don't block during scan

src/lib/scanner.ts

@@ -573,29 +573,37 @@ async function scanComics(library: Library, libraryRoot: string): Promise<void>
       scanned_at = excluded.scanned_at
   `)
 
+  type SeriesRec = Parameters<typeof upsertSeries.run>[0]
+  type IssueRec  = Parameters<typeof upsertIssue.run>[0]
+  type BatchEntry = { type: 'series'; rec: SeriesRec } | { type: 'issue'; rec: IssueRec }
+
+  // Collect all records before touching the DB so we can batch-insert with event-loop yields.
+  // Note: between clearLibraryItems and the final batch, the library will appear partially
+  // populated — acceptable for a background scan.
+  const allRecords: BatchEntry[] = []
   let issueCount = 0
 
-  db.transaction(() => {
-    for (const item of items) {
-      if ('issues' in item) {
-        const series = item as ScannedComicSeries
-        const seriesKey = `${library.id}:comic_series:${series.id}`
-        upsertSeries.run({
+  for (const item of items) {
+    if ('issues' in item) {
+      const series = item as ScannedComicSeries
+      const seriesKey = `${library.id}:comic_series:${series.id}`
+      allRecords.push({
+        type: 'series',
+        rec: {
           library_id: library.id,
           item_key: seriesKey,
           item_type: 'comic_series',
           title: series.title,
-          metadata: JSON.stringify({
-            issueCount: series.issueCount,
-            coverUrl: series.coverUrl,
-          }),
+          metadata: JSON.stringify({ issueCount: series.issueCount, coverUrl: series.coverUrl }),
           file_path: null,
           scanned_at: now,
-        })
-
-        for (const issue of series.issues) {
-          const issueKey = `${library.id}:comic_issue:${issue.id}`
-          upsertIssue.run({
+        },
+      })
+      for (const issue of series.issues) {
+        const issueKey = `${library.id}:comic_issue:${issue.id}`
+        allRecords.push({
+          type: 'issue',
+          rec: {
             library_id: library.id,
             item_key: issueKey,
             item_type: 'comic_issue',
@@ -609,13 +617,16 @@ async function scanComics(library: Library, libraryRoot: string): Promise<void>
             }),
             file_path: issue.filePath,
             scanned_at: now,
-          })
-          issueCount++
-        }
-      } else {
-        const issue = item as ComicIssue
-        const issueKey = `${library.id}:comic_issue:${issue.id}`
-        upsertIssue.run({
+          },
+        })
+        issueCount++
+      }
+    } else {
+      const issue = item as ComicIssue
+      const issueKey = `${library.id}:comic_issue:${issue.id}`
+      allRecords.push({
+        type: 'issue',
+        rec: {
           library_id: library.id,
           item_key: issueKey,
           item_type: 'comic_issue',
@@ -629,13 +640,27 @@ async function scanComics(library: Library, libraryRoot: string): Promise<void>
           }),
           file_path: issue.filePath,
           scanned_at: now,
-        })
-        issueCount++
-      }
+        },
+      })
+      issueCount++
     }
-  })()
+  }
 
-  // Prewarm CBZ cover thumbnails
+  // Insert in batches of 500, yielding the event loop between batches so the app
+  // remains responsive to HTTP requests during a large scan.
+  const BATCH_SIZE = 500
+  for (let i = 0; i < allRecords.length; i += BATCH_SIZE) {
+    const batch = allRecords.slice(i, i + BATCH_SIZE)
+    db.transaction(() => {
+      for (const entry of batch) {
+        if (entry.type === 'series') upsertSeries.run(entry.rec)
+        else upsertIssue.run(entry.rec)
+      }
+    })()
+    await new Promise<void>((r) => setImmediate(r))
+  }
+
+  // Prewarm CBZ cover thumbnails — fire-and-forget so they don't block scan completion.
   for (const item of items) {
     const issuesToWarm: ComicIssue[] = 'issues' in item
       ? (item as ScannedComicSeries).issues.slice(0, 1)
@@ -643,11 +668,9 @@ async function scanComics(library: Library, libraryRoot: string): Promise<void>
 
     for (const issue of issuesToWarm) {
       const absPath = path.join(libraryRoot, issue.filePath)
-      try {
-        await getCbzThumbnailPath(absPath, library.id)
-      } catch (err) {
+      getCbzThumbnailPath(absPath, library.id).catch((err) => {
         console.warn(`[scanner]   Could not generate CBZ thumbnail for ${issue.filePath}:`, err instanceof Error ? err.message : err)
-      }
+      })
     }
   }