fix(train): the wheel is learnt from rides GPS covered, whatever its size (ADR 0030, D56)

The measure was held to GPS making 90 % of the wheel's way at the
circumference taken, 2105 mm to start: a real wheel under some 1.9 m fell
short of it on every ride and was never learnt. A ride now measures where
precise fixes followed it for 95 % of its moving time, its quotient between
1 and 3 m as one typed may be.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

apps/train/halkyon_train_flutter/lib/src/feature/recording/data/recorded_workout.dart

@@ -168,9 +168,10 @@ int? _wheelTurns(Recording recording) {
 
 /// The wheel's circumference, in millimetres, [recording] measured by GPS
 /// (D49): its track's length over the wheel's revolutions, where GPS
-/// covered the ride (its distance is GPS's: a tunnel's stretch would read
-/// as a smaller wheel), it went 2 km at least by both and they make a wheel
-/// (1.5 to 2.5 m); else null.
+/// covered the ride's moving time (`_gpsCovered`; a tunnel's straight line
+/// would read as another wheel), it went 2 km at least and they make a
+/// wheel (1 to 3 m, as one typed may be); else null. Held to time, not to
+/// the wheel taken: a smaller wheel's ride falls short of it.
 int? measuredWheelMm(Recording recording) {
   final gps = _metres(recording);
   final turns = _wheelTurns(recording);
@@ -178,11 +179,79 @@ int? measuredWheelMm(Recording recording) {
       turns == null ||
       turns == 0 ||
       gps < 2000 ||
-      usesWheel(gps, wheelMetresOf(recording))) {
+      !_gpsCovered(recording)) {
     return null;
   }
   final mm = (gps * 1000 / turns).round();
-  return mm >= 1500 && mm <= 2500 ? mm : null;
+  return mm >= 1000 && mm <= 3000 ? mm : null;
+}
+
+/// The longest GPS may go without a precise fix while moving, its track
+/// still the way it went.
+const _longestGap = Duration(seconds: 30);
+
+/// The share of the moving time GPS must cover for its track to measure
+/// the wheel.
+const _coveredShare = 0.95;
+
+/// Whether precise fixes followed [recording] for [_coveredShare] of its
+/// moving time, from its first wheel reading to its last: the time between
+/// two fixes counts where it is at most [_longestGap] and no pause falls
+/// between them.
+bool _gpsCovered(Recording recording) {
+  final wheel = recording.wheel;
+  if (wheel.length < 2) {
+    return false;
+  }
+  final from = wheel.first.time;
+  final to = wheel.last.time;
+  final pauses = recording.pauses;
+  var next = 0;
+  var paused = false;
+  Fix? last;
+  var covered = Duration.zero;
+  for (final fix in recording.fixes) {
+    if (fix.time.isBefore(from) || fix.time.isAfter(to)) {
+      continue;
+    }
+    while (next < pauses.length && !pauses[next].time.isAfter(fix.time)) {
+      paused = pauses[next++].paused;
+      last = null;
+    }
+    if (paused || fix.accuracyCm > maxAccuracyCm) {
+      continue;
+    }
+    if (last != null) {
+      final gap = fix.time.difference(last.time);
+      if (gap <= _longestGap) {
+        covered += gap;
+      }
+    }
+    last = fix;
+  }
+  final moving = _movingBetween(recording, from, to);
+  return moving > Duration.zero &&
+      covered.inMilliseconds >= moving.inMilliseconds * _coveredShare;
+}
+
+/// How long [recording] moved between [from] and [to], its pauses left out.
+Duration _movingBetween(Recording recording, DateTime from, DateTime to) {
+  DateTime clamp(DateTime time) =>
+      time.isBefore(from) ? from : (time.isAfter(to) ? to : time);
+  var moving = to.difference(from);
+  DateTime? pausedAt;
+  for (final mark in recording.pauses) {
+    if (mark.paused) {
+      pausedAt ??= clamp(mark.time);
+    } else if (pausedAt != null) {
+      moving -= clamp(mark.time).difference(pausedAt);
+      pausedAt = null;
+    }
+  }
+  if (pausedAt != null) {
+    moving -= to.difference(pausedAt);
+  }
+  return moving;
 }
 
 /// The metres the rower counted while not paused: each frame's growth over

apps/train/halkyon_train_flutter/test/feature/recording/recorded_workout_test.dart

