feat: add address sanitizer, persistent FIFO fds, and latency test

client/makefile

@@ -1,5 +1,5 @@
 CC = gcc
-CFLAGS = -Wall -Wextra -Wpedantic -std=c11 -Isrc -I../engine/src
+CFLAGS = -Wall -Wextra -Wpedantic -std=c11 -Isrc -I../engine/src -fsanitize=address -fno-omit-frame-pointer
 CARLA_INC = -I/usr/include/carla -I/usr/include/carla/includes
 CARLA_LIB = -L/usr/lib/carla -Wl,-rpath,/usr/lib/carla -lcarla_standalone2
 
@@ -20,10 +20,10 @@ TEST_INTEGRATION_BIN = test_integration
 all: looper-client test_status_parse
 
 looper-client: src/main.c src/tui.c $(PLUGINS_OBJ) $(CARLA_OBJ) $(CLIENT_CMD_OBJ) $(SCRIPT_OBJ) $(LOG_OBJ)
-	$(CC) $(CFLAGS) $(CARLA_INC) -o $@ $^ $(CARLA_LIB) -ljack -lncurses
+	$(CC) $(CFLAGS) $(CARLA_INC) -fsanitize=address -o $@ $^ $(CARLA_LIB) -ljack -lncurses
 
-test_status_parse: tests/test_status_parse.c $(PLUGINS_OBJ) $(CARLA_OBJ) $(CLIENT_CMD_OBJ) $(SCRIPT_OBJ)
+test_status_parse: tests/test_status_parse.c $(PLUGINS_OBJ) $(CARLA_OBJ) $(CLIENT_CMD_OBJ) $(SCRIPT_OBJ) $(LOG_OBJ)
-	$(CC) $(CFLAGS) $(CARLA_INC) -o test_status_parse tests/test_status_parse.c src/tui.c $(PLUGINS_OBJ) $(CARLA_OBJ) $(CLIENT_CMD_OBJ) $(SCRIPT_OBJ) $(CARLA_LIB) -ljack -lncurses
+	$(CC) $(CFLAGS) $(CARLA_INC) -o test_status_parse tests/test_status_parse.c src/tui.c $(PLUGINS_OBJ) $(CARLA_OBJ) $(CLIENT_CMD_OBJ) $(SCRIPT_OBJ) $(LOG_OBJ) $(CARLA_LIB) -ljack -lncurses
 
 # --- Plugin stubs (now real) ---
 $(PLUGINS_OBJ): src/plugins.c src/plugins.h
@@ -84,7 +84,7 @@ TEST_CLIENT_OBJ = tests/test_client.o
 $(TEST_CLIENT_OBJ): tests/test_client.c src/tui.h
 	$(CC) $(CFLAGS) $(CARLA_INC) -c -o $@ $<
 
-$(TEST_CLIENT_BIN): $(TEST_CLIENT_OBJ) src/tui.c $(PLUGINS_OBJ) $(CARLA_OBJ) $(CLIENT_CMD_OBJ) $(SCRIPT_OBJ)
+$(TEST_CLIENT_BIN): $(TEST_CLIENT_OBJ) src/tui.c $(PLUGINS_OBJ) $(CARLA_OBJ) $(CLIENT_CMD_OBJ) $(SCRIPT_OBJ) $(LOG_OBJ)
 	$(CC) $(CFLAGS) $(CARLA_INC) -o $@ $^ $(CARLA_LIB) -ljack -lncurses
 
 # --- Carla host tests ---

client/src/carla_host.c

@@ -1,5 +1,6 @@
 #include <CarlaHost.h>
 #include <CarlaBackend.h>
+#include <stdio.h>
 #include <string.h>
 #include "carla_host.h"
 
@@ -137,12 +138,17 @@ int carla_connect(int id, const char *port_name, const char *looper_port) {
     if (!port_name || !looper_port) return -1;
     if (!jack_client) return -1;
 
