Grok Imagine Extend is Grok's video extend & retake model on Versely. This page is its structured prompting reference: the 1 parameters its schema actually exposes, the extend-retake technique that applies to it, copy-ready templates.
Everything here is grounded in the same sources Versely's agent reads — the model's input schema. Where a line is general craft advice rather than a documented fact about Grok Imagine Extend, the page says so.
What Grok Imagine Extend wants
The exact input surface, from the same schema the Versely agent fetches with get_model_input_schema before every generation.
| Parameter | What it does | Values |
|---|---|---|
promptreq | Continuation guidance (REQUIRED per docs) | string |
- — Only accepts prior Grok Imagine taskIds — external URLs rejected
- — Verified against docs.kie.ai/market/grok-imagine/extend
Technique that applies here
Extend/retake: continuing or re-rolling an existing generated clip
- This family covers two different operations, and knowing which one you're on changes what the prompt should say: continuing past the end of a clip (Flux 3 Extend Video, Grok Imagine Extend, VEO 3.1 Extend Video — all take a 'what happens next' prompt) versus redoing a segment inside an existing clip (LTX 2.3 Retake Video — takes an edit instruction, per the schema's own example, 'Remove the man').
- VEO 3.1 Extend Video's duration is locked to exactly '7s' per call — the schema note explains the OpenAPI spec shows a free string but the live endpoint only validates the literal '7s' (a 422 error otherwise, reproduced 2026-07-31); 'up to 30s' describes the total you reach by chaining multiple extend calls, not a single request. Write each extend prompt for one 7-second beat, then issue a fresh extend call — with a fresh prompt — for the next one.
- Grok Imagine Extend only continues clips your own account generated with it: input.task_id takes a prior Grok Imagine taskId, and the schema notes 'external URLs rejected.' It also exposes input.extend_at (seconds, default '0') to choose which point in the source clip the continuation branches from, and a required input.extend_times enum (6 or 10) for how many seconds of new footage to generate.
Copy-ready templates
Replace the bracketed slots; each template says when it's the right shape.
[WHAT HAPPENS NEXT], camera [dolly in / crane up / steadicam follow / static hold], [LIGHTING CONTINUITY NOTE matching the source clip]
Use when: Extending a VEO 3.1 clip one 7-second beat at a time (duration is locked to '7s' per call).
[CONTINUATION: what happens next in the shot] — extend_at: [X]s, extend_times: [6 or 10]
Use when: Continuing your own prior Grok Imagine Extend generation (it only accepts that generation's taskId, never an uploaded video).
How the Versely agent does this automatically
You can use this page by hand, or let the agent apply the same knowledge. Four real mechanisms — no more, no less:
get_model_input_schema— before generating, the agent looks up Grok Imagine Extend's exact input fields, required fields, allowed values, defaults, and min/max bounds. The parameter table above is that same surface.- The prompt enhancer's family rules — 12 per-family rewrite rules (this model's family isn't one of the 12, so only general enhancement applies) shape how a rough prompt gets rewritten.
- The per-provider speech guide — for TTS scripts, the agent follows a provider-specific tag scheme — not relevant to this model, but it's why voiceover scripts come out marked up correctly.
expand_movie_scene— in movie flows, brief scene ideas are rewritten into detailed cinematic descriptions before generation.
Mistakes that waste generations
- Feeding Grok Imagine Extend an uploaded or external video URL — the schema only accepts a prior Grok Imagine task_id, and external URLs are rejected per the docs note.
- Requesting a 10s or 15s VEO 3.1 extend in one call — the live endpoint only validates the literal '7s'; asking for anything else returns a 422 even though the field looks like a free string in the OpenAPI spec.
- Writing an LTX Retake prompt like a continuation ('then she walks off screen') — the field is an edit instruction over an existing segment defined by start_time and duration, not a description of new footage after the clip ends.
Frequently asked questions
Does Grok Imagine Extend support negative prompts?+
No — Grok Imagine Extend's published schema has no negative_prompt parameter. Exclusions have to be phrased positively inside the main prompt, or dropped.
How does the Versely agent know Grok Imagine Extend's parameters?+
Before generating, the agent calls its get_model_input_schema tool, which looks up the exact input fields, required fields, allowed values, defaults, and min/max bounds for the model. Nothing on this page is guessed — it is the same schema surface those tools read.
Related prompting guides
Generate with Grok Imagine Extend
Grok Imagine Extend is live in Versely — paste a template above, or just describe what you want and let the agent map it onto the schema for you.