opencode-halogen-telemetry

Telemetry widget for the halogen flash server (halogen-flash-server, serving qwen3.8-flash-next), rendered inside the opencode TUI.

The plugin detects the server via /health at startup; other halogen servers (e.g. halogen 0.1.x serving qwen3.8-27b) are currently not supported and the plugin stays completely silent for them.

After each assistant turn made with the halogen provider, a Halogen telemetry widget appears in the opencode sidebar (below the LSP/Todo blocks):

Halogen telemetry
prefill  1,339 t/s
gen      35.6 t/s
spec     77%
cache    67%
KV       83%
saved    325,903 tok
(Ctrl+X,T for history)

• prefill — prompt processing speed for the turn
• gen — decode speed for the turn (generated tokens / generation time)
• spec — speculative-decoding (MTP draft) token acceptance
• cache — prompt-cache hit rate for the turn
• KV — current KV cache pool usage (turns yellow at >= 85%)
• saved — prompt tokens saved by the server-side prompt cache this turn

Press Ctrl+X,T (opencode leader + t) to open a history table of the last 50 turns for the current session, with the same columns plus a row index and timestamp.

Data comes from the server's /metrics (Prometheus) and /cache (JSON) endpoints. Nothing is displayed for non-halogen providers; the widget shows idle until the first completed halogen turn.

Install

Clone the repo and point the TUI plugin config at the checkout. In ~/.config/opencode/tui.jsonc (create if missing):

{
  "plugin": [
    ["/path/to/opencode-halogen-telemetry", { "url": "http://127.0.0.1:8731" }]
  ]
}

• url is optional; defaults to http://127.0.0.1:8731 or the HALOGEN_TELEMETRY_URL environment variable.
• Restart the TUI after changing the config.
• The plugin imports solid-js / @opentui/solid from the opencode config directory (~/.config/opencode/node_modules); opencode installs them automatically when listed in ~/.config/opencode/package.json (solid-js, @opentui/core, @opentui/solid).
• Note: installing via the github: plugin spec currently fails silently in the opencode 1.18 plugin loader (the plugin module is never imported); use the local-checkout method above.

Requirements

• opencode >= 1.18 with the v2 TUI plugin runtime
• a halogen flash server (halogen-flash-server) exposing /health, /metrics and /cache

License

MIT