Add the guarded JamesDSP audio controller

frontend/jamesdsp-app.test.js

@@ -0,0 +1,30 @@
+const { test } = require('node:test');
+const assert = require('node:assert/strict');
+const { readFileSync } = require('node:fs');
+const { join } = require('node:path');
+
+const app = readFileSync(join(__dirname, 'app.js'), 'utf8');
+
+test('the persisted engine is Standard by default and upgrades missing JamesDSP settings safely', () => {
+  assert.match(app, /jamesDsp: \{ enabled: false, preset: 'flat', params: \{\} \}/);
+  assert.match(app, /enabled: saved\.enabled === true/);
+  assert.match(app, /preset: typeof saved\.preset === 'string' \? saved\.preset : 'flat'/);
+  assert.match(app, /settings: normalizeJamesDspSettings\(\{ \.\.\.DEFAULT_SETTINGS, \.\.\.\(loaded\.settings \|\| \{\}\) \}\)/);
+  assert.match(app, /data\.settings = normalizeJamesDspSettings\(\{ \.\.\.DEFAULT_SETTINGS, \.\.\.payload\.settings \}\)/);
+});
+
+test('live JamesDSP shares the existing iOS gate and never stacks over EqRender copies', () => {
+  assert.match(app, /const available = \(\) => !!AC && \(!isIOS \|\| data\.settings\.liveAudioIOS === true\)/);
+  assert.match(app, /if \(data\.settings\?\.jamesDsp\?\.enabled\) return null/);
+  assert.match(app, /const active = \(\) => EQ\.isIOS\(\) && WEB && !data\.settings\?\.jamesDsp\?\.enabled/);
+  assert.match(app, /if \(rendered\(\)\) throw new Error\('This song is already playing a Standard processed copy\./);
+});
+
+test('EQ creates no second context or element source and passes Standard fallback routing to the controller', () => {
+  assert.equal((app.match(/\.createMediaElementSource\(/g) || []).length, 0);
+  assert.match(app, /st\.ctx = AudioGraph\.context\(\)/);
+  assert.match(app, /AudioGraph\.connect\(el, st\.filters\[0\]\)/);
+  assert.match(app, /standardInput: st\.filters\[0\]/);
+  assert.match(app, /dspController\.setLevelDb\(st\.levelDb\)/);
+  assert.match(app, /if \(data\.settings\.jamesDsp\?\.enabled\) \{[\s\S]{0,450}startDsp\(\)/);
+});