(crate) const WARN5_FRAMES: u32 = 312; // ~2.5 s
+
+// 10-min warning — small foreshadow.
+pub(crate) const WARN10_RADIUS_START: f32 = 30.0;
+pub(crate) const WARN10_TURNS: f32 = 2.0;
+pub(crate) const WARN10_FRAMES: u32 = 187; // ~1.5 s
+
+// Offsets from Active-entry. The hsmc parent timer rule: timers in a parent
+// state start on parent entry and survive sibling-substate transitions, so
+// these three `after`s race concurrently against the same epoch.
+pub(crate) const WARN_10_AT: Duration = RUN_BEFORE_SHUTDOWN.saturating_sub(Duration::from_mins(10));
+pub(crate) const WARN_5_AT: Duration = RUN_BEFORE_SHUTDOWN.saturating_sub(Duration::from_mins(5));
+
+// ── Watchdog (independent task) ────────────────────────────────────
+pub(crate) const WATCHDOG_TIMEOUT: EDuration = EDuration::from_secs(8);
+pub(crate) const WATCHDOG_FEED_INTERVAL: EDuration = EDuration::from_secs(5);
+
+// ── Jiggle dwell ───────────────────────────────────────────────────
+pub(crate) const PIXEL_DWELL: EDuration = EDuration::from_millis(25);
+
+// ── Boot LED sweep ─────────────────────────────────────────────────
+// Brief power-on confirmation. Kept short so the cursor shake — the actual
+// "wake the display" gesture — happens promptly after reset.
+pub(crate) const BOOT_SWEEP_STEP: EDuration = EDuration::from_millis(60);
+
+// ── Shutdown LED flashes ───────────────────────────────────────────
+pub(crate) const SHUTDOWN_FLASH_STEP: EDuration = EDuration::from_millis(400);
diff --git a/src/kbd.rs b/src/kbd.rs
new file mode 100644
index 0000000..6d2069d
--- /dev/null
+++ b/src/kbd.rs
@@ -0,0 +1,36 @@
+//! Keyboard HID: report send + the F13-tap host-wake helper.
+
+use embassy_time::{Duration as EDuration, Timer, with_timeout};
+use embassy_usb::class::hid::HidWriter;
+use usbd_hid::descriptor::KeyboardReport;
+
+use crate::config::{KBD_KEY_F13, KBD_TAP_GAP, KBD_TAP_HOLD, KBD_WAKE_TAPS};
+use crate::usb::UsbDriver;
+
+pub(crate) type KbdHid = HidWriter<'static, UsbDriver, 8>;
+
+// Tap F13 four times. macOS reliably wakes from any keyboard event but is
+// inconsistent about waking from raw mouse motion. Plain oneshot helper —
+// the action method that calls this races it against KBD_WAKE_DEADLINE
+// AND unconditionally sends an all-keys-released cleanup report after,
+// to make sure we never leave a key held on the host.
+pub(crate) async fn wake_with_keyboard(kbd: &mut KbdHid) {
+    for _ in 0..KBD_WAKE_TAPS {
+        send_kbd(kbd, 0, [KBD_KEY_F13, 0, 0, 0, 0, 0]).await;
+        Timer::after(KBD_TAP_HOLD).await;
+        send_kbd(kbd, 0, [0; 6]).await;
+        Timer::after(KBD_TAP_GAP).await;
+    }
+}
+
+// ── HID primitive ──────────────────────────────────────────────────
+
+pub(crate) async fn send_kbd(kbd: &mut KbdHid, modifier: u8, keycodes: [u8; 6]) {
+    let report = KeyboardReport {
+        modifier,
+        reserved: 0,
+        leds: 0,
+        keycodes,
+    };
+    let _ = with_timeout(EDuration::from_secs(3), kbd.write_serialize(&report)).await;
+}
diff --git a/src/led.rs b/src/led.rs
new file mode 100644
index 0000000..a57a4f1
--- /dev/null
+++ b/src/led.rs
@@ -0,0 +1,146 @@
+//! WS2812 NeoPixel: paint primitive, breath/blink math, and the
+//! long-running `during` activities the statechart drives during
+//! Booting / WakingHost / Settling / Spinning / Active / Ending.
+
+use core::f32::consts::PI;
+
+use embassy_rp::{
+    gpio::Output,
+    peripherals::PIO0,
+    pio_programs::ws2812::{Grb, PioWs2812},
+};
+use embassy_time::{Duration as EDuration, Instant, Timer};
+use libm::cosf;
+use smart_leds::RGB8;
+
+use crate::chart::Ev;
+use crate::config::{
+    BOOT_SWEEP_STEP, BREATHE_FLOOR, BREATHE_PEAK, FAST_RED_AT, FAST_RED_PERIOD, LED_TICK,
+    RED_AT, RED_PERIOD, RUN_BEFORE_SHUTDOWN, SETTLING_PULSE_PERIOD, SLOW_GREEN_PERIOD,
+    SPINNER_FADE_DURATION, WAKING_PULSE_PERIOD, YELLOW_AT, YELLOW_PERIOD,
+};
+
+pub(crate) type Neo = PioWs2812<'static, PIO0, 0, 1, Grb>;
+
+// ── During activities (free async fns) ─────────────────────────────
+
+pub(crate) async fn boot_sweep(neo: &mut Neo, neo_pwr: &mut Output<'static>) -> Ev {
+    neo_pwr.set_high();
+    Timer::after_millis(2).await;
+
+    paint(neo, BREATHE_PEAK, 0, 0).await;
+    Timer::after(BOOT_SWEEP_STEP).await;
+    paint(neo, 0, BREATHE_PEAK, 0).await;
+    Timer::after(BOOT_SWEEP_STEP).await;
+    paint(neo, 0, 0, BREATHE_PEAK).await;
+    Timer::after(BOOT_SWEEP_STEP).await;
+    paint(neo, 0, 0, 0).await;
+    Ev::BootDone
+}
+
+pub(crate) async fn breathe_color(neo: &mut Neo, active_start: &mut Option<Instant>) -> Ev {
+    loop {
+        let elapsed = active_start.map(|s| s.elapsed()).unwrap_or_default();
+        let total_run = run_before_shutdown_e();
+        let remaining = total_run
+            .checked_sub(elapsed)
+            .unwrap_or(EDuration::from_ticks(0));
+        let (r, g, b) = breathe_for(remaining, elapsed);
+        paint(neo, r, g, b).await;
+        Timer::after(LED_TICK).await;
+    }
+}
+
+pub(crate) async fn blink_fast_red(neo: &mut Neo) -> Ev {
+    let start = Instant::now();
+    loop {
+        let t = start.elapsed();
+        let level = if blink_on(FAST_RED_PERIOD, t) {
+            BREATHE_PEAK
+        } else {
+            BREATHE_FLOOR
+        };
+        paint(neo, level, 0, 0).await;
+        Timer::after(LED_TICK).await;
+    }
+}
+
+pub(crate) async fn pulse_blue(neo: &mut Neo) -> Ev {
+    let start = Instant::now();
+    loop {
+        let level = sin_breath(WAKING_PULSE_PERIOD, start.elapsed(), BREATHE_FLOOR, BREATHE_PEAK);
+        paint(neo, 0, 0, level).await;
+        Timer::after(LED_TICK).await;
+    }
+}
+
+pub(crate) async fn pulse_white(neo: &mut Neo) -> Ev {
+    let start = Instant::now();
+    loop {
+        let level = sin_breath(SETTLING_PULSE_PERIOD, start.elapsed(), BREATHE_FLOOR, BREATHE_PEAK);
+        paint(neo, level, level, level).await;
+        Timer::after(LED_TICK).await;
+    }
+}
+
+// Linear fade from white(peak) → green(peak) so the LED hands off into
+// Active's green breathing without a visible jump.
