From 15338c3e643aa2bebd11b16245819c15fb4c3290 Mon Sep 17 00:00:00 2001
From: Astro <coreyluke.cordwell@gmail.com>
Date: Mon, 25 May 2026 22:37:42 +1000
Subject: [PATCH 1/2] Stage 1: mixer drawer (12 strips) + propagate dispatcher
 guards + raise test floor

Mixer drawer (window.AbxMixer): 12 orbit-backed channel strips with a dB-linear gain
fader (unity at 75%, top = 2.0 to match the card gain knob), pan, FX1=room / FX2=delay
sends (native per-orbit SuperDirt effects, no SC changes), mute/solo (shared data-cmd
path with the cards so they stay in sync), a meter, and a mini-scope (reuses
AbxScope.draw). Pure math single-sourced in dashboard-mixer.js, unit-tested via
src/mixer.test.ts (12 cases). In-file CONSTRAINT: 12 strips, not 16 (SuperDirt numOrbits=12).

Rebased onto main after PR #1. Resolved the dashboard.js dispatcher region by keeping
main's window.AbxX guards AND adding the same guard to the new AbxMixer.handleClick /
handleInput call-sites: propagation of the Stage 0 fix to new code, not a new concern.

Raised run-tests.mjs FLOOR 19 -> 31 (track 7 + dsp 12 + mixer 12), applying the
"raise the floor in the same commit that adds tests" convention so a discovery regression
cannot silently drop the mixer tests.
---
 mcp/dashboard-mixer.d.ts |  17 +++++
 mcp/dashboard-mixer.js   | 140 +++++++++++++++++++++++++++++++++++++++
 mcp/dashboard.html       |  35 ++++++++++
 mcp/dashboard.js         |   3 +
 mcp/run-tests.mjs        |   2 +-
 mcp/src/mixer.test.ts    |  79 ++++++++++++++++++++++
 6 files changed, 275 insertions(+), 1 deletion(-)
 create mode 100644 mcp/dashboard-mixer.d.ts
 create mode 100644 mcp/dashboard-mixer.js
 create mode 100644 mcp/src/mixer.test.ts

diff --git a/mcp/dashboard-mixer.d.ts b/mcp/dashboard-mixer.d.ts
new file mode 100644
index 0000000..9c5d9db
--- /dev/null
+++ b/mcp/dashboard-mixer.d.ts
@@ -0,0 +1,17 @@
+// Ambient types for dashboard-mixer.js (window.AbxMixer), the mixer module. The browser loads it
+// as a classic <script>; Node tests import it for side-effect and read globalThis.AbxMixer. Only
+// the pure math is typed here (the tested surface); the DOM/UI methods are runtime-only.
+export interface AbxMixerApi {
+  /** Fader position 0..1 -> SuperDirt gain. dB-linear; unity at 0.75; top (1.0) = 2.0; <=0.02 = silence. */
+  faderToGain(p: number): number;
+  /** Inverse of faderToGain; out-of-range gains park at the nearest fader end. */
+  gainToFader(g: number): number;
+  /** Pan position 0..1 -> formatted pan value string (0.5 = centre). */
+  panPositionToString(p: number): string;
+  /** Parse a pan value string back to position; clamps to 0..1, centre on garbage. */
+  panStringToPosition(s: string): number;
+}
+declare global {
+  // eslint-disable-next-line no-var
+  var AbxMixer: AbxMixerApi;
+}
diff --git a/mcp/dashboard-mixer.js b/mcp/dashboard-mixer.js
new file mode 100644
index 0000000..6580bea
--- /dev/null
+++ b/mcp/dashboard-mixer.js
@@ -0,0 +1,140 @@
+// dashboard-mixer.js — mixer drawer (window.AbxMixer): vertical channel strips with a fader,
+// pan, two FX sends (reverb/delay), mute/solo, a meter, and a mini-scope.
