Ship Windows 11 x64 + NVIDIA support

[brxs]

Summary

Ship a supported Windows 11 x64 desktop build for systems with a supported NVIDIA GPU, distributed as a signed per-user NSIS installer with full LSDJ feature parity.

Dependencies

• Refactor LSDJ's cross-platform application foundation #107
• Add a production PyTorch MRT2 backend for Linux and Windows #110
• Add a portable Stable Audio 3 TFLite backend #111
• Add third-party model licensing, attribution, and download acknowledgement #108

Optional Windows Stable Audio GPU acceleration is tracked in #114 and must not block this release.

Supported configuration

• Windows 11 x64.
• NVIDIA GPU/driver/PyTorch-CUDA floor determined by Spike: validate Apolinario's PyTorch MRT2 port for LSDJ #109 and the production backend qualification.
• Minimum VRAM, CPU, RAM, and free disk documented from measured results. CPU/RAM matter because Stable Audio uses the TFLite baseline.
• Signed per-user NSIS installer.

Scope

Audio

• Validate Refactor LSDJ's cross-platform application foundation #107's shared sample-format/channel/resampling path on WASAPI hosts and make Windows-specific fixes only where required.
• Support default-device selection/change, shared-mode 48 kHz and non-48 kHz devices, stereo output, and FLX4 four-channel routing.
• Recover clearly from device removal, format renegotiation, sleep/resume, and default-device changes.
• Ensure the callback remains allocation-free and model/service work cannot block it.

MIDI and controller behavior

• Pioneer/AlphaTheta DDJ-FLX4 is the required controller for release qualification.
• DDJ-400 remains best-effort regression coverage unless separately advertised as supported.
• Validate WinMM MIDI naming, hotplug/reconnect, transport, mixer controls, jog wheels, LEDs, and required SysEx behavior.
• Provide actionable diagnostics when another application owns or interferes with a device.

Process and local-service security

• Use Refactor LSDJ's cross-platform application foundation #107's Windows process-tree lifetime mechanism so normal quit, crash, uninstall, and update leave no Python or GPU worker descendants.
• Bind local services to 127.0.0.1 only and do not request public network or firewall exposure.
• Use bounded, credential-redacted logs and clear startup/readiness/crash errors.

Desktop and filesystem behavior

• Store per-user configuration, models, runtimes, and cache under the defined non-roaming LocalAppData roots.
• Test with Windows long-path support disabled and with spaces, Unicode, and non-ASCII profile names.
• Validate titlebar/window behavior, file/folder dialogs, notifications, opener/trash behavior, packaged resources, sleep/resume, and update/restart.

Runtime and model experience

• Provide a clean first-run flow that installs verified MRT2 and Stable Audio runtimes/models without system Python, Git, a CUDA toolkit, WSL, or shell commands.
• Use the PyTorch MRT2 backend and TFLite Stable Audio baseline.
• Show backend, model/runtime state, required storage, driver incompatibility, download verification, and recovery errors clearly.
• Protect live decks from Stable Audio CPU/RAM load.
• Test release candidates against current Microsoft Defender definitions and document a response path for false positives; do not promise that third-party antivirus will never flag the app.

Installer and uninstall behavior

• Produce a per-user NSIS installer with version metadata, upgrade/downgrade behavior, Start menu integration, and clean app-binary removal.
• Preserve downloaded models, runtimes, settings, and user data by default on uninstall.
• Offer an explicit, clearly worded checkbox to remove those preserved assets and show the affected storage location/size before deletion.
• Select and document a WebView2 strategy, including offline/error behavior where bootstrap installation is necessary.

Authenticode signing

There is no current Authenticode certificate/provider or signing service. This issue includes:

• selecting and procuring a suitable code-signing provider/certificate;
• defining protected CI identity, key/certificate storage, access, rotation, and incident/revocation procedures;
• signing and timestamping all executable payloads and the final NSIS installer;
• verifying signatures and timestamps in CI and failing closed if any required payload is unsigned, invalid, or untimestamped;
• documenting the expected publisher identity and SmartScreen/reputation limitations.

CI and release pipeline

• Add Windows compile, unit, path, installer, signature, update, and uninstall tests where hosted CI can exercise them.
• Keep packaged WASAPI/MIDI/NVIDIA qualification as an explicit real-hardware gate.
• Add Windows as a required artifact producer to Refactor LSDJ's cross-platform application foundation #107's single-publisher release orchestration; the release must not publish if the Windows producer, signing step, or verification fails.

Documentation

• Installation, hardware/driver floor, expected publisher identity, Defender troubleshooting, audio/MIDI setup, model storage, uninstall preservation/removal, diagnostics, and known limitations.

Required real-hardware checklist

Record exact Windows build, CPU, RAM, GPU, VRAM, NVIDIA driver, audio device, MIDI controller, security state, and runtime/model revisions.

• Run both MRT2 decks for at least 10 minutes in 25-frame / approximately 1-second mode.
• Run both armed decks for at least 10 minutes in 5-frame / approximately 200-ms mode.
• Require zero engine-reported underruns and capture p50/p95/p99 generation latency, queue depth, WASAPI buffer settings, temperature, and throttling notes.
• Exercise FLX4 four-channel audio, all required controls, LED feedback, hotplug/reconnect, default-device change, and sleep/resume.
• Exercise Stable Audio music, SFX, audio-to-audio, continuation, inpainting, Small/Medium, LoRA, cancellation, and long-duration validation while decks remain active.
• Confirm normal and abnormal app exit leave no worker descendants.
• Install, upgrade, uninstall with preservation, uninstall with explicit data removal, and validate signatures/timestamps on a clean machine.

Acceptance criteria

• A fresh supported Windows 11 x64/NVIDIA machine can install and run LSDJ without developer tools, system Python, CUDA toolkit, Git, WSL, or a shell.
• The installer and every executable payload are validly Authenticode-signed and timestamped under the documented publisher identity.
• Full MRT2 and Stable Audio feature parity is available under the documented backend limitations.
• The FLX4 audio/MIDI workflow passes the required real-hardware checklist.
• Both two-deck scheduling modes pass the 10-minute zero-engine-underrun gate on the published minimum hardware.
• Uninstall preserves user/model/runtime data by default and removes it only through explicit opt-in.
• Runtime/model installs, updates, interruptions, and corrupt downloads recover without losing the previous verified version.
• The central publisher refuses to publish when the required Windows artifact, signing, or verification step fails.

Out of scope

• Windows 10.
• Windows on ARM.
• AMD or Intel GPU support.
• ASIO-specific support.
• MSI, Microsoft Store, or portable ZIP distribution.
• WSL-based runtime support.