+pub(crate) async fn fade_to_green(neo: &mut Neo) -> Ev {
+    let start = Instant::now();
+    let total_ms = SPINNER_FADE_DURATION.as_millis() as f32;
+    loop {
+        let t = ((start.elapsed().as_millis() as f32) / total_ms).min(1.0);
+        let rb = (BREATHE_PEAK as f32 * (1.0 - t)) as u8;
+        paint(neo, rb, BREATHE_PEAK, rb).await;
+        Timer::after(LED_TICK).await;
+    }
+}
+
+// ── Color / breathing helpers ──────────────────────────────────────
+
+fn run_before_shutdown_e() -> EDuration {
+    // RUN_BEFORE_SHUTDOWN is a `core::time::Duration`; convert to the embassy
+    // type once at the call site so the comparator below is apples-to-apples.
+    EDuration::from_secs(RUN_BEFORE_SHUTDOWN.as_secs())
+}
+
+fn breathe_for(remaining: EDuration, elapsed: EDuration) -> (u8, u8, u8) {
+    if remaining > YELLOW_AT {
+        let level = sin_breath(SLOW_GREEN_PERIOD, elapsed, BREATHE_FLOOR, BREATHE_PEAK);
+        (0, level, 0)
+    } else if remaining > RED_AT {
+        // Green is perceptually brighter on WS2812 — scale it down for a warm yellow.
+        let level = sin_breath(YELLOW_PERIOD, elapsed, BREATHE_FLOOR, BREATHE_PEAK);
+        (level, ((level as u16 * 5) / 10) as u8, 0)
+    } else if remaining > FAST_RED_AT {
+        let level = sin_breath(RED_PERIOD, elapsed, BREATHE_FLOOR, BREATHE_PEAK);
+        (level, 0, 0)
+    } else {
+        let level = if blink_on(FAST_RED_PERIOD, elapsed) {
+            BREATHE_PEAK
+        } else {
+            BREATHE_FLOOR
+        };
+        (level, 0, 0)
+    }
+}
+
+fn sin_breath(period: EDuration, t: EDuration, floor: u8, peak: u8) -> u8 {
+    let period_ms = period.as_millis() as f32;
+    let t_ms = (t.as_millis() % period.as_millis()) as f32;
+    let phase = 2.0 * PI * t_ms / period_ms;
+    let val = (1.0 - cosf(phase)) * 0.5;
+    let span = peak.saturating_sub(floor) as f32;
+    floor + (val * span) as u8
+}
+
+fn blink_on(period: EDuration, t: EDuration) -> bool {
+    let period_ms = period.as_millis();
+    (t.as_millis() % period_ms) < (period_ms / 2)
+}
+
+// ── LED primitive ──────────────────────────────────────────────────
+
+pub(crate) async fn paint(neo: &mut Neo, r: u8, g: u8, b: u8) {
+    neo.write(&[RGB8 { r, g, b }]).await;
+}
diff --git a/src/main.rs b/src/main.rs
index 6925e39..8a1bd48 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,718 +1,47 @@
 #![no_std]
 #![no_main]
 
-use core::f32::consts::PI;
-
 use embassy_executor::Spawner;
 use embassy_rp::{
-    Peri, bind_interrupts,
-    clocks::RoscRng,
-    dma,
-    flash::Flash,
+    bind_interrupts, dma,
     gpio::{Level, Output},
-    peripherals::{DMA_CH0, FLASH, PIO0, USB},
+    peripherals::{DMA_CH0, PIO0, USB},
     pio::{InterruptHandler as PioInterruptHandler, Pio},
-    pio_programs::ws2812::{Grb, PioWs2812, PioWs2812Program},
+    pio_programs::ws2812::{PioWs2812, PioWs2812Program},
     usb::{Driver, InterruptHandler as UsbInterruptHandler},
     watchdog::Watchdog,
 };
 use embassy_sync::{blocking_mutex::raw::CriticalSectionRawMutex, channel::Channel};
-use embassy_time::{Duration as EDuration, Instant, Timer, with_timeout};
+use embassy_time::Timer;
 use embassy_usb::{
-    Builder, Config as UsbConfig, UsbDevice,
+    Builder, Config as UsbConfig,
     class::hid::{Config as HidConfig, HidBootProtocol, HidSubclass, HidWriter, State},
 };
-use hsmc::{Duration, statechart};
-use libm::{cosf, powf, roundf, sinf};
 #[cfg(not(feature = "defmt"))]
 use panic_reset as _;
-use smart_leds::RGB8;
 use static_cell::StaticCell;
 use usbd_hid::descriptor::{KeyboardReport, MouseReport, SerializedDescriptor};
 #[cfg(feature = "defmt")]
 use {defmt_rtt as _, panic_probe as _};
 
+mod chart;
+mod config;
+mod kbd;
+mod led;
+mod mouse;
+mod usb;
+
+use chart::{Ctx, Ev, Jiggly};
+use config::{WATCHDOG_FEED_INTERVAL, WATCHDOG_TIMEOUT};
+use led::Neo;
+use usb::{make_serial, usb_task, watchdog_task};
+
 bind_interrupts!(struct Irqs {
     USBCTRL_IRQ => UsbInterruptHandler<USB>;
     PIO0_IRQ_0 => PioInterruptHandler<PIO0>;
     DMA_IRQ_0 => dma::InterruptHandler<DMA_CH0>;
 });
 
-type UsbDriver = Driver<'static, USB>;
-type Neo = PioWs2812<'static, PIO0, 0, 1, Grb>;
-type MouseHid = HidWriter<'static, UsbDriver, 5>;
-type KbdHid = HidWriter<'static, UsbDriver, 8>;
-
-// ── Lifecycle timing (statechart Durations) ────────────────────────
-// 4h00m: optimum from the 4-D Monte Carlo (RUN_DURATION × YELLOW_AT ×
-// RED_AT × FAST_RED_AT) over a typical office workday distribution
-// with a per-minute press-on-warning user model. Lands the screen-sleep
-// in the 12:15–12:45 sweet spot on ~52 % of days and somewhere in
-// lunch on ~74 %. See the README's "Why four hours…" section and
-// `scripts/tune_runtime.py` for the simulation.
