18. What is not there yet

Said plainly, because a manual that oversells is worse than none:

• Plug-in hosting (VST etc.) — planned; the plug-in boundary is drafted, no host yet.
• Translations — the UI is ready to translate; no translated build ships yet.
• macOS — build script only, untested, and no MIDI input there.
• An AI assistant inside the app — planned as an add-on that drives the same Control API.
• Multi-core rendering — the render is single-threaded today.

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Note, 3 November 2026. Since this copy was written, 0.3.0-alpha.278 was announced — CLAP plug-in hosting, the whole MIDI hardware phase and a multi-core live mixer are in it (see the release notes). What is still true, and what will not change:

• VST3 is not supported, and cannot be. The VST3 SDK is dual-licensed GPLv3-or-Steinberg-proprietary and Nebula ships under the Functional Source License, so a GPL dependency cannot go into the binary. CLAP (MIT) is the format it hosts. VST2, LV2 and AU are not implemented either.
• A hosted plug-in's own editor window is never shown. The plug-in's GUI is not offered at all; its parameters appear as ordinary knobs in Nebula's own interface.
• The plug-in manager screen is only just being added. Discovery and hosting are built and tested, but nothing in the app can yet list a scanned plug-in or add one to a track.
• Nothing in the app's audio path calls the separate-process bridge yet, and CLAP fault containment is Windows-only.
• No real MIDI hardware was attached while the release was built: the driver paths are verified against test drivers, not against a drum machine on a desk.
• macOS is unverified — build script only, no Mac in the toolchain, no CoreMIDI input.
• Translations are a skeleton; no translated interface ships.

Update, 3 November 2026. Two lines above are out of date since this copy was written: plug-in hosting arrived (as CLAP hosting) in 0.3.0-alpha.278, and the renderer is no longer single-threaded — the live mixer now renders independent tracks at once (see the release notes). Three things are still true and will not change:

• VST3 is not supported, and cannot be. The VST3 SDK is dual-licensed GPLv3-or-Steinberg-proprietary and Nebula ships under the Functional Source License, so a GPL dependency cannot go into the binary. CLAP (MIT) is the format it hosts; VST2, LV2 and AU are not implemented.
• A hosted plug-in's own editor window is never shown. The plug-in's GUI is not offered at all; its parameters appear as ordinary knobs in Nebula's own interface.
• The plug-in manager screen is only just being added. Discovery and hosting are built and tested, but nothing in the app can yet list a scanned plug-in or add one to a track.

The rest of the list above stands: translations are a skeleton with no translated build, macOS is unverified (build script only, no MIDI input there), and the AI assistant is a planned closed-source add-on. Also worth saying plainly: no real MIDI hardware was attached while that release was built — the MIDI driver paths are verified against test drivers, not against a drum machine on a desk. And nothing in the app's audio path calls the separate-process plug-in bridge yet.