+//
+// CONSTRAINT: 12 strips, not 16. Driven by the SuperDirt boot config (numOrbits = 12 in
+// sc/superdirt_startup.scd). d13-d16 exist in Tidal but have NO orbit, so no per-channel
+// reverb/delay (room/delay are per-orbit effects) and no scope. Do NOT raise MIX_CH to 16
+// without first raising SuperDirt's numOrbits, or you get four dead strips.
+//
+// The pure math (faderToGain/gainToFader/pan*) is single-sourced here and unit-tested via
+// mixer.test.ts (which imports this file under Node). The DOM/UI is guarded by `typeof document`
+// so that Node import stays clean. The browser loads this as a classic <script> AFTER dashboard.js
+// (consumes Abx.*) and dashboard-scope.js (reuses AbxScope.draw).
+(function(){
+  // ---------------- pure math (single source; tested by mixer.test.ts) ----------------
+  // Top of travel is a true doubling (+6.02 dB) so the fader top equals the card gain knob's max (2.0).
+  var TOP_DB = 20 * Math.log10(2);
+  function faderToGain(p){
+    // Deadband: the bottom 2% is HARD silence, not -54 dB bleeding through. A fader resting near
+    // the bottom should be silent. (This makes the round-trip lossy below 0.02 by design; see below.)
+    if (p <= 0.02) return 0;
+    var dB = p <= 0.75 ? (p / 0.75) * 60 - 60 : (p - 0.75) / 0.25 * TOP_DB;
+    return Math.pow(10, dB / 20);
+  }
+  function gainToFader(g){
+    // Inverse of faderToGain. The deadband is lossy by design: gainToFader(faderToGain(0.01)) === 0,
+    // NOT 0.01 -- do not "fix" the round-trip below the deadband, or you reintroduce the silent-leak bug.
+    // Out-of-range gains park at the nearest valid end: gain is never < 0 in valid Tidal, and the fader
+    // cannot represent > max, so clamping (NaN included -> bottom) is the right answer, not a junk position.
+    if (!(g > 0)) return 0;
+    var dB = 20 * Math.log10(g);
+    var f = dB <= 0 ? (dB + 60) / 60 * 0.75 : 0.75 + (dB / TOP_DB) * 0.25;
+    return Math.max(0, Math.min(1, f));
+  }
+  function clamp01(v){ return v < 0 ? 0 : v > 1 ? 1 : v; }
+  function panPositionToString(p){ return clamp01(p).toFixed(2); }
+  // garbage-in-centred-out: an unparseable pan defaults to centre (0.5); left or right would surprise.
+  function panStringToPosition(s){ var v = parseFloat(s); return isNaN(v) ? 0.5 : clamp01(v); }
+
+  // ---------------- UI (browser only) ----------------
+  var MIX_CH = 12;   // see CONSTRAINT above
+  var GAIN_DP = 4;   // gain is written with this many decimals (clean code; the wiring test mirrors it)
+  var LABEL = { bd:"kick", sn:"snare", sd:"snare", hh:"hat", hc:"hat", ho:"hat", cp:"clap", cr:"crash", rim:"rim", perc:"perc", arpy:"pluck", jvbass:"bass", bass:"bass", wind:"atmos", "808":"808" };
+  var mdisp = {};    // eased meter level per slot (matches the master meter's feel)
+
+  function labelFor(code){
+    if (!code) return "";
+    var syn = code.match(/(?:s|sound)\s+"(super\w+|default)"/);  // a synth (noteful layer)
+    if (syn) return syn[1].replace(/^super/, "");
+    var sm = code.match(/(?:s|sound)\s+"([a-z0-9]+)/i);          // first sample token
+    if (sm) return LABEL[sm[1]] || sm[1];
+    return "";
+  }
+  function meterVal(slot){ var sc = (Abx.state().scopes || {})[slot]; return sc ? Math.min(1, sc.peak || 0) : 0; }
+
+  function stripHTML(slot){
+    var st = Abx.state(), code = (st.slots || {})[slot], active = !!code, col = Abx.color.chan(slot);
