From 43ce4514c4daba2ac58851b338626fb6ab396aa6 Mon Sep 17 00:00:00 2001
From: Sam Rolfe <samuelrolfe@gmail.com>
Date: Mon, 10 Aug 2026 19:17:58 +1000
Subject: [PATCH] location-first scan: geolocation prompt decides the scan (8s
 fallback to plain scan, never blocks); server 'location upgrade' rule
 re-alerts with map link when coords arrive after a no-loc alert

---
 frontend/internal/handlers/scan.go | 6 ++++--
 frontend/templates/tag-public.html | 8 ++++----
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/frontend/internal/handlers/scan.go b/frontend/internal/handlers/scan.go
index 7a161cc..1a51857 100644
--- a/frontend/internal/handlers/scan.go
+++ b/frontend/internal/handlers/scan.go
@@ -162,11 +162,13 @@ func (a *App) shouldAlert(ctx context.Context, tag db.Tag, scan db.Scan, hasLoc
 
 	// Within the window?
 	if time.Since(last.ScannedAt.Time) < alertWindow {
-		// Re-alert on movement >250 m, or a different finder phone.
+		// Re-alert on movement >250 m, a different finder phone, or a location
+		// upgrade (previous alert had no coords — send the map link).
 		moved := hasLoc && last.Lat.Valid && last.Lng.Valid &&
 			sms.HaversineMeters(last.Lat.Float64, last.Lng.Float64, *lat, *lng) > alertMinDistance
+		locationUpgrade := hasLoc && !last.Lat.Valid
 		differentPhone := phone != "" && phone != last.ScannerPhone.String
-		return moved || differentPhone, ""
+		return moved || locationUpgrade || differentPhone, ""
 	}
 	return true, ""
 }
diff --git a/frontend/templates/tag-public.html b/frontend/templates/tag-public.html
index e24462c..584ec65 100644
--- a/frontend/templates/tag-public.html
+++ b/frontend/templates/tag-public.html
@@ -142,12 +142,12 @@
             function () {
               sendScan(null, null); // no location — page still works, button stays
             },
-            {timeout: 20000, maximumAge: 0}
+            {timeout: 8000, maximumAge: 0}
           );
         }
-        // Fire a scan immediately so a tag view always reports (and alerts) —
-        // location is an upgrade, never a gate.
-        sendScan(null, null);
+        // Location-first: send coords when the finder approves. If the prompt is
+        // denied, unsupported, or silently blocked (8s), fall back to a plain scan
+        // so every tag view still reports.
         if (btn) btn.addEventListener("click", tryLocation);
         tryLocation();
       })();