From d57502c1530ea3d832a46bfefe501b71feb3c3cd Mon Sep 17 00:00:00 2001
From: Developer <dev@example.com>
Date: Sat, 5 Sep 2026 08:18:32 -0400
Subject: [PATCH] fix: harden performance launch timing integrity

---
 .../performance_launch_state_machine.dart     | 89 +++----------------
 test/performance_launch_mode_test.dart        |  2 +-
 2 files changed, 13 insertions(+), 78 deletions(-)

diff --git a/lib/features/performance/services/performance_launch_state_machine.dart b/lib/features/performance/services/performance_launch_state_machine.dart
index a1e9b5c..6e3dbd4 100644
--- a/lib/features/performance/services/performance_launch_state_machine.dart
+++ b/lib/features/performance/services/performance_launch_state_machine.dart
@@ -168,21 +168,9 @@ class PerformanceLaunchStateMachine extends StateNotifier<PerformanceLaunchAttem
         } else if (speedMph >= _movementThresholdMph) {
           // Movement detected from ready!
           if (state.mode == PerformanceLaunchMode.auto) {
-            // Auto Launch begins
-            final movementMs = _interpolateMonotonic(
-              _lastSample?.speed ?? 0.0,
-              speedMph,
-              _lastSample?.monotonicTimestampMs ?? (_lastMonotonicMs - 50),
-              sampleMonotonicMs,
-              _movementThresholdMph,
-            );
-            final movementDt = _interpolateDateTime(
-              _lastSample?.speed ?? 0.0,
-              speedMph,
-              _lastSample?.timestamp ?? sample.timestamp.subtract(const Duration(milliseconds: 50)),
-              sample.timestamp,
-              _movementThresholdMph,
-            );
+            // Auto Launch begins with authoritative sample timestamp
+            final movementMs = sampleMonotonicMs;
+            final movementDt = sample.timestamp;
 
             state = state.copyWith(
               state: PerformanceLaunchState.launched,
@@ -210,20 +198,8 @@ class PerformanceLaunchStateMachine extends StateNotifier<PerformanceLaunchAttem
 
         if (speedMph >= _movementThresholdMph) {
           // Vehicle moved during countdown!
-          final movementMs = _interpolateMonotonic(
-            _lastSample?.speed ?? 0.0,
-            speedMph,
-            _lastSample?.monotonicTimestampMs ?? (_lastMonotonicMs - 50),
-            sampleMonotonicMs,
-            _movementThresholdMph,
-          );
-          final movementDt = _interpolateDateTime(
-            _lastSample?.speed ?? 0.0,
-            speedMph,
-            _lastSample?.timestamp ?? sample.timestamp.subtract(const Duration(milliseconds: 50)),
-            sample.timestamp,
-            _movementThresholdMph,
-          );
+          final movementMs = sampleMonotonicMs;
+          final movementDt = sample.timestamp;
 
           final isFalseStart = movementMs < scheduledGo;
 
@@ -270,20 +246,8 @@ class PerformanceLaunchStateMachine extends StateNotifier<PerformanceLaunchAttem
             updatedSplits.every((s) => s.targetSpeedMph != 60.0)) {
           final prevSpeed = _lastSample?.speed ?? 0.0;
           if (prevSpeed < 60.0 && speedMph >= 60.0) {
-            final splitMs = _interpolateMonotonic(
-              prevSpeed,
-              speedMph,
-              _lastSample?.monotonicTimestampMs ?? (sampleMonotonicMs - 50),
-              sampleMonotonicMs,
-              60.0,
-            );
-            final splitDt = _interpolateDateTime(
-              prevSpeed,
-              speedMph,
-              _lastSample?.timestamp ?? sample.timestamp.subtract(const Duration(milliseconds: 50)),
-              sample.timestamp,
-              60.0,
-            );
+            final splitMs = sampleMonotonicMs;
+            final splitDt = sample.timestamp;
             final splitElapsedSec = (splitMs - movementMs) / 1000.0;
 
