fix: three provisioning bugs causing beacon write failures

1. Minor allocation: reject minor=0 from API instead of silently using it.
   API returning null/0 means the service point isn't configured right.

2. DXSmart write reliability:
   - Add per-command retry (1 retry with 500ms backoff)
   - Increase inter-command delay from 200ms to 500ms
   - Increase post-auth settle from 100ms to 500ms
   - Add 2s cooldown in FallbackProvisioner between provisioner attempts
   The beacon's BLE stack gets hammered by KBeacon's 15 failed auth
   attempts before DXSmart even gets a chance. These timings give it
   breathing room.

3. KBeacon passwords: password 5 was a duplicate of password 3
   (both "1234567890123456"). Replaced with "000000" (6-char variant).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

PayfritBeacon/Provisioners/DXSmartProvisioner.swift

@@ -172,14 +172,30 @@ final class DXSmartProvisioner: NSObject, BeaconProvisioner {
 
         for (index, (name, packet)) in commands.enumerated() {
             await diagnosticLog?.log("write", "[\(index + 1)/\(commands.count)] \(name) (\(packet.count) bytes)")
+
+            // Retry each command up to 2 times — beacon BLE stack can be flaky after KBeacon fallback
+            var lastError: Error?
+            for writeAttempt in 1...2 {
                 do {
                     try await writeToCharAndWaitACK(writeChar, data: packet, label: name)
+                    lastError = nil
+                    break
                 } catch {
-                await diagnosticLog?.log("write", "[\(index + 1)/\(commands.count)] \(name) FAILED: \(error.localizedDescription)", isError: true)
+                    lastError = error
-                throw error
+                    if writeAttempt == 1 {
+                        await diagnosticLog?.log("write", "[\(index + 1)/\(commands.count)] \(name) retry after: \(error.localizedDescription)")
+                        try await Task.sleep(nanoseconds: 500_000_000) // 500ms before retry
                     }
-            // 200ms between commands (matches Android SDK timer interval)
+                }
-            try await Task.sleep(nanoseconds: 200_000_000)
+            }
+            if let lastError {
+                await diagnosticLog?.log("write", "[\(index + 1)/\(commands.count)] \(name) FAILED: \(lastError.localizedDescription)", isError: true)
+                throw lastError
+            }
+
+            // 500ms between commands — beacon needs time to process, especially after
+            // prior KBeacon auth attempts that may have stressed the BLE stack
+            try await Task.sleep(nanoseconds: 500_000_000)
         }
     }
 
@@ -320,7 +336,9 @@ final class DXSmartProvisioner: NSObject, BeaconProvisioner {
         // Step 2: Auth password — fire and forget
         if let authData = Self.defaultPassword.data(using: .utf8) {
             peripheral.writeValue(authData, for: ffe3, type: .withoutResponse)
-            try await Task.sleep(nanoseconds: 100_000_000) // 100ms settle
+            // 500ms settle after auth — beacon needs time to enter config mode,
+            // especially if BLE stack was stressed by prior provisioner attempts
+            try await Task.sleep(nanoseconds: 500_000_000)
         }
     }
 

PayfritBeacon/Provisioners/FallbackProvisioner.swift

@@ -56,6 +56,12 @@ final class FallbackProvisioner: BeaconProvisioner {
                 provisioner.disconnect()
                 lastError = error
                 await diagnosticLog?.log("fallback", "\(typeNames[index]) failed: \(error.localizedDescription)", isError: true)
+                // 2s cooldown between provisioner attempts — let the beacon's BLE stack recover
+                // from failed auth/connection before the next provisioner hammers it
+                if index < provisioners.count - 1 {
+                    await diagnosticLog?.log("fallback", "Cooling down 2s before next provisioner…")
+                    try? await Task.sleep(nanoseconds: 2_000_000_000)
+                }
             }
         }
 

PayfritBeacon/Provisioners/KBeaconProvisioner.swift

@@ -24,12 +24,14 @@ final class KBeaconProvisioner: NSObject, BeaconProvisioner {
     }
 
     // MARK: - Known passwords (tried in order, matching Android)
+    // Known KBeacon default passwords (tried in order)
+    // Note: password 5 was previously a duplicate of password 3 — replaced with "000000" (6-char variant)
     private static let passwords: [Data] = [
-        "kd1234".data(using: .utf8)!,
+        "kd1234".data(using: .utf8)!,                                                              // KBeacon factory default
-        Data(repeating: 0, count: 16),
+        Data(repeating: 0, count: 16),                                                             // Binary zeros (16 bytes)
-        Data([0x31,0x32,0x33,0x34,0x35,0x36,0x37,0x38,0x39,0x30,0x31,0x32,0x33,0x34,0x35,0x36]),
+        Data([0x31,0x32,0x33,0x34,0x35,0x36,0x37,0x38,0x39,0x30,0x31,0x32,0x33,0x34,0x35,0x36]), // "1234567890123456"
-        "0000000000000000".data(using: .utf8)!,
+        "0000000000000000".data(using: .utf8)!,                                                    // ASCII zeros (16 bytes)
-        "1234567890123456".data(using: .utf8)!
+        "000000".data(using: .utf8)!,                                                              // Short zero default (6 bytes)
     ]
 
     // MARK: - State

PayfritBeacon/Services/APIClient.swift

@@ -201,7 +201,10 @@ actor APIClient {
         guard resp.OK else {
             throw APIError.serverError(resp.MESSAGE ?? resp.ERROR ?? "Failed to allocate minor")
         }
-        return resp.BeaconMinor ?? 0
+        guard let minor = resp.BeaconMinor, minor > 0 else {
+            throw APIError.serverError("API returned invalid minor value: \(resp.BeaconMinor ?? 0). Service point may not be configured correctly.")
+        }
+        return minor
     }
 
     /// API returns: { "OK": true, "BeaconHardwareID": 42, ... }