DeepSeek V4-Pro sometimes returns no visible response after API reasoning completes

Description

Bug Description

When using DeepSeek V4-Pro in OpenCode, the model occasionally enters the reasoning/thinking phase and the API request appears to complete successfully, but no final response is displayed in the chat output.

Expected Behavior

After the reasoning process finishes, the model response should be returned and rendered normally in the conversation.

Actual Behavior

The API call seems to execute normally and the model spends tokens on reasoning, but the final assistant message is missing or empty.

Possible Symptoms

The request shows as completed
Tokens are consumed
Thinking/reasoning logs may appear
No assistant reply is rendered
Sometimes the issue occurs randomly and cannot be reproduced consistently

Environment

OpenCode
Model: DeepSeek V4-Pro

Additional Notes

This issue appears intermittently and may be related to streaming, response parsing, or handling of reasoning outputs.

Plugins

zero

OpenCode version

All software versions that have been used have this problem, including the latest one.

Steps to reproduce

No response

Screenshot and/or share link

There is content between the two sentences I sent.

Operating System

win11

Terminal

No response

This issue might be a duplicate of existing issues. Please check:

Provider stream truncation (finishReason="other" with zero output) silently accepted, persisting half-finished assistant messages #26170: Provider stream truncation silently accepted — API call completes but response is half-finished or empty, very similar symptom
Silent completion failure for non-default FOSS models on OpenRouter (Kimi K2.6, DeepSeek-R1, llama-3.3-70b) #26244: Silent completion failure where model returns no visible response through opencode's adapter layer (affects DeepSeek-R1 among others)
deepseek V4 flash 或者pro 出现链接中断，中断后再也不能正常对话工作了Error from provider (DeepSeek): The reasoning_content in the thinking mode must be passed back to the API. #24920: DeepSeek V4 Pro / Flash specifically — reasoning interruptions and missing responses after tool calls

If "Show Reasoning Content" is enabled, it can be seen that the API actually responded correctly.

This issue affected my work severely, I've checked out to deepseek official API temporarily.

can confirm -- I'm trying to work around this shortcoming using various methods, haven't found any reliable enough yet. It just "gets in a mood" and returns only whitespaces in "content" - a few, a couple of dozens - it varies.

To stay organized issues are automatically closed after 60 days of no activity. If the issue is still relevant please open a new one.

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DeepSeek V4-Pro sometimes returns no visible response after API reasoning completes #28955

Description

Bug Description

Expected Behavior

Actual Behavior

Possible Symptoms

Environment

Additional Notes

Plugins

OpenCode version

Steps to reproduce

Screenshot and/or share link

Operating System

Terminal

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DeepSeek V4-Pro sometimes returns no visible response after API reasoning completes #28955

Description

Description

Bug Description

Expected Behavior

Actual Behavior

Possible Symptoms

Environment

Additional Notes

Plugins

OpenCode version

Steps to reproduce

Screenshot and/or share link

Operating System

Terminal

Activity

github-actions commented on May 23, 2026

tanfeifan commented on May 23, 2026

ListenLove commented on May 23, 2026

dit-darius commented on Jun 15, 2026

github-actions commented on Aug 15, 2026

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