Merge branch '3-integrate-carla'

Co-authored-by: aider (deepseek/deepseek-reasoner) <aider@aider.chat>

docs/6-sampling-and-recording.md

@@ -0,0 +1,45 @@
+# Sampling and Recording (WAV Load/Save)
+
+The looper supports loading a WAV file into channel 0 and saving the current loop of channel 0 as a WAV file. Both operations use the **libsndfile** library, ensuring correct handling of RIFF headers, chunk sizes, and sample format conversion.
+
+## Load Command
+
+- **MIDI note 70** with the control key (note 64) triggers loading.
+- The file `loop.wav` (located in the working directory) is read by `wav_read()` in `src/wav.c`.
+- The function calls `sf_open(path, SFM_READ, &info)`.
+- It accepts only mono PCM WAV files. If the file is not mono or has an invalid sample rate, it returns `-1`.
+- The number of frames read is capped at `LOOP_BUF_SIZE` (5 seconds at 48 kHz).
+- The data is stored in `channels[0].loop_buffer` and `channels[0].loop_count` is set atomically.
+- The state of channel 0 is set to `STATE_LOOPING` and `prev_state` is set to `-1` to trigger the loop start in the next audio cycle.
+
+## Save Command
+
+- **MIDI note 71** with the control key (note 64) triggers saving.
+- The looper must currently be in `STATE_LOOPING` and have a non‑zero `loop_count`.
+- A ring buffer (`RingBuf`) is allocated with capacity `2 × loop_count` samples.
+- The pointer to the ring buffer is published via `atomic_store_explicit` on `channels[0].save_ring`.
+- In each audio callback cycle, if the channel is looping and a save ring exists, the audio output data is written into the ring buffer.
+- A dedicated **writer thread** (`writer_thread`) is launched (detached) to consume the ring buffer.
+- The writer thread reads `loop_count` samples from the ring buffer, sleeping 10 ms between empty reads.
+- Once all samples are collected, it writes them to `save.wav` using `sf_writef_float()`.
+- After writing, the ring buffer is destroyed and freed, and the save ring pointer is set to `NULL`.
+
+## Dependencies
+
+- **libsndfile** must be installed (development headers). Add `-lsndfile` to your linker flags (already present in the provided `makefile`).
+
+## Implementation Files
+
+- `src/wav.c` – contains `wav_read()` and `wav_write()` based on libsndfile.
+- `src/looper.c` – contains the load/save command handling in `looper_process_commands()` and the writer thread function.
+- `src/channel.h` – defines `save_ring` as `_Atomic RingBuf *`.
+
+## Testing
+
+- The integration test `test_wav_load` creates a short 440 Hz WAV file, loads it via MIDI, and checks for ≥3 bursts of audio output.
+- The integration test `test_wav_save` records a beep, loops it, issues the save command, and verifies the resulting WAV file has non‑zero data size.
+
+## Notes
+
+- The save operation is asynchronous: the writer thread runs in the background while the audio callback continues to fill the ring buffer. The test waits 2 s for the file to be written before checking.
+- The load operation is synchronous: the callback sleeps 1 s after the MIDI command to give the main loop time to process it.

engine/makefile

@@ -1,8 +1,8 @@
 CC ?= gcc
 CFLAGS ?= -Wall -Wextra -g -Isrc 
-LDFLAGS ?= -ljack -lm
+LDFLAGS ?= -ljack -lm -lsndfile -lpthread
 
-SRC = src/main.c src/looper.c src/channel.c src/midi.c src/queue.c src/pipe.c
+SRC = src/main.c src/looper.c src/channel.c src/midi.c src/queue.c src/pipe.c src/ringbuffer.c src/wav.c
 OBJ = $(SRC:.c=.o)
 
 looper: $(OBJ)
@@ -12,10 +12,10 @@ src/%.o: src/%.c
 	$(CC) $(CFLAGS) -c -o $@ $<
 
 integration: looper tests/integration.c
-	$(CC) $(CFLAGS) -o integration_test tests/integration.c -ljack -lm
+	$(CC) $(CFLAGS) -o integration_test tests/integration.c -ljack -lm -lsndfile -lpthread
 
 test_status_fifo: looper tests/test_status_fifo.c
-	$(CC) $(CFLAGS) -o test_status_fifo tests/test_status_fifo.c -ljack -lm
+	$(CC) $(CFLAGS) -o test_status_fifo tests/test_status_fifo.c -ljack -lm -lsndfile -lpthread
 
 test: integration test_status_fifo
 	./test_status_fifo

engine/src/channel.c

@@ -6,131 +6,123 @@
 #include <string.h>
 
 /* Helper: zero a scene and set its state to IDLE */
-static void init_scene(scene_t *sc) {
+void init_scene(scene_t *sc) {
   memset(sc, 0, sizeof(scene_t));
   atomic_store(&sc->state, STATE_IDLE);
   atomic_store(&sc->prev_state, -1);
 }
 
 void channel_add(jack_client_t *client, int idx) {
-  struct channel_t *cur = get_channels_array();
-
   char in_name[64], out_name[64];
   snprintf(in_name, sizeof(in_name), "channel%d_input", next_channel_id);
   snprintf(out_name, sizeof(out_name), "channel%d_output", next_channel_id);
 
-  cur[idx].audio_in = jack_port_register(
+  /* Always register audio ports (needed for pass-through even for MIDI channels?) */
+  channels[idx].audio_in = jack_port_register(
       client, in_name, JACK_DEFAULT_AUDIO_TYPE, JackPortIsInput, 0);
-  cur[idx].audio_out = jack_port_register(
+  channels[idx].audio_out = jack_port_register(
       client, out_name, JACK_DEFAULT_AUDIO_TYPE, JackPortIsOutput, 0);
-  if (!cur[idx].audio_in || !cur[idx].audio_out) {
+  if (!channels[idx].audio_in || !channels[idx].audio_out) {
     fprintf(stderr, "Failed to register ports for channel %d\n",
             next_channel_id);
-    atomic_store(&cur[idx].active, 0);
+    /* Do NOT mark channel active – process loop will skip it */
+    atomic_store(&channels[idx].active, 0);
     return;
   }
 
-  atomic_store(&cur[idx].active, 1);
-  cur[idx].type = CHANNEL_AUDIO;
-  atomic_store(&cur[idx].scene_count, 1);
-  atomic_store(&cur[idx].current_scene, 0);
-  init_scene(&cur[idx].scenes[0]);
-
-  next_channel_id++;
-  atomic_fetch_add(&channel_count, 1);
-}
-
-void channel_add_midi(jack_client_t *client, int idx) {
-  struct channel_t *cur = get_channels_array();
-
-  char in_name[64], out_name[64];
-  snprintf(in_name, sizeof(in_name), "channel%d_midi_in", next_channel_id);
-  snprintf(out_name, sizeof(out_name), "channel%d_midi_out", next_channel_id);
-
-  cur[idx].midi_in = jack_port_register(client, in_name, JACK_DEFAULT_MIDI_TYPE,
-                                        JackPortIsInput, 0);
-  cur[idx].midi_out = jack_port_register(
-      client, out_name, JACK_DEFAULT_MIDI_TYPE, JackPortIsOutput, 0);
-  if (!cur[idx].midi_in || !cur[idx].midi_out) {
-    fprintf(stderr, "Failed to register MIDI ports for channel %d\n",
-            next_channel_id);
-    atomic_store(&cur[idx].active, 0);
-    return;
+  /* If this is a MIDI channel, register MIDI ports */
+  if (channels[idx].type == CHANNEL_MIDI) {
+      char midi_in_name[64], midi_out_name[64];
+      snprintf(midi_in_name, sizeof(midi_in_name), "channel%d_midi_in", next_channel_id);
+      snprintf(midi_out_name, sizeof(midi_out_name), "channel%d_midi_out", next_channel_id);
+      channels[idx].midi_in = jack_port_register(
+          client, midi_in_name, JACK_DEFAULT_MIDI_TYPE, JackPortIsInput, 0);
+      channels[idx].midi_out = jack_port_register(
+          client, midi_out_name, JACK_DEFAULT_MIDI_TYPE, JackPortIsOutput, 0);
+      if (!channels[idx].midi_in || !channels[idx].midi_out) {
+          fprintf(stderr, "Failed to register MIDI ports for channel %d\n",
+                  next_channel_id);
+          atomic_store(&channels[idx].active, 0);
+          jack_port_unregister(client, channels[idx].audio_in);
+          jack_port_unregister(client, channels[idx].audio_out);
+          return;
+      }
+  } else {
+      channels[idx].midi_in = NULL;
+      channels[idx].midi_out = NULL;
   }
 
