feat(register): key devices by deviceId and replace FCM tokens in place

Require deviceId on POST /notifications/register, upsert by deviceId
while preserving lastNotifiedAt and internal id, prune duplicate token
rows, migrate legacy fcmToken-keyed JSON, and add register logs.
Extend StoredRow and Device with deviceId; resolve pushes by scanning
fcmToken.

src/db/fcmTokens.ts

@@ -8,6 +8,7 @@ const dataFile = path.join(dataDir, "fcm-tokens.json");
 
 export type StoredRow = {
   id: string;
+  deviceId: string;
   fcmToken: string;
   platform: string;
   testMode?: boolean;
@@ -16,40 +17,114 @@ export type StoredRow = {
   lastNotifiedAt?: number;
 };
 
-type ParsedRow = Omit<StoredRow, "id" | "lastNotifiedAt"> & {
+type ParsedRow = {
   id?: string;
+  deviceId?: string;
+  fcmToken: string;
+  platform: string;
+  testMode?: boolean;
+  createdAt: string;
+  updatedAt: string;
   lastNotifiedAt?: number | string;
 };
 
+function mergeDeviceRows(
+  deviceId: string,
+  a: StoredRow,
+  b: StoredRow
+): StoredRow {
+  const primary =
+    new Date(a.updatedAt) >= new Date(b.updatedAt) ? a : b;
+  const lastMs = Math.max(a.lastNotifiedAt ?? 0, b.lastNotifiedAt ?? 0);
+  const created =
+    new Date(a.createdAt) <= new Date(b.createdAt)
+      ? a.createdAt
+      : b.createdAt;
+  return {
+    ...primary,
+    id: primary.id,
+    deviceId,
+    fcmToken: primary.fcmToken,
+    lastNotifiedAt: lastMs > 0 ? lastMs : undefined,
+    createdAt: created,
+  };
+}
+
+function normalizeParsedRow(
+  mapKey: string,
+  r: ParsedRow,
+  onMutate: () => void
+): StoredRow {
+  let id = r.id;
+  if (id === undefined || id === "") {
+    id = randomUUID();
+    onMutate();
+  }
+
+  let lastNotifiedAt: number | undefined;
+  if (typeof r.lastNotifiedAt === "string") {
+    const ms = Date.parse(r.lastNotifiedAt);
+    lastNotifiedAt = Number.isNaN(ms) ? undefined : ms;
+    onMutate();
+  } else if (typeof r.lastNotifiedAt === "number") {
+    lastNotifiedAt = Number.isNaN(r.lastNotifiedAt)
+      ? undefined
+      : r.lastNotifiedAt;
+  }
+
+  const deviceId = (r.deviceId ?? r.fcmToken ?? mapKey).trim();
+  if (r.deviceId === undefined || r.deviceId === "") {
+    onMutate();
+  }
+
+  return {
+    id,
+    deviceId,
+    fcmToken: r.fcmToken,
+    platform: r.platform,
+    testMode: r.testMode,
+    createdAt: r.createdAt,
+    updatedAt: r.updatedAt,
+    lastNotifiedAt,
+  };
+}
+
 async function load(): Promise<Record<string, StoredRow>> {
   try {
     const raw = await readFile(dataFile, "utf8");
-    const records = JSON.parse(raw) as Record<string, ParsedRow>;
+    const parsed = JSON.parse(raw) as Record<string, ParsedRow>;
     let dirty = false;
+    const markDirty = (): void => {
+      dirty = true;
+    };
 
-    for (const key of Object.keys(records)) {
-      let r: ParsedRow = records[key];
+    const buckets = new Map<string, StoredRow[]>();
 
-      if (r.id === undefined || r.id === "") {
-        r = { ...r, id: randomUUID() };
-        records[key] = r;
-        dirty = true;
-      }
+    for (const [mapKey, rawRow] of Object.entries(parsed)) {
+      const row = normalizeParsedRow(mapKey, rawRow, markDirty);
+      if (mapKey !== row.deviceId) markDirty();
+      const list = buckets.get(row.deviceId) ?? [];
+      list.push(row);
+      buckets.set(row.deviceId, list);
+    }
 
