Monorepo for Aesthetic.Computer
aesthetic.computer
docs(reports): session report on notepat percussion + dj hotplug + help panel
Progress report covering the full session's work: two-step DOWN/UP
drum architecture across all 12 pads, stochastic variation, BPM-locked
flam, animated graphic notation, kit-geometry pan, full-screen drum
flash visuals, reverse loop pedal on space bar, USB /media stale-mount
fix, categorized adaptive-width help panel rewrite, and install-to-HD
robustness work. Lists all commits and build pipeline history.
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reports/2026-04-10-notepat-percussion-and-dj-hotplug.md
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reports/2026-04-10-notepat-percussion-and-dj-hotplug.md
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# 2026-04-10 — notepat percussion kit + dj hotplug + help panel
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Session focus: turn notepat's percussion mode into a fully realized drum
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instrument (synth + sampling + visuals + stereo + reverse-loop pedal), fix a
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USB hotplug regression that broke DJ track detection, and rebuild the meta-held
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shortcut help panel so it's readable at any screen size.
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All work shipped via the oven build pipeline (compush → oven → `ac-os pull`).
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Final combined build at the time of writing is `57b818dd-8` on commit
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`18dbc5986`, carrying every feature listed below.
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---
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## 1. Percussion kit — complete rework
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### 1.1 Two-step DOWN / UP architecture
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Every drum in the 12-pad kit now fires as a two-stage pair instead of a
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simultaneous layer stack:
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| Drum | DOWN (impact) | UP (release) |
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|---|---|---|
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| **kick** | beater click + body thump + sawtooth grit | sub-bass wobble bloom + mid fill |
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| **snare** | stick-on-head pop | wire rattle + shell ring |
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| **clap** | dark palm strike | bright release transient |
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| **snap** | finger-release click | skin slap body ring |
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| **closed hat** | stick contact tick | tight metallic sizzle |
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| **open hat** | metallic chip strike | sustained airy shimmer |
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| **ride** | bell-like ping | long shimmer wash |
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| **crash** | explosive metal impact | long sustained wash |
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| **splash** | thin high metal tick | short bright wash |
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| **cowbell** | stick-on-metal tink | resonant detuned ring |
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| **wood block** | stick contact tick | hollow wood body |
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| **tambourine** | frame strike | jingle rattle |
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Gap between DOWN and UP is BPM-locked (`flam × rn(...)` per hit) so rolls
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tighten at higher tempos and widen at slower ones. Kick and crash use tight
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4–9 ms gaps so the punch+bloom feels unified; ride and open hi-hat use longer
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gaps for audible strike→shimmer separation.
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Commits: [`46ab9b132`](../fedac/native/pieces/notepat.mjs), [`cebfb6737`](../fedac/native/pieces/notepat.mjs)
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### 1.2 Stochastic variation on every drum
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Per-hit jitter helpers `rj(center, frac)` / `rn(min, max)` applied across all
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12 drums:
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- **Tone jitter**: ±3–12% on every oscillator frequency
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- **Volume jitter**: ±5–12% per voice
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- **Duration jitter**: ±5–14% on longer tails
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- **Pan jitter**: ±0.05 offset per DOWN/UP step for subtle stereo movement
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- **Flam timing jitter**: `rn(...)` inside the `setTimeout` delay for the UP step
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No two hits sound identical. Tambourines get the widest jitter because real
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tambourines never sound the same twice.
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Commit: [`b520136ee`](../fedac/native/pieces/notepat.mjs)
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### 1.3 Animated graphic notation inside drum pads
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Each pad renders an animated glyph showing the drum's internal structure:
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tonal bars for sine/triangle/square/sawtooth layers at log-frequency Y
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positions, random dots for noise bursts. `PERCUSSION_NOTATION` table describes
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each drum's voices; `NOTATION_WAVE_RGB` maps wave types to accent colors.
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Drawn with per-frame random jitter so viewers see the stochastic mechanism in
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action while the pad is idle.
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Commit: [`d1064820b`](../fedac/native/pieces/notepat.mjs)
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### 1.4 Kit-geometry pan (not pitch-based)
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Tones pan by pitch (`(semitones − 12) / 15`) — low notes left, high notes
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right. Drums were inheriting that same formula so a kick (C) was getting
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hard-panned left just because C is the lowest note.
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New `drumPanFor(letter, gridOffset)` combines two factors:
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- **Grid bias**: left grid → -0.32, right grid → +0.32
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- **Drum-type offset** (`DRUM_PAN_OFFSET`) per kit geometry:
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kick 0.00, snare -0.05, clap +0.10, snap -0.10, closed hat +0.25,
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open hat +0.32, ride +0.45 (far right), crash -0.45, splash -0.55
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(far left), cowbell +0.22, block -0.18, tambo +0.30
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Final pan = `clamp(gridBias + drumOffset * 0.7, ±0.9)`. Grid side dominates
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so both grids stay distinguishable; drum offset modulates for kit color.