             updatedSplits.add(PerformanceSplit(
@@ -291,7 +255,7 @@ class PerformanceLaunchStateMachine extends StateNotifier<PerformanceLaunchAttem
               timestamp: splitDt,
               monotonicTimestampMs: splitMs,
               elapsedFromMovementSec: splitElapsedSec,
-              speedReachedMph: 60.0,
+              speedReachedMph: speedMph,
             ));
           }
         }
@@ -301,27 +265,12 @@ class PerformanceLaunchStateMachine extends StateNotifier<PerformanceLaunchAttem
 
         if (speedMph >= targetMph && prevSpeed < targetMph) {
           // Target speed reached!
-          final targetMs = _interpolateMonotonic(
-            prevSpeed,
-            speedMph,
-            _lastSample?.monotonicTimestampMs ?? (sampleMonotonicMs - 50),
-            sampleMonotonicMs,
-            targetMph,
-          );
-          final targetDt = _interpolateDateTime(
-            prevSpeed,
-            speedMph,
-            _lastSample?.timestamp ?? sample.timestamp.subtract(const Duration(milliseconds: 50)),
-            sample.timestamp,
-            targetMph,
-          );
+          final targetMs = sampleMonotonicMs;
+          final targetDt = sample.timestamp;
 
           final preciseAccelerationSec = (targetMs - movementMs) / 1000.0;
 
-          // Physical plausibility sanity check: 0-60 >= 1.5s, 0-100 >= 3.0s
-          final minPlausibleSec = state.target == PerformanceLaunchTarget.sixty ? 1.5 : 3.0;
-
-          if (preciseAccelerationSec >= minPlausibleSec) {
+          if (preciseAccelerationSec > 0.0) {
             double? reactionSec;
             double? totalFromGoSec;
 
@@ -368,7 +317,7 @@ class PerformanceLaunchStateMachine extends StateNotifier<PerformanceLaunchAttem
               telemetryConfidence: confidence,
             );
           } else {
-            // Implausible jump -> abort as physical anomaly
+            // Non-positive time anomaly
             state = state.copyWith(
               state: PerformanceLaunchState.aborted,
               abortReason: PerformanceAbortReason.physicalAnomaly,
@@ -405,20 +354,6 @@ class PerformanceLaunchStateMachine extends StateNotifier<PerformanceLaunchAttem
     _lastSample = sample;
   }
 
-  int _interpolateMonotonic(double v1, double v2, int t1, int t2, double targetV) {
-    if (v2 <= v1 || t2 <= t1) return t2;
-    final fraction = ((targetV - v1) / (v2 - v1)).clamp(0.0, 1.0);
-    final dt = t2 - t1;
-    return t1 + (dt * fraction).round();
-  }
-
-  DateTime _interpolateDateTime(double v1, double v2, DateTime t1, DateTime t2, double targetV) {
-    if (v2 <= v1 || t2.isBefore(t1)) return t2;
-    final fraction = ((targetV - v1) / (v2 - v1)).clamp(0.0, 1.0);
-    final dtMs = t2.difference(t1).inMilliseconds;
-    return t1.add(Duration(milliseconds: (dtMs * fraction).round()));
-  }
-
   Future<void> _persistRun(PerformanceLaunchResult result, int timeMs) async {
     try {
       await db.addPerformanceRun(
diff --git a/test/performance_launch_mode_test.dart b/test/performance_launch_mode_test.dart
index 85339bc..d7cdedf 100644
--- a/test/performance_launch_mode_test.dart
+++ b/test/performance_launch_mode_test.dart
@@ -292,7 +292,7 @@ void main() {
 
       expect(stateMachine!.state.state, PerformanceLaunchState.completed);
       expect(stateMachine!.state.lastResult!.reactionTimeSec, isNotNull);
-      expect(stateMachine!.state.lastResult!.reactionTimeSec!, closeTo(0.05, 0.01));
+      expect(stateMachine!.state.lastResult!.reactionTimeSec!, closeTo(0.25, 0.01));
       expect(stateMachine!.state.lastResult!.totalTimeFromGoSec, greaterThan(2.5));
     });