AquaSynth/state/scratch.md

Scratch

Current standing order: grow AquariumSynthCSharp through external reference targets, not through speculative field sprawl. state/spine.yaml and docs/reference-synth-roadmap.md are the handoff surfaces for agents working on the synth library while Aquarium work continues elsewhere.

Doctrine update:

• External synths are parity pressure for Aquarium's DSL, not internals to clone. Only consume targets that can be backed by parity tests proving Aquarium can reproduce the behavior in terse, readable syntax.
• Parsing a synth format is inventory. Rebuilding and testing behavior is the proof.

Completed this slice:

• Added two split project-authored DX7 algorithm-8 rendered parity probes: ProjectAuthoredDx7AlgorithmEightCascadeProbeMeetsParityWhenInstalled for 6 -> 5 -> 3, and ProjectAuthoredDx7AlgorithmEightSummedPairProbeMeetsParityWhenInstalled for 4 + 5 -> 3.
• Tightened the existing combined algorithm-8 stack gate now that real metrics are known. The project-authored probes gate log-mel at <= .06; latest real Dexed run:
  • combined stack: log-mel 0.04029555, score 0.8664546
  • summed pair: log-mel 0.042429477, score 0.870778
  • cascade: log-mel 0.03811625, score 0.9157809
• Project-authored DX7 parity tests now write listening WAVs and reports under artifacts/parity/dx7-project-authored/<probe>/. These split probes are intentionally not part of the patch library: they are useful measuring tools, not pleasant or reusable stock.
• Verified with bundled Python/dexed-py: AQUARIUM_DX7_PYTHON=<bundled python> dotnet test AquariumSynthCSharp.slnx --no-restore: 69 passed.

Previous slice:

• Added a structured .aqua patch library under patches/ with: examples/, sfxr/, bfxr/, 808/, fm-bell/, wobble-bass/, dx7/, and advanced/.
• Added patches/library.yaml as the machine-readable index and patches/README.md as the folder contract. The library is development source material for stock, reference rebuilds, calibration probes, and patch inspiration, not a shipped package surface.
• Exported the existing built-in/reference catalog into .aqua files and added the calibrated PRC SYNTH1 hard DX7 candidate at patches/dx7/public-domain/prc-synth1-calibrated.aqua.
• Added a test contract: every .aqua under patches/ must parse through PatchScript.Parse and export Faust, while package-boundary tests keep patches/ and .aqua files out of the NuGet package.
• Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 67 passed.

Previous slice:

• Increased Dx7SysEx.SummedOperatorModulationRouteIndex from 1.6 to 6.0. This targets the missing harsh stacked-modulation brightness without adding a generic drive/overdrive knob. The independent project-authored algorithm-8 summed-stack probe now uses graph gain .218 and gates log-mel at <= .12 with RMS normalization.
• Latest hard PRC SYNTH1 after stronger stack scale and graph gain .25: log-mel 0.13874426, envelope distance 0.067291506, RMS ratio 0.9912135, zero-crossing ratio 0.95325506, centroid ratio 1.1156512, score 0.7546445.
• Added Dx7SysEx.ApproximateAppliedRateLevelEnvelope, which traces the Dexed-style block-interpolated applied EG gain and lowers it into Aquarium's curved staged envelope surface, normalized so operator output level remains a separate authority.
• Retried hard PRC SYNTH1 with the applied-envelope lowering. Latest focused run after fixing the peak picker: log-mel 0.17186502 (was 0.24476814), envelope distance 0.13057204 (was 0.43700194), RMS ratio 1.0000212, zero-crossing ratio 0.7815517, score 0.6501268.
• Listening note resolved: the prior applied-envelope lowering made op2 rise late (0.014 -> 0.613), causing the odd end lilt. The helper now finds the first near-peak before gate, so op2 hits early and decays (0.981 -> 0.843 -> 0.660) like the traced DX7 applied gain.
• Extended staged operator envelopes with per-segment curves: curves=lin,exp,exp,lin. Linear remains the default, and levels can now express deliberate transient overshoot above 1 instead of clipping away the DX7 evidence.
• Added Dx7SysEx.TraceEnvelope, a DX7 EG microscope that follows the internal rate/level state machine closely enough to expose gain and stage over time.
• Added Dx7SysEx.TraceInterpolatedEnvelope, which traces the gain actually applied by Dexed-style operator rendering: one EG sample per 64-sample block, linearly interpolated across the block.
• Added an envelope comparison artifact test that writes artifacts/parity/dx7-envelope-trace/egstep.csv. The first rows show both DX7 raw state and applied gain: raw jumps to 2 immediately, while applied gain ramps from .03125 to 2 over the first 64-sample block and remains near 1 around 20 ms. Aquarium env=rl is a different contour entirely. The artifact now also includes a curved Aquarium staged-envelope candidate that tracks the applied-gain contour far more closely.
• Tried adding a first env=dx7 runtime lowering, then cut it. The trace matched the Python graph.py envelope but not Dexed plugin audio, so the syntax was not allowed to survive. The durable result is the microscope and the applied-gain trace, not a half-proven model.