+    var muted = (st.muted || []).indexOf(slot) >= 0, solo = st.solo === slot;
+    var gain = active ? Abx.fnum(code, "gain") : null;   if (gain == null) gain = 1;
+    var pan  = active ? Abx.fnum(code, "pan")  : null;   if (pan == null)  pan = 0.5;
+    var room = active ? Abx.fnum(code, "room") : null;   if (room == null) room = 0;
+    var dly  = active ? Abx.fnum(code, "delay"): null;   if (dly == null)  dly = 0;
+    var dis = active ? "" : " disabled";   // ghost strips render the layout but their controls are inert
+    return '<div class="strip' + (active ? "" : " empty") + (muted ? " muted" : "") + (solo ? " solo" : "") + '" data-slot="' + slot + '" style="--rc:' + col + '">'
+      + '<div class="striphd"><span class="slot" style="color:' + col + '">' + slot + '</span><span class="lbl">' + Abx.esc(labelFor(code)) + '</span></div>'
+      + '<canvas class="mixscope" data-slot="' + slot + '" height="40"></canvas>'
+      + '<div class="sends">'
+        + '<label class="send">FX1<input type="range" class="fx1" data-slot="' + slot + '" min="0" max="1" step="0.02" value="' + room + '"' + dis + ' title="reverb send (room)"></label>'
+        + '<label class="send">FX2<input type="range" class="fx2" data-slot="' + slot + '" min="0" max="1" step="0.02" value="' + dly + '"' + dis + ' title="delay send"></label>'
+      + '</div>'
+      + '<div class="panrow"><input type="range" class="pan" data-slot="' + slot + '" min="0" max="1" step="0.02" value="' + panPositionToString(pan) + '"' + dis + ' title="pan (0.5 = centre)"></div>'
+      + '<div class="fadarea"><span class="vmeter"><i></i></span>'
+        + '<input type="range" class="fader" data-slot="' + slot + '" min="0" max="1" step="0.005" value="' + gainToFader(gain) + '"' + dis + ' title="volume (dB fader, unity at 75%)"></div>'
+      + '<div class="msbtns">'
+        + '<button class="ms' + (muted ? " on" : "") + '" data-cmd="' + (muted ? "unmute" : "mute") + '" data-slot="' + slot + '"' + dis + ' title="mute">M</button>'
+        + '<button class="ms' + (solo ? " on" : "") + '" data-cmd="' + (solo ? "unsolo" : "solo") + '" data-slot="' + slot + '"' + dis + ' title="solo">S</button>'
+      + '</div></div>';
+  }
+  function render(){
+    var wrap = document.getElementById("mixrows"); if (!wrap) return;
+    var h = ""; for (var i = 1; i <= MIX_CH; i++) h += stripHTML("d" + i);
+    wrap.innerHTML = h;
+  }
+  function isOpen(){ var w = document.getElementById("mixwrap"); return !!(w && w.classList.contains("open")); }
+  function openMixer(){
+    var w = document.getElementById("mixwrap"); if (!w) return;
+    var nowOpen = !w.classList.contains("open");
+    w.classList.toggle("open", nowOpen);
+    var b = document.getElementById("mixBtn"); if (b) b.classList.toggle("on", nowOpen);
+    if (nowOpen) render();   // CSS handles the slide; we only build the strips on open
+  }
+
+  // write a param via the same cmd:set path the card knobs use; ghost strips have nothing to write to.
+  function setParam(slot, param, value){
+    if (!((Abx.state().slots || {})[slot])) return;
+    Abx.send({ cmd: "set", slot: slot, param: param, value: value });
+  }
+  // delegates (mirror the AbxSeq/AbxCurves contract). M/S go through the core data-cmd dispatcher
+  // (shared with the cards), so mute/solo stay in sync both ways for free.