-const RUN_DURATION: Duration = Duration::from_hours(4);
-const SHUTDOWN_LEAD: Duration = Duration::from_secs(30);
-const RUN_BEFORE_SHUTDOWN: Duration = RUN_DURATION.saturating_sub(SHUTDOWN_LEAD);
-const SHUTDOWN_ANIM_BUDGET: Duration = Duration::from_secs(5);
-const QUIET_AFTER_ANIM: Duration = SHUTDOWN_LEAD.saturating_sub(SHUTDOWN_ANIM_BUDGET);
-const JIGGLE_PERIOD: Duration = Duration::from_secs(270);
-const FLASH_DURATION: Duration = Duration::from_millis(100);
-
-// Phase boundaries — compared against time *remaining* in Active.
-// Joint optimum from `scripts/tune_runtime.py`. Yellow and red are
-// kept deliberately short (5 min each); the long phase is fast-red.
-// See the README's "Why four hours…" section for the rationale.
-const YELLOW_AT: EDuration = EDuration::from_secs(30 * 60);
-const RED_AT: EDuration = EDuration::from_secs(25 * 60);
-const FAST_RED_AT: EDuration = EDuration::from_secs(20 * 60);
-
-// LED breathing math
-const LED_TICK: EDuration = EDuration::from_millis(20);
-const SLOW_GREEN_PERIOD: EDuration = EDuration::from_secs(4);
-const YELLOW_PERIOD: EDuration = EDuration::from_secs(3);
-const RED_PERIOD: EDuration = EDuration::from_secs(2);
-const FAST_RED_PERIOD: EDuration = EDuration::from_millis(500);
-
-// Wake-up LED feedback periods. Blue on WakingHost (kbd+mouse), white on
-// Settling, then a linear white→green fade across the Spinning duration so
-// the LED hands off cleanly to Active's green breathing.
-const WAKING_PULSE_PERIOD: EDuration = EDuration::from_millis(800);
-const SETTLING_PULSE_PERIOD: EDuration = EDuration::from_millis(1200);
-const SPINNER_FADE_DURATION: EDuration = EDuration::from_millis(600);
-
-// LED brightness (raw WS2812 PWM, 0..=255).
-const BREATHE_FLOOR: u8 = 1;
-const BREATHE_PEAK: u8 = 16;
-const FLASH_PEAK: u8 = 160;
-
-// ── Animation parameters ───────────────────────────────────────────
-// 8ms frames + HID poll_ms=8 means each frame's report actually reaches the
-// host instead of being coalesced — at 16ms frames against a 60ms poll the
-// shake looked sluggish because three reports out of four were dropped on the
-// floor.
-const ANIM_FRAME: EDuration = EDuration::from_millis(8);
-
-// Frantic side-to-side, the gesture a person makes to wake a sleeping display.
-// 10 full oscillations × 8 frames of full period = 80 frames × 8 ms = 640 ms,
-// which works out to a ~12 Hz alternation — visibly "shaking", not "sweeping".
-const WAKE_OSCILLATIONS: u32 = 10;
-const WAKE_FRAMES_PER_HALF: u32 = 4;
-const WAKE_AMPLITUDE: f32 = 60.0;
-const WAKE_JITTER: f32 = 1.0;
-
-// 2 s pause after the shake so the display has time to actually wake before
-// we draw the spinner. The user wants this delay to live *here*, not before
-// the shake.
-const SETTLING_DELAY: Duration = Duration::from_secs(2);
-
-// ── Keyboard wake (host-wake first pass) ───────────────────────────
-// macOS often won't wake from raw HID mouse motion alone, but reliably wakes
-// from any keyboard event. We tap **F13** four times before the mouse shake.
-// F13–F24 are intentionally unmapped on every mainstream OS, so even in the
-// nightmare scenario where the deadline preempts the loop *between* a key-
-// down and key-up report and the host ends up holding F13 forever, nothing
-// visible happens — unlike with Shift, which would silently capitalise every
-// keystroke from the user's real keyboard until they unplug the device.
-// Earlier versions used Left Shift; that turned out to be exactly that
-// nightmare scenario in practice.
-const KBD_WAKE_TAPS: u32 = 4;
-const KBD_TAP_HOLD: EDuration = EDuration::from_millis(30);
-const KBD_TAP_GAP: EDuration = EDuration::from_millis(50);
-// Hard internal deadline on the keyboard-wake entry action. The taps total
-// ~320 ms so they finish well before this; the deadline only kicks in if a
-// USB write blocks (e.g. the host hasn't bound the keyboard endpoint yet).
-const KBD_WAKE_DEADLINE: EDuration = EDuration::from_millis(500);
-// Statechart timer for the WakingWithKeyboard state — chosen above the
-// internal deadline so the chart timer is what drives the transition out.
-const KBD_PHASE_DURATION: Duration = Duration::from_millis(550);
-// HID Keyboard usage page keycode for F13.
-const KBD_KEY_F13: u8 = 0x68;
-// Final-cleanup deadline — the all-keys-released report we send after the
-// main work loop is bounded by this so a misbehaving endpoint can't pin
-// the chart. Best-effort; if it doesn't land we tried.
-const KBD_RELEASE_DEADLINE: EDuration = EDuration::from_millis(100);
-
-// ── Mouse wake (host-wake second pass) ─────────────────────────────
-// Internal deadline on the mouse-shake entry action — the shake itself takes
-// ~640 ms; the cap exists so a misbehaving USB endpoint can't pin the chart.
-const MOUSE_WAKE_DEADLINE: EDuration = EDuration::from_millis(1000);
-const MOUSE_PHASE_DURATION: Duration = Duration::from_millis(1050);
-
-// Three quick clockwise circles read more clearly as "spinner / running"
-// than one slow lap. 25 frames per circle × 3 × 8 ms = 600 ms total.
-const RUN_RADIUS: f32 = 40.0;
-const RUN_FRAMES_PER_CIRCLE: u32 = 25;
-const RUN_CIRCLES: u32 = 3;
-
-// Shared "spin-down" spiral. Both radius and angle are driven by an eased phase
-// u(t) = t^EASE_POW with EASE_POW > 1 — slow at the start, ~EASE_POW× the
-// average rate at the finish. Because radius and angle share u, the inward
-// spiral and the rotation accelerate together: a coin/Euler-disk feel.
