Split prompts into pre/prompt/post and tidy the AIGen video form.

Keep wrappers off the library mid-prompt so Use as input and Extend restore the same split, send stills to xAIGen as hidden inputs, and stop the two-column library from growing with the list.

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

server/utils/imageChainV2.ts

@@ -8,6 +8,7 @@ import { imageDimensions } from '~/server/utils/resolution'
 import { emitChainJob } from '~/server/utils/watch'
 import { saveStill, stillChainName } from '~/server/utils/library'
 import { comfyJobPrefix } from '~/utils/outputNames'
+import { composePromptParts } from '~/utils/promptParts'
 import { parseImageV2Engine, type ImageV2Engine, type ImageV2Mode, type ImageV2Task } from '~/utils/imageV2'
 import type { EditImageFile } from '~/server/utils/imageChain'
 
@@ -194,7 +195,7 @@ export async function runEditV2(job: Job, params: EditV2RunParams) {
           mode: params.mode,
           engine,
           task: params.task,
-          prompt,
+          prompt: composePromptParts(library.promptPre || '', prompt, library.promptPost || ''),
           negative: params.negative,
           imageAName: uploaded?.name,
           imageBName: uploadedRef?.name,
@@ -264,6 +265,8 @@ export async function runEditV2(job: Job, params: EditV2RunParams) {
           role: 'output',
           name: passName || undefined,
           prompt,
+          promptPre: library.promptPre,
+          promptPost: library.promptPost,
           familyId: library.familyId,
           parentStillId: batch ? (params.sourceStillId || library.stillId) : parentStillId,
           chainIndex: index,