Scan with allow-duplicates — Nearby presence froze and culled advertising boards

Apps/MetaWear/Info.plist

@@ -19,7 +19,7 @@
 	<key>CFBundleShortVersionString</key>
 	<string>10.0</string>
 	<key>CFBundleVersion</key>
-	<string>2</string>
+	<string>3</string>
 	<key>ITSAppUsesNonExemptEncryption</key>
 	<false/>
 	<key>LSRequiresIPhoneOS</key>

Apps/MetaWear/MetaWearApp.xcodeproj/project.pbxproj

@@ -412,7 +412,7 @@
 				ASSETCATALOG_COMPILER_GLOBAL_ACCENT_COLOR_NAME = AccentColor;
 				CODE_SIGN_ENTITLEMENTS = MetaWear.entitlements;
 				CODE_SIGN_STYLE = Automatic;
-				CURRENT_PROJECT_VERSION = 2;
+				CURRENT_PROJECT_VERSION = 3;
 				DEVELOPMENT_TEAM = S2273LZ6GL;
 				ENABLE_PREVIEWS = YES;
 				GENERATE_INFOPLIST_FILE = NO;
@@ -449,7 +449,7 @@
 				ASSETCATALOG_COMPILER_GLOBAL_ACCENT_COLOR_NAME = AccentColor;
 				CODE_SIGN_ENTITLEMENTS = MetaWear.entitlements;
 				CODE_SIGN_STYLE = Automatic;
-				CURRENT_PROJECT_VERSION = 2;
+				CURRENT_PROJECT_VERSION = 3;
 				DEVELOPMENT_TEAM = S2273LZ6GL;
 				ENABLE_PREVIEWS = YES;
 				GENERATE_INFOPLIST_FILE = NO;
@@ -484,7 +484,7 @@
 			buildSettings = {
 				BUNDLE_LOADER = "$(TEST_HOST)";
 				CODE_SIGN_STYLE = Automatic;
-				CURRENT_PROJECT_VERSION = 2;
+				CURRENT_PROJECT_VERSION = 3;
 				DEVELOPMENT_TEAM = S2273LZ6GL;
 				GENERATE_INFOPLIST_FILE = YES;
 				IPHONEOS_DEPLOYMENT_TARGET = 26.0;
@@ -506,7 +506,7 @@
 			buildSettings = {
 				BUNDLE_LOADER = "$(TEST_HOST)";
 				CODE_SIGN_STYLE = Automatic;
-				CURRENT_PROJECT_VERSION = 2;
+				CURRENT_PROJECT_VERSION = 3;
 				DEVELOPMENT_TEAM = S2273LZ6GL;
 				GENERATE_INFOPLIST_FILE = YES;
 				IPHONEOS_DEPLOYMENT_TARGET = 26.0;
@@ -527,7 +527,7 @@
 			isa = XCBuildConfiguration;
 			buildSettings = {
 				CODE_SIGN_STYLE = Automatic;
-				CURRENT_PROJECT_VERSION = 2;
+				CURRENT_PROJECT_VERSION = 3;
 				DEVELOPMENT_TEAM = S2273LZ6GL;
 				GENERATE_INFOPLIST_FILE = YES;
 				MARKETING_VERSION = 1.0;
@@ -547,7 +547,7 @@
 			isa = XCBuildConfiguration;
 			buildSettings = {
 				CODE_SIGN_STYLE = Automatic;
-				CURRENT_PROJECT_VERSION = 2;
+				CURRENT_PROJECT_VERSION = 3;
 				DEVELOPMENT_TEAM = S2273LZ6GL;
 				GENERATE_INFOPLIST_FILE = YES;
 				MARKETING_VERSION = 1.0;

Sources/MetaWear/MetaWearScanner.swift

@@ -121,15 +121,34 @@ public final class MetaWearScanner {
             for await result in stream {
                 let id = result.identifier
                 let name = result.name ?? ""
+                // The scan runs with allow-duplicates (presence and RSSI must
+                // keep updating), so advertisements arrive several times per
+                // second per board. Guard every write on actual change —
+                // @Observable treats same-value dictionary writes as
+                // mutations, and unguarded writes would invalidate observers
+                // at advertising rate.
+                //
                 // Record every advertisement's name so renamed devices remain
                 // observable even when they no longer match the MetaWear prefix.
-                self.advertisedNames[id] = name
-                self.advertisementRSSI[id] = result.rssi
-                self.advertisementLastSeen[id] = .now
+                if self.advertisedNames[id] != name {
+                    self.advertisedNames[id] = name
+                }
+                if self.advertisementRSSI[id] != result.rssi {
+                    self.advertisementRSSI[id] = result.rssi
+                }
+                // 1 s granularity is plenty for the UI's freshness window.
+                if let seen = self.advertisementLastSeen[id] {
+                    if Date.now.timeIntervalSince(seen) >= 1 {
+                        self.advertisementLastSeen[id] = .now
+                    }
+                } else {
+                    self.advertisementLastSeen[id] = .now
+                }
                 // Record manufacturer data when present — lets tests verify a
                 // board has flipped into iBeacon mode by inspecting the Apple
                 // company-ID payload broadcast on air.
-                if let mfg = result.manufacturerData {
+                if let mfg = result.manufacturerData,
+                   self.advertisementManufacturerData[id] != mfg {
                     self.advertisementManufacturerData[id] = mfg
                     // Boards configured to broadcast their MAC (company
                     // 0x626D) identify themselves here without a connection.

Sources/MetaWear/Transport/MWCentralManager.swift

@@ -115,7 +115,14 @@ actor MWCentralManager: NSObject {
             return
         }
         mwLog("[BLE] beginScan: starting scan")
-        central.scanForPeripherals(withServices: services, options: nil)
+        central.scanForPeripherals(
+            withServices: services,
+            // Without allow-duplicates, iOS delivers each peripheral ONCE per
+            // scan session - advertisementLastSeen would freeze at discovery
+            // and presence/RSSI could never update. Scans here are foreground
+            // + user-visible, the sanctioned use for this energy-costly flag.
+            options: [CBCentralManagerScanOptionAllowDuplicatesKey: true]
+        )
     }
 
     private func endScan() {
@@ -185,7 +192,14 @@ extension MWCentralManager: CBCentralManagerDelegate {
         if state == .poweredOn, scanContinuation != nil {
             // A scan was requested before BT was ready — start it now.
             mwLog("[BLE] handleStateUpdate: BT now poweredOn, starting deferred scan")
-            central.scanForPeripherals(withServices: pendingScanServices, options: nil)
+            central.scanForPeripherals(
+            withServices: pendingScanServices,
+            // Without allow-duplicates, iOS delivers each peripheral ONCE per
+            // scan session - advertisementLastSeen would freeze at discovery
+            // and presence/RSSI could never update. Scans here are foreground
+            // + user-visible, the sanctioned use for this energy-costly flag.
+            options: [CBCentralManagerScanOptionAllowDuplicatesKey: true]
+        )
         }
     }