-const EASE_POW: f32 = 2.5;
-const SPIRAL_RADIUS_END: f32 = 2.0;
-
-// Final spiral — the dramatic full version, 30 s before USB goes silent.
-const FINAL_SPIRAL_RADIUS_START: f32 = 80.0;
-const FINAL_SPIRAL_TURNS: f32 = 5.0;
-const FINAL_SPIRAL_FRAMES: u32 = 625; // 5.0 s @ 8 ms/frame
-
-// 5-min warning — medium escalation.
-const WARN5_RADIUS_START: f32 = 50.0;
-const WARN5_TURNS: f32 = 3.0;
-const WARN5_FRAMES: u32 = 312; // ~2.5 s
-
-// 10-min warning — small foreshadow.
-const WARN10_RADIUS_START: f32 = 30.0;
-const WARN10_TURNS: f32 = 2.0;
-const WARN10_FRAMES: u32 = 187; // ~1.5 s
-
-// Offsets from Active-entry. The hsmc parent timer rule: timers in a parent
-// state start on parent entry and survive sibling-substate transitions, so
-// these three `after`s race concurrently against the same epoch.
-const WARN_10_AT: Duration = RUN_BEFORE_SHUTDOWN.saturating_sub(Duration::from_mins(10));
-const WARN_5_AT: Duration = RUN_BEFORE_SHUTDOWN.saturating_sub(Duration::from_mins(5));
-
-// ── Watchdog (independent task) ────────────────────────────────────
-const WATCHDOG_TIMEOUT: EDuration = EDuration::from_secs(8);
-const WATCHDOG_FEED_INTERVAL: EDuration = EDuration::from_secs(5);
-
-// ── Jiggle dwell ───────────────────────────────────────────────────
-const PIXEL_DWELL: EDuration = EDuration::from_millis(25);
-
-// ── Boot LED sweep ─────────────────────────────────────────────────
-// Brief power-on confirmation. Kept short so the cursor shake — the actual
-// "wake the display" gesture — happens promptly after reset.
-const BOOT_SWEEP_STEP: EDuration = EDuration::from_millis(60);
-
-// ── Shutdown LED flashes ───────────────────────────────────────────
-const SHUTDOWN_FLASH_STEP: EDuration = EDuration::from_millis(400);
-
-pub struct Ctx {
-    pub mouse: MouseHid,
-    pub kbd: KbdHid,
-    pub neo: Neo,
-    pub neo_pwr: Output<'static>,
-    pub active_start: Option<Instant>,
-}
-
-#[derive(Debug, Clone)]
-pub enum Ev {
-    BootDone,
-    SpinDone,
-    Jiggled,
-    WarnDone,
-    SpiralDone,
-}
-
-statechart! {
-Jiggly {
-    context: Ctx;
-    events: Ev;
-    default(Booting);
-
-    state Booting {
-        during: boot_sweep(neo, neo_pwr);
-        on(BootDone) => WakingHost;
-    }
-
-    // Wake the host using whichever input the host actually responds to.
-    // Keyboard first (more reliable on macOS), then a mouse shake as
-    // belt-and-suspenders. Each substate runs a oneshot entry action with
-    // its own internal deadline; the chart timer is what advances the
-    // chart. No durings, no events — purely entry + timer.
-    state WakingHost {
-        during: pulse_blue(neo);
-        default(WakingWithKeyboard);
-
-        state WakingWithKeyboard {
-            entry: keyboard_wake;
-            on(after KBD_PHASE_DURATION) => WakingWithMouse;
-        }
-
-        state WakingWithMouse {
-            entry: mouse_wake;
-            on(after MOUSE_PHASE_DURATION) => Settling;
-        }
-    }
-
-    // Quiet pause so the display has time to come out of sleep before the
-    // cursor starts drawing the spinner.
-    state Settling {
-        during: pulse_white(neo);
-        on(after SETTLING_DELAY) => Spinning;
-    }
-
-    state Spinning {
-        during: animate_spinner(mouse);
-        during: fade_to_green(neo);
-        on(SpinDone) => Active;
-    }
-
-    state Active {
-        entry: capture_active_start;
-        on(every JIGGLE_PERIOD) => jiggle_pair;
-        on(after WARN_10_AT) => Warning10;
-        on(after WARN_5_AT) => Warning5;
-        on(after RUN_BEFORE_SHUTDOWN) => Ending;
-        default(Breathing);
-
-        state Breathing {
-            during: breathe_color(neo, active_start);
-            on(Jiggled) => Flashing;
-        }
-
-        state Flashing {
-            entry: paint_white;
-            on(after FLASH_DURATION) => Breathing;
-        }
-
-        state Warning10 {
-            during: animate_warning_10(mouse);
-            on(WarnDone) => Breathing;
-        }
-
-        state Warning5 {
-            during: animate_warning_5(mouse);
-            on(WarnDone) => Breathing;
-        }
-    }
-
-    state Ending {
-        during: blink_fast_red(neo);
-        default(Spiraling);
-
-        state Spiraling {
-            during: animate_final_spiral(mouse);
-            on(SpiralDone) => Quiet;
-        }
-
-        state Quiet {
-            on(after QUIET_AFTER_ANIM) => PoweringDown;
-        }
-    }
-
-    state PoweringDown {
-        entry: shutdown_flashes;
-        entry: power_off_neo;
-    }
-}
-}
-
-impl JigglyActions for JigglyActionContext<'_> {
-    async fn capture_active_start(&mut self) {
-        self.active_start = Some(Instant::now());
-    }
-
-    async fn keyboard_wake(&mut self) {
-        let result = embassy_futures::select::select(
-            wake_with_keyboard(&mut self.kbd),
-            Timer::after(KBD_WAKE_DEADLINE),
-        )
-        .await;
-        #[cfg(feature = "defmt")]
-        match result {
-            embassy_futures::select::Either::First(_) => defmt::info!("kbd wake: completed"),
-            embassy_futures::select::Either::Second(_) => {
-                defmt::warn!(
-                    "kbd wake: deadline hit ({} ms)",
-                    KBD_WAKE_DEADLINE.as_millis()
-                )
-            }
-        }
-        #[cfg(not(feature = "defmt"))]
-        let _ = result;
-        // Belt-and-suspenders: always send an all-keys-released report,
-        // even if the deadline preempted the loop *between* a key-down
-        // and its key-up. Without this, a stuck modifier (Shift!) or key
-        // on the host side could persist until the user unplugs the
-        // device. Bounded by KBD_RELEASE_DEADLINE so a misbehaving
-        // endpoint can't pin the chart.
