diff --git a/FEATURES.md b/FEATURES.md
index 274a1f7e..ab7791be 100644
--- a/FEATURES.md
+++ b/FEATURES.md
@@ -74,7 +74,10 @@ Phase 2 ✅ (auto-fit Map view with cos(lat) aspect compensation; LEFT/RIGHT cyc
     and total distance skips segment boundaries
 Phase 3 ✅ (per-point list view with HH:MM local time + delta-from-previous;
    segment-start rows show "start" instead of a delta)
-Phase 4 📋 (context menu: reset, save → slot N, load ← slot N, GPX export over USB)
+Phase 4 ✅ (Hold-Enter popup grows Save / Load / Reset / Export GPX entries.
+   Single flash slot at /trail (binary header with magic+version+count+
+   accumulated_ms then raw TrailPoint records). GPX 1.1 dump goes over USB
+   Serial; segments respect SEG_START boundaries)
 Phase 5 ✅ (Settings + actions consolidated into a single Hold-Enter popup —
    Min dist + Units cycled with LEFT/RIGHT (popup stays open), plus
    Start/Stop tracking and Reset action items. Short Enter never toggles —