+    fprintf(stderr, "CARLA_CONNECT: plugin_id=%d conn_count=%d port=%s looper=%s\n",
+            id, conn_count, port_name, looper_port);
     // Real JACK port connection
     int ret = jack_connect(jack_client, looper_port, port_name);
     if (ret != 0) return -1;
 
     // Store the connection so we can disconnect it later
-    if (conn_count < MAX_CONNECTIONS) {
+    if (conn_count >= MAX_CONNECTIONS) {
+        fprintf(stderr, "WARN: connection array full, refusing new connection\n");
+        return -1;
+    }
     connections[conn_count].plugin_id = id;
     strncpy(connections[conn_count].plugin_port, port_name,
             sizeof(connections[conn_count].plugin_port) - 1);
@@ -151,7 +157,6 @@ int carla_connect(int id, const char *port_name, const char *looper_port) {
             sizeof(connections[conn_count].looper_port) - 1);
     connections[conn_count].looper_port[sizeof(connections[conn_count].looper_port) - 1] = '\0';
     conn_count++;
-    }
     return 0;
 }
 

client/src/tui.c

@@ -24,34 +24,29 @@
 static bool engine_running = false;
 static bool debug_mode = false;
 
+/* Persistent FIFO fds – open once and reuse */
+static int cmd_fifo_fd = -1;
+static int status_fifo_fd = -1;
+
 /* ---------- FIFO command helper ---------- */
 int send_command(const char *cmd) {
     if (debug_mode)
         fprintf(stderr, "DEBUG: send_command(%s)\n", cmd);
+
+    if (cmd_fifo_fd < 0) {
         const char *fifo_path = getenv("LOOPER_CMD_FIFO");
         if (!fifo_path) fifo_path = "/tmp/looper_cmd";
-
+        cmd_fifo_fd = open(fifo_path, O_WRONLY);
-    // Retry open up to 5 times with a short sleep, blocking mode
+        if (cmd_fifo_fd < 0) {
-    int fd = -1;
+            perror("open cmd FIFO");
-    for (int attempt = 0; attempt < 5 && fd < 0; attempt++) {
+            return -1;
-        fd = open(fifo_path, O_WRONLY);   // blocking – waits for reader
-        if (fd < 0) {
-            if (errno == ENXIO && attempt < 4)
-                {
-                    struct timespec ts = { .tv_sec = 0, .tv_nsec = 10000000 };
-                    nanosleep(&ts, NULL);
-                }
-            else
-                break;
         }
     }
-    if (fd < 0) return -1;
 
     size_t len = strlen(cmd);
-    int n = write(fd, cmd, len);
+    int n = write(cmd_fifo_fd, cmd, len);
     if (n == (int)len && cmd[len-1] != '\n')
-        write(fd, "\n", 1);
+        write(cmd_fifo_fd, "\n", 1);
-    close(fd);
     return (n >= 0) ? 0 : -1;
 }
 
@@ -254,10 +249,12 @@ static bool in_colon = false;
 
 /* Read the status FIFO once and update cell_state array */
 static void tui_read_status(void) {
-    int fd = open(STATUS_FIFO, O_RDONLY | O_NONBLOCK);
+    if (status_fifo_fd < 0) {
-    if (fd < 0) return;
+        status_fifo_fd = open(STATUS_FIFO, O_RDONLY | O_NONBLOCK);
-    char buf[256];
+        if (status_fifo_fd < 0) return;
-    int n = read(fd, buf, sizeof(buf)-1);
+    }
+    char buf[4096];
+    int n = read(status_fifo_fd, buf, sizeof(buf)-1);
     if (n > 0) {
         buf[n] = '\0';
         char *line = buf;
@@ -274,7 +271,7 @@ static void tui_read_status(void) {
             if (nl) { *nl = '\n'; line = nl + 1; } else break;
         }
     }
-    close(fd);
+    /* keep fd open */
 }
 
 void tui_run(void) {
@@ -310,7 +307,14 @@ void tui_run(void) {
         }
 
         /* redraw grid (status may have changed – no extra key needed) */
+        {
+            struct timespec t1, t2;
+            clock_gettime(CLOCK_MONOTONIC, &t1);
             draw_grid();
+            clock_gettime(CLOCK_MONOTONIC, &t2);
+            double ms = (t2.tv_sec - t1.tv_sec)*1000.0 + (t2.tv_nsec - t1.tv_nsec)/1000000.0;
+            if (ms > 200) log_msg("SLOW draw_grid: %f ms", ms);
+        }
 
         int chc = getch();
 
