Opus 4.8 bug in dev branch.

[coin-seeker]

Description

I got the message from sub-agent opus 4.8.

Plugins

No response

OpenCode version

dev branch

Steps to reproduce

build the dev branch and summon the subagent with opus 4.8

Screenshot and/or share link

No response

Operating System

macos

Terminal

cmux

[github-actions]

This issue doesn't fully meet our contributing guidelines.

What needs to be fixed:

• The Description field contains only a screenshot with no textual explanation of the bug, what was expected, or what actually happened.
• Steps to reproduce is empty (_No response_) — please describe how to trigger this issue.
• OpenCode version is empty — please include your version number.
• Operating System is empty — please include your OS.
• Terminal is empty — please include your terminal.

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[github-actions]

Thanks for updating the issue! It now meets our contributing guidelines and has been marked as compliant.

[rekram1-node]

send me the session if u can opencode export > session.json

[rekram1-node]

I cannot replicate it

[ysm-dev]

+1

[rluisr]

latest published version:

The final block in an assistant message cannot be `thinking`.

[cheeseandcereal]

I got it in 1.15.12 on opus 4.8 when trying to do manual compaction:

undefined: The model returned the following errors: messages.7.content.43: `thinking` or `redacted_thinking` blocks in the latest assistant message cannot be modified. These blocks must remain as they were in the original response.

Closing/reopening opencode, reloading the same session, then retrying to run compaction worked, though. Not sure what would have changed.

[rekram1-node]

I cannot replicate, once again plz send me a session where this happened if possible

[cheeseandcereal]

Here's a session I have that consistently replicates it in my environment (even when I undo back to previous messages, then run compaction manually again, and even between closing/reopening opencode and resuming the session, it consistently fails): https://d.robit.pw/dpWXf08vnp/sess.json

(Switching to another model including opus 4.7 with same provider/config to do the compaction works fine)

It looks like claude-code has also ran into this in the past on previous opus models too: anthropics/claude-code#12311

[rekram1-node]

oh if ur using bedrock ik why, thats separate but ill fix