@@ -122,14 +122,21 @@ void main() {
   });
 
   group("the wheel's distance (D49)", () {
-    /// A ride of [seconds] with GPS [gpsMetres] a second and the wheel
-    /// turning twice a second, its 2.1 m round.
-    Recording ride({required int seconds, required num gpsMetres}) => Recording(
+    /// A ride of [seconds] with GPS [gpsMetres] a second, no fix between
+    /// the seconds [lostFrom] and [lostTo], and the wheel turning twice a
+    /// second, taken for 2.1 m round.
+    Recording ride({
+      required int seconds,
+      required num gpsMetres,
+      int? lostFrom,
+      int? lostTo,
+    }) => Recording(
       activity: Activity.cycling,
       startedAt: start,
       fixes: [
         for (var s = 0; s <= seconds; s += 10)
-          north(s, (s * gpsMetres).round()),
+          if (lostFrom == null || s <= lostFrom || s >= lostTo!)
+            north(s, (s * gpsMetres).round()),
       ],
       wheel: [
         for (var s = 0; s <= seconds; s++) Reading(time: at(s), value: s * 2),
@@ -162,15 +169,39 @@ void main() {
       () {
         expect(measuredWheelMm(ride(seconds: 200, gpsMetres: 4.2)), isNull);
         expect(measuredWheelMm(ride(seconds: 600, gpsMetres: 8)), isNull);
+        expect(measuredWheelMm(ride(seconds: 1200, gpsMetres: 1.6)), isNull);
       },
     );
 
-    test("one whose GPS fell short of the wheel's way (a tunnel) measures "
-        'none: its quotient would read as a smaller wheel', () {
-      // 3.6 m a second by GPS, 4.2 by the wheel: 86 %, a 1.8 m wheel.
-      final tunnel = ride(seconds: 1500, gpsMetres: 3.6);
-      expect(rodeByWheel(tunnel), isTrue);
+    test('a smaller wheel than the one taken is measured all the same: '
+        "GPS's track is held to time, not to the wheel taken", () {
+      // 3 m a second by GPS, two turns: a 20" wheel's 1.5 m.
+      final small = ride(seconds: 900, gpsMetres: 3);
+      expect(measuredWheelMm(small), closeTo(1500, 5));
+      // A child's 16" wheel, 1.25 m.
+      expect(
+        measuredWheelMm(ride(seconds: 900, gpsMetres: 2.5)),
+        closeTo(1250, 5),
+      );
+    });
+
+    test('one whose GPS was lost for a while (a tunnel) measures none: the '
+        'straight line across would read as another wheel', () {
+      final tunnel = ride(
+        seconds: 1500,
+        gpsMetres: 4.2,
+        lostFrom: 600,
+        lostTo: 720,
+      );
       expect(measuredWheelMm(tunnel), isNull);
+      // A fix lost now and then, as on any ride, still measures.
+      final patchy = ride(
+        seconds: 1500,
+        gpsMetres: 4.2,
+        lostFrom: 600,
+        lostTo: 620,
+      );
+      expect(measuredWheelMm(patchy), closeTo(2100, 5));
     });
   });
 

docs/adr/0030-halkyon-train.md

@@ -1187,10 +1187,10 @@ Strava. What was found, 27 Oct:
     progress and live speed are the wheel's where GPS made less than 90 % of the wheel's
     way (a turbo trainer, a tunnel, no fix), else GPS's (`usesWheel`, `rodeByWheel`).
     The circumference starts at 2105 mm (700×25C) and is learnt from rides with at least
-    2 km of GPS whose quotient falls between 1.5 and 2.5 m: the first sets it, each later
-    one moves it a quarter of the way (`measuredWheelMm`); one typed on the Record sheet
-    (1000 to 3000 mm) stays until cleared, which measures again. Auto-pause still follows
-    GPS alone on a trainer.
+    2 km of GPS covering the ride (D56) whose quotient falls between 1 and 3 m: the
+    first sets it, each later one moves it a quarter of the way (`measuredWheelMm`); one
+    typed on the Record sheet (1000 to 3000 mm) stays until cleared, which measures
+    again. Auto-pause still follows GPS alone on a trainer.
 - **D50 The instance's own map and searching for places** (recommended, the developer's
   but the search's region; 29 Oct; step 12, what D22, D23 and D44 left for later):
   - **Tiles** (12a): Protomaps' basemap (schema v4, zooms 0 to 15, ODbL, OpenStreetMap's
@@ -1416,6 +1416,14 @@ Strava. What was found, 27 Oct:
   written, and the other version is offered instead (`LoopFailed('another update')`).
   The relay's calls to Polar have timeouts, caps on their size and https on every
   hop, one fetch per file at a time, and a limit per person.
+- **D56 The wheel learnt from GPS that covered the ride** (recommended, the developer's;
+  30 Oct; revises D49's measure): a ride measures the wheel where precise fixes followed
+  it for 95 % of its moving time (gaps of 30 s at most count, a pause cuts), not where
+  GPS made 90 % of the wheel's way at the circumference taken: that held every wheel to
+  the one taken, so a real wheel under some 1.9 m (20", 24", a child's 16") was never
+  learnt from the 2105 mm a sensor starts with. Its quotient may fall between 1 and 3 m,
+  as one typed may (`measuredWheelMm`, `_gpsCovered`). A tunnel's straight line still
+  measures nothing. The distance still follows `usesWheel`, against the wheel as learnt.
 
 ## Consequences