A sound FX was a single line from Input to Output, so two versions of one sound could not be heard together. The new Mix node joins two ways again, and each way can carry its own effects, its own Pitch included. - Mix has the audio inputs a and b and a number input mix (0 to 1, default 0.5). At 0 only a is heard, at 1 only b. Like every number it can come from a parameter of the Input and is held to its range. - The compiled plan and the chain a voice gets are now a tree. A source carries a pitch and stages, a mix carries a, b and the stages after it. A Mix that ends at exactly 0 or 1 collapses to the one way heard, so the silent way is never worked out. - A Pitch is still worked out on the sound as it starts (#312). Behind a Mix it goes to both of its sounds. An effect before a Pitch therefore acts as if it came after it, the node now says so. - The player starts one source per pitch, all at once and all of the same length, and two ways at the same pitch share one. A mix becomes two gain nodes with 1 - mix and mix into a sum. A voice leaves the count when all of its sources have ended. - stats().last reports pitches (one per source) instead of pitch. Tests: - soundfx.test.ts: 27 tests (+5), sound-library.test.ts: 12 (+2), node-catalog.test.ts: 368, all green. Typecheck, ESLint, Prettier clean. - Counter-check: a Pitch behind the Mix given to a only, and b mixed at 1 - mix, each fails its new test. - e2e 34 on melektaus-atx: ALL PASSED, 29 checks (+1). The new check plays the pitched way mixed with the dry Input in the browser: two sources at 5 and 0 semitones, as long as the sound itself. - The full gate did not run before this commit. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>