diff --git a/app/src/main/java/com/mindmachine/mvp/MainActivity.kt b/app/src/main/java/com/mindmachine/mvp/MainActivity.kt
index 35c24b1..148abfa 100644
--- a/app/src/main/java/com/mindmachine/mvp/MainActivity.kt
+++ b/app/src/main/java/com/mindmachine/mvp/MainActivity.kt
@@ -812,14 +812,25 @@ private fun rememberSplitFlashFrame(
             return@produceState
         }
 
+        // Lock the sequencer's time base to Compose's frame clock.
+        // Mixing System.nanoTime() (start) with withFrameNanos() (updates) can introduce
+        // an arbitrary offset that looks like irregular intervals.
         val sequencer = SplitFlashSequencer(
-            startTimeNanos = System.nanoTime(),
+            startTimeNanos = 0L,
             flashOnMs = latestFlashOnMs.value,
             flashOffMs = latestFlashOffMs.value,
         )
 
+        var started = false
+
         while (true) {
             withFrameNanos { frameTimeNanos ->
+                if (!started) {
+                    // Initialize phaseStartNanos to the first real frame timestamp.
+                    // This keeps phase transitions aligned to the same monotonic clock.
+                    sequencer.frameAt(frameTimeNanos)
+                    started = true
+                }
                 sequencer.updateIntervals(latestFlashOnMs.value, latestFlashOffMs.value)
                 value = sequencer.frameAt(frameTimeNanos)
             }