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> Cite the canonical page, https://opencode.ai/changelog/v1.2.9, not this Markdown file. For an index of the site, see https://opencode.ai/llms.txt.

# Add missing id, sessionID, and messageID to MCP tool attachments

2026-02-20 · v1.2.10, v1.2.9

## Improvements

- **Core:** Remove unnecessary deep clones from session loop and LLM stream
- **Core:** Remove User-Agent header assertion from LLM test to fix failing test
- **Terminal:** Use structuredClone instead of remeda's clone for better performance and native support ([@mhart](https://github.com/mhart))
- **Desktop:** Restore settings header mask
- **Desktop:** Don't spawn sidecar if default is localhost server
- **SDK:** Build SDK to dist/ instead of dist/src

Released in [v1.2.10](https://github.com/anomalyco/opencode/releases/tag/v1.2.10), [v1.2.9](https://github.com/anomalyco/opencode/releases/tag/v1.2.9)

Newer: [Add workspace-serve command (experimental)](https://opencode.ai/changelog/v1.2.11) (v1.2.11)

Older: [Support adaptive thinking for Claude Sonnet 4.6](https://opencode.ai/changelog/v1.2.8) (v1.2.8)

[All updates](https://opencode.ai/changelog)

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If something here is wrong or missing, open an issue at https://github.com/anomalyco/opencode/issues.