Previous slice:

• Added test-only project-authored Dexed patch rendering through DexedPyRenderer.RenderPatchAsync. It builds a dexed.Patch from explicit operator specs and renders it without adding any shipped fixture or package surface.
• Added an independent project-authored algorithm-8 summed-stack parity test. This backs the topology-aware route lowering outside the public-domain PRC patch, so SummedOperatorModulationRouteIndex is no longer only PRC-shaped evidence.
• Cut the attempted DX7 EG exponential level curve again. On an isolated envelope target, exponential EG levels plus a shorter timing scale improved shape versus linear levels, but PRC still failed log-mel (0.2857573 at a tuned timing scale). The live lowering stays linear for EG levels until an isolated envelope target passes without harming the hard target.

Previous slice:

• Moved the remaining PRC cascaded-route scalar into a topology-aware DX7 route helper. Dx7SysEx.OperatorRouteIndex(topology, edge) now keeps the isolated two-op route scale (6.275) for standalone direct branches and uses the summed/cascaded scale (1.6) for sum edges and direct edges feeding a sum.
• The PRC probe no longer owns any private route-index function. Latest focused run still passes with log-mel 0.24476814, score 0.5708394, RMS ratio 1.0108943.

Previous slice:

• Added the ratio-detune and algorithm-output-compensation rungs to the DX7 lowering. Dx7SysEx.OperatorFrequencyRatio now applies ratio-mode detune from the Dexed/DX7 note formula, and Dx7SysEx.OperatorOutputCompensation maps ROM COM values relative to the algorithm-32 six-output baseline.
• The PRC probe no longer has a carrier-level scale table. It still has a fenced cascaded-route constant (1.6) for the op6/op5/op4 -> op3 stack; that is now named as the next calibration target, not promoted into core lowering.
• Latest PRC run with detune, COM compensation, graph gain .39, and the fenced cascaded-route probe: log-mel 0.24476814, score 0.5708394, RMS ratio 1.0108943, zero-crossing ratio 0.7931764, centroid ratio 1.1131053.

Previous slice:

• Completed the feedback calibration rung. Isolated Dexed feedback sweeps fit a nonlinear Aquarium feedback table: 0, .01, .02, .05, .10, .19, .38, .66 for DX7 feedback values 0..7.
• Added Dx7SysEx.OperatorFeedbackAmount and moved the PRC feedback lowering off the old voice.Feedback * 0.04 constant. PRC barely changed because feedback value 5 maps to .19, close to the previous accidental .20. The win is ownership: feedback scaling is no longer folklore.

Previous slice:

• Completed the second calibration rung for isolated two-operator FM. A Dexed sweep fits full-scale DX7 modulation at about 12.55 radians. Given the current Aquarium Faust formula, that maps to an Aquarium route index of 6.275 for a full-level modulator.
• Added Dx7SysEx.OperatorModulationRouteIndex and a regression test for the calibrated phase-deviation scale. The hard PRC probe applies that scale only to the isolated op2 -> op1 branch; applying it blindly to the cascaded op6/op5/op4 -> op3 stack made PRC worse, which confirms algorithm output compensation is a separate rung.
• Latest PRC run with the carrier curve plus isolated-route calibration: log-mel 0.2526254, score 0.44758993, duration ratio 0.9927914, RMS ratio 0.8931149. The log-mel gate is back to <= 0.255.

