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1. shakedlokits

   added

   bugSomething isn't workingSomething isn't working

   on Feb 8, 2026
2. github-actions

   assigned

   fwang

   on Feb 8, 2026
3. github-actions

   added

   zenRelates to ZenRelates to Zen

   on Feb 8, 2026
4. github-actions commented on Feb 8, 2026

   

   github-actionsbot

   on Feb 8, 2026 – with GitHub Actions

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   This issue appears to be related to existing problems with Claude Opus 4.6 context window configuration. Please check:

   • Beta header context-1m-2025-08-07 not sent for Claude Opus 4.6, causing 200k hard limit #12507: Beta header 'context-1m-2025-08-07' not sent for Claude Opus 4.6, causing 200k hard limit — This is the root cause. OpenCode needs to send the proper beta header to unlock the 1M context window.
   • fix(zen): 1M context window beta not sent for Opus 4.6 and Sonnet 4.5 #12452: fix(zen): 1M context window beta not sent for Opus 4.6 and Sonnet 4.5 — A proposed fix for the same issue
   • Claude Opus 4.6 context window limits still 200k #12438: Claude Opus 4.6 context window limits still 200k — Another user experiencing the same problem even after manual config updates
   • Model IDs are wrong for Opus 4.6 on AWS Bedrock #12330: Model IDs are wrong for Opus 4.6 on AWS Bedrock — Potential additional issue with Bedrock model ID configuration

   The core issue is that the context-1m-2025-08-07 beta header is not being sent for Opus 4.6 models, which prevents the Anthropic API from allowing requests beyond 200k tokens despite the model supporting 1M tokens.
5. Badbird5907 commented on Feb 12, 2026

   

   Badbird5907

   on Feb 12, 2026

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   I'm also getting this issue on Amazon Bedrock
6. shakedlokits commented on Feb 15, 2026

   

   shakedlokits

   on Feb 15, 2026

   Last edited by shakedlokits

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   It's not fixed as of 1.2.4, currently cannot use Opus 4.6 on my work laptop.

   👍React with 👍3Reacted by LucaNerlich, Nderim and jeremysamuel13
7. smashah commented on Feb 15, 2026

   

   smashah

   on Feb 15, 2026

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   happening on 4.6 via antigravity auth also.
8. LucaNerlich commented on Feb 19, 2026

   

   LucaNerlich

   on Feb 19, 2026

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   Same here. AutoCompaction is either missing or not kicking in. Switching to another model, seems to trigger the compaction, after which one cat switch back to 4.6 etc.
9. nathanl commented on Mar 6, 2026

   

   nathanl

   on Mar 6, 2026

   Last edited by nathanl

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   I accidentally opened a duplicate issue for this. A possible workaround: override the model's limit in ~/.config/opencode/opencode.json:

   {
     "provider": {
       "amazon-bedrock": {
         "models": {
           "us.anthropic.claude-opus-4-6-v1": {
             "limit": {
               "context": 200000,
               "output": 32000
             }
           }
         }
       }
     }
   }

   With this, the "% used" in OpenCode's sidebar appears to be correct for 200K tokens.
10. thdxr

    removed

    bugSomething isn't workingSomething isn't working

    zenRelates to ZenRelates to Zen

    on May 3, 2026
11. github-actions commented on Jul 3, 2026

    

    github-actionsbot

    on Jul 3, 2026 – with GitHub Actions

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

    closed this as not plannedon Jul 3, 2026