-        let _ = embassy_futures::select::select(
-            send_kbd(&mut self.kbd, 0, [0; 6]),
-            Timer::after(KBD_RELEASE_DEADLINE),
-        )
-        .await;
-    }
-
-    async fn mouse_wake(&mut self) {
-        let result = embassy_futures::select::select(
-            wake_with_mouse(&mut self.mouse),
-            Timer::after(MOUSE_WAKE_DEADLINE),
-        )
-        .await;
-        #[cfg(feature = "defmt")]
-        match result {
-            embassy_futures::select::Either::First(_) => defmt::info!("mouse wake: completed"),
-            embassy_futures::select::Either::Second(_) => defmt::warn!(
-                "mouse wake: deadline hit ({} ms)",
-                MOUSE_WAKE_DEADLINE.as_millis()
-            ),
-        }
-        #[cfg(not(feature = "defmt"))]
-        let _ = result;
-    }
-
-    async fn jiggle_pair(&mut self) {
-        let (dx, dy): (i8, i8) = if (RoscRng::next_u8() & 1) == 0 {
-            (1, 0)
-        } else {
-            (0, 1)
-        };
-        #[cfg(feature = "defmt")]
-        defmt::info!("jiggle: dx={} dy={}", dx, dy);
-        send_mouse(&mut self.mouse, dx, dy).await;
-        Timer::after(PIXEL_DWELL).await;
-        send_mouse(&mut self.mouse, -dx, -dy).await;
-        let _ = self.emit(Ev::Jiggled);
-    }
-
-    async fn paint_white(&mut self) {
-        paint(&mut self.neo, FLASH_PEAK, FLASH_PEAK, FLASH_PEAK).await;
-    }
-
-    async fn shutdown_flashes(&mut self) {
-        for _ in 0..3 {
-            paint(&mut self.neo, 0, BREATHE_PEAK, 0).await;
-            Timer::after(SHUTDOWN_FLASH_STEP).await;
-            paint(&mut self.neo, 0, 0, 0).await;
-            Timer::after(SHUTDOWN_FLASH_STEP).await;
-        }
-    }
-
-    async fn power_off_neo(&mut self) {
-        self.neo_pwr.set_low();
-    }
-}
-
-// ── During activities (free async fns) ─────────────────────────────
-
-async fn boot_sweep(neo: &mut Neo, neo_pwr: &mut Output<'static>) -> Ev {
-    neo_pwr.set_high();
-    Timer::after_millis(2).await;
-
-    paint(neo, BREATHE_PEAK, 0, 0).await;
-    Timer::after(BOOT_SWEEP_STEP).await;
-    paint(neo, 0, BREATHE_PEAK, 0).await;
-    Timer::after(BOOT_SWEEP_STEP).await;
-    paint(neo, 0, 0, BREATHE_PEAK).await;
-    Timer::after(BOOT_SWEEP_STEP).await;
-    paint(neo, 0, 0, 0).await;
-    Ev::BootDone
-}
-
-// Tap F13 four times. macOS reliably wakes from any keyboard event but is
-// inconsistent about waking from raw mouse motion. Plain oneshot helper —
-// the action method that calls this races it against KBD_WAKE_DEADLINE
-// AND unconditionally sends an all-keys-released cleanup report after,
-// to make sure we never leave a key held on the host.
-async fn wake_with_keyboard(kbd: &mut KbdHid) {
-    for _ in 0..KBD_WAKE_TAPS {
-        send_kbd(kbd, 0, [KBD_KEY_F13, 0, 0, 0, 0, 0]).await;
-        Timer::after(KBD_TAP_HOLD).await;
-        send_kbd(kbd, 0, [0; 6]).await;
-        Timer::after(KBD_TAP_GAP).await;
-    }
-}
-
-// Frantic horizontal mouse shake. Plain oneshot helper — the action method
-// that calls this races it against MOUSE_WAKE_DEADLINE.
-async fn wake_with_mouse(mouse: &mut MouseHid) {
-    let period_frames = (WAKE_FRAMES_PER_HALF * 2) as f32;
-    let total_frames = WAKE_OSCILLATIONS * WAKE_FRAMES_PER_HALF * 2;
-    let mut prev_x: f32 = 0.0;
-    let mut prev_y: f32 = 0.0;
-    let mut acc_x: f32 = 0.0;
-    let mut acc_y: f32 = 0.0;
-    for f in 0..total_frames {
-        let phase = (f as f32) * 2.0 * PI / period_frames;
-        let next_x = WAKE_AMPLITUDE * sinf(phase);
-        let jitter = ((RoscRng::next_u8() as f32) / 255.0 - 0.5) * 2.0 * WAKE_JITTER;
-        let next_y = jitter;
-        let (dx, dy, used_x, used_y) = step_delta(prev_x, prev_y, next_x, next_y, acc_x, acc_y);
-        acc_x = used_x;
-        acc_y = used_y;
-        send_mouse(mouse, dx, dy).await;
-        prev_x = next_x;
-        prev_y = next_y;
-        Timer::after(ANIM_FRAME).await;
-    }
-}
-
-async fn animate_spinner(mouse: &mut MouseHid) -> Ev {
-    let total_frames = RUN_CIRCLES * RUN_FRAMES_PER_CIRCLE;
-    let period_frames = RUN_FRAMES_PER_CIRCLE as f32;
-    let mut prev_x: f32 = 0.0;
-    let mut prev_y: f32 = 0.0;
-    let mut acc_x: f32 = 0.0;
-    let mut acc_y: f32 = 0.0;
-    for f in 0..total_frames {
-        let angle = (f as f32) * 2.0 * PI / period_frames;
-        let next_x = RUN_RADIUS * sinf(angle);
-        let next_y = RUN_RADIUS * (1.0 - cosf(angle));
-        let (dx, dy, used_x, used_y) = step_delta(prev_x, prev_y, next_x, next_y, acc_x, acc_y);
-        acc_x = used_x;
-        acc_y = used_y;
-        send_mouse(mouse, dx, dy).await;
-        prev_x = next_x;
-        prev_y = next_y;
-        Timer::after(ANIM_FRAME).await;
-    }
-    Ev::SpinDone
-}
-
-async fn animate_spiral(
-    mouse: &mut MouseHid,
-    radius_start: f32,
-    radius_end: f32,
-    turns: f32,
-    frames: u32,
-) {
-    let mut prev_x: f32 = 0.0;
-    let mut prev_y: f32 = 0.0;
-    let mut acc_x: f32 = 0.0;
-    let mut acc_y: f32 = 0.0;
-    for f in 0..frames {
-        let t = (f as f32) / (frames as f32);
-        let u = powf(t, EASE_POW);
-        let angle = u * 2.0 * PI * turns;
-        let radius = radius_start + (radius_end - radius_start) * u;
-        // Subtract starting offset so the spiral begins at the cursor's entry point.