-  atomic_store(&cur[idx].active, 1);
-  cur[idx].type = CHANNEL_MIDI;
-  atomic_store(&cur[idx].scene_count, 1);
-  atomic_store(&cur[idx].current_scene, 0);
-  init_scene(&cur[idx].scenes[0]);
+  atomic_store(&channels[idx].active, 1);
+  /* Initialise first scene */
+  channels[idx].scene_count = 1;
+  channels[idx].current_scene = 0;
+  init_scene(&channels[idx].scenes[0]);
+
+  channels[idx].save_ring = NULL;
+  atomic_store(&channels[idx].save_complete, 0);
 
   next_channel_id++;
-  atomic_fetch_add(&channel_count, 1);
+  channel_count++;
 }
 
 void channel_remove(jack_client_t *client, int idx) {
   (void)client;
-  struct channel_t *cur = get_channels_array();
-  atomic_store(&cur[idx].active, 0);
+  atomic_store(&channels[idx].active, 0);
   atomic_fetch_sub(&channel_count, 1);
 }
 
 void channel_add_scene(jack_client_t *client, int idx) {
   (void)client;
-  struct channel_t *cur = get_channels_array();
-  if (atomic_load(&cur[idx].scene_count) >= MAX_SCENES)
+  if (atomic_load(&channels[idx].scene_count) >= MAX_SCENES)
     return;
-  int ns = atomic_load(&cur[idx].scene_count);
-  init_scene(&cur[idx].scenes[ns]);
-  atomic_fetch_add(&cur[idx].scene_count, 1);
+  int ns = atomic_load(&channels[idx].scene_count);
+  init_scene(&channels[idx].scenes[ns]);
+  atomic_fetch_add(&channels[idx].scene_count, 1);
 }
 
 void channel_remove_scene(jack_client_t *client, int idx) {
   (void)client;
-  struct channel_t *cur = get_channels_array();
-  int sc = atomic_load(&cur[idx].scene_count);
+  int sc = atomic_load(&channels[idx].scene_count);
   if (sc <= 1)
     return;
-  int cs = atomic_load(&cur[idx].current_scene);
+  int cs = atomic_load(&channels[idx].current_scene);
   /* shift remaining scenes down (atomic copy of fields) */
   for (int i = cs; i < sc - 1; i++) {
-    atomic_store(&cur[idx].scenes[i].loop_count,
-                 atomic_load(&cur[idx].scenes[i + 1].loop_count));
-    atomic_store(&cur[idx].scenes[i].record_pos,
-                 atomic_load(&cur[idx].scenes[i + 1].record_pos));
-    atomic_store(&cur[idx].scenes[i].playback_pos,
-                 atomic_load(&cur[idx].scenes[i + 1].playback_pos));
-    atomic_store(&cur[idx].scenes[i].state,
-                 atomic_load(&cur[idx].scenes[i + 1].state));
-    atomic_store(&cur[idx].scenes[i].prev_state,
-                 atomic_load(&cur[idx].scenes[i + 1].prev_state));
+    atomic_store(&channels[idx].scenes[i].loop_count,
+                 atomic_load(&channels[idx].scenes[i + 1].loop_count));
+    atomic_store(&channels[idx].scenes[i].record_pos,
+                 atomic_load(&channels[idx].scenes[i + 1].record_pos));
+    atomic_store(&channels[idx].scenes[i].playback_pos,
+                 atomic_load(&channels[idx].scenes[i + 1].playback_pos));
+    atomic_store(&channels[idx].scenes[i].state,
+                 atomic_load(&channels[idx].scenes[i + 1].state));
+    atomic_store(&channels[idx].scenes[i].prev_state,
+                 atomic_load(&channels[idx].scenes[i + 1].prev_state));
     /* copy loop data (may race with RT thread; acceptable for this release) */
-    memcpy(cur[idx].scenes[i].loop.audio_buffer,
-           cur[idx].scenes[i + 1].loop.audio_buffer,
+    memcpy(channels[idx].scenes[i].loop.audio_buffer,
+           channels[idx].scenes[i + 1].loop.audio_buffer,
            LOOP_BUF_SIZE * sizeof(float));
   }
-  atomic_fetch_sub(&cur[idx].scene_count, 1);
-  int new_sc = atomic_load(&cur[idx].scene_count);
+  atomic_fetch_sub(&channels[idx].scene_count, 1);
+  int new_sc = atomic_load(&channels[idx].scene_count);
   if (cs >= new_sc)
-    atomic_store(&cur[idx].current_scene, new_sc - 1);
+    atomic_store(&channels[idx].current_scene, new_sc - 1);
 }
 
 void channel_next_scene(jack_client_t *client, int idx) {
   (void)client;
-  struct channel_t *cur = get_channels_array();
-  int sc = atomic_load(&cur[idx].scene_count);
+  int sc = atomic_load(&channels[idx].scene_count);
   if (sc > 1) {
-    int cs = atomic_load(&cur[idx].current_scene);
-    atomic_store(&cur[idx].current_scene, (cs + 1) % sc);
+    int cs = atomic_load(&channels[idx].current_scene);
+    atomic_store(&channels[idx].current_scene, (cs + 1) % sc);
   }
 }
 
 void channel_prev_scene(jack_client_t *client, int idx) {
   (void)client;
-  struct channel_t *cur = get_channels_array();
-  int sc = atomic_load(&cur[idx].scene_count);
+  int sc = atomic_load(&channels[idx].scene_count);
   if (sc > 1) {
-    int cs = atomic_load(&cur[idx].current_scene);
-    atomic_store(&cur[idx].current_scene, (cs - 1 + sc) % sc);
+    int cs = atomic_load(&channels[idx].current_scene);
+    atomic_store(&channels[idx].current_scene, (cs - 1 + sc) % sc);
   }
 }

engine/src/channel.c~

@@ -0,0 +1,117 @@
+// cppcheck-suppress missingIncludeSystem
+#include "channel.h"
+#include <jack/jack.h>
+#include <stdatomic.h>
+#include <stdio.h>
+#include <string.h>
+
+<<<<<<< HEAD
+=======
+/* Helper: zero a scene and set its state to IDLE */
+static void init_scene(scene_t *sc) {
+  memset(sc, 0, sizeof(scene_t));
+  atomic_store(&sc->state, STATE_IDLE);
+  atomic_store(&sc->prev_state, -1);
+}
+
+>>>>>>> 3-integrate-carla
+void channel_add(jack_client_t *client, int idx) {
+  char in_name[64], out_name[64];
+  snprintf(in_name, sizeof(in_name), "channel%d_input", next_channel_id);
+  snprintf(out_name, sizeof(out_name), "channel%d_output", next_channel_id);
+
+  channels[idx].audio_in = jack_port_register(
+      client, in_name, JACK_DEFAULT_AUDIO_TYPE, JackPortIsInput, 0);
+  channels[idx].audio_out = jack_port_register(
+      client, out_name, JACK_DEFAULT_AUDIO_TYPE, JackPortIsOutput, 0);
+  if (!channels[idx].audio_in || !channels[idx].audio_out) {
+    fprintf(stderr, "Failed to register ports for channel %d\n",
+            next_channel_id);
+    /* Do NOT mark channel active – process loop will skip it */
+    atomic_store(&channels[idx].active, 0);
+    return;
+  }
+
+  atomic_store(&channels[idx].active, 1);
+  atomic_store(&channels[idx].state, STATE_IDLE);
+  channels[idx].prev_state = -1;
+  channels[idx].loop_count = 0;
+  channels[idx].record_pos = 0;
+  channels[idx].playback_pos = 0;
+  channels[idx].save_ring = NULL;
+
+  next_channel_id++;
+  channel_count++;
+}
+
+void channel_remove(jack_client_t *client, int idx) {
+  (void)client;
+<<<<<<< HEAD
+  atomic_store(&channels[idx].active, 0);
+  channel_count--;
+=======
+  struct channel_t *cur = get_channels_array();
+  atomic_store(&cur[idx].active, 0);
+  atomic_fetch_sub(&channel_count, 1);
+}
+
+void channel_add_scene(jack_client_t *client, int idx) {
+  (void)client;
+  struct channel_t *cur = get_channels_array();
+  if (atomic_load(&cur[idx].scene_count) >= MAX_SCENES)
+    return;
+  int ns = atomic_load(&cur[idx].scene_count);
+  init_scene(&cur[idx].scenes[ns]);
+  atomic_fetch_add(&cur[idx].scene_count, 1);
+}
+
+void channel_remove_scene(jack_client_t *client, int idx) {
+  (void)client;
+  struct channel_t *cur = get_channels_array();
+  int sc = atomic_load(&cur[idx].scene_count);
+  if (sc <= 1)
+    return;
+  int cs = atomic_load(&cur[idx].current_scene);
+  /* shift remaining scenes down (atomic copy of fields) */
+  for (int i = cs; i < sc - 1; i++) {
+    atomic_store(&cur[idx].scenes[i].loop_count,
+                 atomic_load(&cur[idx].scenes[i + 1].loop_count));
+    atomic_store(&cur[idx].scenes[i].record_pos,
+                 atomic_load(&cur[idx].scenes[i + 1].record_pos));
+    atomic_store(&cur[idx].scenes[i].playback_pos,
+                 atomic_load(&cur[idx].scenes[i + 1].playback_pos));
+    atomic_store(&cur[idx].scenes[i].state,
+                 atomic_load(&cur[idx].scenes[i + 1].state));
+    atomic_store(&cur[idx].scenes[i].prev_state,
+                 atomic_load(&cur[idx].scenes[i + 1].prev_state));
+    /* copy loop data (may race with RT thread; acceptable for this release) */
+    memcpy(cur[idx].scenes[i].loop.audio_buffer,
+           cur[idx].scenes[i + 1].loop.audio_buffer,
+           LOOP_BUF_SIZE * sizeof(float));
+  }
+  atomic_fetch_sub(&cur[idx].scene_count, 1);
+  int new_sc = atomic_load(&cur[idx].scene_count);
+  if (cs >= new_sc)
+    atomic_store(&cur[idx].current_scene, new_sc - 1);
+}
+
+void channel_next_scene(jack_client_t *client, int idx) {
+  (void)client;
+  struct channel_t *cur = get_channels_array();
+  int sc = atomic_load(&cur[idx].scene_count);
+  if (sc > 1) {
+    int cs = atomic_load(&cur[idx].current_scene);
+    atomic_store(&cur[idx].current_scene, (cs + 1) % sc);
+  }
+}
+
+void channel_prev_scene(jack_client_t *client, int idx) {
+  (void)client;
+  struct channel_t *cur = get_channels_array();
+  int sc = atomic_load(&cur[idx].scene_count);
+  if (sc > 1) {
+    int cs = atomic_load(&cur[idx].current_scene);
+    atomic_store(&cur[idx].current_scene, (cs - 1 + sc) % sc);
+  }
+>>>>>>> 3-integrate-carla
+}