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Wired through keyboard, touch-tap, and drag-rollover drum paths.
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Commit: [`665ef824f`](../fedac/native/pieces/notepat.mjs)
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### 1.5 Full-screen background flash per drum
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Tones already painted the whole background from their note colors while held.
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Drums, being one-shots, never got that visual response. Now they do.
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- New `drumFlashes` queue (up to 8 concurrent entries, life = 14 frames
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≈ 230 ms) holds `{color, frame, life}`
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- `flashDrum(letter)` pushes an entry on every hit
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- Alpha curve: full 1.0 for first 2 frames (punchy blink), then linear decay
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- Paint-time blend: tone layer + drum layer are weighted-summed (drums get
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1.2× weight so a single hit still reads against held tones)
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- Tone layer snaps instantly; drum-only decays smoothly at 0.55/frame so
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rapid hits stack into a color wash but single hits fade out cleanly
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Colors sourced from existing `PERCUSSION_COLORS` palette (kick = deep orange,
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snare = tan, ride = silver-blue, crash = lavender, splash = pink, etc).
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Wired into all 4 drum trigger sites (keyboard, touch-tap, drag-rollover,
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reverse-playback replay).
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Commit: [`18dbc5986`](../fedac/native/pieces/notepat.mjs)
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### 1.6 Earlier percussion work
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- **Percussion layout toggle**: PgUp (left grid) / PgDn (right grid) map the
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7 naturals + 5 sharps of that octave to drum pads with synth recipes and
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optional per-drum recorded samples (existing from before this session,
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verified still working)
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- **Per-drum microphone sampling**: hold `End` to arm, then tap any drum pad
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to record a sample directly into `percussionSampleBank[drumName]`; release
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to save (confirmed working on build)
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- **Wub/wobble kick + sharper clap + whistle de-air**: earlier audio tuning
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commit [`2e4333327`](../fedac/native/pieces/notepat.mjs)
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---
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## 2. Reverse playback loop pedal (space bar)
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Pressing and holding space starts playing back the last 12 seconds of
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keyboard/drum hits in reverse, in real time, while the user can keep playing
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new notes on top. Releasing ends the phase; the next press unwinds whatever
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was played during that press — creating a "bounce loop" where repeated
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presses alternate forward→reverse→forward→reverse.
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Implementation:
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- `playbackHistory` rolling buffer (256 events / 12 s), recorded from every
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note + drum trigger site
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- `startReversePlayback()`: snapshots history, **clears** `playbackHistory`
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for the new phase, builds `reverseQueue` with time-mirrored delays
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- `stopReversePlayback()` drains the queue
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- `playReverseEvent()` fires the sound AND re-records it into the new phase,
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which is what creates the bounce loop semantics
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- `sim()` tick drains `reverseQueue` each frame (~16 ms resolution)
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- Fallback kick drum on first press (empty history)
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The duration of a held press effectively sets the loop's "out point" — very
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dynamic, very fun.
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Commit: [`da8a795b3`](../fedac/native/pieces/notepat.mjs)
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---
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## 3. USB hotplug → DJ regression fix
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### Symptom
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Plug a USB stick with music → DJ detects it once. Unplug → DJ stops working.
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Re-plug → nothing happens. Browsing tracks never starts again.
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### Root cause
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`mountMusic()` in `js-bindings.c` used `stat("/media/.").st_dev !=
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stat("/.").st_dev` to decide "already mounted". When a USB is physically
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yanked, `/media` stays as a **stale mount point** — `st_dev` still differs
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from root, so the function returned `JS_TRUE` forever. The JS hot-plug loop
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then thought USB was still connected and never re-scanned.
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### Fix
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Parse `/proc/mounts` to find the actual device backing `/media`. Verify:
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1. Device file still exists (`stat` + `S_ISBLK`)
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2. `opendir("/media")` succeeds
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If either check fails (stale mount from a yanked USB), `umount2(MNT_DETACH)`
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lazily before falling through to the normal mount loop. Re-plugs now get
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detected instead of seeing a stale "already mounted" response forever.
