Enforce 500 m minimum segment length in UI and API

bincio/serve/server.py

@@ -2445,8 +2445,8 @@ async def create_segment(
     user = _require_user(bincio_session)
     if len(body.polyline) < 2:
         raise HTTPException(400, "polyline must have at least 2 points")
-    if body.distance_m <= 0:
+    if body.distance_m < 500:
-        raise HTTPException(400, "distance_m must be positive")
+        raise HTTPException(400, "segment must be at least 500 m long")
 
     lats = [p[0] for p in body.polyline]
     lons = [p[1] for p in body.polyline]

site/src/components/SegmentCreate.svelte

@@ -53,7 +53,7 @@
   $: endPct   = maxIdx > 0 ? (endIdx   / maxIdx) * 100 : 100;
   $: selectedPolyline = gpsPoints.slice(startIdx, endIdx + 1);
   $: selectedDistance = polylineDistance(selectedPolyline);
-  $: canSave = segName.trim().length > 0 && selectedPolyline.length >= 2 && !saving;
+  $: canSave = segName.trim().length > 0 && selectedPolyline.length >= 2 && selectedDistance >= 500 && !saving;
 
   // ── Init ──────────────────────────────────────────────────────────────────
   onMount(async () => {
@@ -379,6 +379,9 @@
         <p class="text-xs text-zinc-400 mt-2">
           Selected: <span class="text-white font-medium">{formatDistance(selectedDistance)}</span>
           ({selectedPolyline.length} points)
+          {#if selectedDistance < 500}
+            <span class="text-amber-400 ml-1">— minimum 500 m</span>
+          {/if}
         </p>
       </div>