A second StemDeck no longer adopts the first one's backend

app/main.py

@@ -289,6 +289,15 @@ def health() -> dict[str, object]:
         "ffmpeg_configured": FFMPEG_BIN.is_file(),
         "demucs_model": DEMUCS_MODEL,
         "demucs_device": get_demucs_device(),
+        # Which process is answering. The desktop shell spawns this backend and
+        # then polls this endpoint to know it came up -- but a 200 alone only
+        # proves *something* is listening on that port, not that it is the child
+        # the shell just started. When a second StemDeck was launched, the new
+        # window adopted the already-running instance's backend, and with it
+        # that instance's data directory and library (#424). The shell compares
+        # this against the PID it spawned, so a stranger on the port is refused
+        # rather than silently trusted.
+        "pid": os.getpid(),
     }
 
 

desktop/src-tauri/Cargo.toml

@@ -17,6 +17,10 @@ reqwest = { version = "0.12", default-features = false, features = ["rustls-tls"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 sha2 = "0.10"
+# Binding a port without listening on it. std's TcpListener always listens, and
+# a listener on 0.0.0.0 makes StemDeck.exe itself a server in the eyes of
+# Windows Firewall, prompting the user. Reserving a port is not serving on it.
+socket2 = "0.6"
 tar = "0.4"
 tauri = { version = "2", features = [] }
 tauri-plugin-dialog = "2"