From a414f98c56efaec65c1d732eaf6729e779011411 Mon Sep 17 00:00:00 2001
From: Mitchell R <root@mitchellr.info>
Date: Sat, 23 May 2026 01:39:22 +0200
Subject: [PATCH] feat(events): dedup ONVIF events within 2s window (Hikvision
 double-fire fix)

---
 server/src/plugins/service-api-http/index.ts | 22 ++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/server/src/plugins/service-api-http/index.ts b/server/src/plugins/service-api-http/index.ts
index cebe87c..0007977 100644
--- a/server/src/plugins/service-api-http/index.ts
+++ b/server/src/plugins/service-api-http/index.ts
@@ -275,6 +275,9 @@ function registerPairingRoutes(
 
 // ---- Kiosk routes (require Bearer kiosk key) --------------------------------
 
+// Event deduplication cache: key → last-seen timestamp (ms).
+const eventDedupCache = new Map<string, number>();
+
 function registerKioskRoutes(
   app: H3,
   repo: Repository,
@@ -530,6 +533,25 @@ function registerKioskRoutes(
 
     if (!body?.topic) throw createError({ statusCode: 400, statusMessage: "topic required" });
 
+    // Dedup: Hikvision cameras send duplicate ONVIF events within ~1s.
+    // Key = kiosk_id:camera_id:topic:source_keys_hash. Window = 2s.
+    const dedupKey = `${kiosk.id}:${body.camera_id ?? 0}:${body.topic}:${JSON.stringify(body.payload?.["source"] ?? "")}`;
+    const now = Date.now();
+    if (eventDedupCache.has(dedupKey)) {
+      const lastSeen = eventDedupCache.get(dedupKey)!;
+      if (now - lastSeen < 2000) {
+        return { ok: true, event_id: null, deduplicated: true };
+      }
+    }
+    eventDedupCache.set(dedupKey, now);
+    // Trim cache periodically (prevent unbounded growth).
+    if (eventDedupCache.size > 10_000) {
+      const cutoff = now - 5000;
+      for (const [k, v] of eventDedupCache) {
+        if (v < cutoff) eventDedupCache.delete(k);
+      }
+    }
+
     const eventId = repo.insertEvent({
       source_kiosk_id: kiosk.id,
       source_camera_id: body.camera_id ?? null,