-        let next_x = radius * cosf(angle) - radius_start;
-        let next_y = radius * sinf(angle);
-        let (dx, dy, used_x, used_y) = step_delta(prev_x, prev_y, next_x, next_y, acc_x, acc_y);
-        acc_x = used_x;
-        acc_y = used_y;
-        send_mouse(mouse, dx, dy).await;
-        prev_x = next_x;
-        prev_y = next_y;
-        Timer::after(ANIM_FRAME).await;
-    }
-}
-
-async fn animate_final_spiral(mouse: &mut MouseHid) -> Ev {
-    animate_spiral(
-        mouse,
-        FINAL_SPIRAL_RADIUS_START,
-        SPIRAL_RADIUS_END,
-        FINAL_SPIRAL_TURNS,
-        FINAL_SPIRAL_FRAMES,
-    )
-    .await;
-    Ev::SpiralDone
-}
-
-async fn animate_warning_5(mouse: &mut MouseHid) -> Ev {
-    animate_spiral(
-        mouse,
-        WARN5_RADIUS_START,
-        SPIRAL_RADIUS_END,
-        WARN5_TURNS,
-        WARN5_FRAMES,
-    )
-    .await;
-    Ev::WarnDone
-}
-
-async fn animate_warning_10(mouse: &mut MouseHid) -> Ev {
-    animate_spiral(
-        mouse,
-        WARN10_RADIUS_START,
-        SPIRAL_RADIUS_END,
-        WARN10_TURNS,
-        WARN10_FRAMES,
-    )
-    .await;
-    Ev::WarnDone
-}
-
-async fn breathe_color(neo: &mut Neo, active_start: &mut Option<Instant>) -> Ev {
-    loop {
-        let elapsed = active_start.map(|s| s.elapsed()).unwrap_or_default();
-        let total_run = run_before_shutdown_e();
-        let remaining = total_run
-            .checked_sub(elapsed)
-            .unwrap_or(EDuration::from_ticks(0));
-        let (r, g, b) = breathe_for(remaining, elapsed);
-        paint(neo, r, g, b).await;
-        Timer::after(LED_TICK).await;
-    }
-}
-
-async fn blink_fast_red(neo: &mut Neo) -> Ev {
-    let start = Instant::now();
-    loop {
-        let t = start.elapsed();
-        let level = if blink_on(FAST_RED_PERIOD, t) {
-            BREATHE_PEAK
-        } else {
-            BREATHE_FLOOR
-        };
-        paint(neo, level, 0, 0).await;
-        Timer::after(LED_TICK).await;
-    }
-}
-
-async fn pulse_blue(neo: &mut Neo) -> Ev {
-    let start = Instant::now();
-    loop {
-        let level = sin_breath(WAKING_PULSE_PERIOD, start.elapsed(), BREATHE_FLOOR, BREATHE_PEAK);
-        paint(neo, 0, 0, level).await;
-        Timer::after(LED_TICK).await;
-    }
-}
-
-async fn pulse_white(neo: &mut Neo) -> Ev {
-    let start = Instant::now();
-    loop {
-        let level = sin_breath(SETTLING_PULSE_PERIOD, start.elapsed(), BREATHE_FLOOR, BREATHE_PEAK);
-        paint(neo, level, level, level).await;
-        Timer::after(LED_TICK).await;
-    }
-}
-
-// Linear fade from white(peak) → green(peak) so the LED hands off into
-// Active's green breathing without a visible jump.
-async fn fade_to_green(neo: &mut Neo) -> Ev {
-    let start = Instant::now();
-    let total_ms = SPINNER_FADE_DURATION.as_millis() as f32;
-    loop {
-        let t = ((start.elapsed().as_millis() as f32) / total_ms).min(1.0);
-        let rb = (BREATHE_PEAK as f32 * (1.0 - t)) as u8;
-        paint(neo, rb, BREATHE_PEAK, rb).await;
-        Timer::after(LED_TICK).await;
-    }
-}
-
-// ── Color / breathing helpers ──────────────────────────────────────
-
-fn run_before_shutdown_e() -> EDuration {
-    // RUN_BEFORE_SHUTDOWN is a `core::time::Duration`; convert to the embassy
-    // type once at the call site so the comparator below is apples-to-apples.
-    EDuration::from_secs(RUN_BEFORE_SHUTDOWN.as_secs())
-}
-
-fn breathe_for(remaining: EDuration, elapsed: EDuration) -> (u8, u8, u8) {
-    if remaining > YELLOW_AT {
-        let level = sin_breath(SLOW_GREEN_PERIOD, elapsed, BREATHE_FLOOR, BREATHE_PEAK);
-        (0, level, 0)
-    } else if remaining > RED_AT {
-        // Green is perceptually brighter on WS2812 — scale it down for a warm yellow.
-        let level = sin_breath(YELLOW_PERIOD, elapsed, BREATHE_FLOOR, BREATHE_PEAK);
-        (level, ((level as u16 * 5) / 10) as u8, 0)
-    } else if remaining > FAST_RED_AT {
-        let level = sin_breath(RED_PERIOD, elapsed, BREATHE_FLOOR, BREATHE_PEAK);
-        (level, 0, 0)
-    } else {
-        let level = if blink_on(FAST_RED_PERIOD, elapsed) {
-            BREATHE_PEAK
-        } else {
-            BREATHE_FLOOR
-        };
-        (level, 0, 0)
-    }
-}
-
-fn sin_breath(period: EDuration, t: EDuration, floor: u8, peak: u8) -> u8 {
-    let period_ms = period.as_millis() as f32;
-    let t_ms = (t.as_millis() % period.as_millis()) as f32;
-    let phase = 2.0 * PI * t_ms / period_ms;
-    let val = (1.0 - cosf(phase)) * 0.5;
-    let span = peak.saturating_sub(floor) as f32;
-    floor + (val * span) as u8
-}
-
-fn blink_on(period: EDuration, t: EDuration) -> bool {
-    let period_ms = period.as_millis();
-    (t.as_millis() % period_ms) < (period_ms / 2)
-}
-
-// Translate continuous (next_x, next_y) target into clamped i8 deltas while
-// carrying sub-pixel residue forward, so a 90-frame circle of radius 50 doesn't
-// lose ~half its motion to truncation. Returns (dx, dy, residual_x, residual_y).