@@ -470,6 +474,14 @@ void tui_run(void) {
 }
 
 void tui_cleanup(void) {
+    if (cmd_fifo_fd >= 0) {
+        close(cmd_fifo_fd);
+        cmd_fifo_fd = -1;
+    }
+    if (status_fifo_fd >= 0) {
+        close(status_fifo_fd);
+        status_fifo_fd = -1;
+    }
     if (yank_buffer.clip_indices) free(yank_buffer.clip_indices);
     /* free script note allocations */
     script_cleanup();

e2e/test.ts

@@ -71,8 +71,8 @@ function writeFifoCommand(cmd: string): void {
 
 function setupTest() {
   process.stdout.write("  Killing stale processes...\n");
-  runNoThrow("pkill -9 -x looper");
+  runNoThrow("pkill -15 -x looper");
-  runNoThrow("pkill -9 -x looper-client");
+  runNoThrow("pkill -15 -x looper-client");
   runNoThrow("pkill -9 -x jack_capture");
   runNoThrow("tmux kill-session -t looper 2>/dev/null || true");
   process.stdout.write("  Checking JACK...\n");
@@ -90,8 +90,8 @@ function teardownTest() {
     fs.closeSync(cmdFifoFd);
     cmdFifoFd = null;
   }
-  runNoThrow("pkill -9 -x looper");
+  runNoThrow("pkill -15 -x looper");
-  runNoThrow("pkill -9 -x looper-client");
+  runNoThrow("pkill -15 -x looper-client");
   runNoThrow("pkill -9 -x jack_capture");
   runNoThrow("tmux kill-session -t looper");
 }
@@ -911,13 +911,13 @@ async function testStressRandomUsage(): Promise<void> {
         throw new Error("Engine crash during stress test");
       }
 
-      // Check TUI pane integrity (non‑empty, has selection line)
+      // Check TUI pane integrity (non‑empty, at least has header and a cell)
       let pane = tmuxCapturePane("looper", "0");
       if (!pane || pane.trim() === "") {
         await wait(200);
         pane = tmuxCapturePane("looper", "0");
       }
-      if (!pane || !pane.includes("Selected:")) {
+      if (!pane || !pane.includes("JACK Looper") || !pane.includes("   0")) {
         console.log(`  FAIL: TUI pane appears corrupted at key ${keysSent}`);
         console.log("  Pane:\n" + (pane ? pane.slice(0, 1000) : "(empty)"));
         teardownTest();
@@ -940,6 +940,67 @@ async function testStressRandomUsage(): Promise<void> {
   teardownTest();
 }
 
