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Background subagent result resets the main session model #28735
Description
Description
When a background subagent finishes and its result is delivered back into the current main session, the active model in the main session appears to be reset to the agent/default model.
This is not just a case where I changed the selector but had not sent anything yet. I switch the main session model first, for example from a GLM model to a GPT model, then send at least one normal main-session message with that new model. Later, while work is ongoing, an async/background subagent result returns and the main session is switched back to the previous/default model.
This feels related to older model-state issues such as #6636 and #21728, but the important detail here is that the newly selected model had already been used for a main-session message before the async subagent result arrived.
Plugins
No plugin is required for this behavior. The issue appears on the native background subagent/session model path; plugins do not appear to affect the repro.
OpenCode version
1.15.6
Steps to reproduce
- Start a session with the default model set to model A, for example GLM.
- Launch a background subagent/task that will return later.
- Switch the main session to model B, for example GPT.
- Send at least one normal main-session message using model B.
- While work continues, wait for the background subagent result to be delivered back into the main session.
- Observe that the main session model is switched back to model A/default.
Expected: once the main session has sent a message with model B, an async subagent result should not overwrite the active main-session model back to model A/default.
Screenshot and/or share link
N/A for now.
Operating System
Ubuntu 24.04.4 LTS on WSL
Terminal
Not terminal-specific.
Activity
github-actions commentedon May 21, 2026
This issue might be a duplicate of existing issues. Please check:
If your issue is distinct from these, feel free to clarify the differences.
wanyaoluo commentedon May 21, 2026
Thanks, I checked #21728 and #21351. This looks related, but I don't think it is the same repro.
I'm using the experimental native background subagents path (
task(background=true)/task_status), not a directPOST /session/:id/prompt_asyncnotification and not a Plan/Build mode switch.The main session had already switched to the new model and sent a normal message with it. Later, when the background subagent result was injected back into the main session, the main session model reset to the default.
github-actions commentedon Jul 21, 2026
To stay organized issues are automatically closed after 60 days of no activity. If the issue is still relevant please open a new one.