v0.21.5 (v2026.9.24) — Patch release

Released: September 24, 2026 Theme: A patch release that rolls up about 460 merged PRs since v0.21.4

The official notes do not list every change. The full notes ship with v0.22.0.

Highlights

  • Desktop app: a plugin SDK, Simple and Advanced interface modes, and a Connectors page that replaces the MCP tab. It adds French, German and Spanish, plus a text-direction setting.
  • Custom model names: type a model name directly in the composer and Settings pickers.
  • CLI/TUI: the live dock shows the standing /goal and queued prompts.
  • Profile control: stop, start or restart each profile on its own. gateway.standalone opts a profile out of the host multiplexer.
  • Webhooks: delivered content is mirrored into the target chat session.
  • New models: GPT-6 Sol/Terra/Luna and Claude Opus 5.5 in the Nous and OpenRouter catalogs.
  • Integrations and plugins: an official Blender Lab integration, NVIDIA plugins, and dozens of new community plugins.
  • Performance: config loading, the tool registry, gateway message handling and the model picker are faster.

Hermes Agent v0.21.5 release notes

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