-fn step_delta(
-    prev_x: f32,
-    prev_y: f32,
-    next_x: f32,
-    next_y: f32,
-    acc_x: f32,
-    acc_y: f32,
-) -> (i8, i8, f32, f32) {
-    let want_x = (next_x - prev_x) + acc_x;
-    let want_y = (next_y - prev_y) + acc_y;
-    let dx = roundf(want_x.clamp(-127.0, 127.0)) as i8;
-    let dy = roundf(want_y.clamp(-127.0, 127.0)) as i8;
-    (dx, dy, want_x - dx as f32, want_y - dy as f32)
-}
-
-// ── HID + LED primitives ───────────────────────────────────────────
-
-async fn send_mouse(mouse: &mut MouseHid, x: i8, y: i8) {
-    let report = MouseReport {
-        buttons: 0,
-        x,
-        y,
-        wheel: 0,
-        pan: 0,
-    };
-    let _ = with_timeout(EDuration::from_secs(3), mouse.write_serialize(&report)).await;
-}
-
-async fn send_kbd(kbd: &mut KbdHid, modifier: u8, keycodes: [u8; 6]) {
-    let report = KeyboardReport {
-        modifier,
-        reserved: 0,
-        leds: 0,
-        keycodes,
-    };
-    let _ = with_timeout(EDuration::from_secs(3), kbd.write_serialize(&report)).await;
-}
-
-async fn paint(neo: &mut Neo, r: u8, g: u8, b: u8) {
-    neo.write(&[RGB8 { r, g, b }]).await;
-}
-
-// ── USB serial number from RP2040 unique chip ID ───────────────────
-// Reads the 64-bit unique ID baked into the on-board SPI flash, formats
-// it as 16 ASCII hex chars in a static buffer, and returns a `'static`
-// string suitable for `embassy_usb::Config::serial_number`. This makes
-// the device's USB identity stable per-board across replugs (so hosts
-// stop treating each plug as a new device) while still being unique
-// between different boards.
-const FLASH_SIZE: usize = 2 * 1024 * 1024; // Xiao RP2040 has 2 MB.
-
-fn make_serial(flash_periph: Peri<'static, FLASH>) -> &'static str {
-    static SERIAL: StaticCell<[u8; 16]> = StaticCell::new();
-    const HEX: &[u8; 16] = b"0123456789ABCDEF";
-
-    let mut flash = Flash::<_, _, FLASH_SIZE>::new_blocking(flash_periph);
-    let mut id = [0u8; 8];
-    let _ = flash.blocking_unique_id(&mut id);
-
-    let buf = SERIAL.init([0; 16]);
-    for (i, &b) in id.iter().enumerate() {
-        buf[i * 2] = HEX[(b >> 4) as usize];
-        buf[i * 2 + 1] = HEX[(b & 0x0f) as usize];
-    }
-    core::str::from_utf8(buf).unwrap()
-}
-
-// ── Tasks ──────────────────────────────────────────────────────────
-
-#[embassy_executor::task]
-async fn usb_task(mut device: UsbDevice<'static, UsbDriver>) {
-    device.run().await;
-}
-
-#[embassy_executor::task]
-async fn watchdog_task(mut wd: Watchdog) -> ! {
-    loop {
-        wd.feed(WATCHDOG_TIMEOUT);
-        Timer::after(WATCHDOG_FEED_INTERVAL).await;
-    }
-}
-
-// ── Main ───────────────────────────────────────────────────────────
-
 #[embassy_executor::main]
 async fn main(spawner: Spawner) {
     let p = embassy_rp::init(Default::default());
diff --git a/src/mouse.rs b/src/mouse.rs
new file mode 100644
index 0000000..994b7a0
--- /dev/null
+++ b/src/mouse.rs
@@ -0,0 +1,163 @@
+//! Mouse HID: report send + the family of cursor animations
+//! (wake-shake, spinner, eased spirals).
+
+use core::f32::consts::PI;
+
+use embassy_rp::clocks::RoscRng;
+use embassy_time::{Duration as EDuration, Timer, with_timeout};
+use embassy_usb::class::hid::HidWriter;
+use libm::{cosf, powf, roundf, sinf};
+use usbd_hid::descriptor::MouseReport;
+
+use crate::chart::Ev;
+use crate::config::{
+    ANIM_FRAME, EASE_POW, FINAL_SPIRAL_FRAMES, FINAL_SPIRAL_RADIUS_START, FINAL_SPIRAL_TURNS,
+    RUN_CIRCLES, RUN_FRAMES_PER_CIRCLE, RUN_RADIUS, SPIRAL_RADIUS_END, WAKE_AMPLITUDE,
+    WAKE_FRAMES_PER_HALF, WAKE_JITTER, WAKE_OSCILLATIONS, WARN5_FRAMES, WARN5_RADIUS_START,
+    WARN5_TURNS, WARN10_FRAMES, WARN10_RADIUS_START, WARN10_TURNS,
+};
+use crate::usb::UsbDriver;
+
+pub(crate) type MouseHid = HidWriter<'static, UsbDriver, 5>;
+
+// Frantic horizontal mouse shake. Plain oneshot helper — the action method
+// that calls this races it against MOUSE_WAKE_DEADLINE.
+pub(crate) async fn wake_with_mouse(mouse: &mut MouseHid) {
+    let period_frames = (WAKE_FRAMES_PER_HALF * 2) as f32;
+    let total_frames = WAKE_OSCILLATIONS * WAKE_FRAMES_PER_HALF * 2;
+    let mut prev_x: f32 = 0.0;
+    let mut prev_y: f32 = 0.0;
+    let mut acc_x: f32 = 0.0;
+    let mut acc_y: f32 = 0.0;
+    for f in 0..total_frames {
+        let phase = (f as f32) * 2.0 * PI / period_frames;
+        let next_x = WAKE_AMPLITUDE * sinf(phase);
+        let jitter = ((RoscRng::next_u8() as f32) / 255.0 - 0.5) * 2.0 * WAKE_JITTER;
+        let next_y = jitter;
+        let (dx, dy, used_x, used_y) = step_delta(prev_x, prev_y, next_x, next_y, acc_x, acc_y);
+        acc_x = used_x;
+        acc_y = used_y;
+        send_mouse(mouse, dx, dy).await;
+        prev_x = next_x;
+        prev_y = next_y;
+        Timer::after(ANIM_FRAME).await;
+    }
+}
+
+pub(crate) async fn animate_spinner(mouse: &mut MouseHid) -> Ev {
+    let total_frames = RUN_CIRCLES * RUN_FRAMES_PER_CIRCLE;
+    let period_frames = RUN_FRAMES_PER_CIRCLE as f32;
+    let mut prev_x: f32 = 0.0;
+    let mut prev_y: f32 = 0.0;
+    let mut acc_x: f32 = 0.0;
+    let mut acc_y: f32 = 0.0;
+    for f in 0..total_frames {
+        let angle = (f as f32) * 2.0 * PI / period_frames;
+        let next_x = RUN_RADIUS * sinf(angle);
+        let next_y = RUN_RADIUS * (1.0 - cosf(angle));
+        let (dx, dy, used_x, used_y) = step_delta(prev_x, prev_y, next_x, next_y, acc_x, acc_y);
+        acc_x = used_x;
+        acc_y = used_y;
+        send_mouse(mouse, dx, dy).await;
+        prev_x = next_x;
+        prev_y = next_y;
+        Timer::after(ANIM_FRAME).await;
+    }
+    Ev::SpinDone
+}
+
+async fn animate_spiral(
+    mouse: &mut MouseHid,
+    radius_start: f32,
+    radius_end: f32,
+    turns: f32,
+    frames: u32,
+) {
+    let mut prev_x: f32 = 0.0;
+    let mut prev_y: f32 = 0.0;
+    let mut acc_x: f32 = 0.0;
+    let mut acc_y: f32 = 0.0;
+    for f in 0..frames {
+        let t = (f as f32) / (frames as f32);
+        let u = powf(t, EASE_POW);
+        let angle = u * 2.0 * PI * turns;
+        let radius = radius_start + (radius_end - radius_start) * u;
+        // Subtract starting offset so the spiral begins at the cursor's entry point.
