feat: add tag picker in sensor calibration flow

lib/data/repositories/phoenix_sensor_repository.dart

@@ -80,6 +80,12 @@ class PhoenixSensorRepository implements SensorRepository {
     );
   }
 
+  @override
+  Future<int> setCalibrationTag(int id, String tagId) async {
+    final json = await client.setCalibrationTag(id, tagId);
+    return json['samples_needed'] as int;
+  }
+
   @override
   Future<void> cancelCalibration(int id) => client.cancelCalibration(id);
 

lib/data/repositories/sensor_repository.dart

@@ -32,6 +32,9 @@ abstract class SensorRepository {
   /// result. Returns the fitted (rssiRef, pathLossExp) pair.
   Future<({double rssiRef, double pathLossExp})> finishCalibration(int id);
 
+  /// Commits a specific tag for calibration stages. Returns samples_needed.
+  Future<int> setCalibrationTag(int id, String tagId);
+
   /// Aborts calibration and discards all accumulated stage data.
   Future<void> cancelCalibration(int id);
 

lib/data/sources/localiser/sensor_client.dart

@@ -52,6 +52,12 @@ class SensorClient extends LocaliserdClient {
         '/api/sensors/$id/calibration/finish',
       ) as Map<String, dynamic>;
 
+  Future<Map<String, dynamic>> setCalibrationTag(int id, String tagId) async =>
+      await post('/api/sensors/$id/calibration/tag', {
+            'tag_id': tagId,
+          })
+          as Map<String, dynamic>;
+
   Future<void> cancelCalibration(int id) =>
       delete('/api/sensors/$id/calibration');
 

lib/domain/models/calibration.dart

@@ -1,4 +1,4 @@
-enum CalibrationPhase { idle, ready, collecting, done, error }
+enum CalibrationPhase { idle, selectingTag, ready, collecting, done, error }
 
 const calibrationDistances = [0.5, 1.0, 2.0, 3.0];
 
@@ -14,6 +14,8 @@ class CalibrationState {
     this.avgRssi,
     this.resultRssiRef,
     this.resultPathLossExp,
+    this.tagRssiReadings = const {},
+    this.selectedTagId,
     this.error,
   });
 
@@ -28,6 +30,10 @@ class CalibrationState {
   final double? avgRssi;
   final double? resultRssiRef;
   final double? resultPathLossExp;
+  /// Latest scan RSSI per tag device ID, updated during selectingTag phase.
+  final Map<String, double> tagRssiReadings;
+  /// The tag device ID committed for this calibration session.
+  final String? selectedTagId;
   final String? error;
 
   bool get canFinish =>
@@ -47,10 +53,14 @@ class CalibrationState {
     double? avgRssi,
     double? resultRssiRef,
     double? resultPathLossExp,
+    Map<String, double>? tagRssiReadings,
+    String? selectedTagId,
     String? error,
     bool clearSelectedDistance = false,
     bool clearLatestRssi = false,
     bool clearAvgRssi = false,
+    bool clearTagRssiReadings = false,
+    bool clearSelectedTagId = false,
     bool clearError = false,
   }) =>
       CalibrationState(
@@ -66,6 +76,11 @@ class CalibrationState {
         avgRssi: clearAvgRssi ? null : avgRssi ?? this.avgRssi,
         resultRssiRef: resultRssiRef ?? this.resultRssiRef,
         resultPathLossExp: resultPathLossExp ?? this.resultPathLossExp,
+        tagRssiReadings: clearTagRssiReadings
+            ? const {}
+            : tagRssiReadings ?? this.tagRssiReadings,
+        selectedTagId:
+            clearSelectedTagId ? null : selectedTagId ?? this.selectedTagId,
         error: clearError ? null : error ?? this.error,
       );
 }

lib/features/sensors/calibration_notifier.dart

@@ -25,22 +25,22 @@ class CalibrationNotifier extends StateNotifier<CalibrationState> {
   /// Channel subscription is set up first to guarantee no reading events are
   /// dropped before the server acknowledges the stage start.
   Future<void> beginCalibration() async {
-    // Subscribe first, then call REST.
     _sub = repo
         .calibrationEvents(sensorDeviceId)
         .listen(_onEvent, onError: _onError);
 
     try {
       final samplesNeeded = await repo.beginCalibration(sensorId);
-      final firstUncompleted = calibrationDistances.first;
       state = state.copyWith(
-        phase: CalibrationPhase.ready,
+        phase: CalibrationPhase.selectingTag,
         samplesNeeded: samplesNeeded,
         samplesCollected: 0,
-        selectedDistance: firstUncompleted,
+        selectedDistance: calibrationDistances.first,
         completedDistances: {},
         waveform: [],
         clearLatestRssi: true,
+        clearTagRssiReadings: true,
+        clearSelectedTagId: true,
       );
     } catch (e) {
       _sub?.cancel();
@@ -52,6 +52,28 @@ class CalibrationNotifier extends StateNotifier<CalibrationState> {
     }
   }
 