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Commit: [`325209975`](../fedac/native/src/js-bindings.c)
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---
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## 4. Meta-held shortcut help panel rewrite
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### Problems with the old panel
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- Fixed 280 px width wasted screen space on wider displays
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- 24 single-column rows bled off the bottom on small screens
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- Two flat colors gave no visual grouping
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- Bindings were stale: `space` still listed as "kick drum" when it's now the
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reverse loop pedal; F1–F4 listed as "Fn+F1" when the media-key aliases
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had been removed weeks ago
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### New panel
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- **9 color-coded categories**: NOTES (cyan), DRUMS (orange), WAVE (magenta),
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DECK (green), HOLD (yellow), TEMPO (amber), SAMPLE (pink), FX (teal),
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SYSTEM (gray) — colors applied to both category headers and the
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key-column text
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- **Adaptive 1/2/3 columns** based on screen width (`COL_W = 172 px`)
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- **Hard-clamped panel height** so it never bleeds off the bottom; overflow
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rows are clipped rather than pushed off-screen
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- **Dark/light theme-aware**: key colors brightened in dark mode, darkened
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in light mode for legibility on both
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- **Drop shadow + outline + title underline** for depth
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- **All bindings refreshed** to reflect current code state (space = reverse
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loop pedal, F1/F2/F3/F4 direct deck control, delete = clear sample bank,
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etc.)
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Commit: [`325209975`](../fedac/native/pieces/notepat.mjs) (shipped alongside
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the DJ fix)
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---
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## 5. Install-to-HD robustness
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From earlier in the session, before the main percussion work:
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- **SIGPIPE handler**: added `signal(SIGPIPE, SIG_IGN)` so websocket close
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doesn't kill the process (fix for observed exit=141 crash)
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- **setTimeout polyfill**: QuickJS has no timers. Added `__pendingTimeouts`
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queue flushed from `sim()` so pieces can use `setTimeout()` naturally
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(fix for "setTimeout is not defined" on ESC)
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- **Loop-unmount install path**: `force_unmount_disk()` parses `/proc/mounts`
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until no entries match, `blkrrpart_with_retry()` uses exponential backoff
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(0 → 250 → 500 → 1000 → 2000 ms), install-debug.log on tmpfs survives
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/mnt repartition (copied back at end of auto_install_to_hd)
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- **Flash verify instrumentation**: dedicated `/tmp/flash-trace.log` so the
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ac_log_pause() pattern no longer eats diagnostics; added size-check first
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in verify; bumped sync wait 500 ms → 3 s
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Commits: [`7c11b5ca7`](../fedac/native/src/ac-native.c), [`ea6cf8f24`](../fedac/native/src/js-bindings.c)
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---
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## 6. Commit list (this session, newest first)
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```
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18dbc5986 feat(percussion): drums pulse full-screen background in drum colors
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665ef824f feat(percussion): drums pan by kit geometry + grid bias (not tone pitch)
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325209975 fix(dj): detect stale /media mount on unplug + rebuild notepat help panel
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cebfb6737 feat(percussion): every drum is now two-step (DOWN impact + UP release)
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46ab9b132 feat(percussion): two-step clap + open hi-hat with down/up bursts
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846782476 Merge remote-tracking branch 'tangled/main'
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da8a795b3 feat(notepat): space bar = instant-replay reverse loop pedal
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d1064820b feat(notepat): animated stochastic graphic notation inside drum pads
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b520136ee feat(percussion): stochastic per-hit variation + BPM-locked flam timing
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2e4333327 fix(percussion): wub kick + sharper clip-clap + aggressive whistle de-air
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7c11b5ca7 fix(native): loop unmount until /mnt stack is clean + tmpfs debug log
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```
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All commits pushed to both `origin` (github) and `tangled` (knot) remotes.
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---
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## 7. Build pipeline state
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Current in-flight build: **`57b818dd-8`** on ref `18dbc5986`, triggered via
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`POST /native-build` to `oven.aesthetic.computer`. Carries every feature
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above in one artifact.
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Watcher `/tmp/watch-build.sh` (PID at time of report) polls the oven every
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20 s and will auto-flash via `ssh me@172.17.0.1 'cd
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/home/me/aesthetic-computer/fedac/native && ./ac-os pull'` on success.
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Several earlier builds in this session were cancelled mid-flight so
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sequential features could be combined into one flash cycle:
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- `1ff8e31b-7` — cancelled (was running on stale `f58d1bc57` after push/merge
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confusion; reconciled tangled/main into origin/main as `846782476`)
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- `2491da75-5` (clap + hat only) — cancelled to combine with the remaining
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10 drums
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- `23e163b2-7` (all 12 two-step drums) — cancelled to combine with USB
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hotplug + help panel fix
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- `121e68d3-9` (+ hotplug + help panel) — cancelled at 55% kernel stage to
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combine with drum pan geometry
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- `fd5cc814-a` (+ drum pan) — cancelled at 55% kernel stage to combine with
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full-screen drum visuals
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- `57b818dd-8` (+ drum visuals) — **running to completion** (combined final)
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---
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## 8. Outstanding / deferred
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- `native-notepat-*` → `ac-native-*` OTA artifact rename (user flagged as
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"vestigial" earlier; analysis done, implementation deferred to avoid
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mid-session pipeline disruption)
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- Delete key in sample mode currently clears only the melodic sample bank,
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not `percussionSampleBank` — small one-line follow-up if desired