[Bug]: OpenCode Zen Big Pickle reasoning_content must be passed back to the API

[oniony]

Bug Description

Similar to #3146, I'm seeing this error using OpenCode Zen Big Pickle.

Steps to Reproduce

1. Switch to provider OpenCode Zen
2. Switch to model Big Pickle
3. Enter any prompt

Expected Behavior

No, error, response to my query.

Actual Behavior

I get the following error:

● [16:54:45] ERROR: POST https://opencode.ai/zen/v1/chat/completions

Caused by:
    0: 400 Bad Request Reason: {"error":{"message":"Error from provider (DeepSeek): The `reasoning_content` in the thinking mode must be passed back to the API.","type":"invalid_request_error","param":null,"code":"invalid_request_error"}}
    1: Invalid Status Code: 400

Forge Version

v2.12.16

Operating System & Version

Arch Linux 7.0.9-arch1-1

AI Provider

Other

Model

OpenCode Big Pickle

Installation Method

Other

Configuration

n/a

[oniony]

Note the error mentions DeepSeek as I think BigPickle must be routing to DeepSeek.