+  void selectTag(String tagId) {
+    if (state.phase != CalibrationPhase.selectingTag) return;
+    state = state.copyWith(selectedTagId: tagId);
+  }
+
+  Future<void> commitTag() async {
+    final tagId = state.selectedTagId;
+    if (tagId == null || state.phase != CalibrationPhase.selectingTag) return;
+    try {
+      final samplesNeeded = await repo.setCalibrationTag(sensorId, tagId);
+      state = state.copyWith(
+        phase: CalibrationPhase.ready,
+        samplesNeeded: samplesNeeded,
+      );
+    } catch (e) {
+      state = state.copyWith(
+        phase: CalibrationPhase.error,
+        error: e.toString(),
+      );
+    }
+  }
+
   void selectDistance(double distance) {
     if (state.phase != CalibrationPhase.ready) return;
     if (state.completedDistances.contains(distance)) return;
@@ -111,6 +133,11 @@ class CalibrationNotifier extends StateNotifier<CalibrationState> {
 
   void _onEvent(({String event, Map<String, dynamic> payload}) msg) {
     switch (msg.event) {
+      case 'scan_reading':
+        _handleScanReading(msg.payload);
+      case 'tag_set':
+        final tagId = msg.payload['tag_id'] as String;
+        state = state.copyWith(selectedTagId: tagId);
       case 'reading':
         _handleReading(msg.payload);
       case 'stage_complete':
@@ -122,6 +149,14 @@ class CalibrationNotifier extends StateNotifier<CalibrationState> {
     }
   }
 
+  void _handleScanReading(Map<String, dynamic> payload) {
+    final tagId = payload['tag_id'] as String;
+    final rssi = (payload['rssi'] as num).toDouble();
+    state = state.copyWith(
+      tagRssiReadings: {...state.tagRssiReadings, tagId: rssi},
+    );
+  }
+
   void _handleReading(Map<String, dynamic> payload) {
     final rssi = (payload['rssi'] as num).toDouble();
     final progress = payload['stage_progress'] as Map<String, dynamic>;

lib/features/sensors/calibration_sheet.dart

@@ -5,6 +5,7 @@ import 'package:flutter/services.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 import '../../domain/models/calibration.dart';
+import '../../domain/models/tag.dart';
 import '../../providers.dart';
 
 void showCalibrationSheet(
@@ -71,11 +72,22 @@ class _CalibrationSheetState extends ConsumerState<CalibrationSheet> {
     }
   }
 
+  Future<void> _commitTag() async {
+    await ref.read(calibrationProvider(_key).notifier).commitTag();
+    if (mounted) {
+      _pageController.animateToPage(
+        2,
+        duration: const Duration(milliseconds: 300),
+        curve: Curves.easeInOut,
+      );
+    }
+  }
+
   Future<void> _finish() async {
     await ref.read(calibrationProvider(_key).notifier).finishCalibration();
     if (mounted) {
       _pageController.animateToPage(
-        2,
+        3,
         duration: const Duration(milliseconds: 300),
         curve: Curves.easeInOut,
       );
@@ -115,6 +127,11 @@ class _CalibrationSheetState extends ConsumerState<CalibrationSheet> {
                 onBegin: _begin,
                 onCancel: () => _cancelAndClose(context),
               ),
+              _TagSelectionPage(
+                state: state,
+                sensorKey: _key,
+                onNext: _commitTag,
+              ),
               _CollectingPage(
                 state: state,
                 sensorKey: _key,
@@ -214,7 +231,170 @@ class _IntroPage extends StatelessWidget {
 }
 
