Stop notification storms: transient notifications, single instance, no empty-result alerts

- notify-send notifications are now transient (boolean:transient:true) with a
  2.5s expiry, so they no longer pile up in the message tray / lock screen.
- Single-instance guard (abstract unix socket) in the entry point: a second
  `tray`/`gui`/`run` launch exits instead of starting a duplicate daemon — the
  duplicate caused two wakeword listeners + two recorders.
- Empty/quiet/keyword-only results now only log, instead of firing a desktop
  notification on every (often false) wakeword trigger.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

linux/blitztext/blitztext.py

@@ -13,6 +13,23 @@ from pathlib import Path
 from . import __version__
 from .config import CONFIG_PATH, ensure_default, load
 
+# Held for the process lifetime to enforce a single running instance.
+_SINGLE_INSTANCE_SOCK = None
+
+
+def _acquire_single_instance() -> bool:
+    """Bind an abstract unix socket; False if another instance already holds it."""
+    global _SINGLE_INSTANCE_SOCK
+    import socket
+
+    sock = socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM)
+    try:
+        sock.bind("\0blitztext-single-instance")  # abstract namespace (auto-freed on exit)
+    except OSError:
+        return False
+    _SINGLE_INSTANCE_SOCK = sock
+    return True
+
 
 def main(argv: list[str] | None = None) -> int:
     parser = argparse.ArgumentParser(prog="blitztext", description="Native dictation for Linux.")
@@ -36,6 +53,12 @@ def main(argv: list[str] | None = None) -> int:
         print(ensure_default(CONFIG_PATH))
         return 0
 
+    # Only one live daemon/tray/gui at a time — prevents duplicate wakeword
+    # listeners and recorders (which caused notification storms).
+    if cmd in ("gui", "tray", "run") and not _acquire_single_instance():
+        print("[blitztext] already running — not starting a second instance.", file=sys.stderr)
+        return 0
+
     if cmd in ("gui", "tray"):
         ensure_default(CONFIG_PATH)
         from .gtkui import run_gui

linux/blitztext/daemon.py

@@ -319,7 +319,7 @@ class Daemon:
                                  min_seconds=self.cfg.min_speech_seconds,
                                  silence_rms=self.cfg.silence_rms):
                 self._emit("idle", label, "Too quiet")
-                self._notify("Nothing heard", "No speech detected.", "low")
+                log("Nothing heard — clip too quiet/short.")
                 return
 
             self._emit("busy", label, "Transcribing…")
@@ -337,7 +337,7 @@ class Daemon:
             text = quality.clean(text, strip_trailing_punctuation=self.cfg.strip_trailing_punctuation)
             if not text or (self.cfg.reject_hallucinations and quality.is_hallucination(text, duration)):
                 self._emit("idle", label, "No speech detected")
-                self._notify("Nothing heard", "No speech detected.", "low")
+                log("Nothing heard — no speech detected.")
                 return
 
             # Voice routing: pick the preset from a spoken keyword, strip it.
@@ -355,7 +355,7 @@ class Daemon:
             if target and target.mode == "rewrite" and target.prompt:
                 if not text:
                     self._emit("idle", label, "Only a keyword heard")
-                    self._notify("Nothing to do", "Only the keyword was heard.", "low")
+                    log("Only the keyword was heard — nothing to type.")
                     return
                 self._emit("busy", label, "Rewriting…")
                 self._notify(f"⌛ {label}", "Rewriting…")

linux/blitztext/notify.py

@@ -12,20 +12,23 @@ _APP = "Blitztext"
 _REPLACE_ID = "99317"
 
 
-def notify(title: str, body: str = "", *, urgency: str = "normal", enabled: bool = True) -> None:
+def notify(title: str, body: str = "", *, urgency: str = "normal", enabled: bool = True,
+           transient: bool = True) -> None:
     if enabled and _HAVE_NOTIFY:
         try:
-            subprocess.run(
-                [
+            args = [
                 "notify-send",
                 "--app-name", _APP,
                 "--urgency", urgency,
+                "--expire-time", "2500",
+                # Replace the previous bubble instead of stacking.
                 "--hint", f"string:x-canonical-private-synchronous:{_REPLACE_ID}",
-                    title,
-                    body,
-                ],
-                check=False,
-            )
+            ]
+            if transient:
+                # Don't keep it in the notification log / lock screen.
+                args += ["--hint", "boolean:transient:true"]
+            args += [title, body]
+            subprocess.run(args, check=False)
             return
         except OSError:
             pass