From caf800b40b8c69c8393dcb753989e26f48a13d6f Mon Sep 17 00:00:00 2001
From: Jan-Henrik Bruhn <hi@jhbruhn.de>
Date: Mon, 15 Dec 2025 13:45:09 +0100
Subject: [PATCH] fix: Detect unpaired Bluetooth devices during connection
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The application now properly detects when a Brother PP1 machine is not paired with the operating system. Previously, the connection would appear successful but commands would fail silently.

Changes:
- Enhanced sendCommand() to check for empty or invalid responses during initial connection
- Updated connect() to validate the connection with a test command (getMachineState)
- Properly disconnect and clean up when pairing is not established
- Throw BluetoothPairingError with helpful instructions for the user

When the machine is not paired, users now see a clear error message instructing them to:
1. Long-press the Bluetooth button on the machine
2. Pair via the operating system's Bluetooth settings
3. Try connecting again

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
---
 src/services/BrotherPP1Service.ts | 31 +++++++++++++++++++++++++++----
 1 file changed, 27 insertions(+), 4 deletions(-)

diff --git a/src/services/BrotherPP1Service.ts b/src/services/BrotherPP1Service.ts
index c5f3b34..f633066 100644
--- a/src/services/BrotherPP1Service.ts
+++ b/src/services/BrotherPP1Service.ts
@@ -131,12 +131,18 @@ export class BrotherPP1Service {
 
       console.log("Connected to Brother PP1 machine");
 
-      console.log("Send dummy command");
+      // Validate connection by sending a test command
+      // If the device is not paired, it won't respond properly
+      console.log("Validating connection with test command...");
       try {
-        await this.getMachineInfo();
-        console.log("Dummy command success");
+        await this.getMachineState();
+        console.log("Connection validation successful - device is properly paired");
       } catch (e) {
-        console.log(e);
+        console.log("Connection validation failed:", e);
+        // Disconnect to clean up
+        if (this.server) {
+          this.server.disconnect();
+        }
         throw e;
       }
     } finally {
@@ -280,6 +286,23 @@ export class BrotherPP1Service {
           .map((b) => b.toString(16).padStart(2, "0"))
           .join(" ");
 
+        // Detect pairing issues during initial connection - empty or invalid response
+        if (this.isInitialConnection) {
+          if (response.length === 0) {
+            console.log('[BrotherPP1] Empty response received - device likely not paired');
+            throw new BluetoothPairingError(
+              'Device not paired. To pair: long-press the Bluetooth button on the machine, then pair it using your operating system\'s Bluetooth settings. After pairing, try connecting again.'
+            );
+          }
+          // Check for invalid response (less than 3 bytes means no proper command response)
+          if (response.length < 3) {
+            console.log('[BrotherPP1] Invalid response length:', response.length);
+            throw new BluetoothPairingError(
+              'Device not paired. To pair: long-press the Bluetooth button on the machine, then pair it using your operating system\'s Bluetooth settings. After pairing, try connecting again.'
+            );
+          }
+        }
+
         // Parse response
         let parsed = "";
         if (response.length >= 3) {