Alert on genuinely new (never-seen-before) devices

New seen_macs table: permanent, insert-only, MAC-keyed record of the
first time each device was ever seen -- deliberately decoupled from
devices.first_seen (IP-keyed, would false-positive on every DHCP
lease change). Bootstrap-safe: first call seeds the baseline from
whatever's currently on the network without alerting on all 71+
existing devices at once. Verified locally: bootstrap call reports
nothing new, repeat calls with the same MACs report nothing new, one
genuinely new MAC gets reported exactly once.

Pushes a Home Assistant persistent_notification when a new MAC
appears (gated behind HOME_ASSISTANT_TOKEN + homeAssistant.url in
hosts.yaml -- missing config just means no push, detection still
runs). Also surfaced directly in the dashboard as a blue "new" badge
for anything first seen in the last 24h, independent of HA config.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/api/src/discovery/index.ts

@@ -1,6 +1,11 @@
 import { readFile } from "node:fs/promises";
 import type Database from "better-sqlite3";
-import { upsertDevices, type DiscoveredDevice } from "../db/index.js";
+import { upsertDevices, recordSeenMacs, type DiscoveredDevice } from "../db/index.js";
+import { notifyNewDevices, type HomeAssistantConfig, type NewDeviceInfo } from "./homeAssistant.js";
+// mac-oui-lookup is CommonJS; see routes/devices.ts for why this needs the
+// default-import-and-destructure form instead of a named import.
+import macOuiLookup from "mac-oui-lookup";
+const { getVendor } = macOuiLookup;
 
 interface RawEntry {
   ip: string;
@@ -15,7 +20,9 @@ interface RawEntry {
 export async function refreshDevices(
   db: Database.Database,
   filePath: string,
-  knownDevices: Map<string, string>
+  knownDevices: Map<string, string>,
+  homeAssistant: HomeAssistantConfig | undefined,
+  onNotifyError: (err: unknown) => void
 ): Promise<void> {
   let raw: RawEntry[];
   try {
@@ -35,4 +42,21 @@ export async function refreshDevices(
   }));
 
   upsertDevices(db, devices);
+
+  const newMacs = new Set(recordSeenMacs(db, raw.map((r) => r.mac)));
+  if (newMacs.size > 0 && homeAssistant) {
+    const newDevices: NewDeviceInfo[] = raw
+      .filter((r) => newMacs.has(r.mac))
+      .map((r) => ({
+        ip: r.ip,
+        mac: r.mac,
+        vendor: getVendor(r.mac),
+        name: knownDevices.get(r.ip) ?? r.mdnsHostname ?? null,
+      }));
+    try {
+      await notifyNewDevices(homeAssistant, newDevices);
+    } catch (err) {
+      onNotifyError(err);
+    }
+  }
 }