engine/src/channel.h

@@ -5,23 +5,14 @@
 #include <jack/jack.h>
 #include <stdatomic.h>
 
+#define MAX_SCENES 4
 #define LOOP_BUF_SIZE  (5 * 48000)
-
 #define MAX_MIDI_EVENTS 1024
+#define MAX_CHANNELS   16
 
-#define MAX_SCENES 16
+#include "ringbuffer.h"
 
-typedef enum {
-    CHANNEL_AUDIO,
-    CHANNEL_MIDI
-} channel_type_t;
-
-typedef struct {
-    jack_nframes_t timestamp;   /* frame offset relative to loop start */
-    unsigned char  status;
-    unsigned char  note;
-    unsigned char  velocity;
-} midi_event_t;
+typedef enum { CHANNEL_AUDIO, CHANNEL_MIDI } channel_type_t;
 
 typedef enum {
     STATE_IDLE,
@@ -30,46 +21,58 @@ typedef enum {
     STATE_PAUSED
 } looper_state;
 
+/* Structure for a recorded or playing MIDI event */
 typedef struct {
-    union {
-        float         audio_buffer[LOOP_BUF_SIZE];
-        midi_event_t  midi_events[MAX_MIDI_EVENTS];
-    } loop;
-    atomic_int    loop_count;
-    atomic_int    record_pos;
-    atomic_int    playback_pos;
-    atomic_int    state;
-    atomic_int    prev_state;
+    jack_nframes_t timestamp;
+    unsigned char status;
+    unsigned char note;
+    unsigned char velocity;
+} midi_event_t;
+
+/* Loop data for a scene */
+typedef struct {
+    float          audio_buffer[LOOP_BUF_SIZE];
+    midi_event_t   midi_events[MAX_MIDI_EVENTS];
+} loop_data_t;
+
+/* A single scene within a channel */
+typedef struct {
+    atomic_int state;
+    atomic_int prev_state;
+    atomic_int loop_count;
+    atomic_int record_pos;
+    atomic_int playback_pos;
+    loop_data_t loop;
 } scene_t;
 
 struct channel_t {
-    channel_type_t type;
+    channel_type_t type;          /* AUDIO or MIDI */
     atomic_int    active;
     jack_port_t  *audio_in;
     jack_port_t  *audio_out;
-    jack_port_t  *midi_in;
+    jack_port_t  *midi_in;       /* NULL for audio channels */
     jack_port_t  *midi_out;
+    int           scene_count;   /* number of scenes (max MAX_SCENES) */
+    int           current_scene; /* index of currently active scene */
     scene_t       scenes[MAX_SCENES];
-    atomic_int    scene_count;
-    atomic_int    current_scene;
+
+    _Atomic RingBuf *save_ring;
+    atomic_int       save_complete;   /* 1 when writer is done; RT thread must stop writing */
 };
 
 /* Globals declared in looper.c */
-extern struct channel_t *_Atomic channels;
-extern atomic_int  channel_capacity;
+extern struct channel_t channels[MAX_CHANNELS];
 extern atomic_int  channel_count;
+extern atomic_int  channel_capacity;
 extern int         next_channel_id;
+extern atomic_int  cmd_add;
+extern atomic_int  cmd_remove;
+extern atomic_int  cmd_load;
+extern atomic_int  cmd_save;
 
-/* Safe accessor for the real‑time thread (returns a snapshot of the current pointer) */
-static inline struct channel_t *get_channels_array(void) {
-    return atomic_load(&channels);
-}
-
+void init_scene(scene_t *sc);
 void channel_add(jack_client_t *client, int idx);
 void channel_remove(jack_client_t *client, int idx);
-void channel_add_midi(jack_client_t *client, int idx);
-
-/* Scene management (called from main loop) */
 void channel_add_scene(jack_client_t *client, int idx);
 void channel_remove_scene(jack_client_t *client, int idx);
 void channel_next_scene(jack_client_t *client, int idx);

engine/src/command.h

@@ -9,6 +9,8 @@ typedef enum {
     CMD_ADD_CHANNEL,    // add a new dynamic channel
     CMD_REMOVE_CHANNEL, // remove last dynamic channel
     CMD_ADD_MIDI_CHANNEL, // add a new dynamic MIDI channel
+    CMD_LOAD,           // load WAV file into channel 0
+    CMD_SAVE,           // save loop as WAV file
     CMD_NEXT_SCENE,
     CMD_PREV_SCENE,
     CMD_ADD_SCENE,

