Continue new scrapes where the last complete one started

media-scrape/src/store.ts

@@ -657,15 +657,27 @@ export class ScrapeStore {
             .run(preview.hash, preview.bytes, preview.ext ?? "webp", id);
     }
 
-    /** Message span of the walk, for completeness checks. */
-    dbSummary(): { messages: number; oldest: string | null; newest: string | null } {
+    /** Message span of the walk, for completeness checks and incremental scrapes. */
+    dbSummary(): {
+        messages: number;
+        oldest: string | null;
+        newest: string | null;
+        newestId: string | null;
+    } {
         const row = this.db
             .prepare(
-                "SELECT COUNT(*) AS messages, MIN(timestamp) AS oldest, MAX(timestamp) AS newest FROM messages"
+                "SELECT COUNT(*) AS messages, MIN(timestamp) AS oldest, MAX(timestamp) AS newest, MAX(id) AS newestId FROM messages"
             )
-            .get() as { messages: number; oldest: string | null; newest: string | null } | undefined;
+            .get() as
+            | { messages: number; oldest: string | null; newest: string | null; newestId: string | null }
+            | undefined;
 
-        return { messages: row?.messages ?? 0, oldest: row?.oldest ?? null, newest: row?.newest ?? null };
+        return {
+            messages: row?.messages ?? 0,
+            oldest: row?.oldest ?? null,
+            newest: row?.newest ?? null,
+            newestId: row?.newestId ?? null
+        };
     }
 
     /** Preview state for the whole scrape and per kind, for the backfill UI. */

media-scrape/test/run.ts

@@ -1437,6 +1437,23 @@ void (async () => {
         reopened.close();
     });
 
+    await test("dbSummary reports the message span and newest id", () => {
+        const dir = join(root, "summary");
+        mkdirSync(dir, { recursive: true });
+        const store = new ScrapeStore(dir);
+        store.insertPage([
+            message("1800", { timestamp: "2026-09-16T00:00:00.000Z" }),
+            message("1801", { timestamp: "2026-09-17T00:00:00.000Z" })
+        ]);
+
+        const summary = store.dbSummary();
+        assert.equal(summary.messages, 2);
+        assert.equal(summary.oldest, "2026-09-16T00:00:00.000Z");
+        assert.equal(summary.newest, "2026-09-17T00:00:00.000Z");
+        assert.equal(summary.newestId, "1801");
+        store.close();
+    });
+
     await test("message links build for guilds and DMs", () => {
         assert.equal(messageUrlFor("123", "456", "789"), "https://discord.com/channels/123/456/789");
         assert.equal(messageUrlFor(null, "456", "789"), "https://discord.com/channels/@me/456/789");