+  function handleInput(e){
+    var el = e.target, slot = el.dataset && el.dataset.slot; if (!slot) return false;
+    if (el.classList.contains("fader")) { setParam(slot, "gain", +faderToGain(+el.value).toFixed(GAIN_DP)); return true; }
+    if (el.classList.contains("pan"))   { setParam(slot, "pan",  panStringToPosition(el.value)); return true; }
+    if (el.classList.contains("fx1"))   { setParam(slot, "room", +(+el.value).toFixed(2)); return true; }
+    if (el.classList.contains("fx2"))   { setParam(slot, "delay", +(+el.value).toFixed(2)); return true; }
+    return false;
+  }
+  function handleClick(b){ if (b.dataset.act === "mixer") { openMixer(); return true; } return false; }
+
+  // re-render strips when the live slot set / mute / solo changes (called from dashboard.js render()).
+  // Keyed on structure only (not per-value), so dragging a fader does not yank itself mid-gesture.
+  var lastSig = "";
+  function maybeRerender(){
+    if (!isOpen()) return;
+    var st = Abx.state();
+    var sig = JSON.stringify({ s: Object.keys(st.slots || {}), m: st.muted, so: st.solo });
+    if (sig !== lastSig) { lastSig = sig; render(); }
+  }
+  // animate meters + mini-scopes while the drawer is open (reuses AbxScope.draw; own rAF, idle when shut)
+  function tick(){
+    if (isOpen()) {
+      var strips = document.querySelectorAll("#mixrows .strip");
+      for (var i = 0; i < strips.length; i++) {
+        var slot = strips[i].dataset.slot;
+        var tgt = meterVal(slot);
+        mdisp[slot] = (mdisp[slot] || 0) + (tgt - (mdisp[slot] || 0)) * 0.4;   // master-meter feel
+        var bar = strips[i].querySelector(".vmeter i"); if (bar) bar.style.height = (Math.sqrt(mdisp[slot]) * 100).toFixed(1) + "%";
+        var cv = strips[i].querySelector(".mixscope"); if (cv) AbxScope.draw(cv, slot);
+      }
+    }
+    requestAnimationFrame(tick);
+  }
+
+  if (typeof document !== "undefined") {   // DOM wiring only in the browser; the Node test imports the math
+    requestAnimationFrame(tick);
+  }
+  (typeof window !== "undefined" ? window : globalThis).AbxMixer = {
+    faderToGain: faderToGain, gainToFader: gainToFader, panPositionToString: panPositionToString, panStringToPosition: panStringToPosition,
+    openMixer: openMixer, render: render, handleInput: handleInput, handleClick: handleClick, maybeRerender: maybeRerender
+  };
+})();
diff --git a/mcp/dashboard.html b/mcp/dashboard.html
index 613803a..470dc3b 100644
--- a/mcp/dashboard.html
+++ b/mcp/dashboard.html
@@ -150,6 +150,33 @@
   #consoleIn{flex:1;background:#010402;color:#bff7c9;border:1px solid var(--line);border-radius:4px;padding:7px 10px;
     font:13px/1.5 ui-monospace,Consolas,monospace;resize:none;height:34px;}
   #consoleIn:focus{outline:none;border-color:var(--green);box-shadow:0 0 8px rgba(0,255,94,.2);}
+  /* ---- mixer drawer (bottom, collapsible; CSS height transition = no re-render) ---- */
+  #mixwrap{max-height:0;overflow:hidden;transition:max-height .22s ease;background:rgba(4,10,6,.92);}
+  #mixwrap.open{max-height:440px;border-top:1px solid var(--line);border-bottom:1px solid var(--line);}
+  .mixbar{display:flex;align-items:center;gap:12px;padding:8px 16px;border-bottom:1px solid var(--line);}
