Hosting Third-Party Plug-ins (VST3 / Audio Unit)

Scanning

Open the scanner from the browser's Plug-Ins tab (Scan…) or Preferences ▸ Files & Updates ▸ Scan / manage plug-ins…:

• Sources: Audio Units (the macOS registry, on by default), VST3 system folders (/Library/Audio/Plug-Ins/VST3 and the user equivalent, on by default), plus any extra VST3 folders you add.
• Scan runs in the background with inline progress and a Cancel button. Scanning is crash-isolated: each file is probed out-of-process, so a crashing plug-in kills only the scan worker and is blacklisted, never the app. Rescan all clears the failure blacklist and gives everything one more try.
• Apple's ~40 built-in system AUs are filtered out so they don't bury your real plug-ins (the summary says how many were skipped).
• The table is sortable (Name/Format/Manufacturer) and filterable; rows show NEW after a scan, or QUARANTINED in red. Right-click a row: Trust / Quarantine / Remove from list / Reveal in Finder.

Crash protection at runtime

While any hosted plug-ins are live, Zammoth keeps a "dead man's pedal". If the app dies and the crash log names a plug-in that was loaded, that plug-in is auto-quarantined on the next launch — it won't load again until you Trust it (from its box's menu or the scanner). A dirty exit alone is not treated as proof; only a crash that names the plug-in convicts it. Trust and Quarantine are also agent commands, but the agent always needs your explicit confirmation to use them.

Using plug-ins

• Insert — double-click a plug-in in the browser (lands on the selected track), drag it onto a track's device dock, or ask the engineer for it by name. A third-party instrument goes on a MIDI track only: dropped there it replaces the track's instrument, and its box is tagged INST (its browser row reads INST too); dropped on an audio track it is refused and the status line says why; dropped in the empty space below the tracks it makes a new MIDI track. Effects go on either kind.
• The plug-in appears as a box in the dock after the native devices, showing a snapshot preview of its interface (GPU-drawn editors that can't be snapshotted show a clean card instead; right-click ▸ Refresh preview).
• ⏻ on the box (the switch every device has, in the same place) bypasses the plug-in: audio passes through untouched and its state stays; ⌘Z undoes. The engineer reaches the same switch through plugin.enable, and reads each plug-in's enabled in the snapshot.
• Double-click the box to open the plug-in's own editor in its own window (plug-ins without an editor get a generic parameter list). Several editors can be open at once, one window per plug-in; double-clicking a plug-in whose editor is already open brings that window to the front.
• Latency shows in the tag. A plug-in that delays the audio (a look-ahead limiter, a linear-phase EQ) shows how much beside its format, e.g. VST3 · 93 MS. Zammoth compensates for it automatically; the number is there so you know why monitoring feels late. The engineer reads it as latency_ms / latency_samples.
• Right-click the box — Open editor · Remove · Wrap FX in parallel/serial rack · Trust/Quarantine · Preset ▸ (the plug-in's own factory presets, ticked = current; a plug-in whose programs are only unnamed "Prog N" slots shows none — use its own preset browser) · Sidechain from ▸ (every other track; greyed when the plug-in has no sidechain input — key it with the native Duck device instead).
• Plug-in parameters are agent-operable (plugin.set_param), rack-mappable to macros, and their state saves and reloads with the project automatically. The engineer also picks factory presets (plugin.set_program — it replaces the plug-in's whole state, and one undo puts it back exactly) and keys a sidechain (plugin.set_sidechain), and reads each plug-in's programs, program, can_sidechain and sidechain_key.
• Hosted plug-in latency is compensated automatically by the engine.

Racks (parallel chains + eight macro knobs + .zrack presets) are covered in the Devices chapter — they host third-party plug-ins and native devices side by side.