diff --git a/src/system/audio.py b/src/system/audio.py
index d91d567..cbc3872 100644
--- a/src/system/audio.py
+++ b/src/system/audio.py
@@ -323,19 +323,29 @@ class AudioSystem:
             logger.error("jackd not found — install jackd2")
             return False
 
-        # Wait for readiness via jack_wait
+        # Wait for readiness — verify JACK is actually operational
+        # (process exists AND SHM socket is created), not just that
+        # the jackd process spawned. jackd can start but fail to
+        # initialize the audio device, leaving a zombie process that
+        # pgrep finds but jack_lsp can't connect to.
         deadline = time.monotonic() + timeout
         while time.monotonic() < deadline:
             time.sleep(0.3)
             if _jack_is_running():
-                logger.info(
-                    "JACK started: period=%d, nperiods=%d, rate=%d",
-                    profile["period"], profile["nperiods"], profile["rate"],
-                )
-                # Auto-connect ports if enabled
-                if self.config.auto_connect:
-                    self.connect_fx_ports()
-                return True
+                # Double-check JACK is actually operational by testing
+                # the SHM socket — jack_default_0_0 is created only
+                # after the ALSA device is successfully initialized.
+                if Path("/dev/shm/jack_default_0_0").is_socket():
+                    logger.info(
+                        "JACK started: period=%d, nperiods=%d, rate=%d",
+                        profile["period"], profile["nperiods"], profile["rate"],
+                    )
+                    # Auto-connect ports if enabled
+                    if self.config.auto_connect:
+                        self.connect_fx_ports()
+                    return True
+                # JACK process exists but SHM not ready yet — keep waiting
+                continue
 
         # Timed out — check for common issues
         poll = proc.poll()