diff --git a/Packages/StrandAnalytics/Sources/StrandAnalytics/WorkoutDetector.swift b/Packages/StrandAnalytics/Sources/StrandAnalytics/WorkoutDetector.swift
index 40e5ccff7e..70b3090cbd 100644
--- a/Packages/StrandAnalytics/Sources/StrandAnalytics/WorkoutDetector.swift
+++ b/Packages/StrandAnalytics/Sources/StrandAnalytics/WorkoutDetector.swift
@@ -372,8 +372,8 @@ public enum WorkoutDetector {
 
     /// #510: backfill ONLY the avgHr/maxHr/energyKcal/strain fields `real` doesn't already have, from a
     /// detected bout's own computed values — never touching a field that's already present, whether
-    /// typed by the user, imported, or filled by an earlier pass. `real` unchanged (`==`) means it
-    /// already had everything, so the caller can tell whether a write is actually needed. Kotlin twin
+    /// typed by the user, imported, or filled by an earlier pass. `real` unchanged (`==`) means no
+    /// available value was filled, so the caller can tell whether a write is actually needed. Kotlin twin
     /// IntelligenceEngine.backfillWorkoutFromDetectedBout.
     public static func backfillWorkout(_ real: WorkoutRow, avgBpm: Int, peakHR: Int, caloriesKcal: Double?, strain: Double?) -> WorkoutRow {
         WorkoutRow(
@@ -383,7 +383,8 @@ public enum WorkoutDetector {
             avgHr: real.avgHr ?? avgBpm,
             maxHr: real.maxHr ?? peakHR,
             strain: real.strain ?? strain,
-            distanceM: real.distanceM, zonesJSON: real.zonesJSON, notes: real.notes)
+            distanceM: real.distanceM, zonesJSON: real.zonesJSON, notes: real.notes,
+            steps: real.steps)
     }
 }
 
diff --git a/Packages/StrandAnalytics/Tests/StrandAnalyticsTests/WorkoutDetectorBackfillTests.swift b/Packages/StrandAnalytics/Tests/StrandAnalyticsTests/WorkoutDetectorBackfillTests.swift
index 558f3b3c8b..ce122b41a7 100644
--- a/Packages/StrandAnalytics/Tests/StrandAnalyticsTests/WorkoutDetectorBackfillTests.swift
+++ b/Packages/StrandAnalytics/Tests/StrandAnalyticsTests/WorkoutDetectorBackfillTests.swift
@@ -8,19 +8,21 @@ import WhoopStore
 /// though the detector had already computed a valid average for that exact window.
 final class WorkoutDetectorBackfillTests: XCTestCase {
 
-    private func manualRow(avgHr: Int? = nil, maxHr: Int? = nil, energyKcal: Double? = nil, strain: Double? = nil) -> WorkoutRow {
+    private func manualRow(avgHr: Int? = nil, maxHr: Int? = nil, energyKcal: Double? = nil,
+                           strain: Double? = nil, steps: Int? = 4_200) -> WorkoutRow {
         WorkoutRow(startTs: 1_000, endTs: 1_600, sport: "Running", source: "manual",
                    durationS: 600, energyKcal: energyKcal, avgHr: avgHr, maxHr: maxHr,
-                   strain: strain, distanceM: nil, zonesJSON: nil, notes: nil)
+                   strain: strain, distanceM: nil, zonesJSON: nil, notes: nil, steps: steps)
     }
 
-    func testFillsAllMissingFields() {
+    func testFillsAllMissingFieldsAndPreservesSteps() {
         let real = manualRow()
         let filled = WorkoutDetector.backfillWorkout(real, avgBpm: 150, peakHR: 170, caloriesKcal: 80.0, strain: 9.5)
         XCTAssertEqual(filled.avgHr, 150)
         XCTAssertEqual(filled.maxHr, 170)
         XCTAssertEqual(filled.energyKcal, 80.0)
         XCTAssertEqual(filled.strain, 9.5)
+        XCTAssertEqual(filled.steps, 4_200, "stored per-session steps must survive backfill")
         // The rest of the row is carried over untouched.
         XCTAssertEqual(filled.startTs, real.startTs)
         XCTAssertEqual(filled.sport, real.sport)
@@ -37,7 +39,7 @@ final class WorkoutDetectorBackfillTests: XCTestCase {
         XCTAssertEqual(filled.strain, 9.5, "a missing field must still be filled")
     }
 
-    func testRowWithEverythingAlreadyPresentIsUnchanged() {
+    func testRowWithStepsAndEverythingAlreadyPresentIsUnchanged() {
         let real = manualRow(avgHr: 140, maxHr: 160, energyKcal: 50.0, strain: 8.0)
         let filled = WorkoutDetector.backfillWorkout(real, avgBpm: 150, peakHR: 170, caloriesKcal: 80.0, strain: 9.5)
         XCTAssertEqual(filled, real, "nothing to fill -> byte-identical row, so the caller can skip the write")