+  .mixbar .seqlabel{color:var(--green);font-size:11px;letter-spacing:.6px;text-transform:uppercase;}
+  #mixrows{display:flex;gap:6px;padding:10px 16px;overflow-x:auto;}
+  .strip{flex:0 0 76px;display:flex;flex-direction:column;align-items:center;gap:5px;padding:7px 5px;
+    border:1px solid var(--line);border-radius:4px;background:rgba(8,20,12,.6);}
+  .strip.empty{opacity:.3;}
+  .strip.muted{border-color:var(--amber);}
+  .strip.solo{border-color:var(--green);box-shadow:0 0 8px rgba(0,255,94,.25);}
+  .striphd{display:flex;flex-direction:column;align-items:center;line-height:1.2;}
+  .striphd .slot{font-weight:700;font-size:12px;}
+  .striphd .lbl{color:var(--muted);font-size:9px;text-transform:uppercase;letter-spacing:.4px;height:11px;overflow:hidden;}
+  .mixscope{width:64px;height:40px;background:#020503;border:1px solid var(--line);border-radius:2px;display:block;}
+  .strip .sends{display:flex;gap:4px;width:100%;}
+  .strip .send{flex:1;display:flex;flex-direction:column;align-items:center;color:var(--muted);font-size:8px;gap:2px;}
+  .strip .send input[type=range]{width:30px;}
+  .strip .panrow{width:100%;display:flex;justify-content:center;}
+  .strip .panrow input[type=range]{width:58px;}
+  .fadarea{display:flex;align-items:flex-end;gap:5px;height:150px;padding:3px 0;}
+  .vmeter{width:5px;height:100%;background:#020503;border:1px solid var(--line);border-radius:2px;display:flex;align-items:flex-end;overflow:hidden;}
+  .vmeter i{display:block;width:100%;height:0%;background:linear-gradient(0deg,var(--gdim),var(--green) 70%,var(--amber));}
+  .fadarea input[type=range].fader{writing-mode:vertical-lr;direction:rtl;width:6px;height:100%;}
+  .msbtns{display:flex;gap:4px;}
+  .msbtns .ms{padding:3px 7px;font-size:10px;}
+  .msbtns .ms.on{border-color:var(--green);color:var(--green);}
 </style>
 </head>
 <body>
@@ -187,6 +214,7 @@
   <button data-act="cheats">&#128214; Cheat sheet</button>
   <button data-act="steps">&#127929; Step grid</button>
   <button data-act="curves">&#12316; Curves</button>
+  <button data-act="mixer" id="mixBtn">&#127898; Mixer</button>
   <span class="sep"></span>
   <div class="deckgroup"><span style="color:var(--muted);font-size:12px" title="audio output">&#128264;</span><select id="audioSelect" title="switch audio output (speakers / headphones)" style="max-width:185px"><option value="">audio out…</option></select></div>
 </div>
@@ -231,6 +259,12 @@
   </div>
 </div>
 <main><div class="grid" id="grid"></div></main>
+<div id="mixwrap">
+  <div class="mixbar"><span class="seqlabel">&#127898; MIXER</span>
+    <span class="seqhint">12 channels (orbits) · fader = volume (dB, unity at 75%) · FX1 = reverb send · FX2 = delay send · pan · M/S. Empty channels are ghosted.</span>
+  </div>
+  <div id="mixrows"></div>
+</div>
 <div id="console">
   <div id="consoleOut">type Tidal &amp; press Enter — e.g.  d1 $ s "bd sn hh cp"   ·   hush = stop   ·   d3 silence = clear layer 3</div>
   <div id="consoleRow"><span class="prompt">&gt;_</span>
@@ -243,5 +277,6 @@
 <script src="dashboard-cheats.js"></script>
 <script src="dashboard-curves.js"></script>
 <script src="dashboard-seq.js"></script>
+<script src="dashboard-mixer.js"></script>
 </body>
 </html>
