Complete Phase 1: accumulator, exports, and full parity coverage

T05 — ride_accumulator.dart with the cross-batch anchor intact (12 tests).
T06 — ride_export.dart, GPX 1.1 and GeoJSON (15 tests), parsed with real
parsers rather than substring matching.
T07 — parity harness extended to cover export byte output.

GPX and GeoJSON are byte-identical across Kotlin and Dart: same length, same
FNV hash, including the escaped hostile name and all %.7f/%.1f formatting.

Two harness bugs found and fixed while building it. String.hashCode is not
comparable across Java and Dart, so text comparison used FNV-1a instead. And a
missing jar let a failed Kotlin compile pass as a green run -- run.sh now checks
for the artifact and exits non-zero, the same failure mode as the v2 sweep that
hid a compile error behind /dev/null.

Phase 1 done: 79 tests passing, analyze clean.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tool/parity/probe.dart

@@ -1,8 +1,10 @@
+// ignore_for_file: avoid_print -- this is a command-line harness; stdout is the output.
 // Dart side of the cross-language parity harness (T07).
 // Must stay fixture-for-fixture identical to tool/parity/main.kt.
 import 'dart:math' as math;
 
 import 'package:rippr/src/domain/models.dart';
+import 'package:rippr/src/export/ride_export.dart';
 import 'package:rippr/src/geo/geo.dart';
 import 'package:rippr/src/stats/ride_statistics.dart';
 
@@ -18,6 +20,17 @@ class Lcg {
   }
 }
 
+/// FNV-1a 32-bit. Dart's String.hashCode differs from Java's, so it cannot be used to
+/// compare text across languages -- this can.
+int fnv1a(String s) {
+  var h = 2166136261;
+  for (final c in s.codeUnits) {
+    h ^= c;
+    h = (h * 16777619) & 0xFFFFFFFF;
+  }
+  return h;
+}
+
 TrackPoint p(int seg, int ts, double lat, double lon, double sp, double alt, int id) =>
     TrackPoint(id: id, tripId: 1, segmentId: seg, timestamp: ts,
         latitude: lat, longitude: lon, speedKmh: sp, altitudeM: alt);
@@ -61,4 +74,29 @@ void main() {
   final hist = speedHistogram(run, bucketKmh: 10);
   out('hist_buckets', hist.length);
   out('hist_first_millis', hist.first.millis);
+
+  // --- export byte output -------------------------------------------------
+  const etrip = Trip(
+      id: 1,
+      startedAt: 1700000000000,
+      endedAt: 1700000600000,
+      state: TripState.completed,
+      distanceM: 12345.6,
+      maxSpeedKmh: 118.4);
+  const esegs = [
+    Segment(id: 1, tripId: 1, startedAt: 0, endedAt: 1),
+    Segment(id: 2, tripId: 1, startedAt: 2, endedAt: 3),
+  ];
+  final epts = <TrackPoint>[
+    for (final sg in esegs)
+      for (var i = 0; i < 5; i++)
+        p(sg.id, 1700000000000 + i * 1000, 51.0447 + i * 0.0001, -114.0719, 72.0,
+            1045.0, i + 1),
+  ];
+  final g = gpx(etrip, esegs, epts, "Sam & Dave's <ride>");
+  final j = geoJson(etrip, esegs, epts, "Sam & Dave's <ride>");
+  out('gpx_len', g.length);
+  out('gpx_fnv', fnv1a(g));
+  out('geojson_len', j.length);
+  out('geojson_fnv', fnv1a(j));
 }