Claude Opus in GitHub Copilot and Anthropic have different context window #18832

Activity

1. jcubic

   added

   bugSomething isn't workingSomething isn't working

   on Mar 23, 2026
2. jcubic

   changed the title [-]Claude Opus in GitHub Copilot and Anthropic have different token count[/-] [+]Claude Opus in GitHub Copilot and Anthropic have different context window[/+] on Mar 23, 2026
3. github-actions

   assigned

   rekram1-node

   on Mar 23, 2026
4. github-actions

   added

   coreAnything pertaining to core functionality of the application (opencode server stuff)Anything pertaining to core functionality of the application (opencode server stuff)

   on Mar 23, 2026
5. github-actions commented on Mar 23, 2026

   

   github-actionsBot

   on Mar 23, 2026 – with GitHub Actions

   Contributor

   More actions

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

   • Copilot CLI has higher context window than GitHub Copilot extension #16861: Copilot CLI has higher context window than GitHub Copilot extension (same root issue - different context window limits for Copilot vs other providers)
   • Discrepancies on context sizes using Opencode/Copilot CLI #17582: Discrepancies on context sizes using Opencode/Copilot CLI (same symptom - context size differences with Copilot)
   • What is the specific context size of Github Copilot, is it only 128K? #16129: What is the specific context size of Github Copilot, is it only 128K? (related - Copilot context window limits)
   • Session compaction fails with "context exceeds model limit" error #17340: Session compaction fails with "context exceeds model limit" error (related - compaction failing due to context limits)

   Please review those issues to see if your problem is already being tracked, and if so, consider adding a comment there with any additional details rather than opening a new issue.
6. elijahmorg commented on Mar 25, 2026

   

   elijahmorg

   on Mar 25, 2026

   Last edited by elijahmorg

   More actions

   The context window for the Github Copilot Opus 4.6 is smaller :(

   You can check on models.dev for context window size.
7. thdxr

   removed

   bugSomething isn't workingSomething isn't working

   coreAnything pertaining to core functionality of the application (opencode server stuff)Anything pertaining to core functionality of the application (opencode server stuff)

   on May 3, 2026
8. rekram1-node

   closed this as completedon May 13, 2026