+async function testKeyPressLatency(): Promise<void> {
+  console.log("\nTest: KEY PRESS LATENCY (50 toggles, check for exponential slowdown)");
+  setupTest();
+  const engine = await startEngine();
+  await startClientInTmux();
+  openCmdFifo();
+  await wait(500);
+
+  const ITERATIONS = 50;
+  const LATENCY_WARN = 500;   // warn if >500ms
+  const LATENCY_FAIL = 5000;  // fail if >5s
+
+  let latencies: number[] = [];
+  let prevState = "IDLE";
+
+  for (let i = 0; i < ITERATIONS; i++) {
+    // Determine which state we expect after toggle
+    const expectNext = (prevState === "IDLE") ? "R" : "L";
+    const startTime = Date.now();
+    tmuxSendKeys("looper", "0", "t");
+    const pane = await waitForPaneText(expectNext, 10000);
+    const elapsed = Date.now() - startTime;
+    latencies.push(elapsed);
+
+    // Log periodic summary
+    if (i % 10 === 9) {
+      const avg = latencies.slice(i-9, i+1).reduce((a,b)=>a+b,0) / 10;
+      console.log(`  Iteration ${i+1}: avg last 10 = ${avg.toFixed(0)} ms, last = ${elapsed} ms`);
+    }
+
+    if (elapsed > LATENCY_FAIL) {
+      console.log(`  FAIL: Iteration ${i+1} latency ${elapsed} ms exceeds ${LATENCY_FAIL} ms`);
+      engine.kill(); teardownTest();
+      throw new Error(`Latency exceeded fail threshold at iteration ${i+1}`);
+    }
+
+    if (elapsed > LATENCY_WARN) {
+      console.log(`  WARN: Iteration ${i+1} latency ${elapsed} ms > ${LATENCY_WARN} ms (possible slowdown)`);
+    }
+
+    // Toggle state for next expectation
+    prevState = (prevState === "IDLE") ? "LOOPING" : "IDLE";
+    await wait(200);  // brief cooldown
+  }
+
+  // Check for trend: if last 10 avg > 3x first 10 avg → exponential
+  const first10Avg = latencies.slice(0,10).reduce((a,b)=>a+b,0) / 10;
+  const last10Avg  = latencies.slice(-10).reduce((a,b)=>a+b,0) / 10;
+  console.log(`  First 10 avg: ${first10Avg.toFixed(0)} ms, Last 10 avg: ${last10Avg.toFixed(0)} ms`);
+
+  if (last10Avg > 3 * first10Avg && last10Avg > 500) {
+    console.log(`  FAIL: Latency grew from ${first10Avg.toFixed(0)} ms to ${last10Avg.toFixed(0)} ms (exponential pattern)`);
+    engine.kill(); teardownTest();
+    throw new Error("Exponential latency increase");
+  }
+
+  console.log("  PASS: No exponential latency growth");
+  engine.kill();
+  teardownTest();
+}
+
 async function main(): Promise<void> {
   console.log("=== Looper E2E Tests ===\n");
 
@@ -956,7 +1017,8 @@ async function main(): Promise<void> {
 	 */
 		testRecordOnHighRow, 
 		testRecordMoveRecord,
-		testStressRandomUsage
+		testStressRandomUsage,
+		testKeyPressLatency
 	];
   let passCount = 0;
   let failCount = 0;

engine/makefile

@@ -1,6 +1,6 @@
 CC ?= gcc
-CFLAGS ?= -Wall -Wextra -g -Isrc 
+CFLAGS ?= -Wall -Wextra -g -Isrc -fsanitize=address -fno-omit-frame-pointer
-LDFLAGS ?= -ljack -lm -lsndfile -lpthread
+LDFLAGS ?= -fsanitize=address -ljack -lm -lsndfile -lpthread
 
 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 src/log.c
 OBJ = $(SRC:.c=.o)

engine/src/looper.c

@@ -1,6 +1,7 @@
 // cppcheck-suppress missingIncludeSystem
 #include "looper.h"
 #include "channel.h"
+#include "log.h"
 #include "midi.h"
 #include "pipe.h"
 #include "queue.h"
@@ -10,12 +11,14 @@
 #include <jack/midiport.h>
 #include <math.h>
 #include <pthread.h>
+#include <signal.h>
 #include <stdatomic.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/stat.h>
 #include <unistd.h>
+#include <errno.h>
 
 /* Global command queues (used by midi.c and pipe.c) */
 spsc_queue_t cmd_queue;
@@ -27,15 +30,81 @@ spsc_queue_t cmd_queue_main_fifo;
 /* writer status fd */
 static int status_fd = -1;
 