engine/src/looper.c~

@@ -0,0 +1,675 @@
+// cppcheck-suppress missingIncludeSystem
+#include "looper.h"
+#include "channel.h"
+#include "midi.h"
+<<<<<<< HEAD
+#include "wav.h"
+#include "ringbuffer.h"
+#include "pipe.h"
+#include <jack/jack.h>
+#include <sys/stat.h>
+=======
+#include "queue.h"
+>>>>>>> 3-integrate-carla
+#include <fcntl.h>
+#include <jack/jack.h>
+#include <jack/midiport.h>
+#include <math.h>
+#include <pthread.h>
+#include <stdatomic.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+<<<<<<< HEAD
+#include <time.h>
+#include "queue.h"
+#include "command.h"
+
+/* Global command queues */
+spsc_queue_t cmd_queue;
+spsc_queue_t cmd_queue_main_midi;
+spsc_queue_t cmd_queue_main_fifo;
+=======
+#include <sys/stat.h>
+#include <unistd.h>
+>>>>>>> 3-integrate-carla
+
+#define STATUS_FIFO "/tmp/looper_status"
+
+/* writer status fd */
+static int status_fd = -1;
+
+static void looper_write_status(void) {
+<<<<<<< HEAD
+    if (status_fd < 0)
+        return;
+    char buf[256];
+    for (int ch = 0; ch < MAX_CHANNELS; ch++) {
+        if (!atomic_load(&channels[ch].active))
+            continue;
+        int state_val = atomic_load(&channels[ch].state);
+        const char *state_str;
+        switch (state_val) {
+            case STATE_IDLE:    state_str = "IDLE";    break;
+            case STATE_RECORD:  state_str = "RECORD";  break;
+            case STATE_LOOPING: state_str = "LOOPING"; break;
+            case STATE_PAUSED:  state_str = "PAUSED";  break;
+            default:            state_str = "UNKNOWN";
+        }
+        int n = snprintf(buf, sizeof(buf),
+                         "CH=%d SC=%d STATE=%s\n",
+                         ch, 0, state_str);
+        if (n > 0) {
+            int ret = write(status_fd, buf, n);
+            (void)ret;
+        }
+    }
+=======
+  int fd = open(STATUS_FIFO, O_WRONLY | O_NONBLOCK);
+  if (fd < 0)
+    return;
+  struct channel_t *cur = get_channels_array();
+  int cap = atomic_load(&channel_capacity);
+  char buf[256];
+  for (int ch = 0; ch < cap; ch++) {
+    if (!atomic_load(&cur[ch].active))
+      continue;
+    int sc_idx = atomic_load(&cur[ch].current_scene);
+    int state = atomic_load(&cur[ch].scenes[sc_idx].state);
+    const char *state_str;
+    switch (state) {
+    case STATE_IDLE:
+      state_str = "IDLE";
+      break;
+    case STATE_RECORD:
+      state_str = "RECORD";
+      break;
+    case STATE_LOOPING:
+      state_str = "LOOPING";
+      break;
+    case STATE_PAUSED:
+      state_str = "PAUSED";
+      break;
+    default:
+      state_str = "UNKNOWN";
+    }
+    int n = snprintf(buf, sizeof(buf), "CH=%d SC=%d STATE=%s\n", ch, sc_idx,
+                     state_str);
+    if (n > 0) {
+      int ret = write(fd, buf, n);
+      (void)ret;
+    }
+  }
+  close(fd);
+>>>>>>> 3-integrate-carla
+}
+
+/* Global state (shared across files) */
+struct channel_t channels[MAX_CHANNELS];
+atomic_int channel_count = 0;
+atomic_int channel_capacity = MAX_CHANNELS;
+int next_channel_id = 1;
+atomic_int cmd_add = 0;
+atomic_int cmd_remove = 0;
+atomic_int cmd_load = 0;
+atomic_int cmd_save = 0;
+jack_port_t *midi_control_port = NULL;
+jack_port_t *midi_clock_port = NULL;
+atomic_int control_key_active = 0;
+atomic_int bind_channel = 0;
+
+/* Deferred removal index (1 second grace) */
+static int pending_unregister_idx = -1;
+
+/* writer thread function and sample rate holder */
+static void *writer_thread(void *arg);
+static int global_sample_rate = 0;
+
+/* execute a single command (called from looper_process_commands) */
+static void exec_command(command_t cmd, jack_client_t *client) {
+    int ch = cmd.channel;
+    if (ch < 0) ch = 0;
+
+    switch (cmd.type) {
+    case CMD_CYCLE: {
+      int state = atomic_load(&channels[ch].state);
+      switch (state) {
+      case STATE_IDLE:
+        atomic_store(&channels[ch].state, STATE_RECORD);
+        break;
+      case STATE_RECORD:
+        atomic_store(&channels[ch].state, STATE_LOOPING);
+        break;
+      case STATE_LOOPING:
+        atomic_store(&channels[ch].state, STATE_PAUSED);
+        break;
+      case STATE_PAUSED:
+        atomic_store(&channels[ch].state, STATE_LOOPING);
+        break;
+      }
+      atomic_store(&channels[ch].prev_state, -1);
+      break;
+    }
+    case CMD_STOP:
+      atomic_store(&channels[ch].state, STATE_IDLE);
+      atomic_store(&channels[ch].prev_state, -1);
+      break;
+
+    case CMD_ADD_CHANNEL:
+    case CMD_ADD_MIDI_CHANNEL: {
+      int idx;
+      for (idx = 0; idx < MAX_CHANNELS; idx++)
+        if (!channels[idx].active)
+          break;
+      if (idx < MAX_CHANNELS)
+        channel_add(client, idx);
+      break;
+    }
+
+    case CMD_REMOVE_CHANNEL: {
+      int remove_idx = -1;
+      for (int idx = 1; idx < MAX_CHANNELS; idx++)
+        if (channels[idx].active)
+          remove_idx = idx;
+      if (remove_idx != -1) {
+        channel_remove(client, remove_idx);
+        pending_unregister_idx = remove_idx;
+      }
+      break;
+    }
+
+    case CMD_BIND_CHANNEL:
+      atomic_store(&bind_channel, cmd.data);
+      break;
+
+    case CMD_UNBIND:
+      atomic_store(&bind_channel, 0);
+      break;
+
+    case CMD_LOAD:
+      atomic_store(&cmd_load, 1);
+      break;
+
+    case CMD_SAVE:
+      atomic_store(&cmd_save, 1);
+      break;
+
+    case CMD_ADD_SCENE:
+    case CMD_REMOVE_SCENE:
+    case CMD_NEXT_SCENE:
+    case CMD_PREV_SCENE:
+      break;
+
+    default:
+      break;
+    }
+}
+
+/* ----------------------------------------------------------------
+ * process callback
+ * ---------------------------------------------------------------- */
+int process_callback(jack_nframes_t nframes, void *arg) {
+  (void)arg;
+
+  if (midi_control_port) {
+    void *midi_ctrl_buf = jack_port_get_buffer(midi_control_port, nframes);
+    if (midi_ctrl_buf) {
+      midi_handle_events(midi_ctrl_buf, nframes);
+    }
+  }
+
+  /* process each active channel */
+  for (int c = 0; c < MAX_CHANNELS; c++) {
+    if (!atomic_load(&channels[c].active))
+      continue;
+
+    /* Guard against NULL ports (e.g. if port registration failed) */
+    if (!channels[c].audio_in || !channels[c].audio_out) {
+      fprintf(stderr, "WARN: channel %d has NULL audio port(s), skipping\n", c);
+      continue;
+    }
+
+    const jack_default_audio_sample_t *in =
+        (const jack_default_audio_sample_t *)jack_port_get_buffer(
+            channels[c].audio_in, nframes);
+    jack_default_audio_sample_t *out =
+        (jack_default_audio_sample_t *)jack_port_get_buffer(
+            channels[c].audio_out, nframes);
+    if (!out)
+      continue;
+
+    int state = atomic_load(&channels[c].state);
+
+    if (state != atomic_load(&channels[c].prev_state)) {
+      switch (state) {
+      case STATE_RECORD:
+        atomic_store(&channels[c].record_pos, 0);
+        atomic_store(&channels[c].loop_count, 0);
+        break;
+      case STATE_LOOPING:
+        if (atomic_load(&channels[c].prev_state) == STATE_RECORD &&
+            atomic_load(&channels[c].record_pos) > 0)
+          atomic_store(&channels[c].loop_count,
+                       atomic_load(&channels[c].record_pos));
+        atomic_store(&channels[c].playback_pos, 0);
+        break;
+      default:
+        break;
+      }
+    }
+
+<<<<<<< HEAD
+    jack_nframes_t i;
+    switch (state) {
+    case STATE_RECORD:
+      if (in) {
+        float *f_out = (float *)out;
+        const float *f_in = (const float *)in;
+        for (i = 0; i < nframes; i++) {
+          int rp = atomic_fetch_add(&channels[c].record_pos, 1);
+          if (rp < LOOP_BUF_SIZE)
+            channels[c].loop_buffer[rp] = f_in[i];
+          f_out[i] = f_in[i];
+        }
+      } else {
+=======
+    if (active_channels[c].type == CHANNEL_MIDI) {
+      /* MIDI channel handling */
+      switch (state) {
+      case STATE_RECORD: {
+        void *midi_in_buf =
+            jack_port_get_buffer(active_channels[c].midi_in, nframes);
+        if (midi_in_buf) {
+          jack_nframes_t nevents = jack_midi_get_event_count(midi_in_buf);
+          jack_midi_event_t ev;
+          for (jack_nframes_t j = 0; j < nevents; j++) {
+            if (jack_midi_event_get(&ev, midi_in_buf, j) != 0)
+              continue;
+            int rp = atomic_load(&sc->record_pos);
+            if (rp < MAX_MIDI_EVENTS) {
+              sc->loop.midi_events[rp].timestamp = ev.time;
+              sc->loop.midi_events[rp].status = ev.buffer[0];
+              sc->loop.midi_events[rp].note = (ev.size > 1) ? ev.buffer[1] : 0;
+              sc->loop.midi_events[rp].velocity =
+                  (ev.size > 2) ? ev.buffer[2] : 0;
+              atomic_store(&sc->record_pos, rp + 1);
+            }
+          }
+          /* forward incoming MIDI to output during record */
+          void *midi_out_buf =
+              jack_port_get_buffer(active_channels[c].midi_out, nframes);
+          if (midi_out_buf) {
+            jack_midi_clear_buffer(midi_out_buf);
+            for (jack_nframes_t j = 0; j < nevents; j++) {
+              if (jack_midi_event_get(&ev, midi_in_buf, j) != 0)
+                continue;
+              jack_midi_event_write(midi_out_buf, ev.time, ev.buffer, ev.size);
+            }
+          }
+        }
+        break;
+      }
+      case STATE_LOOPING: {
+        void *midi_out_buf =
+            jack_port_get_buffer(active_channels[c].midi_out, nframes);
+        if (midi_out_buf) {
+          jack_midi_clear_buffer(midi_out_buf);
+          int cnt = atomic_load(&sc->loop_count);
+          if (cnt > 0) {
+            for (int e = 0; e < cnt; e++) {
+              unsigned char msg[3];
+              msg[0] = sc->loop.midi_events[e].status;
+              msg[1] = sc->loop.midi_events[e].note;
+              msg[2] = sc->loop.midi_events[e].velocity;
+              jack_midi_event_write(midi_out_buf, 0, msg, 3);
+            }
+          }
+        }
+        break;
+      }
+      case STATE_PAUSED:
+        /* no output */
+        break;
+      default: /* IDLE */
+      {
+        void *midi_in_buf =
+            jack_port_get_buffer(active_channels[c].midi_in, nframes);
+        void *midi_out_buf =
+            jack_port_get_buffer(active_channels[c].midi_out, nframes);
+        if (midi_in_buf && midi_out_buf) {
+          jack_midi_clear_buffer(midi_out_buf);
+          jack_nframes_t nevents = jack_midi_get_event_count(midi_in_buf);
+          jack_midi_event_t ev;
+          for (jack_nframes_t j = 0; j < nevents; j++) {
+            if (jack_midi_event_get(&ev, midi_in_buf, j) != 0)
+              continue;
+            jack_midi_event_write(midi_out_buf, ev.time, ev.buffer, ev.size);
