Health check: confirm the REAPER bridge is running. Returns {pong: true, time: } on success.

Execute arbitrary Lua inside REAPER. The reaper global is available; values you return are sent back as JSON. Use this for anything not covered by a typed tool. Example: return reaper.GetNumTracks(). If you pass args, it is exposed in the chunk as the variable args.

Print the bridge directory the Python side is using. Useful when diagnosing setup issues (it must match the Lua side).

Get an overview of the current REAPER project: file path, sample rate, length in seconds, play state, track count, region count, marker count, time selection. Call this first to orient yourself.

List all tracks with index, name, volume (dB), pan (-1..1), mute, solo, record arm, color (RGB or 0 if none), item count, FX names.

List all regions in the project: {index, name, start_sec, end_sec, color_rgb}.

List all markers (not regions): {enum_index, index, name, time_sec, color_rgb}.

Save the current project to a specific path (.rpp). Creates parent dirs if needed.

Create a brand-new empty project in a new tab and switch to it. Does NOT save the previous project.

Add a new track. name is optional. position is the 0-based index where to insert; -1 (default) appends at the end. Returns {index, name}.

Delete a track by 0-based index.

Rename a track.

Set track volume in dB. Use -150 for -inf (silent). 0 = unity. Typical mix range: -60..+12.

Set track pan. -1.0 = full left, 0 = center, 1.0 = full right.

Mute or unmute a track.

Solo or unsolo a track.

Arm or disarm a track for recording.

Set track color. r/g/b each 0..255. Use r=g=b=0 to clear (revert to default).

Set folder structure depth for a track. 1 = this track starts a folder, 0 = normal (default), -1 = end of one folder, -2 = end of two folders, etc. Use this to group tracks: e.g. set depth=1 on a 'Drums' track and depth=-1 on the last child.

Select tracks by index list (replacing any previous selection). Pass [] to clear selection.

Start playback from the edit cursor.

Stop playback or recording.

Start recording on all armed tracks.

Move the edit cursor to time_sec.

Set the time selection (loop range) in seconds.

Clear the time selection.

Split every item that crosses time_sec at that time. If selected_only is true, only split currently-selected items. Returns count of items created.

Shift the position of all currently selected items by delta_sec seconds.

Set fade-in and fade-out (seconds) on every selected media item. Pass -1 for either to leave it unchanged.

Glue (consolidate) currently selected items. Each contiguous group on a track becomes one item. Useful after a lot of editing.

Set the record input for a track. input is REAPER's input index: 0..N-1 for mono inputs, or use 1024+ch for stereo pair starting at ch. Pass -1 to set to MIDI all-channels-all-devices.

Select items on a track by index range. Pass start=-1, end=-1 to select all items on the track. replace = clear other selections first.

Insert an empty MIDI item on a track, spanning [start_sec, end_sec]. Returns the item index on the track.

Insert MIDI notes into an existing MIDI item. Each note: {pitch: 0..127, start_qn: float, length_qn: float, velocity?: 1..127 (default 96), channel?: 0..15 (default 0)}. Positions are quarter-notes relative to the item start.

Convenience: build a chord progression on a track from scratch. Creates a MIDI item and writes one chord per entry. chords: [{root: 0..11 (C=0), type: 'maj'|'min'|'7'|'maj7'|'min7'|'dim'|'aug', duration_qn: float, octave?: int (default 4)}]. Notes are placed back-to-back starting at item start (start_sec).

Quantize note positions in the active MIDI take of the item at (track_index, item_index) to grid_qn quarter notes. Pass 0.25 for 16th-note grid, 0.5 for 8ths, 1.0 for quarters.

Add an FX plugin to a track. fx_name is matched the way REAPER's FX browser matches: e.g. 'ReaEQ', 'VST:Pro-Q 3', 'ReaComp'. Returns the new FX index on that track, or -1 if not found.

Remove an FX from a track by FX index.

List FX on a track with their parameters. Each entry: {index, name, enabled, num_params, params: [{index, name, value, value_normalized, min, max}]}. Set include_params=false to skip parameter details (faster).

Set an FX parameter. normalized=true (default) means value is in 0..1. Set normalized=false to use the plugin's native units.

Bypass / enable an FX on a track.

Set master track volume in dB. 0 = unity.

Trigger a render using REAPER's current render-dialog settings (non-interactive — no UI popup). Useful if the user has already configured the render dialog.

Render to a directory with the given bounds and file pattern. bounds ∈ {'entire_project','time_selection','all_regions','selected_items','selected_regions'}. file_name_pattern uses REAPER's wildcards: e.g. '$project', '$region', '$track', '$item'. Extension comes from current render format (configure via REAPER once, or call render_with_current_settings).

Get the current render settings: bounds flag, output file/dir, pattern, sample rate, channels.

Rename items on a track in order. pattern supports tokens: $num (1-based, zero-padded to pad_width), $idx (1-based, no padding), $name (original active-take name), $track (track name). If track_index = -1, applies across ALL tracks in track-then-position order. Returns the list of renames applied.

Rename ALL regions in the project in time order. Pattern tokens: $num (1-based, zero-padded to pad_width), $idx, $name (original name).

Render every region in the project to its own file. Uses the project's currently-configured render FORMAT (configure it once in REAPER's Render dialog, then this just changes bounds + output dir + pattern). file_name_pattern supports REAPER wildcards: default '$region' = filename equals region name.

Normalize the perceived loudness of items by adjusting each item's volume (D_VOL). Doesn't modify audio data. target_db: e.g. -14 for streaming, -23 for broadcast EBU R128. kind: 'LUFS-I' (default), 'RMS-I', 'peak', 'true_peak', 'LUFS-M_max', 'LUFS-S_max'. selected_only: true = only currently selected items; false = every item in the project. Requires REAPER 6.40+.

Build a track layout from a template. tracks is a list, processed in order. Each entry may contain: {name, color:[r,g,b]?, volume_db?, pan?, folder_start?:bool, folder_end?:int (1=close one, 2=close two, ...), record_armed?:bool, record_input?:int, fx?:[name,name,...]}. Appends to the current project; does not clear existing tracks. Returns the indices and names of the new tracks.