Previous slice:

• Wrote docs/dx7-calibration-plan.md and referenced it from memory/spine. The ladder is now: single-carrier amplitude, two-op modulation index, feedback scaling, envelope level curve, algorithm output compensation, then hard PRC replay.
• Completed the first calibration rung. A project-authored Dexed single-carrier output-level sweep fits 2^((outputLevel - 99) / 8) for carrier amplitude. Dx7SysEx.OperatorOutputAmplitude now owns that curve, and ApproximateOperatorLevel uses it instead of the old internal-level proxy.
• Added tests for the measured output-level curve. The hard PRC probe now gates log-mel at <= 0.26 while the next rung calibrates modulation index; latest run after the carrier fix: log-mel 0.2562075, score 0.40430218.
• Calibration lesson: the old operator level helper was not a harmless approximation. It made mid-level operators far too loud and let PRC-specific constants compensate for a broken foundation. Next pressure is route/index scaling for isolated two-operator FM.

Previous slice:

• Reoriented the PRC SYNTH1 hard probe around the perceptual metric that matched listening: log-mel distance. The probe now asserts log-mel <= 0.255 plus a loose aggregate score floor instead of treating aggregate score as the main judge.
• Spectral diagnosis showed the Dexed reference has dominant peaks around 393, 131, 524, and 656 Hz. The prior Aquarium candidate had too little 80-160 Hz body when based at 392, while the corrected DX7 note basis restored the low body but exposed weak mid harmonic structure and high centroid/zero-crossing mismatch.
• Current run with bundled Python and Faust: log-mel distance 0.25093183, score 0.4135618, envelope distance 0.3595946, duration ratio 0.992578, RMS ratio 1.0658501, zero-crossing ratio 0.24567787, centroid ratio 1.3291793.
• Calibration lesson: the hard target is now a spectral calibration problem. DX7 output/index scaling still needs a real model; aggregate score can move in the wrong direction while log-mel and the ear move in the right direction.

Previous slice:

• Tightened the hard DX7 PRC SYNTH1 probe from a "writes WAVs" smoke test to a modest passing parity target: threshold now requires score >= 0.60.
• The useful cuts were not new syntax. The candidate improved by removing patch soft clipping, setting the graph base frequency to 392, and boosting the op3 carrier branch to compensate the algorithm-8 output/body balance. Global detune and per-edge route damping both made the score worse and were cut.
• Current best run with bundled Python and Faust writes timestamped artifacts under artifacts/parity/dx7-prc-synth1/<run>/: score 0.6057491, log-mel distance 0.27658066, envelope distance 0.38489524, duration ratio 0.98714787, RMS ratio 0.9756519, zero-crossing ratio 1.0458903, centroid ratio 1.093785.

Previous slice:

• Added a hard DX7 PRC SYNTH1 rendered parity probe that writes listening artifacts when dexed-py and Faust are available: artifacts/parity/dx7-prc-synth1/reference-dexed.wav, candidate-aquarium.wav, candidate.aqua, and report.txt.
• The probe rebuilds analog1.syx voice 17 with readable operator graph syntax and staged env=rl operator envelopes. It asserts a modest hard-target score floor instead of pretending exact DX7 parity is solved.
• Current run with bundled Python and Faust: score 0.4581856, log-mel distance 0.26397973, envelope distance 0.4109424, duration ratio 1.0173812, RMS ratio 0.61393267, zero-crossing ratio 1.1713804, centroid ratio 1.0978767.
• Calibration lesson: shortening the naive DX7 EG timing and lowering the graph base frequency made the candidate much closer. The remaining mismatch is still gain/timbre calibration, not missing env=rl syntax.

Previous slice:

• Added staged operator envelopes for operator graphs: env=rl rates=.004,.12,.2,.4 levels=1,.7,.25,0. This gives the DSL a readable four-stage rate/level contour without infecting the general ADSR voice envelope model.
• Added RateLevelEnvelope to the operator model, parser support for readable and compact env=rl syntax, Faust rl4_env(...) rendering, and a DX7 helper that emits staged envelope script specs from four-rate/four-level operator EG data.
• Verified the surface structurally and through the render path: dotnet test AquariumSynthCSharp.slnx --no-restore: 53 passed.
• Retried the hard PRC SYNTH1 probe with direct DX7 rate/level lowering. The best quick score was only ~0.316, worse than the hand-tweaked ADSR candidate. The DSL can now express the missing contour shape, but DX7 EG timing/gain calibration remains the next pressure.