+          }
+        }
+      } break;
+      }
+      if (state == STATE_LOOPING) {
+        atomic_store(&sc->loop_count, atomic_load(&sc->record_pos));
+      }
+    } else {
+      /* audio channel handling */
+      jack_nframes_t i;
+      switch (state) {
+      case STATE_RECORD:
+        if (in) {
+          float *f_out = (float *)out;
+          const float *f_in = (const float *)in;
+          for (i = 0; i < nframes; i++) {
+            int rp = atomic_load(&sc->record_pos);
+            if (rp < LOOP_BUF_SIZE) {
+              sc->loop.audio_buffer[rp] = f_in[i];
+              atomic_store(&sc->record_pos, rp + 1);
+            }
+            f_out[i] = f_in[i];
+          }
+        } else {
+          memset(out, 0, sizeof(jack_default_audio_sample_t) * nframes);
+        }
+        break;
+
+      case STATE_LOOPING: {
+        int loop_cnt = atomic_load(&sc->loop_count);
+        if (loop_cnt > 0) {
+          float *outf = (float *)out;
+          int pp = atomic_load(&sc->playback_pos);
+          for (i = 0; i < nframes; i++) {
+            outf[i] = sc->loop.audio_buffer[pp];
+            pp = (pp + 1) % loop_cnt;
+          }
+          atomic_store(&sc->playback_pos, pp);
+        } else {
+          memset(out, 0, sizeof(jack_default_audio_sample_t) * nframes);
+        }
+        break;
+      }
+
+      case STATE_PAUSED:
+>>>>>>> 3-integrate-carla
+        memset(out, 0, sizeof(jack_default_audio_sample_t) * nframes);
+      }
+      break;
+
+    case STATE_LOOPING:
+      int lc = atomic_load(&channels[c].loop_count);
+      if (lc > 0) {
+        float *outf = (float *)out;
+        for (i = 0; i < nframes; i++) {
+          int pp = atomic_load(&channels[c].playback_pos);
+          outf[i] = channels[c].loop_buffer[pp];
+          atomic_store(&channels[c].playback_pos, (pp + 1) % lc);
+        }
+      } else {
+        memset(out, 0, sizeof(jack_default_audio_sample_t) * nframes);
+      }
+      break;
+
+    case STATE_PAUSED:
+      memset(out, 0, sizeof(jack_default_audio_sample_t) * nframes);
+      break;
+
+    default: /* IDLE */
+      if (in) {
+        memcpy(out, in, sizeof(jack_default_audio_sample_t) * nframes);
+      } else {
+        memset(out, 0, sizeof(jack_default_audio_sample_t) * nframes);
+      }
+      break;
+    }
+
+    // push loop output into save ring if saving (atomic load)
+    RingBuf *r = (RingBuf *)atomic_load_explicit(&channels[c].save_ring,
+                                                 memory_order_acquire);
+    if (r != NULL) {
+      if (state == STATE_LOOPING && atomic_load(&channels[c].loop_count) > 0) {
+        const float *outf = (const float *)out;
+        ring_write(r, outf, nframes);
+      }
+    }
+
+    atomic_store(&channels[c].prev_state, state);
+  }
+
+  /* MIDI clock events – affect channel 0 only */
+  if (midi_clock_port) {
+    void *midi_clock_buf = jack_port_get_buffer(midi_clock_port, nframes);
+    if (midi_clock_buf) {
+      jack_nframes_t n_clock_events = jack_midi_get_event_count(midi_clock_buf);
+      jack_midi_event_t cev;
+      for (jack_nframes_t j = 0; j < n_clock_events; j++) {
+        if (jack_midi_event_get(&cev, midi_clock_buf, j) != 0)
+          continue;
+        if (cev.size >= 1) {
+          unsigned char msg = cev.buffer[0];
+          switch (msg) {
+          case 0xFA: {
+            int s = atomic_load(&channels[0].state);
+            if (s == STATE_IDLE)
+              atomic_store(&channels[0].state, STATE_RECORD);
+            break;
+          }
+          case 0xFC:
+            atomic_store(&channels[0].state, STATE_IDLE);
+            break;
+          case 0xFB: {
+            int s = atomic_load(&channels[0].state);
+            if (s == STATE_PAUSED)
+              atomic_store(&channels[0].state, STATE_LOOPING);
+            break;
+          }
+          default:
+            break;
+          }
+        }
+      }
+    }
+  }
+
+  return 0;
+}
+
+/* ----------------------------------------------------------------
+ * shutdown callback
+ * ---------------------------------------------------------------- */
+void jack_shutdown_cb(void *arg) {
+  (void)arg;
+  fprintf(stderr, "JACK shutdown\n");
+  exit(0);
+}
+
+
+/* ----------------------------------------------------------------
+ * looper initialisation
+ * ---------------------------------------------------------------- */
+int looper_init(jack_client_t *client) {
+  /* store sample rate for writer thread */
+  global_sample_rate = jack_get_sample_rate(client);
+
+  /* create status FIFO (ignore if already exists) */
+  mkfifo(STATUS_FIFO, 0666);
+
+  /* open the status FIFO for reading+writing so writes work even without reader */
+  status_fd = open(STATUS_FIFO, O_RDWR);
+  if (status_fd < 0) {
+      perror("open status FIFO");
+  }
+
+  queue_init(&cmd_queue);
+  queue_init(&cmd_queue_main_midi);
+  queue_init(&cmd_queue_main_fifo);
+
+  /* start the FIFO reader thread */
+  pipe_start_reader();
+
+
+  /* channel 0 */
+  channels[0].active = 1;
+  atomic_store(&channels[0].state, STATE_IDLE);
+  atomic_store(&channels[0].prev_state, -1);
+  channels[0].loop_count = 0;
+  atomic_store(&channels[0].record_pos, 0);
+  atomic_store(&channels[0].playback_pos, 0);
+  atomic_store_explicit(&channels[0].save_ring, NULL, memory_order_release);
+
+  channels[0].audio_in = jack_port_register(
+      client, "input", JACK_DEFAULT_AUDIO_TYPE, JackPortIsInput, 0);
+  channels[0].audio_out = jack_port_register(
+      client, "output", JACK_DEFAULT_AUDIO_TYPE, JackPortIsOutput, 0);
+  if (!channels[0].audio_in || !channels[0].audio_out) {
+    fprintf(stderr, "Could not create audio ports for channel 0\n");
+    return -1;
+  }
+  channel_count = 1;
+
+  midi_control_port = jack_port_register(
+      client, "control", JACK_DEFAULT_MIDI_TYPE, JackPortIsInput, 0);
+  midi_clock_port = jack_port_register(client, "clock", JACK_DEFAULT_MIDI_TYPE,
+                                       JackPortIsInput, 0);
+  if (!midi_control_port || !midi_clock_port) {
+    fprintf(stderr, "Could not create MIDI ports\n");
+    return -1;
+  }
+
+  return 0;
+}
+
+/* ----------------------------------------------------------------
+ * writer thread – consumes the save ring and writes WAV file
+ * ---------------------------------------------------------------- */
+static void *writer_thread(void *arg) {
+  struct channel_t *ch = (struct channel_t *)arg;
+  RingBuf *ring = (RingBuf *)ch->save_ring;
+  if (!ring)
+    return NULL;
+
+  static const char *path = "save.wav";
+  unsigned sr = (unsigned)global_sample_rate;
+  if (sr == 0)
+    sr = 48000;
+
+  int lc = atomic_load(&ch->loop_count);
+  float *outbuf = malloc((size_t)lc * sizeof(float));
+  if (!outbuf) {
+    ring_destroy(ring);
+    free(ring);
+    ch->save_ring = NULL;
+    return NULL;
+  }
+  size_t collected = 0;
+  size_t want = (size_t)lc;
+  while (collected < want) {
+    size_t got = ring_read(ring, outbuf + collected, want - collected);
+    collected += got;
+    if (got == 0) {
+      struct timespec req = {.tv_sec = 0, .tv_nsec = 10000000};
+      nanosleep(&req, NULL);
+    }
+  }
+  wav_write(path, outbuf, (unsigned)lc, sr);
+  free(outbuf);
+
+  ring_destroy(ring);
+  free(ring);
+  atomic_store_explicit(&ch->save_ring, NULL, memory_order_release);
+  return NULL;
+}
+
+/* ----------------------------------------------------------------
+ * main‑loop command processing
+ * ---------------------------------------------------------------- */
+void looper_process_commands(jack_client_t *client) {
+  /* process commands from the three queues FIRST */
+  command_t cmd;
+  while (queue_pop(&cmd_queue, &cmd))
+    exec_command(cmd, client);
+  while (queue_pop(&cmd_queue_main_midi, &cmd))
+    exec_command(cmd, client);
+  while (queue_pop(&cmd_queue_main_fifo, &cmd))
+    exec_command(cmd, client);
+
+  /* Unregister any ports that were marked for deferred removal.
+     By now the real‑time thread has had at least one full cycle
+     to see the `active = 0` store. */
+  if (pending_unregister_idx != -1) {
+    int idx = pending_unregister_idx;
+    if (channels[idx].audio_in)
+      jack_port_unregister(client, channels[idx].audio_in);
+    if (channels[idx].audio_out)
+      jack_port_unregister(client, channels[idx].audio_out);
+    pending_unregister_idx = -1;
+  }
+
+  /* ---------- add channel ---------- */
+  if (atomic_exchange(&cmd_add, 0)) {
+    int idx;
+    for (idx = 0; idx < MAX_CHANNELS; idx++)
+      if (!channels[idx].active)
+        break;
+    if (idx < MAX_CHANNELS) {
+      channel_add(client, idx);
+    }
+  }
+
+  /* ---------- remove channel ---------- */
+  if (atomic_exchange(&cmd_remove, 0)) {
+    int remove_idx = -1;
+    for (int idx = 1; idx < MAX_CHANNELS; idx++)
+      if (channels[idx].active)
+        remove_idx = idx;
+    if (remove_idx != -1) {
+      /* Mark inactive now; ports will be unregistered next round */
+      channel_remove(client, remove_idx);
+      pending_unregister_idx = remove_idx;
+    }
+  }
+
+  /* ---------- load command ---------- */
+  if (atomic_exchange(&cmd_load, 0)) {
+    float *buf = NULL;
+    unsigned frames = 0;
+    printf("LOAD: wav_read called\n");
+    if (wav_read("loop.wav", &buf, &frames) == 0 && frames > 0) {
+      printf("LOAD: success, frames=%u\n", frames);
+      if (frames > LOOP_BUF_SIZE)
+        frames = LOOP_BUF_SIZE;
+      memcpy(channels[0].loop_buffer, buf, frames * sizeof(float));
+      atomic_store(&channels[0].loop_count, (int)frames);
+      atomic_store(&channels[0].record_pos, 0);
+      atomic_store(&channels[0].playback_pos, 0);
+      atomic_store(&channels[0].state, STATE_LOOPING);
+      atomic_store(&channels[0].prev_state, -1);
+      free(buf);
+    } else {
+      fprintf(stderr, "Failed to load loop.wav\n");
+      printf("LOAD: FAILED\n");
+    }
+  }
+
+  /* ---------- save command (writer thread) ---------- */
+  if (atomic_exchange(&cmd_save, 0)) {
+    int lc = atomic_load(&channels[0].loop_count);
+    if (atomic_load(&channels[0].state) == STATE_LOOPING && lc > 0 &&
+        channels[0].save_ring == NULL) {
+      RingBuf *ring = (RingBuf *)malloc(sizeof(RingBuf));
+      if (ring) {
+        size_t sz = (size_t)lc * 2;
+        if (ring_init(ring, sz) == 0) {
+          atomic_store_explicit(&channels[0].save_ring, (_Atomic RingBuf *)ring,
+                                memory_order_release);
+          pthread_t th;
+          pthread_create(&th, NULL, writer_thread, &channels[0]);
+          pthread_detach(th);
+        } else {
+          free(ring);
+        }
+      }
+    }
+  }
+
+  /* write current state to status FIFO */
+  looper_write_status();
+}

