Fix LM-919 review follow-ups

.claude/CLAUDE.md

@@ -17,7 +17,7 @@ src/ui/              React components, CSS Modules, tokens.css, vendored fonts
 
 - **One session document** is the source of truth. UI dispatches `Command`s; `applyCommand` is pure and tested. The store keeps undo history (knob drags coalesce into one step), notifies the engine (`engine.apply`), and rewrites the share link.
 - **Exploring:** `src/session/library.ts` holds the ready-made patterns (the app opens on the first) and the chords. Holding the first key with no synth steps fills in a default rhythm.
-- **Engine:** `Clock` schedules 100 ms ahead, ticked from a Worker so background tabs keep time. The sound is aimed at dirty French electro (Justice, Daft Punk, a little disco). `mixer.ts` builds the whole signal chain once, shared by the live engine and offline renders. Drums are synthesized per hit in `drums.ts` (808 kick with a 909-style snap, driven 909 snare, clean disco open hat; no samples), each with a DECAY tail multiplier, and run through a `ChannelStrip` (volume → mix bus, with a send to the stereo ping-pong delay in `delay.ts`). The `Synth` is a seven-voice detuned stereo unison plus a sub, through a plucked low-pass, light drive, and a 7 kHz high cut; it starts voices at scheduled times and releases the previous arp note at the next note's start. The synth, delay, and reverb run through the `Pump`, which ducks on every kick like a sidechain; drums bypass it. Everything meets in the mix bus (gentle glue compressor with headroom) before a safety limiter. The playhead (`step`, fired `note`) is published when each step actually sounds.
+- **Engine:** `Clock` schedules 100 ms ahead, ticked from a Worker so background tabs keep time. The sound is aimed at dirty French electro (Justice, Daft Punk, a little disco). `mixer.ts` builds the whole signal chain once. Drums are synthesized per hit in `drums.ts` (808 kick with a 909-style snap, driven 909 snare, clean disco open hat; no samples), each with a DECAY tail multiplier, and run through a `ChannelStrip` (volume → mix bus, with a send to the stereo ping-pong delay in `delay.ts`). The `Synth` is a seven-voice detuned stereo unison plus a sub, through a plucked low-pass, light drive, and a 7 kHz high cut; it starts voices at scheduled times and releases the previous arp note at the next note's start. The synth, delay, and reverb run through the `Pump`, which ducks on every kick like a sidechain; drums bypass it. Everything meets in the mix bus (gentle glue compressor with headroom) before a safety limiter. The playhead (`step`, fired `note`) is published when each step actually sounds.
 - **Share link (v2):** `?s=2~<bpm>~<drum>~…~syn.<…>`, keyed by drum id. See `src/session/url.ts`. Malformed parts fall back to defaults.
 
 ## Adding a drum

README.md

@@ -4,9 +4,10 @@ A drum machine + synth in your browser, styled after the Roland TR-909. Program
 
 ## Features
 
-- **Drums:** 16-step sequencer for hi-hat, snare, and kick, synthesized 909-style in the browser (no samples), each with volume, reverb, and tone knobs
-- **Synth:** arpeggiator over a two-octave keyboard, with a detuned two-oscillator voice, a sub, and a plucked filter. Keys choose which notes play; the synth's step row chooses when. Direction (up, down, up-down), speed (1/4, 1/8, 1/16), and four waveforms
-- **Playback:** on steps carry a soft tint of their instrument's color and light up fully when they fire; a beat band marks the four beats; the synth's key flashes with its step
+- **Drums:** 16-step sequencer for an 808 kick, a 909 snare, and a disco open hat, synthesized in the browser (no samples), each with volume, delay, and decay knobs
+- **Synth:** arpeggiator over a two-octave keyboard, with a seven-voice detuned stereo unison, a sub, and a plucked filter. Keys choose which notes play; the synth's step row chooses when. Direction (up, down, up-down), speed (1/4, 1/8, 1/16), four waveforms, octave, and chord keys
+- **Exploring:** six house patterns to start from, and undo (⌘Z / Ctrl+Z) for every change
+- **Playback:** on steps carry a soft tint of their instrument's color and light up fully when they fire; a beat band marks the four beats; the note playing lights its key's LED
 - **Controls:** knobs click to 11 notches and the fader to 9. Drag, click a notch, scroll, or use the arrow keys
 - **Computer keyboard:** A–C and W–\ toggle notes, like a piano layout
 - **Share links:** the URL holds the whole loop, drums and synth included
@@ -25,7 +26,7 @@ Then open http://localhost:3000.
 ```
 src/
   instruments.ts     registry: drums (id, label, voice, color) and keyboard notes
-  engine/            audio engine, no React: clock, channel strips, reverb, drum voices, synth, arpeggiator
+  engine/            audio engine, no React: clock, mixer, channel strips, delay, pump, reverb, drum voices, synth, arpeggiator
   session/           session types, commands, store, and share-link format
   ui/                React components, design tokens, and fonts
 ```

docs/ROADMAP.md

@@ -1,5 +1,7 @@
 # Loop Machine Style Guide Implementation Roadmap
 
+> **Superseded.** This plan predates the LM-919 rewrite (TypeScript, CSS Modules, no Tailwind). See `README.md` and `.claude/CLAUDE.md` for the current stack and design.
+
 ## Overview
 
 This roadmap outlines the implementation strategy for transforming the Loop Machine into a fully polished, accessible, and responsive application based on **The 1984 Digital Control System** documented in `./design/DESIGN_SYSTEM.md`.

docs/TECH_STACK.md

@@ -1,5 +1,7 @@
 # Tech Stack Evaluation
 
+> **Superseded.** This plan predates the LM-919 rewrite (TypeScript, CSS Modules, no Tailwind). See `README.md` and `.claude/CLAUDE.md` for the current stack and design.
+
 ## Current Stack
 | Layer | Choice | Status |
 |-------|--------|--------|

docs/design/DESIGN_SYSTEM.md

@@ -1,5 +1,7 @@
 # The 1984 Digital Control System
 
+> **Superseded.** This plan predates the LM-919 rewrite (TypeScript, CSS Modules, no Tailwind). See `README.md` and `.claude/CLAUDE.md` for the current stack and design.
+
 A unified design language for retro-inspired musical interfaces—drum machines, synth modules, sequencers, and hybrid workstations. It blends the visual DNA of Roland TR-707, Oberheim OB-series, and early digital lab equipment into a clean, modern, production-ready UI system.
 
 ![1984 Digital Control System](./1984-digital-control-system.png)

eslint.config.js

@@ -20,7 +20,7 @@ export default tseslint.config(
     },
   },
   {
-    // The engine stays framework-free so the web app, Mixtape, and tests can share it.
+    // The engine stays framework-free so the web app and tests can share it.
     files: ['src/engine/**/*.ts'],
     rules: {
       'no-restricted-imports': ['error', { patterns: [{ group: ['react', 'react-dom', 'react/*'], message: 'The engine must not depend on React.' }] }],