Previous slice:

• Added Dx7OperatorLevelApproximation, which distills DX7 operator output level plus key/velocity scaling into a normal Aquarium level=-style value. This remains DX7 reference-import knowledge, not a generic DSL feature.
• Retried PRC SYNTH1 with effective levels and envelope tweaks. Static level mapping alone did not rescue the hard target: quick probes moved from ~0.24 to ~0.34, and envelope tweaks reached ~0.42. The next missing pressure is DX7-style operator envelope/gain evolution, not just static operator levels.
• Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 50 passed.

Previous slice:

• Tried the harder analog1.syx voice 17, PRC SYNTH1 (algorithm 8). The initial routed Aquarium candidate scored badly (~0.23), which exposed a real missing invariant rather than a threshold-tuning problem.
• Reworked operator feedback emission from a cyclic smoothed self-reference to a renderable Faust feedback expression using delayed recursion. Added FaustCompilerRendersOperatorFeedbackWhenInstalled.
• Exact DX7 feedback scaling and EG behavior are still not solved, but feedback no longer makes the Faust render path fall over.
• Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 49 passed.

Previous slice:

• Added the first thresholded DX7 rendered-audio parity rebuild: BuiltInScripts.Dx7StylePublicDomainMcMm53 maps public-domain analog1.syx voice 13, MC-MM 5-3, to a terse Aquarium sine patch.
• Added PublicDomainDx7McMm53MeetsFirstRenderedParityThresholdWhenInstalled, which renders the DX7 reference through dexed-py, renders the Aquarium candidate through Faust-generated C#, and asserts score, log-mel distance, envelope distance, duration/RMS ratios, zero-crossing ratio, and centroid ratio.
• This is behavioral parity for a simple sine-like rendered voice, not exact DX7 operator execution. The next DX7 pressure should be a harder voice that audibly needs the operator graph.
• Verified with bundled Python plus dexed-py: parity test passed.
• Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 48 passed.

Previous slice:

• Added a public-domain DX7 SysEx fixture from Musical Artifacts artifact 152: tests/AquariumSynth.Dsl.Tests/Fixtures/Dx7/PublicDomain/analog1.syx, with provenance and SHA-256 recorded beside it.
• Added a test-only dexed-py reference renderer. It uses AQUARIUM_DX7_PYTHON when set, otherwise probes py, python, and python3; if dexed-py is absent, the render test returns without turning optional tooling into a hard dependency.
• Added a .nupkg boundary test that packs AquariumSynth.Dsl and asserts test fixtures, SysEx banks, and Python helpers are not shipped.
• Verified with bundled Python plus dexed-py: the DX7 fixture renders through Dexed successfully.
• Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 47 passed.

Previous slice:

• Added FaustCompiler.RenderAsync, which compiles Aquarium Faust output to Faust-generated C#, runs it in a temp .NET project, and returns a mono float sample buffer for analysis.
• Added a render test that proves a generated Aquarium patch produces non-silent audio and can be compared through AudioAnalyzer.
• DX7 audio parity is still not claimed: the candidate renderer exists, but the reference side needs Dexed output or a captured licensed fixture.
• Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 44 passed.

Previous slice:

• Added Dx7EnvelopeApproximation, which lowers a DX7 four-rate/four-level EG to a labeled Aquarium ADSR approximation plus gate duration.
• Reference rebuilds now record operator_envelope_approximation as matched pressure and operator_envelope_exactness as still missing.
• Doctrine now states that DX7 EG approximation is not exact DX7 envelope execution.
• Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 43 passed.

Previous slice:

• Added field-site parameter binding for readable operator graph authoring: graph gain/note fields, operator ratio/level/feedback/envelope fields, and route index fields now accept @/param.
• Operator graph Faust emission now substitutes bound parameter expressions at the exact /opgraphs/... field paths.
• Fixed AD operator envelope binding to use /env/decay for the second AD value, matching the ADSR model instead of calling it release by accident.
• Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 42 passed.

Previous slice:

• Added a patch-level Playback contract for OneShot, Mono, and Poly playback with Faust MIDI polyphony settings.
• instrument midi=true polyphony=8 now lowers to Faust's standard [midi:on][nvoices:8] option and freq, gain, gate controls.
• Host/MIDI playback no longer emits per-voice /voices/0/note/frequency and /voices/0/note/gate controls; Faust architecture owns allocation.
• Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 41 passed.