engine/src/main.c

@@ -1,11 +1,10 @@
 // cppcheck-suppress missingIncludeSystem
 #include "looper.h"
-#include "pipe.h"
 #include <jack/jack.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <time.h>
 #include <unistd.h>
+#include <time.h>
 
 int main(int argc, char *argv[]) {
   (void)argc;
@@ -34,12 +33,6 @@ int main(int argc, char *argv[]) {
     return 1;
   }
 
-  if (pipe_start_reader() != 0) {
-    fprintf(stderr, "pipe reader initialisation failed\n");
-    jack_client_close(client);
-    return 1;
-  }
-
   if (jack_activate(client)) {
     fprintf(stderr, "Cannot activate client\n");
     jack_client_close(client);
@@ -50,10 +43,7 @@ int main(int argc, char *argv[]) {
 
   while (1) {
     looper_process_commands(client);
-    {
-      struct timespec ts = {.tv_sec = 0, .tv_nsec = 1000000};
-      nanosleep(&ts, NULL);
-    } /* check commands every 1 ms */
+    { struct timespec ts = { .tv_sec = 0, .tv_nsec = 50000000 }; nanosleep(&ts, NULL); } /* check commands every 50 ms */
   }
 
   jack_client_close(client);

engine/src/midi.c

@@ -1,16 +1,20 @@
 // cppcheck-suppress missingIncludeSystem
 #include "midi.h"
 #include "channel.h"
-#include "command.h"
 #include "queue.h"
 #include <jack/jack.h>
 #include <jack/midiport.h>
 #include <stdatomic.h>
 
-extern atomic_int control_key_active;
-extern atomic_int bind_channel;
+/* queues declared in looper.c */
 extern spsc_queue_t cmd_queue;
 extern spsc_queue_t cmd_queue_main_midi;
+extern atomic_int control_key_active;
+extern atomic_int cmd_add;
+extern atomic_int cmd_remove;
+extern atomic_int cmd_load;
+extern atomic_int cmd_save;
+extern atomic_int bind_channel;
 
 void midi_handle_events(void *port_buffer, jack_nframes_t nframes) {
   (void)nframes;
@@ -35,27 +39,36 @@ void midi_handle_events(void *port_buffer, jack_nframes_t nframes) {
         int ck = atomic_load(&control_key_active);
         if (ck) {
           atomic_store(&control_key_active, 0);
-          if (note < 16 && note < atomic_load(&channel_capacity)) {
-            command_t cmd = {
-                .type = CMD_BIND_CHANNEL, .channel = -1, .data = note};
-            queue_push(&cmd_queue, cmd);
+          if (note < 16) {
+            atomic_store(&bind_channel, note);
           } else {
             switch (note) {
-            case 60: {
-              command_t cmd = {
-                  .type = CMD_ADD_CHANNEL, .channel = -1, .data = 0};
-              queue_push(&cmd_queue_main_midi, cmd);
-            } break;
-            case 61: {
-              command_t cmd = {
-                  .type = CMD_REMOVE_CHANNEL, .channel = -1, .data = 0};
-              queue_push(&cmd_queue_main_midi, cmd);
-            } break;
-            case 62: {
+            case 60:
+              atomic_store(&cmd_add, 1);
+              break;
+            case 61:
+              atomic_store(&cmd_remove, 1);
+              break;
+            case 62: /* trigger looper – channel via bind_channel */
+            {
               int bch = atomic_load(&bind_channel);
-              if (bch >= 0 && bch < atomic_load(&channel_capacity)) {
-                command_t cmd = {.type = CMD_CYCLE, .channel = bch, .data = 0};
-                queue_push(&cmd_queue, cmd);
+              if (bch >= 0 && bch < MAX_CHANNELS) {
+                int sc_idx = atomic_load(&channels[bch].current_scene);
+                int cur = atomic_load(&channels[bch].scenes[sc_idx].state);
+                switch (cur) {
+                case STATE_IDLE:
+                  atomic_store(&channels[bch].scenes[sc_idx].state, STATE_RECORD);
+                  break;
+                case STATE_RECORD:
+                  atomic_store(&channels[bch].scenes[sc_idx].state, STATE_LOOPING);
+                  break;
+                case STATE_LOOPING:
+                  atomic_store(&channels[bch].scenes[sc_idx].state, STATE_PAUSED);
+                  break;
+                case STATE_PAUSED:
+                  atomic_store(&channels[bch].scenes[sc_idx].state, STATE_LOOPING);
+                  break;
+                }
               }
             } break;
             case 63: {
@@ -97,19 +110,31 @@ void midi_handle_events(void *port_buffer, jack_nframes_t nframes) {
         } else {
           /* direct mapping */
           switch (note) {
-          case 1: {
-            command_t cmd = {.type = CMD_CYCLE, .channel = 0, .data = 0};
-            queue_push(&cmd_queue, cmd);
-          } break;
-          case 60: {
-            command_t cmd = {.type = CMD_ADD_CHANNEL, .channel = -1, .data = 0};
-            queue_push(&cmd_queue_main_midi, cmd);
-          } break;
-          case 61: {
-            command_t cmd = {
-                .type = CMD_REMOVE_CHANNEL, .channel = -1, .data = 0};
-            queue_push(&cmd_queue_main_midi, cmd);
+          case 1: /* toggle channel 0 */
+          {
+            int sc0 = atomic_load(&channels[0].current_scene);
+            int cur0 = atomic_load(&channels[0].scenes[sc0].state);
+            switch (cur0) {
+            case STATE_IDLE:
+              atomic_store(&channels[0].scenes[sc0].state, STATE_RECORD);
+              break;
+            case STATE_RECORD:
+              atomic_store(&channels[0].scenes[sc0].state, STATE_LOOPING);
+              break;
+            case STATE_LOOPING:
+              atomic_store(&channels[0].scenes[sc0].state, STATE_PAUSED);
+              break;
+            case STATE_PAUSED:
+              atomic_store(&channels[0].scenes[sc0].state, STATE_LOOPING);
+              break;
+            }
           } break;
+          case 60:
+            atomic_store(&cmd_add, 1);
+            break;
+          case 61:
+            atomic_store(&cmd_remove, 1);
+            break;
           default:
             break;
           }

