Add Extend prompt + custom start image controls (README.md)

README.md

@@ -13,16 +13,18 @@ short_description: Wan 2.2 I2V + Extend chaining for ~10–20s clips
 
 # Wan 2.2 Image → Video + Extend
 
-Private helper Space for **Casey (Simzy)**: generate a short [Wan 2.2](https://huggingface.co/spaces/kulkas2pintu/wan222) image-to-video clip on **free ZeroGPU**, then **Extend** by chaining from the last frame until you reach roughly **10–20 seconds**.
+Private helper Space for **Casey (Simzy)**: generate a short [Wan 2.2](https://huggingface.co/spaces/kulkas2pintu/wan222) image-to-video clip on **free ZeroGPU**, then **Extend** by chaining until you reach roughly **10–20 seconds**.
 
 This Space does **not** load the 14B Wan weights itself. It calls the public ZeroGPU Space `kulkas2pintu/wan222` via `gradio_client`, then stitches segments with ffmpeg.
 
 ## How to use
 
-1. Upload a still image and write a motion prompt.
+1. Upload a still image and write a **Generate prompt**.
 2. Click **Generate** — wait for ZeroGPU (often 1–3 minutes when busy).
-3. Click **Extend** to continue from the last frame (same or updated prompt).
-4. Or set a target length and use **Auto-extend** (capped at 6 segments).
+3. Optionally set an **Extend prompt** (leave blank to reuse Generate prompt) and choose **Extend start**:
+   - **Last frame from video** (default) — current behavior
+   - **Upload custom image** — use a different image as the I2V start for the next segment
+4. Click **Extend** to continue, or set a target length and use **Auto-extend** (capped at 6 segments).
 5. Download the concatenated MP4.
 
 ### Length guide
@@ -43,7 +45,7 @@ This Space does **not** load the 14B Wan weights itself. It calls the public Zer
 
 ```
 [Your image] → Generate → clip1.mp4
-                              ↓ last frame
+                              ↓ last frame (or custom upload)
                          Extend → clip2.mp4 → ffmpeg concat → longer.mp4
                               ↓ …
 ```
@@ -53,6 +55,8 @@ Upstream API: `generate_video` on `kulkas2pintu/wan222` (same endpoint used by C
 ## Local files
 
 Source also lives at `/workspace/wan22-extend/` on the agent box for re-push if needed.
+Safe snapshot of v1: `/workspace/wan22-extend-snapshots/v1-working-20260922-055108/` (+ `.tgz`).
+HF branch `backup-v1-working` is frozen and should not be overwritten.
 
 ## License / ToS