v0.21.4 (v2026.9.21) — Patch release

Released: September 21, 2026 Theme: A patch release that rolls up about 1,812 merged PRs since v0.21.3

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

Highlights

  • One gateway per host: a lock prevents a second one from starting. The desktop app attaches to the running backend instead of starting another.
  • Structured CLI output: --format stream-json prints JSONL.
  • Pinned skills: skills.auto_load puts chosen skills into every new session.
  • Unauthorized DMs: the gateway gained a decline behavior.
  • MCP discovery limit: set it with mcp.discovery_concurrency.
  • session_search accepts before/after time bounds.
  • Plugin catalog: every plugin and author has a web page, and about a dozen community plugins were added.
  • A large run of fixes for profile isolation, cron, kanban, the desktop app and state.db.

Hermes Agent v0.21.4 release notes

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