engine/src/midi.c~

@@ -0,0 +1,154 @@
+// cppcheck-suppress missingIncludeSystem
+#include "midi.h"
+#include "channel.h"
+#include <jack/jack.h>
+#include <jack/midiport.h>
+#include <stdatomic.h>
+
+extern atomic_int control_key_active;
+extern atomic_int cmd_add;
+extern atomic_int cmd_remove;
+extern atomic_int cmd_load;
+extern atomic_int cmd_save;
+extern atomic_int bind_channel;
+
+void midi_handle_events(void *port_buffer, jack_nframes_t nframes) {
+  (void)nframes;
+  jack_nframes_t nevents = jack_midi_get_event_count(port_buffer);
+  jack_midi_event_t ev;
+
+  for (jack_nframes_t i = 0; i < nevents; i++) {
+    if (jack_midi_event_get(&ev, port_buffer, i) != 0)
+      continue;
+    if (ev.size < 3)
+      continue;
+
+    unsigned char status = ev.buffer[0];
+    unsigned char note = ev.buffer[1];
+    unsigned char vel = ev.buffer[2];
+
+    /* note‑on */
+    if ((status & 0xf0) == 0x90 && vel > 0) {
+      if (note == 64) {
+        atomic_store(&control_key_active, 1);
+      } else {
+        int ck = atomic_load(&control_key_active);
+        if (ck) {
+          atomic_store(&control_key_active, 0);
+          if (note < 16) {
+            atomic_store(&bind_channel, note);
+          } else {
+            switch (note) {
+            case 60:
+              atomic_store(&cmd_add, 1);
+              break;
+            case 61:
+              atomic_store(&cmd_remove, 1);
+              break;
+            case 62: /* trigger looper – channel via bind_channel */
+            {
+              int bch = atomic_load(&bind_channel);
+              if (bch >= 0 && bch < MAX_CHANNELS) {
+                int cur = atomic_load(&channels[bch].state);
+                switch (cur) {
+                case STATE_IDLE:
+                  atomic_store(&channels[bch].state, STATE_RECORD);
+                  break;
+                case STATE_RECORD:
+                  atomic_store(&channels[bch].state, STATE_LOOPING);
+                  break;
+                case STATE_LOOPING:
+                  atomic_store(&channels[bch].state, STATE_PAUSED);
+                  break;
+                case STATE_PAUSED:
+                  atomic_store(&channels[bch].state, STATE_LOOPING);
+                  break;
+                }
+              }
+            } break;
+<<<<<<< HEAD
+            case 63: /* unbind – reset bind to channel 0 */
+              atomic_store(&bind_channel, 0);
+              break;
+            case 70: /* load WAV into channel 0 */
+              atomic_store(&cmd_load, 1);
+              break;
+            case 71: /* save WAV of channel 0 */
+              atomic_store(&cmd_save, 1);
+              break;
+=======
+            case 63: {
+              command_t cmd = {.type = CMD_UNBIND, .channel = -1, .data = 0};
+              queue_push(&cmd_queue, cmd);
+            } break;
+            case 65: {
+              command_t cmd = {.type = CMD_STOP, .channel = -1, .data = 0};
+              queue_push(&cmd_queue, cmd);
+            } break;
+            case 66: {
+              command_t cmd = {
+                  .type = CMD_ADD_MIDI_CHANNEL, .channel = -1, .data = 0};
+              queue_push(&cmd_queue_main_midi, cmd);
+            } break;
+            case 67: {
+              command_t cmd = {
+                  .type = CMD_NEXT_SCENE, .channel = -1, .data = 0};
+              queue_push(&cmd_queue_main_midi, cmd);
+            } break;
+            case 68: {
+              command_t cmd = {
+                  .type = CMD_PREV_SCENE, .channel = -1, .data = 0};
+              queue_push(&cmd_queue_main_midi, cmd);
+            } break;
+            case 69: {
+              command_t cmd = {.type = CMD_ADD_SCENE, .channel = -1, .data = 0};
+              queue_push(&cmd_queue_main_midi, cmd);
+            } break;
+            case 70: {
+              command_t cmd = {
+                  .type = CMD_REMOVE_SCENE, .channel = -1, .data = 0};
+              queue_push(&cmd_queue_main_midi, cmd);
+            } break;
+>>>>>>> 3-integrate-carla
+            default:
+              break;
+            }
+          }
+        } else {
+          /* direct mapping */
+          switch (note) {
+          case 1: /* toggle channel 0 */
+          {
+            int cur0 = atomic_load(&channels[0].state);
+            switch (cur0) {
+            case STATE_IDLE:
+              atomic_store(&channels[0].state, STATE_RECORD);
+              break;
+            case STATE_RECORD:
+              atomic_store(&channels[0].state, STATE_LOOPING);
+              break;
+            case STATE_LOOPING:
+              atomic_store(&channels[0].state, STATE_PAUSED);
+              break;
+            case STATE_PAUSED:
+              atomic_store(&channels[0].state, STATE_LOOPING);
+              break;
+            }
+          } break;
+          case 60:
+            atomic_store(&cmd_add, 1);
+            break;
+          case 61:
+            atomic_store(&cmd_remove, 1);
+            break;
+          default:
+            break;
+          }
+        }
+      }
+    } else if ((status & 0xf0) == 0x80 ||
+               ((status & 0xf0) == 0x90 && vel == 0)) {
+      atomic_store(&control_key_active, 0);
+    }
+  }
+}

engine/src/pipe.c

@@ -37,14 +37,14 @@ static void *pipe_thread_func(void *arg) {
 
       if (strcmp(line, "add") == 0) {
         command_t cmd = {.type = CMD_ADD_CHANNEL, .channel = -1, .data = 0};
-        queue_push(&cmd_queue_main_fifo, cmd);
+        queue_push(&cmd_queue, cmd);
       } else if (strcmp(line, "add_midi") == 0) {
         command_t cmd = {
             .type = CMD_ADD_MIDI_CHANNEL, .channel = -1, .data = 0};
         queue_push(&cmd_queue_main_fifo, cmd);
       } else if (strcmp(line, "remove") == 0) {
         command_t cmd = {.type = CMD_REMOVE_CHANNEL, .channel = -1, .data = 0};
-        queue_push(&cmd_queue_main_fifo, cmd);
+        queue_push(&cmd_queue, cmd);
       } else if (strncmp(line, "record ", 7) == 0) {
         int ch = atoi(line + 7);
         command_t cmd = {.type = CMD_CYCLE, .channel = ch, .data = 0};
@@ -61,16 +61,22 @@ static void *pipe_thread_func(void *arg) {
         queue_push(&cmd_queue, cmd);
       } else if (strcmp(line, "scene_add") == 0) {
         command_t cmd = {.type = CMD_ADD_SCENE, .channel = -1, .data = 0};
-        queue_push(&cmd_queue_main_fifo, cmd);
+        queue_push(&cmd_queue, cmd);
       } else if (strcmp(line, "scene_remove") == 0) {
         command_t cmd = {.type = CMD_REMOVE_SCENE, .channel = -1, .data = 0};
-        queue_push(&cmd_queue_main_fifo, cmd);
+        queue_push(&cmd_queue, cmd);
       } else if (strcmp(line, "scene_next") == 0) {
         command_t cmd = {.type = CMD_NEXT_SCENE, .channel = -1, .data = 0};
-        queue_push(&cmd_queue_main_fifo, cmd);
+        queue_push(&cmd_queue, cmd);
       } else if (strcmp(line, "scene_prev") == 0) {
         command_t cmd = {.type = CMD_PREV_SCENE, .channel = -1, .data = 0};
-        queue_push(&cmd_queue_main_fifo, cmd);
+        queue_push(&cmd_queue, cmd);
+      } else if (strcmp(line, "load") == 0) {
+        command_t cmd = {.type = CMD_LOAD, .channel = -1, .data = 0};
+        queue_push(&cmd_queue, cmd);
+      } else if (strcmp(line, "save") == 0) {
+        command_t cmd = {.type = CMD_SAVE, .channel = -1, .data = 0};
+        queue_push(&cmd_queue, cmd);
       }
       /* ignore unknown lines */
     }