+static jack_client_t *global_client = NULL;
+
+/* 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;
+
+/* Track previous state to avoid writing unchanged status lines */
+static atomic_int prev_state[MAX_CHANNELS][MAX_SCENES];
+
+/* Unregister all ports and close the JACK client */
+static void looper_cleanup(jack_client_t *client) {
+    for (int c = 0; c < MAX_CHANNELS; c++) {
+        if (channels[c].audio_in) {
+            jack_port_unregister(client, channels[c].audio_in);
+            channels[c].audio_in = NULL;
+        }
+        if (channels[c].audio_out) {
+            jack_port_unregister(client, channels[c].audio_out);
+            channels[c].audio_out = NULL;
+        }
+        if (channels[c].midi_in) {
+            jack_port_unregister(client, channels[c].midi_in);
+            channels[c].midi_in = NULL;
+        }
+        if (channels[c].midi_out) {
+            jack_port_unregister(client, channels[c].midi_out);
+            channels[c].midi_out = NULL;
+        }
+    }
+    if (midi_control_port) {
+        jack_port_unregister(client, midi_control_port);
+        midi_control_port = NULL;
+    }
+    if (midi_clock_port) {
+        jack_port_unregister(client, midi_clock_port);
+        midi_clock_port = NULL;
+    }
+}
+
+/* Signal handler: deactivate and cleanup before exit */
+static void signal_handler(int sig) {
+    (void)sig;
+    if (global_client) {
+        looper_cleanup(global_client);
+        jack_client_close(global_client);
+    }
+    log_close();
+    exit(0);
+}
+
 static void looper_write_status(void) {
   if (status_fd < 0)
     return;
-  char buf[256];
+  char buf[4096];
+  int pos = 0;
   for (int ch = 0; ch < MAX_CHANNELS; ch++) {
     if (!atomic_load(&channels[ch].active))
       continue;
     int sc_idx = atomic_load(&channels[ch].current_scene);
     int state = atomic_load(&channels[ch].scenes[sc_idx].state);
+    int prev = atomic_load(&prev_state[ch][sc_idx]);
+    if (state == prev)
+      continue;   /* unchanged, skip */
+    atomic_store(&prev_state[ch][sc_idx], state);
+
     const char *state_str;
     switch (state) {
     case STATE_IDLE:
@@ -53,28 +122,16 @@ static void looper_write_status(void) {
     default:
       state_str = "UNKNOWN";
     }
-    int n = snprintf(buf, sizeof(buf), "CH=%d SC=%d STATE=%s\n", ch, sc_idx,
+    int n = snprintf(buf + pos, sizeof(buf) - pos,
-                     state_str);
+                     "CH=%d SC=%d STATE=%s\n", ch, sc_idx, state_str);
-    if (n > 0) {
+    if (n > 0) pos += n;
-      int ret = write(status_fd, buf, n);
+    if (pos >= (int)sizeof(buf) - 128) break;
+  }
+  if (pos > 0) {
+    int ret = write(status_fd, buf, pos);
     (void)ret;
   }
 }
-}
-
-/* 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;
@@ -465,16 +522,28 @@ int looper_init(jack_client_t *client) {
   /* store sample rate for writer thread */
   global_sample_rate = jack_get_sample_rate(client);
 
+  global_client = client;
+
+  /* Install signal handlers for graceful shutdown */
+  signal(SIGINT, signal_handler);
+  signal(SIGTERM, signal_handler);
+  signal(SIGQUIT, signal_handler);
+
   /* 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);
+  status_fd = open(STATUS_FIFO, O_RDWR | O_NONBLOCK);
   if (status_fd < 0) {
     perror("open status FIFO");
   }
 
+  /* initialise prev_state to -1 */
+  for (int ch = 0; ch < MAX_CHANNELS; ch++)
+    for (int sc = 0; sc < MAX_SCENES; sc++)
+      atomic_init(&prev_state[ch][sc], -1);
+
   queue_init(&cmd_queue);
   queue_init(&cmd_queue_main_midi);
   queue_init(&cmd_queue_main_fifo);