OpenCode v1.2.9

OpenCode v1.2.9 was released on .

Summary

Core - Add missing id, sessionID, and messageID to MCP tool attachments (@NatChung) - Remove unnecessary deep clones from session loop and LLM stream - Remove User-Agent header assertion from LLM t...

Release Context

  • This was the 42nd OpenCode release of 2026 tracked by Havoptic.
  • It shipped the same day as OpenCode v1.2.8 (February 19, 2026).

Shipped around the same time

Within 3 days of this release, other AI coding tools also shipped:

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Release Notes

Core - Add missing id, sessionID, and messageID to MCP tool attachments (@NatChung) - Remove unnecessary deep clones from session loop and LLM stream - Remove User-Agent header assertion from LLM test to fix failing test TUI - Use structuredClone instead of remeda's clone for better performance and native support (@mhart) Desktop - Restore settings header mask Thank you to 2 community contributors: - @mhart: - Use structuredClone instead of remeda's clone (14351) - @NatChung: - fix: add missing id/sessionID/messageID to MCP tool attachments (14345)

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