 // ---------------------------------------------------------------------------
-// Page 2 — Collecting
+// Page 2 — Tag selection
+// ---------------------------------------------------------------------------
+
+class _TagSelectionPage extends ConsumerWidget {
+  const _TagSelectionPage({
+    required this.state,
+    required this.sensorKey,
+    required this.onNext,
+  });
+
+  final CalibrationState state;
+  final ({int id, String deviceId}) sensorKey;
+  final Future<void> Function() onNext;
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final theme = Theme.of(context);
+    final notifier = ref.read(calibrationProvider(sensorKey).notifier);
+    final tagsAsync = ref.watch(tagsProvider);
+
+    final tags = tagsAsync.whenOrNull(data: (t) => t) ?? const [];
+    final readings = state.tagRssiReadings;
+
+    // Sort: tags with readings by RSSI descending (nearest first),
+    // then tags without readings by id.
+    final sorted = [...tags]..sort((a, b) {
+        final ra = readings[a.tagId];
+        final rb = readings[b.tagId];
+        if (ra != null && rb != null) return rb.compareTo(ra);
+        if (ra != null) return -1;
+        if (rb != null) return 1;
+        return a.id.compareTo(b.id);
+      });
+
+    return SafeArea(
+      child: Padding(
+        padding: const EdgeInsets.fromLTRB(24, 16, 24, 24),
+        child: Column(
+          crossAxisAlignment: CrossAxisAlignment.stretch,
+          children: [
+            Center(
+              child: Container(
+                width: 32,
+                height: 4,
+                decoration: BoxDecoration(
+                  color: theme.colorScheme.outlineVariant,
+                  borderRadius: BorderRadius.circular(2),
+                ),
+              ),
+            ),
+            const SizedBox(height: 20),
+            const Text(
+              'Select your tag',
+              style: TextStyle(fontSize: 18, fontWeight: FontWeight.w500),
+              textAlign: TextAlign.center,
+            ),
+            const SizedBox(height: 4),
+            Text(
+              'Hold each tag near the sensor — the one you\'re using will show a stronger signal.',
+              style: TextStyle(
+                fontSize: 13,
+                color: theme.colorScheme.onSurfaceVariant,
+              ),
+              textAlign: TextAlign.center,
+            ),
+            const SizedBox(height: 16),
+            Expanded(
+              child: tags.isEmpty
+                  ? Center(
+                      child: Text(
+                        'No tags enrolled',
+                        style: TextStyle(
+                            color: theme.colorScheme.onSurfaceVariant),
+                      ),
+                    )
+                  : ListView.builder(
+                      itemCount: sorted.length,
+                      itemBuilder: (context, i) {
+                        final tag = sorted[i];
+                        final rssi = readings[tag.tagId];
+                        final selected = tag.tagId == state.selectedTagId;
+                        return _TagListTile(
+                          key: ValueKey(tag.tagId),
+                          tag: tag,
+                          rssi: rssi,
+                          selected: selected,
+                          onTap: () => notifier.selectTag(tag.tagId),
+                        );
+                      },
+                    ),
+            ),
+            const SizedBox(height: 16),
+            _AsyncButton(
+              onPressed: onNext,
+              enabled: state.selectedTagId != null,
+              label: 'Next',
+              icon: Icons.arrow_forward,
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
+class _TagListTile extends StatelessWidget {
+  const _TagListTile({
+    super.key,
+    required this.tag,
+    required this.rssi,
+    required this.selected,
+    required this.onTap,
+  });
+
+  final Tag tag;
+  final double? rssi;
+  final bool selected;
+  final VoidCallback onTap;
+
+  @override
+  Widget build(BuildContext context) {
+    final cs = Theme.of(context).colorScheme;
+    return ListTile(
+      selected: selected,
+      selectedTileColor: cs.primaryContainer,
+      shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(12)),
+      leading: Icon(
+        selected ? Icons.radio_button_checked : Icons.radio_button_unchecked,
+        color: selected ? cs.primary : cs.outline,
+      ),
+      title: Text(tag.name),
+      subtitle: Text(
+        tag.tagId,
+        style: TextStyle(fontSize: 12, color: cs.onSurfaceVariant),
+      ),
+      trailing: rssi != null
+          ? TweenAnimationBuilder<double>(
+              tween: Tween(begin: rssi, end: rssi),
+              duration: const Duration(milliseconds: 300),
+              builder: (context, value, child) => Chip(
+                label: Text(
+                  '${value.round()} dBm',
+                  style: const TextStyle(fontFamily: 'monospace', fontSize: 12),
+                ),
+                backgroundColor: cs.primaryContainer,
+                side: BorderSide.none,
+                padding: const EdgeInsets.symmetric(horizontal: 4),
+              ),
+            )
+          : Chip(
+              label: Text(
+                '—',
+                style: TextStyle(fontSize: 12, color: cs.onSurfaceVariant),
+              ),
+              side: BorderSide.none,
+              padding: const EdgeInsets.symmetric(horizontal: 4),
+            ),
+      onTap: onTap,
+    );
+  }
+}
+
+// ---------------------------------------------------------------------------
+// Page 3 — Collecting
 // ---------------------------------------------------------------------------
 
 class _CollectingPage extends ConsumerWidget {
@@ -772,12 +952,14 @@ class _AsyncButton extends StatefulWidget {
     required this.label,
     this.icon,
     this.compact = false,
+    this.enabled = true,
   });
 
   final Future<void> Function() onPressed;
   final String label;
   final IconData? icon;
   final bool compact;
+  final bool enabled;
 
   @override
   State<_AsyncButton> createState() => _AsyncButtonState();
@@ -806,12 +988,14 @@ class _AsyncButtonState extends State<_AsyncButton> {
                   Icon(widget.icon, size: 18),
                 ],
               )
-            : Text(widget.label);
+            : Text(widget.label, style: TextStyle(fontSize: 36, color: Theme.of(context).colorScheme.primary));
+
+    final canPress = !_loading && widget.enabled;
 
     if (widget.compact) {
       return TextButton(
-        style: TextButton.styleFrom(shape: shape, textStyle: const .new(fontSize: 32)),
+        style: TextButton.styleFrom(shape: shape, textStyle: const TextStyle(fontSize: 36, color: Colors.black)),
-        onPressed: _loading ? null : _run,
+        onPressed: canPress ? _run : null,
         child: child,
       );
     }
@@ -821,7 +1005,7 @@ class _AsyncButtonState extends State<_AsyncButton> {
         shape: shape,
         minimumSize: const Size.fromHeight(48),
       ),
-      onPressed: _loading ? null : _run,
+      onPressed: canPress ? _run : null,
       child: child,
     );
   }