Group extension chains in the library and add shot-script queues.

Keep every saved segment, show the longest clip with an expand list, branch on extend, and parse shot 2/3 blocks into a shared-duration queue with live part status.

server/api/generate.post.ts

@@ -169,7 +169,8 @@ export default defineEventHandler(async (event) => {
     chainIndex: 0,
     chainStep: 1,
     chainTotal,
-    chainLabel: extensions.length ? 'Initial' : undefined
+    chainLabel: extensions.length ? 'Initial' : undefined,
+    familyId: crypto.randomUUID()
   }
   emitChainJob(job, { type: 'status', message: 'Checking ComfyUI...', progress: 1 })
 
@@ -341,7 +342,10 @@ async function queueMiniMax(
       imageName: job.library.imageName,
       imageSubfolder: job.library.imageSubfolder,
       extendTmpDir: job.library.extendTmpDir,
-      extendPart1Path: job.library.extendPart1Path
+      extendPart1Path: job.library.extendPart1Path,
+      familyId: job.library.familyId,
+      parentClipId: job.library.parentClipId,
+      chainIndex: job.library.chainIndex
     })
   }
   emitChainJob(job, { type: 'status', message: 'Job queued on ComfyUI', progress: 8 })