diff --git a/mcp/dashboard.js b/mcp/dashboard.js
index 9ca67cc..6af8b1f 100644
--- a/mcp/dashboard.js
+++ b/mcp/dashboard.js
@@ -194,6 +194,7 @@
     if(el.type==="range") lastInput=Date.now();   // suppress card re-render while dragging any slider
     if(window.AbxSeq && AbxSeq.handleInput(e)) return;      // seqname / seqvol / seqSwing
     if(el.type!=="range")return;
+    if(window.AbxMixer && AbxMixer.handleInput(e)) return;    // mixer fader / pan / FX1 / FX2 (range + data-slot, no data-param)
     if(el.dataset.tempo!==undefined){ document.getElementById("bpm").textContent=el.value; pendingTempo=+el.value; return; }
     if(el.dataset.slot){ var vb=document.getElementById("v-"+el.dataset.slot+"-"+el.dataset.param); if(vb)vb.textContent=el.value;
       pending[el.dataset.slot+"|"+el.dataset.param]={slot:el.dataset.slot,param:el.dataset.param,value:+el.value}; }
@@ -210,6 +211,7 @@
     if(!b)return;
     if(window.AbxSeq && AbxSeq.handleClick(b)) return;       // steps / seqadd / seqclear / row mute+clear / pattern / song
     if(window.AbxCurves && AbxCurves.handleClick(b)) return;    // curves panel / curve toggle+preset
+    if(window.AbxMixer && AbxMixer.handleClick(b)) return;     // mixer drawer toggle (strip M/S use data-cmd, shared with cards)
     if(b.dataset.act==="run"){ runCode(); return; }
     if(b.dataset.act==="boot"){ var o=document.getElementById("consoleOut"); o.textContent="booting the sound engine… (~30-40s) — watch the status light top-left"; o.className=""; send({cmd:"boot"}).then(function(){poll();}); return; }
     if(b.dataset.act==="reset"){ if(confirm("Reboot the engine? Wipes everything, fresh start (~30s).")) cmd("reset"); return; }
@@ -318,6 +320,7 @@
     }
     grid.innerHTML=h;
     if(window.AbxCurves) AbxCurves.maybeRerender(keys);
+    if(window.AbxMixer) AbxMixer.maybeRerender();
   }
   function poll(){ fetch("/state").then(function(r){return r.json();}).then(render).catch(function(){
     document.getElementById("engstate").textContent="disconnected"; document.getElementById("engdot").className="dot error"; }); }
diff --git a/mcp/run-tests.mjs b/mcp/run-tests.mjs
index 96e29a2..a33e80e 100644
--- a/mcp/run-tests.mjs
+++ b/mcp/run-tests.mjs
@@ -21,7 +21,7 @@ import { dirname, join } from "node:path";
 import { run } from "node:test";
 import { spec } from "node:test/reporters";
 
-const FLOOR = 19; // current test count on this branch (track 7 + dsp 12)
+const FLOOR = 31; // current test count: track 7 + dsp 12 + mixer 12 (raised with the mixer tests)
 
 const distDir = join(dirname(fileURLToPath(import.meta.url)), "dist");
 let files = [];
diff --git a/mcp/src/mixer.test.ts b/mcp/src/mixer.test.ts
new file mode 100644
index 0000000..ab4294f
--- /dev/null
+++ b/mcp/src/mixer.test.ts
@@ -0,0 +1,79 @@
+import { test } from "node:test";
+import assert from "node:assert/strict";
+
+// Single source: the browser loads dashboard-mixer.js (window.AbxMixer) as a classic <script>;
+// here we import it for side-effect under Node and read the same pure math off globalThis.AbxMixer.
+// The module's DOM/UI parts are guarded by `typeof document`, so importing it in Node is safe, and
+// there is no separate src/mixer.ts to drift from (same pattern as dashboard-dsp.js).
