Add clip extension from the last frame with FFmpeg stitching.

Let a finished player continue into a new MiniMax segment, then losslessly concat the parts and discard the intermediate files so the library keeps one extended MP4.

Co-authored-by: Cursor <cursoragent@cursor.com>

server/api/library/clips/[id]/last-frame.get.ts

@@ -0,0 +1,25 @@
+import { existsSync, readFileSync } from 'node:fs'
+
+export default defineEventHandler(async (event) => {
+  const { owner } = assertLibraryOwner(event)
+  const id = String(getRouterParam(event, 'id') || '')
+  const clip = getClip(owner, id)
+  assertFolderAccess(event, clip.folderId)
+  const videoPath = clipVideoPath(owner, clip.id)
+  if (!existsSync(videoPath)) {
+    throw createError({ statusCode: 404, statusMessage: 'Video file is missing' })
+  }
+  const framePath = clipLastFramePath(owner, clip.id)
+  if (!existsSync(framePath)) {
+    try {
+      await extractLastFrame(videoPath, framePath)
+    } catch (error) {
+      const message = error instanceof Error ? error.message : String(error)
+      throw createError({ statusCode: 500, statusMessage: `Could not extract the last frame: ${message}` })
+    }
+  }
+  const buf = readFileSync(framePath)
+  setHeader(event, 'Content-Type', 'image/png')
+  setHeader(event, 'Cache-Control', 'private, no-store')
+  return buf
+})