v0.4.7

Added

• BUS_TRIM opcode — per-bus mixer fader. Multiplies a bus scratch pair in place by a host-poked gain, applied between the mixer(N) closure and the sum into bus 0, so a fader reaches both the real master and the post-fader stem tap. Unity fallback when unpoked (exactly ×1.0, nondestructive); a ~5 ms one-pole ramp keeps moves click-free.
• Friendly bus labels. bus(), mixer() and master() take an optional trailing string label — mixer(1, (s) -> s, "drums") — that surfaces on BusBufferMapping so hosts can name stems and mixer strips.
• nkido render --stems and --float32. --stems writes one WAV per non-master bus next to the master file, tapped post-mixer and post-trim; --float32 renders 32-bit float WAVs.
• Per-bus hot-swap crossfade. The per-bus scratch pairs now crossfade across a hot-swap the same way the master always has, so stems stay glitch-free through a recompile.
• IS_STUDIO studio panels in the web bundle: mixer, transport, capture, render and takes.

Fixed

• mixer() / master() silently dropped a non-string extra argument. The semantic analyzer accepted it on optional_count and codegen only consumed a trailing StringLit, so mixer(1, c, 5) compiled with the 5 thrown away. Now E260.
• BUS_TRIM was reported as stateless by opcode_is_stateful() even though op_bus_trim owns a SlewState, causing WASM disassembly and state-id enumeration to under-report state.
• nkido render --stems overwrote colliding stems. Two buses sharing a label — or two labels sanitizing to the same filename — wrote to the same path, silently losing the earlier output. Colliding names now get a _busN suffix.
• SequenceState arena blocks are reclaimed on hot-swap re-init.
• Void arguments coerce to silence instead of wiring the 0xFFFF sentinel into a buffer slot.