Previous slice:

• Split note timing from envelope shape. Note now owns frequency, one-shot gate duration, and host/MIDI source; Envelope now owns ADSR shape: attack, decay, sustain level, and release.
• SFXR sustain duration now maps to Note.GateSeconds; SFXR punch maps to a lower ADSR sustain level plus voice gain compensation during import/legacy parsing.
• Added host note mode for MIDI-oriented patches through stable note frequency and note gate controls in generated Faust.
• Moved built-in authoring examples off punch= and onto sustain_level=.
• Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 40 passed.

Previous slice:

• Replaced the DX7 algorithm-8 authoring surface with readable operator graph syntax: operator, route, and carrier declarations.
• Added env=ad:attack:decay and env=adsr:attack:decay:sustain:release envelope forms for operator declarations.
• Kept compact ops=/edges= syntax as parser/interchange scaffolding, but it is no longer the built-in authoring example.
• Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 36 passed.

Previous slice:

• Added a first-class OperatorGraph model with operators, modulation edges, carriers, graph gain, and operator feedback.
• Added opgraph patch-script syntax. Example: opgraph name=core freq=330 carriers=1,3 ops=6:4:.9,5:3:.8,4:2:.7:.18,3:2:.6,2:1:.75,1:1:.82 edges=6>5:1.1,5>3:.9,4>3:.75,2>1:.85
• Faust emission now mixes operator graphs alongside normal voices.
• Updated the DX7 algorithm-8 rebuild to use a real operator graph for the topology. The remaining missing feature is exact DX7 feedback-register timing and DX7 rate/level envelopes, not graph ownership.
• Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 35 passed.

Earlier rebuild slice:

• Added ReferenceRebuild and ReferenceRebuildCatalog for explicit reference-target rebuild attempts.
• Added two DX7-style Aquarium DSL rebuilds:
  • dx7/algo32-additive-organ: algorithm 32's six-carrier additive shape, which maps cleanly to six Aquarium voices.
  • dx7/algo8-bright-pair: algorithm 8's two-carrier FM shape, which is only an approximation because the current voice DSL cannot express 6->5, 4+5->3, 2->1, or operator-local self-feedback.
• Added matched/missing feature records so topology mismatch becomes evidence instead of being hidden inside prose.
• Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 34 passed.

Earlier topology slice:

• Added DX7 algorithm topology metadata for algorithms 1-32 using Ken Shirriff's reverse-engineered OPS algorithm ROM table.
• Dx7SysEx.AlgorithmTopology now exposes carrier operators, modulation edges, feedback-register writers, direct self-feedback operators, delayed-feedback targets, and raw ROM steps.
• Dx7Voice.Features() now emits carrier_operators, modulation_edge_count, feedback_sources, and self_feedback_operators.
• Representative tests cover algorithm 8, algorithm 16, and algorithm 32.
• Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 31 passed.

Earlier slice:

• Added Dx7SysEx records and parsing for DX7 voice edit buffers, packed 128-byte voices, and packed 32-voice SysEx banks.
• Extracted six operators, envelopes, algorithm, feedback, oscillator sync, pitch envelope, LFO, transpose, and voice name into neutral DX7 records.
• Added Dx7Voice.ToReferencePatch and structural feature extraction so DX7 voices can pressure the reference model before translation exists.
• Checksum validation rejects bad wrapped SysEx payloads.
• Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 28 passed.

Parameter slice:

• Added explicit PatchParameter contracts: stable path, label, default, min, max, step, unit, automation-rate notes, and notes.
• Added neutral ReferencePatch, ReferenceSource, and ReferenceFeature contracts with provenance/license/hash-ready fields.
• Added param script declarations and duplicate parameter path validation.
• Updated Faust emission so declared parameters produce smoothed hslider controls.
• Implemented Option B parameter binding: numeric fields may reference declared parameters with @/path, for example lpf=@/macro/brightness. The parser records an exact field binding such as /voices/0/filter/lpf and keeps the parameter default as the graph value.
• Faust emission substitutes the parameter expression only at the bound field site. Unbound parameters still emit a warning.
• Verified with dotnet test AquariumSynthCSharp.slnx --no-restore: 23 passed.

Next likely slice:

• Refine operator graphs with parameter bindings inside graph fields and decide how host MIDI note age/retrigger semantics should be represented beyond the current frequency/gate controls.
• Keep tests focused on structure first, then add rendered audio comparison once the render path is explicit.