-      if (typeof r.lastNotifiedAt === "string") {
-        const ms = Date.parse(r.lastNotifiedAt);
-        r = {
-          ...r,
-          lastNotifiedAt: Number.isNaN(ms) ? undefined : ms,
-        };
-        records[key] = r;
-        dirty = true;
+    const out: Record<string, StoredRow> = {};
+    for (const [did, rows] of buckets) {
+      if (rows.length === 1) {
+        out[did] = rows[0];
+      } else {
+        out[did] = rows
+          .slice(1)
+          .reduce(
+            (acc, cur) => mergeDeviceRows(did, acc, cur),
+            rows[0]
+          );
+        markDirty();
       }
     }
 
-    const normalized = records as Record<string, StoredRow>;
-    if (dirty) await save(normalized);
-    return normalized;
+    if (dirty) await save(out);
+    return out;
   } catch (e: unknown) {
     const code = (e as NodeJS.ErrnoException).code;
     if (code === "ENOENT") return {};
@@ -67,17 +142,19 @@ async function save(records: Record<string, StoredRow>): Promise<void> {
 
 export const db = {
   async upsert(row: {
+    deviceId: string;
     fcmToken: string;
     platform: string;
     testMode?: boolean;
     updatedAt: Date;
   }): Promise<void> {
     const all = await load();
-    const key = row.fcmToken;
+    const key = row.deviceId;
     const prev = all[key];
     const now = row.updatedAt.toISOString();
     all[key] = {
       id: prev?.id ?? randomUUID(),
+      deviceId: row.deviceId,
       fcmToken: row.fcmToken,
       platform: row.platform,
       testMode: row.testMode,
@@ -85,6 +162,13 @@ export const db = {
       createdAt: prev?.createdAt ?? now,
       lastNotifiedAt: prev?.lastNotifiedAt,
     };
+
+    for (const k of [...Object.keys(all)]) {
+      if (k !== key && all[k].fcmToken === row.fcmToken) {
+        delete all[k];
+      }
+    }
+
     await save(all);
   },
 
@@ -93,9 +177,14 @@ export const db = {
     return Object.values(all);
   },
 
+  async getByDeviceId(deviceId: string): Promise<StoredRow | undefined> {
+    const all = await load();
+    return all[deviceId];
+  },
+
   async getByFcmToken(fcmToken: string): Promise<StoredRow | undefined> {
     const all = await load();
-    return all[fcmToken];
+    return Object.values(all).find((r) => r.fcmToken === fcmToken);
   },
 
   async update(id: string, patch: { lastNotifiedAt: number }): Promise<void> {

src/models/device.ts

@@ -1,6 +1,9 @@
 export interface Device {
+  /** Internal row id used for persistence updates. */
   id: string;
-  pushToken: string;
+  /** Client-provided stable physical device identity. */
+  deviceId: string;
+  fcmToken: string;
   platform: "ios" | "android" | "web";
   createdAt: Date;
   updatedAt: Date;

src/routes/notifications.ts

@@ -18,12 +18,17 @@ notificationsRouter.post("/refresh", async (_req, res) => {
 });
 
 notificationsRouter.post("/register", async (req, res) => {
-  const { fcmToken, platform, testMode } = req.body as {
+  const { deviceId, fcmToken, platform, testMode } = req.body as {
+    deviceId?: unknown;
     fcmToken?: unknown;
     platform?: unknown;
     testMode?: unknown;
   };
 
+  if (typeof deviceId !== "string" || deviceId.trim().length === 0) {
+    res.status(400).json({ error: "deviceId is required" });
+    return;
+  }
   if (typeof fcmToken !== "string" || fcmToken.length === 0) {
     res.status(400).json({ error: "fcmToken is required" });
     return;
@@ -33,8 +38,17 @@ notificationsRouter.post("/register", async (req, res) => {
     return;
   }
 
+  const canonicalDeviceId = deviceId.trim();
+
   try {
+    const existing = await db.getByDeviceId(canonicalDeviceId);
+    console.log("[Register] Upserting device:", canonicalDeviceId);
+    if (existing !== undefined && existing.fcmToken !== fcmToken) {
+      console.log("[Register] Replacing token for device:", canonicalDeviceId);
+    }
+
     await db.upsert({
+      deviceId: canonicalDeviceId,
       fcmToken,
       platform,
       testMode: typeof testMode === "boolean" ? testMode : undefined,