Pipeline:
- process() dispatches to _process_mono() or _process_4cm() based on routing_mode
- _process_4cm() splits chain at routing_breakpoint: pre blocks on ch0, post on ch1
- _process_single_block() extracted for reuse in both mono and 4cm paths
- routing_mode/routing_breakpoint load from preset via load_preset()
- set_routing() for runtime configuration
- Properties: routing_mode (mono|4cm), routing_breakpoint with validation
Web server:
- GET /api/routing — current routing mode and breakpoint
- POST /api/routing — set routing mode/breakpoint, persist to current preset, WS broadcast
- _gather_state() includes routing_mode and routing_breakpoint
Web UI:
- Settings page: 4CM toggle + breakpoint slider with routing description
- Dashboard: routing badge (4CM/Mono) with breakpoint info
- app.js: WebSocket handler, updateRoutingUI(), toggle4cm(), set4cmBreakpoint()
- style.css: .badge, .badge-4cm, .badge-mono, .routing-status, .routing-desc
Tests: mock pipeline fixture updated with routing_mode/routing_breakpoint
- Full FFT overlap-add IR convolution in IRLoader (process(), set_mix(), toggle)
- Lazy FFT computation — IR FFT padded to correct block+ir size on first process()
- Wet/dry mix control, enabled/disabled toggle with tail clearing
- Fixed pipeline._apply_ir_cab() to delegate to IRLoader.process() instead of
poking internals (old code had array-size mismatch bug: IR FFT at ir_len vs
block FFT at conv_size)
- 46 tests: loading, convolution correctness, overlap-add state, mix, toggle,
directory listing, performance budget (all <5ms even at 8192 taps), edge cases
- scripts/download_irs.sh: free IR pack downloader (God's Cab, Seacow)
- 15 FX blocks implemented with per-block state isolation
- All blocks <500us per 256-sample block (reverb closest at 465us on x86)
- 57 unit tests all passing (per-effect, chain, bypass, state isolation)
- Benchmark script at scripts/benchmark_fx.py
- Vectorised delay reads via read_block_varying()
- scipy.lfilter for EQ (3-band RBJ) and reverb damping
- Fixed _DelayLine.write_block wraparound crash for large blocks
- Comb/Allpass buffers sized to BLOCK_SIZE * 2 minimum
shawn