engine/src/pipe.c~

@@ -0,0 +1,111 @@
+#include "pipe.h"
+#include "command.h"
+#include "queue.h"
+#include <errno.h>
+#include <fcntl.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <time.h>
+#include <unistd.h>
+
+#define FIFO_PATH "/tmp/looper_cmd"
+#define LINE_MAX 256
+
+/* forward‑declare the global queues (defined in looper.c) */
+extern spsc_queue_t cmd_queue;
+extern spsc_queue_t cmd_queue_main_fifo;
+
+static void *pipe_thread_func(void *arg) {
+  (void)arg;
+  char line[LINE_MAX];
+
+  while (1) {
+    FILE *fifo = fopen(FIFO_PATH, "r");
+    if (!fifo) {
+      perror("fopen fifo");
+      return NULL;
+    }
+
+    while (fgets(line, sizeof(line), fifo)) {
+      /* strip newline */
+      size_t len = strlen(line);
+      if (len > 0 && line[len - 1] == '\n')
+        line[len - 1] = '\0';
+
+      if (strcmp(line, "add") == 0) {
+        command_t cmd = {.type = CMD_ADD_CHANNEL, .channel = -1, .data = 0};
+        queue_push(&cmd_queue, cmd);
+      } else if (strcmp(line, "add_midi") == 0) {
+<<<<<<< HEAD
+        command_t cmd = {.type = CMD_ADD_MIDI_CHANNEL, .channel = -1, .data = 0};
+        queue_push(&cmd_queue, cmd);
+=======
+        command_t cmd = {
+            .type = CMD_ADD_MIDI_CHANNEL, .channel = -1, .data = 0};
+        queue_push(&cmd_queue_main_fifo, cmd);
+>>>>>>> 3-integrate-carla
+      } else if (strcmp(line, "remove") == 0) {
+        command_t cmd = {.type = CMD_REMOVE_CHANNEL, .channel = -1, .data = 0};
+        queue_push(&cmd_queue, cmd);
+      } else if (strncmp(line, "record ", 7) == 0) {
+        int ch = atoi(line + 7);
+        command_t cmd = {.type = CMD_CYCLE, .channel = ch, .data = 0};
+        queue_push(&cmd_queue, cmd);
+      } else if (strcmp(line, "stop") == 0) {
+        command_t cmd = {.type = CMD_STOP, .channel = -1, .data = 0};
+        queue_push(&cmd_queue, cmd);
+      } else if (strncmp(line, "bind ", 5) == 0) {
+        int ch = atoi(line + 5);
+        command_t cmd = {.type = CMD_BIND_CHANNEL, .channel = -1, .data = ch};
+        queue_push(&cmd_queue, cmd);
+      } else if (strcmp(line, "unbind") == 0) {
+        command_t cmd = {.type = CMD_UNBIND, .channel = -1, .data = 0};
+        queue_push(&cmd_queue, cmd);
+      } else if (strcmp(line, "scene_add") == 0) {
+        command_t cmd = {.type = CMD_ADD_SCENE, .channel = -1, .data = 0};
+        queue_push(&cmd_queue, cmd);
+      } else if (strcmp(line, "scene_remove") == 0) {
+        command_t cmd = {.type = CMD_REMOVE_SCENE, .channel = -1, .data = 0};
+        queue_push(&cmd_queue, cmd);
+      } else if (strcmp(line, "scene_next") == 0) {
+        command_t cmd = {.type = CMD_NEXT_SCENE, .channel = -1, .data = 0};
+        queue_push(&cmd_queue, cmd);
+      } else if (strcmp(line, "scene_prev") == 0) {
+        command_t cmd = {.type = CMD_PREV_SCENE, .channel = -1, .data = 0};
+        queue_push(&cmd_queue, cmd);
+      } else if (strcmp(line, "load") == 0) {
+        command_t cmd = {.type = CMD_LOAD, .channel = -1, .data = 0};
+        queue_push(&cmd_queue, cmd);
+      } else if (strcmp(line, "save") == 0) {
+        command_t cmd = {.type = CMD_SAVE, .channel = -1, .data = 0};
+        queue_push(&cmd_queue, cmd);
+      }
+      /* ignore unknown lines */
+    }
+    /* EOF – all writers closed, reopen for next connection */
+    fclose(fifo);
+    {
+      struct timespec ts = {.tv_sec = 0, .tv_nsec = 50000000};
+      nanosleep(&ts, NULL);
+    } /* small pause before retrying */
+  }
+  return NULL; /* unreachable */
+}
+
+int pipe_start_reader(void) {
+  /* create FIFO if it doesn't exist */
+  if (mkfifo(FIFO_PATH, 0666) != 0 && errno != EEXIST) {
+    perror("mkfifo");
+    return -1;
+  }
+  pthread_t tid;
+  if (pthread_create(&tid, NULL, pipe_thread_func, NULL) != 0) {
+    perror("pthread_create");
+    return -1;
+  }
+  pthread_detach(tid); /* we don't need to join */
+  return 0;
+}

engine/src/queue.h

@@ -1,6 +1,7 @@
 #ifndef QUEUE_H
 #define QUEUE_H
 
+#include <stdatomic.h>
 #include "command.h"
 #include <stdbool.h>
 
@@ -15,8 +16,8 @@ typedef struct {
     command_t  buffer[QUEUE_CAPACITY];
     /* head: index where next element will be written (producer only)
      * tail: index of next element to read (consumer only) */
-    int head;
-    int tail;
+    atomic_int head;
+    atomic_int tail;
 } spsc_queue_t;
 
 /* Initialise queue (must be called once before any push/pop). */

engine/src/ringbuffer.c

@@ -0,0 +1,76 @@
+#include "ringbuffer.h"
+#include <stdlib.h>
+
+static inline size_t load_head(const RingBuf *r) {
+  return atomic_load_explicit(&r->head, memory_order_relaxed);
+}
+static inline size_t load_tail(const RingBuf *r) {
+  return atomic_load_explicit(&r->tail, memory_order_relaxed);
+}
+static inline void store_head(RingBuf *r, size_t v) {
+  atomic_store_explicit(&r->head, v, memory_order_relaxed);
+}
+static inline void store_tail(RingBuf *r, size_t v) {
+  atomic_store_explicit(&r->tail, v, memory_order_relaxed);
+}
+
+int ring_init(RingBuf *r, size_t capacity) {
+  r->buf = (float *)malloc(capacity * sizeof(float));
+  if (!r->buf)
+    return -1;
+  r->capacity = capacity;
+  store_head(r, 0);
+  store_tail(r, 0);
+  return 0;
+}
+
+void ring_destroy(RingBuf *r) {
+  free(r->buf);
+  r->buf = NULL;
+  r->capacity = 0;
+}
+
+static size_t ring_readable(const RingBuf *r) {
+  size_t h = load_head(r);
+  size_t t = load_tail(r);
+  if (h >= t)
+    return h - t;
+  else
+    return r->capacity - (t - h);
+}
+
+static size_t ring_writeable(const RingBuf *r) {
+  return r->capacity - 1 - ring_readable(r);
+}
+
+size_t ring_write(RingBuf *r, const float *data, size_t count) {
+  size_t avail = ring_writeable(r);
+  if (count > avail)
+    count = avail;
+  if (count == 0)
+    return 0;
+  size_t head = load_head(r);
+  size_t cap = r->capacity;
+  for (size_t i = 0; i < count; ++i) {
+    r->buf[head] = data[i];
+    head = (head + 1) % cap;
+  }
+  store_head(r, head);
+  return count;
+}
+
+size_t ring_read(RingBuf *r, float *data, size_t count) {
+  size_t avail = ring_readable(r);
+  if (count > avail)
+    count = avail;
+  if (count == 0)
+    return 0;
+  size_t tail = load_tail(r);
+  size_t cap = r->capacity;
+  for (size_t i = 0; i < count; ++i) {
+    data[i] = r->buf[tail];
+    tail = (tail + 1) % cap;
+  }
+  store_tail(r, tail);
+  return count;
+}

engine/src/ringbuffer.h

@@ -0,0 +1,19 @@
+#ifndef RINGBUFFER_H
+#define RINGBUFFER_H
+
+#include <stddef.h>
+#include <stdatomic.h>
+
+typedef struct {
+    atomic_size_t head;
+    atomic_size_t tail;
+    size_t        capacity;
+    float        *buf;
+} RingBuf;
+
+int  ring_init(RingBuf *r, size_t capacity);
+void ring_destroy(RingBuf *r);
+size_t ring_write(RingBuf *r, const float *data, size_t count);
+size_t ring_read(RingBuf *r, float *data, size_t count);
+
+#endif

engine/src/wav.c

@@ -0,0 +1,41 @@
+#include "wav.h"
+#include "channel.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <sndfile.h>
+
+int wav_read(const char *path, float **buffer, unsigned *frames) {
+    SF_INFO info;
+    info.format = 0;
+    SNDFILE *sf = sf_open(path, SFM_READ, &info);
+    if (!sf) return -1;
+
+    /* We need mono 16-bit PCM; refuse anything else */
+    if (info.channels != 1 || info.samplerate <= 0) {
+        sf_close(sf);
+        return -1;
+    }
+
+    unsigned total = (info.frames > (sf_count_t)LOOP_BUF_SIZE) ? LOOP_BUF_SIZE : (unsigned)info.frames;
+    float *buf = (float*)malloc(total * sizeof(float));
+    if (!buf) { sf_close(sf); return -1; }
+
+    sf_count_t nread = sf_readf_float(sf, buf, total);
+    sf_close(sf);
+    *buffer = buf;
+    *frames = (unsigned)nread;
+    return 0;
+}
+
+int wav_write(const char *path, const float *data, unsigned frames, unsigned sample_rate) {
+    SF_INFO info;
+    info.samplerate = sample_rate;
+    info.channels = 1;
+    info.format = SF_FORMAT_WAV | SF_FORMAT_PCM_16;
+    SNDFILE *sf = sf_open(path, SFM_WRITE, &info);
+    if (!sf) return -1;
+
+    sf_writef_float(sf, data, frames);
+    sf_close(sf);
+    return 0;
+}

engine/src/wav.h

@@ -0,0 +1,9 @@
+#ifndef WAV_H
+#define WAV_H
+
+#include <stddef.h>
+
+int wav_read(const char *path, float **buffer, unsigned *frames);
+int wav_write(const char *path, const float *data, unsigned frames, unsigned sample_rate);
+
+#endif

makefile

@@ -1,4 +1,4 @@
-# Top‑level Makefile – delegates build/clean/test to subdirectories
+# Top-level Makefile – delegates build/clean/test to subdirectories
 
 SUBDIRS = engine client