[BUG] DeepSeek V4 Flash Vision Exp on OpenCode Go incorrectly limited to 4 images per request #47965

Description

When using deepseek-v4-flash-vision-exp through OpenCode Go, a session that uses several images eventually fails with:

Streaming response failed: [400] At most 4 image(s) may be provided in one prompt. (parameter=image)

This appears specific to deepseek-v4-flash-vision-exp on OpenCode Go.

According to the official DeepSeek Vision API documentation, this model supports up to 600 images per request, not 4.

Steps to reproduce

1. Use OpenCode Go.
2. Select deepseek-v4-flash-vision-exp.
3. Have the agent process more than 4 images/screenshots during a session.
4. Continue the session.

Actual behavior

The request fails with:

[400] At most 4 image(s) may be provided in one prompt. (parameter=image)

After the images accumulate in conversation history, subsequent requests can also fail because those images continue to be included.

Expected behavior

deepseek-v4-flash-vision-exp should not be restricted to 4 images when the upstream model supports substantially more.

OpenCode Go should either:

• use the correct image limit for this model, or
• document why the OpenCode Go deployment intentionally has a lower limit.

Additional context

DeepSeek documentation currently lists:

Max images per request: 600

This may also interact with the session-history issue discussed in #47493, where OpenCode keeps previous images in outgoing requests.

However, the primary issue here appears to be the unexpectedly low 4-image limit specifically for DeepSeek V4 Flash Vision Exp on OpenCode Go.