Report engine, clock, sample rate, DSP load, every Apollo in the cascade and the effective safety limits. Use when: starting a session, before any write, or when something is not behaving and you need to know the clock, the sample rate or which safety mode is active. Not for: channel levels or meters - use uad_list_channels and uad_peek_meters.

List every strip across every unit, grouped by device, with name, I/O type, fader, mute, solo, pan, hidden and stereo link. Use when: you need to find a channel by name, or to see the current mix state before changing it. Not for: meter levels (uad_peek_meters) or plugin contents (uad_get_inserts).

Batch-set channel state. Each item: {target: name or index, device?, kind?, fader_db?, pan?, pan2?, mute?, solo?, solo_safe?, name?, hidden?, stereo?, enabled?}. Every item reports resolved {device,index,name} and per-property {verified, before, after, warnings}. Use when: changing faders, mutes, solos, pans, names or visibility on one or many channels at once. Not for: the control-room monitor (uad_set_monitor), preamp gain (uad_set_preamp) or send levels (uad_set_sends).

Set preamp controls on one mic/line input: gain_db, pad, low_cut, phase, hi_z, source ('Mic' or 'Line'), and 48V phantom power. Use when: setting recording gain or input options on a channel whose has_preamp is true. 48V requires confirm_condenser_mic=true because phantom power destroys ribbon microphones. Not for: fader level (that is uad_set_channels fader_db) or digital inputs, which have no preamp at all.

Batch-set send levels into aux and cue buses. Each item: {target, send: 'aux1' | 'cue1'... or index, device?, level_db?, pan?, bypass?}. Use when: building a performer's cue/headphone mix or feeding a reverb aux. Not for: the headphone output level itself, which this protocol cannot set - see uad://limitations.

Set the control-room monitor: level_db (hard-railed), dim, mute, mono fold, alt speaker selection, dim attenuation. Unmuting, un-dimming and LOWERING dim_attenuation_db are all treated as level events and can be refused; level_db is written first and the release is railed against the level the engine reports back. Use when: changing what the control room hears, or recovering after uad_safe_state. Not for: headphone level - the protocol cannot set it; see uad://limitations.

Turn talkback on or off and set its level, with an auto-off timer (default 30 s) so an open talkback mic cannot be forgotten. Calling it again replaces the timer. Use when: the engineer needs to speak to the live room. Not for: routing the talkback mic or choosing which mic it is - that is set in Console.

Panic button: mute every monitor output and turn talkback off. Takes no arguments and needs no confirmation. Use when: there is feedback, a runaway level, or anything unexpectedly loud. Call it first and diagnose afterwards. Not for: normal muting of a single channel - use uad_set_channels.

Change the clock source (Internal, Word Clock, ADAT, S/PDIF), verify ClockLocked afterwards, and revert automatically if the new source does not lock. Use when: slaving to or from external digital gear, or recovering from an unlocked clock. Requires confirm=true and refuses while audio is flowing. Not for: changing the sample rate - that is uad_set_sample_rate.

Change the system sample rate (e.g. 44100, 48000, 96000). Requires confirm=true and refuses while audio is flowing, because every running stream will glitch. Use when: a session needs a different rate, or to match an external clock master. Not for: fixing a lock failure on its own - check the clock source first with uad_get_status.

List the installed UAD plugin catalog: name, categories, Unison capability, authorization status. Filterable and limited by default. Use when: choosing a plugin to load, or checking whether one is authorized. Not for: what is currently loaded on channels - that is uad_get_inserts.

Show what is loaded where: every insert slot plus the Unison slot, with plugin name, power state and preset, across one channel or all of them. Use when: auditing a channel's processing chain or finding a free slot. Not for: parameter values inside a plugin - use uad_get_plugin_params.

Load a UAD plugin into an insert slot (slot=0,1,2,3...) or the Unison preamp slot (slot='unison'), then poll up to 5 s for its parameter nodes to materialize and report whether they did. Use when: adding processing to a channel. Optionally recall a preset in the same call. Not for: changing parameters (uad_set_plugin_params) or clearing a slot (uad_remove_plugin).

Clear an insert or Unison slot by writing an empty EffectName, and report what was removed. Use when: freeing DSP or removing processing from a channel. Not for: bypassing a plugin while keeping it loaded - set its Power instead via uad_load_plugin(power=false) on the same slot.

List a loaded plugin's parameters with their names, normalized 0-1 values and the engine's own display text. Use when: you need the exact parameter names before setting them, or to read back what a preset did. Not for: an empty slot - parameter nodes only exist once a plugin is loaded.

Batch-set a loaded plugin's parameters by name using normalized 0-1 values: params=[{name: 'Peak Reduction', normalized: 0.4}, ...]. Use when: dialling in a plugin after loading it. Read uad_get_plugin_params first for exact names and current values. Not for: dB or Hz values - the protocol exposes normalized values only; the display text is read-only.

Recall a preset by name into a loaded plugin slot, validated against that plugin's preset browser when the engine lists it. Use when: a named factory or user preset is a faster starting point than setting parameters. Not for: channel-strip or Console session presets, which this server does not manage - see uad://limitations.

One-shot meter read (level, peak, clip) for all channels or a named subset, with at-floor channels called out. Use when: checking whether signal is arriving, or which channel is hot right now. Not for: waiting for signal to appear - use uad_watch_meters, which polls and exits early.

Poll meters for up to duration_s (capped at 30 s) and return as soon as any watched channel exceeds threshold_db, reporting per-channel peaks. Use when: verifying that a source is live, setting gain against a performance, or hunting an intermittent signal. Not for: long-term monitoring - it is capped at 30 s per call by design.

Whole-rig snapshots: action='save' captures every writable property, 'list' shows what is saved, 'diff' reports what changed since one (ignore accepts glob patterns), 'restore' writes one back in a safe order. Restore defaults to dry_run=true and returns the exact ordered write list. Use when: saving a session state before experimenting, seeing what drifted, or putting a known-good state back. A real restore captures a pre-restore snapshot first. Not for: Console sessions or plugin scenes, which this server cannot touch.

Read any node or property in the engine tree verbatim, with its metadata. Use when: a tool does not cover something and you need to inspect the tree, or to confirm a property's type, range or enum values. Not for: writing - that is deliberately separate and only available in full mode.