diff --git a/apps/api/src/db/index.ts b/apps/api/src/db/index.ts
index 671b417..064e566 100644
--- a/apps/api/src/db/index.ts
+++ b/apps/api/src/db/index.ts
@@ -58,10 +58,16 @@ export function openDb(path: string): Database.Database {
     -- Deliberately separate from the devices table (keyed by IP, which churns
     -- on DHCP renewal) -- keying "have we ever seen this MAC" by IP would
     -- generate a false new-device alert every time an existing device's
-    -- lease just happened to change.
+    -- lease just happened to change. is_bootstrap marks rows seeded by the
+    -- very first (empty-table) call -- without it, the "New" UI badge (which
+    -- just checks "seen within 24h") would flag the entire pre-existing
+    -- device population as new on the day this feature is first deployed,
+    -- since bootstrap timestamps are, correctly, "now". Caught by actually
+    -- checking the deployed API response, not just the notification-side unit test.
     CREATE TABLE IF NOT EXISTS seen_macs (
       mac TEXT PRIMARY KEY,
-      first_seen TEXT NOT NULL DEFAULT (datetime('now'))
+      first_seen TEXT NOT NULL DEFAULT (datetime('now')),
+      is_bootstrap INTEGER NOT NULL DEFAULT 0
     );
   `);
   // Migration for the devices table pre-dating mdns_hostname (CREATE TABLE IF
@@ -73,6 +79,19 @@ export function openDb(path: string): Database.Database {
     (c) => c.name === "mdns_hostname"
   );
   if (!hasMdnsColumn) db.exec(`ALTER TABLE devices ADD COLUMN mdns_hostname TEXT`);
+
+  // Same situation for seen_macs.is_bootstrap. Any rows that already existed
+  // before this column was added were, by definition, from a table that had
+  // no bootstrap tracking at all -- backfill them as bootstrap rows (the
+  // true history) so they don't show up as "new" in the UI once this
+  // migration lands on an already-deployed instance.
+  const hasBootstrapColumn = (db.pragma("table_info(seen_macs)") as { name: string }[]).some(
+    (c) => c.name === "is_bootstrap"
+  );
+  if (!hasBootstrapColumn) {
+    db.exec(`ALTER TABLE seen_macs ADD COLUMN is_bootstrap INTEGER NOT NULL DEFAULT 0`);
+    db.exec(`UPDATE seen_macs SET is_bootstrap = 1`);
+  }
   return db;
 }
 
@@ -196,6 +215,7 @@ export interface DeviceRow {
   first_seen: string;
   last_seen: string;
   first_ever_seen: string | null;
+  is_bootstrap: number | null;
 }
 
 // Devices not seen in the last 24h (unplugged, moved, DHCP lease expired) are
@@ -210,7 +230,7 @@ export function getRecentDevices(db: Database.Database, sinceHours = 24): Device
   return db
     .prepare(
       `SELECT d.ip, d.mac, d.known_name, d.mdns_hostname, l.label AS manual_label,
-              d.first_seen, d.last_seen, s.first_seen AS first_ever_seen
+              d.first_seen, d.last_seen, s.first_seen AS first_ever_seen, s.is_bootstrap
        FROM devices d
        LEFT JOIN device_labels l ON l.mac = d.mac
        LEFT JOIN seen_macs s ON s.mac = d.mac
@@ -250,9 +270,11 @@ export function recordSeenMacs(db: Database.Database, macs: string[]): string[]
   );
   const newMacs = macs.filter((mac) => !alreadySeen.has(mac));
 
-  const insert = db.prepare(`INSERT OR IGNORE INTO seen_macs (mac) VALUES (@mac)`);
+  const insert = db.prepare(
+    `INSERT OR IGNORE INTO seen_macs (mac, is_bootstrap) VALUES (@mac, @isBootstrap)`
+  );
   const tx = db.transaction((items: string[]) => {
-    for (const mac of items) insert.run({ mac });
+    for (const mac of items) insert.run({ mac, isBootstrap: isBootstrap ? 1 : 0 });
   });
   tx(macs);
 
diff --git a/apps/api/src/routes/devices.ts b/apps/api/src/routes/devices.ts
index ab37316..236b230 100644
--- a/apps/api/src/routes/devices.ts
+++ b/apps/api/src/routes/devices.ts
@@ -37,6 +37,11 @@ function isRecent(isoTimestamp: string | null, hours: number): boolean {
 
 function toApiDevice(r: DeviceRow) {
   const name = r.manual_label ?? r.known_name ?? null;
+  // is_bootstrap excludes devices that were only ever "new" because this
+  // feature had just been turned on, not because they actually just
+  // appeared -- otherwise the whole pre-existing device population shows as
+  // "new" for 24h after every fresh deploy of this feature.
+  const isNew = r.is_bootstrap === 0 && isRecent(r.first_ever_seen, NEW_DEVICE_WINDOW_HOURS);
   return {
     ip: r.ip,
     mac: r.mac,
@@ -44,7 +49,7 @@ function toApiDevice(r: DeviceRow) {
     known: r.manual_label !== null || r.known_name !== null,
     vendor: getVendor(r.mac),
     mdnsHostname: r.mdns_hostname,
-    isNew: isRecent(r.first_ever_seen, NEW_DEVICE_WINDOW_HOURS),
+    isNew,
     firstSeen: r.first_seen,
     lastSeen: r.last_seen,
   };