Add extension-frame refine and lossless anchor options.

Prefer clip anchor PNGs for handoffs, optionally run Bilateral+Flux cleanup before I2V, and save decoded last-frame anchors so sequential extensions accumulate less compression damage.

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

server/utils/videoChain.ts

@@ -7,9 +7,13 @@ import { comfyFilenamePrefix, queuePrompt, uploadImage } from '~/server/utils/co
 import { buildWorkflow } from '~/server/utils/workflow'
 import { isLtxWorkflow, isTextToVideo, parseVideoWorkflow, workflowForExtension, type VideoWorkflowId } from '~/utils/videoModels'
 import { clipVideoPath, clipTitle, deleteRetryDraft, extendTempDir, getClip, nextFamilyPartName, removeExtendTemp, stillPath } from '~/server/utils/library'
-import { extractLastFrame, probeHasAudio } from '~/server/utils/ffmpeg'
+import { probeHasAudio } from '~/server/utils/ffmpeg'
 import { ensureComfyReady } from '~/server/utils/comfyLifecycle'
 import { onLiveVideoSettled, onStudioQueueBurstStarted } from '~/server/utils/studioQueue'
+import {
+  refineExtensionHandoffFrame,
+  resolveExtensionHandoffFrame
+} from '~/server/utils/extensionFrame'
 import {
   finishQueueBurst,
   getShotQueue,
@@ -216,6 +220,7 @@ export async function queueMiniMax(
     duration: params.duration,
     useIdentityRefs: params.useIdentityRefs,
     referenceImageNames: params.useIdentityRefs ? referenceNames : [],
+    saveLosslessAnchor: job.library?.saveLosslessAnchor === true,
     ...persistLoraFields(params.loraStack || params.loraName)
   })
 
@@ -373,7 +378,12 @@ export async function continueQueuedExtensions(
       const parentVideo = parentId ? clipVideoPath(job.library.ownerKey, parentId) : ''
       const extractSource = parentVideo && existsSync(parentVideo) ? parentVideo : part1Path
       try {
-        await extractLastFrame(extractSource, framePath)
+        await resolveExtensionHandoffFrame({
+          ownerKey: job.library.ownerKey,
+          sourceClipId: parentId,
+          sourceVideoPath: extractSource,
+          destPath: framePath
+        })
       } catch (error) {
         const detail = error instanceof Error ? error.message : String(error)
         throw new Error(detail.includes('last frame')
@@ -385,10 +395,30 @@ export async function continueQueuedExtensions(
         job.library.stopAfterCurrent = true
         break
       }
-      const frame = readFileSync(framePath)
+      let frame = readFileSync(framePath)
       if (!frame.length || frame.length < 64) {
         throw new Error('Could not extract the last frame for the next extension: the frame file was empty')
       }
+      if (job.library.refineExtensionFrame !== false) {
+        emitChainJob(job, { type: 'status', message: 'Refining extension handoff frame...', progress: 2 })
+        try {
+          frame = await refineExtensionHandoffFrame({
+            frame,
+            denoise: job.library.refinementDenoise,
+            clientId: job.clientId,
+            jobId: job.id,
+            onStatus: (message) => emitChainJob(job, { type: 'status', message, progress: 3 })
+          })
+          writeFileSync(framePath, frame)
+        } catch (error) {
+          const detail = error instanceof Error ? error.message : String(error)
+          emitChainJob(job, {
+            type: 'status',
+            message: `Frame refine skipped (${detail}). Using source frame.`,
+            progress: 3
+          })
+        }
+      }
       job.library.extendPart1Path = part1Path
       job.library.prompt = composePromptParts(wrappers.promptPre, ext.prompt, wrappers.promptPost)
       job.library.promptMid = ext.prompt