+        let next_x = radius * cosf(angle) - radius_start;
+        let next_y = radius * sinf(angle);
+        let (dx, dy, used_x, used_y) = step_delta(prev_x, prev_y, next_x, next_y, acc_x, acc_y);
+        acc_x = used_x;
+        acc_y = used_y;
+        send_mouse(mouse, dx, dy).await;
+        prev_x = next_x;
+        prev_y = next_y;
+        Timer::after(ANIM_FRAME).await;
+    }
+}
+
+pub(crate) async fn animate_final_spiral(mouse: &mut MouseHid) -> Ev {
+    animate_spiral(
+        mouse,
+        FINAL_SPIRAL_RADIUS_START,
+        SPIRAL_RADIUS_END,
+        FINAL_SPIRAL_TURNS,
+        FINAL_SPIRAL_FRAMES,
+    )
+    .await;
+    Ev::SpiralDone
+}
+
+pub(crate) async fn animate_warning_5(mouse: &mut MouseHid) -> Ev {
+    animate_spiral(
+        mouse,
+        WARN5_RADIUS_START,
+        SPIRAL_RADIUS_END,
+        WARN5_TURNS,
+        WARN5_FRAMES,
+    )
+    .await;
+    Ev::WarnDone
+}
+
+pub(crate) async fn animate_warning_10(mouse: &mut MouseHid) -> Ev {
+    animate_spiral(
+        mouse,
+        WARN10_RADIUS_START,
+        SPIRAL_RADIUS_END,
+        WARN10_TURNS,
+        WARN10_FRAMES,
+    )
+    .await;
+    Ev::WarnDone
+}
+
+// Translate continuous (next_x, next_y) target into clamped i8 deltas while
+// carrying sub-pixel residue forward, so a 90-frame circle of radius 50 doesn't
+// lose ~half its motion to truncation. Returns (dx, dy, residual_x, residual_y).
+fn step_delta(
+    prev_x: f32,
+    prev_y: f32,
+    next_x: f32,
+    next_y: f32,
+    acc_x: f32,
+    acc_y: f32,
+) -> (i8, i8, f32, f32) {
+    let want_x = (next_x - prev_x) + acc_x;
+    let want_y = (next_y - prev_y) + acc_y;
+    let dx = roundf(want_x.clamp(-127.0, 127.0)) as i8;
+    let dy = roundf(want_y.clamp(-127.0, 127.0)) as i8;
+    (dx, dy, want_x - dx as f32, want_y - dy as f32)
+}
+
+// ── HID primitive ──────────────────────────────────────────────────
+
+pub(crate) async fn send_mouse(mouse: &mut MouseHid, x: i8, y: i8) {
+    let report = MouseReport {
+        buttons: 0,
+        x,
+        y,
+        wheel: 0,
+        pan: 0,
+    };
+    let _ = with_timeout(EDuration::from_secs(3), mouse.write_serialize(&report)).await;
+}
diff --git a/src/usb.rs b/src/usb.rs
new file mode 100644
index 0000000..c708bdb
--- /dev/null
+++ b/src/usb.rs
@@ -0,0 +1,57 @@
+//! USB driver type aliases, identity helpers, and infra tasks
+//! (USB device pump + watchdog feeder).
+
+use embassy_rp::{
+    Peri,
+    flash::Flash,
+    peripherals::{FLASH, USB},
+    usb::Driver,
+    watchdog::Watchdog,
+};
+use embassy_time::Timer;
+use embassy_usb::UsbDevice;
+use static_cell::StaticCell;
+
+use crate::config::{WATCHDOG_FEED_INTERVAL, WATCHDOG_TIMEOUT};
+
+pub(crate) type UsbDriver = Driver<'static, USB>;
+
+// ── USB serial number from RP2040 unique chip ID ───────────────────
+// Reads the 64-bit unique ID baked into the on-board SPI flash, formats
+// it as 16 ASCII hex chars in a static buffer, and returns a `'static`
+// string suitable for `embassy_usb::Config::serial_number`. This makes
+// the device's USB identity stable per-board across replugs (so hosts
+// stop treating each plug as a new device) while still being unique
+// between different boards.
+const FLASH_SIZE: usize = 2 * 1024 * 1024; // Xiao RP2040 has 2 MB.
+
+pub(crate) fn make_serial(flash_periph: Peri<'static, FLASH>) -> &'static str {
+    static SERIAL: StaticCell<[u8; 16]> = StaticCell::new();
+    const HEX: &[u8; 16] = b"0123456789ABCDEF";
+
+    let mut flash = Flash::<_, _, FLASH_SIZE>::new_blocking(flash_periph);
+    let mut id = [0u8; 8];
+    let _ = flash.blocking_unique_id(&mut id);
+
+    let buf = SERIAL.init([0; 16]);
+    for (i, &b) in id.iter().enumerate() {
+        buf[i * 2] = HEX[(b >> 4) as usize];
+        buf[i * 2 + 1] = HEX[(b & 0x0f) as usize];
+    }
+    core::str::from_utf8(buf).unwrap()
+}
+
+// ── Tasks ──────────────────────────────────────────────────────────
+
+#[embassy_executor::task]
+pub(crate) async fn usb_task(mut device: UsbDevice<'static, UsbDriver>) {
+    device.run().await;
+}
+
+#[embassy_executor::task]
+pub(crate) async fn watchdog_task(mut wd: Watchdog) -> ! {
+    loop {
+        wd.feed(WATCHDOG_TIMEOUT);
+        Timer::after(WATCHDOG_FEED_INTERVAL).await;
+    }
+}