+import "../dashboard-mixer.js";
+
+const { faderToGain, gainToFader, panPositionToString, panStringToPosition } = globalThis.AbxMixer;
+const close = (a: number, b: number, eps = 1e-9) => Math.abs(a - b) <= eps;
+
+// ---------------- faderToGain ----------------
+test("faderToGain: bottom and the whole deadband are hard silence (no leak)", () => {
+  assert.equal(faderToGain(0), 0);
+  assert.equal(faderToGain(0.01), 0);
+  assert.equal(faderToGain(0.02), 0); // deadband upper edge is still silent
+});
+
+test("faderToGain: just above the deadband is near-silent, not unity", () => {
+  const g = faderToGain(0.021);
+  assert.ok(g > 0 && g < 0.005); // ~ -58 dB
+});
+
+test("faderToGain: unity at 0.75", () => {
+  assert.ok(close(faderToGain(0.75), 1.0));
+});
+
+test("faderToGain: midpoint 0.5 is -20 dB (gain 0.1)", () => {
+  assert.ok(close(faderToGain(0.5), 0.1));
+});
+
+test("faderToGain: top at 1.0 is exactly 2.0 (matches the card gain knob max)", () => {
+  assert.ok(close(faderToGain(1.0), 2.0));
+});
+
+test("faderToGain: monotonically non-decreasing across the travel", () => {
+  let prev = -1;
+  for (let i = 0; i <= 100; i++) { const g = faderToGain(i / 100); assert.ok(g >= prev); prev = g; }
+});
+
+// ---------------- gainToFader (inverse) ----------------
+test("gainToFader: unity -> 0.75, max -> 1.0, silence -> 0", () => {
+  assert.ok(close(gainToFader(1.0), 0.75));
+  assert.ok(close(gainToFader(2.0), 1.0));
+  assert.equal(gainToFader(0), 0);
+});
+
+test("gainToFader/faderToGain round-trip is stable above the deadband", () => {
+  for (const p of [0.1, 0.25, 0.3, 0.5, 0.75, 0.9, 1.0]) {
+    assert.ok(close(gainToFader(faderToGain(p)), p), `p=${p}`);
+  }
+});
+
+test("gainToFader: out-of-range gains park at the nearest valid fader end", () => {
+  assert.equal(gainToFader(-0.5), 0);      // gain is never < 0 in valid Tidal -> bottom
+  assert.equal(gainToFader(0), 0);         // exact silence -> bottom
+  assert.ok(close(gainToFader(3.0), 1.0)); // above the 2.0 max -> parked at top (fader can't exceed max)
+  assert.equal(gainToFader(NaN), 0);       // defensive -> bottom
+});
+
+// ---------------- pan ----------------
+test("panPositionToString: centre / hard left / hard right", () => {
+  assert.equal(panPositionToString(0.5), "0.50");
+  assert.equal(panPositionToString(0), "0.00");
+  assert.equal(panPositionToString(1), "1.00");
+});
+
+test("pan position round-trips through the string", () => {
+  for (const p of [0, 0.25, 0.5, 0.75, 1]) {
+    assert.ok(close(panStringToPosition(panPositionToString(p)), p), `p=${p}`);
+  }
+});
+
+test("panStringToPosition: clamps to range and defaults to centre on garbage", () => {
+  assert.equal(panStringToPosition("-1"), 0);   // clamp left
+  assert.equal(panStringToPosition("2"), 1);    // clamp right
+  assert.equal(panStringToPosition("abc"), 0.5); // unparseable -> centre default
+});

From f16d39b30539a39bc11c921fdc4b5870bea31de8 Mon Sep 17 00:00:00 2001
From: Astro <coreyluke.cordwell@gmail.com>
Date: Mon, 25 May 2026 23:10:53 +1000
Subject: [PATCH 2/2] README: add mixer view to the features list

The standing review checks that new features appear in the feature list,
and the Stage 1 mixer was missing. One bullet, neutral wording (no FL
references), matching the existing voice.
---
 README.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/README.md b/README.md
index f997f83..0f31a6c 100644
--- a/README.md
+++ b/README.md
@@ -26,6 +26,7 @@ Each instrument gets its own wavelength colour and a **live waveform of its own
 
 - **Live layer cards** (`d1`–`d16`) — each shows its code, a plain-English explanation, per-layer knobs, and a **live waveform of that channel's own audio**
 - **Per-channel oscilloscope** — every card draws a real, phase-locked waveform tapped from its own voice; plus a master L/R meter and a **wavelength-coloured spectrum** (low freq red → high freq blue)
+- **Mixer view** with all 12 channels as strips: a volume fader, pan, reverb + delay sends, mute/solo, a meter, and a live mini-scope each
 - **Step sequencer** with **per-step velocity** (scroll a pad), **drag-to-paint** + right-click erase, swing, and a playhead **locked to the audio** so each lit step flashes exactly when you hear it
 - **Pattern slots (A/B/C/D)** you can chain into a song that advances each bar
 - **Drag-and-drop sample browser** — drag a sound onto a channel to swap it; drag channels to reorder