v0.4.2

Added

• _ placeholder in specialized call handlers. The _ argument
  placeholder now works inside builtins routed through specialized
  codegen call handlers, not just generic calls.
• Growable chunked BufferPool. Cedar's BufferPool now backs its
  registers with up to 64 lazily-allocated 256-buffer slabs (default
  cap raised from 256 to 16384 total). Slab pointers are stable across
  growth, so the audio thread's in-flight reads survive a hot-swap
  that armed new slabs on the compile thread. Hosts (nkido CLI play /
  serve / ui / render and the web/wasm worklet) call
  pool.ensure_capacity(required_buffers) off-cycle before publishing
  the new bytecode.
• CompileResult::required_buffers. Codegen now reports the peak
  distinct buffer indices used by the program so hosts can size the
  pool exactly. Backwards compatible: hosts that ignore the field still
  work for programs that fit in the default slab.

Changed

• Codegen sum/mix accumulator. sum() and mean() over arrays now
  emit one accumulator buffer + N-1 in-place ADD instructions instead
  of an N-1-buffer linear chain. Programs that fan out wide (e.g.
  unison(..., voices: 8) summed under poly) no longer exhaust the
  pool on the per-voice sum. Bit-identical output.
• BufferAllocator reuses freed indices. Codegen now has a
  BufferAllocator::release(idx) that puts indices back into a LIFO
  free list. reset_to(mark) drains free-list entries past the mark.
  Used by the sum/mix accumulator and reserved for future
  refcount-driven release across general opcodes.
• cedar::MAX_BUFFERS semantics. Previously the size of a single
  flat buffer array (256). Now the total addressable buffer index
  space (16384 by default). Per-slab size lives in
  cedar::SLAB_BUFFERS. The CEDAR_MAX_BUFFERS build flag still
  works; it must be a positive multiple of SLAB_BUFFERS.
• BUFFER_ZERO is now an explicit constant. Pinned at 255 (last
  slot of slab 0) so it stays in the pre-allocated slab regardless of
  any future cap changes.

Fixed

• Live IDE deep links 404'd on live.nkido.cc. Opening a shared
  patch (/p#code=…) or any non-prerendered route returned Netlify's
  "Page not found". The deploy never applied the repo's netlify.toml,
  so the SPA fallback rewrite, SharedArrayBuffer COOP/COEP headers,
  and immutable-asset caching were all missing in production. The deploy
  now applies netlify.toml and also ships _redirects / _headers in
  the build artifact.
• scales dispatcher compile failure on a non-literal scrutinee.
  Selecting a scale with a runtime (non-literal) argument no longer
  fails to compile.