Response headers

Plugboard adds x-plugboard-* headers to model answers. They tell you what happened to a request without reading logs. A browser page can read them when its origin is in cors.origins.

A streamed answer sends its headers with the first event, so headers that need the finished answer (x-plugboard-usage, x-plugboard-opencode-tools) are only on non-streamed answers.

Header	When	Value
x-plugboard-request-id	Every response	12 hex characters. The same id is on the request's log lines.
x-request-id	The request sent one	The caller's own id, echoed. Plugboard keeps it when it is 1 to 128 characters of letters, digits and _ . : / + = -, and ignores any other value. The request's log line carries it as clientRequestId. It never replaces x-plugboard-request-id.
x-plugboard-model	Every answer	The provider/model#variant that answered. With a fallback chain, the target that won.
x-plugboard-fallbacks	A fallback chain moved past a failing target	How many targets failed before the one that answered.
x-plugboard-session	Every answer	The OpenCode session id of the request. See History.
x-plugboard-session-url	sessionUrl is set	A link to that session's page.
x-plugboard-usage	Usage recording on, not streamed	input=<n>; output=<n>; cache_read=<n>; cache_write=<n>; cost_usd=<x>. The cost is left out for a model with no price.
x-plugboard-cache	The app uses the response cache	hit or miss.
x-plugboard-affinity	The app uses prompt-cache anchors	anchor, or none when the request got no anchor.
x-plugboard-dropped-params	Sampling parameters were dropped	The dropped names, comma separated, such as temperature,top_p,top_k,seed. See dropUnsupportedParams.
x-plugboard-dropped-tools	A Responses request declared hosted tools	The types left out, comma separated, such as web_search. See Responses tools. Streamed answers carry it too.
x-plugboard-thinking	Thinking or a reasoning effort was asked for, and the model has no variant for it	unavailable. The request ran without thinking.
x-plugboard-policy	The app's policy changed the request	tools-stripped: the app has tools: false and the caller's tools were removed.
x-plugboard-parallel-tools	parallel_tool_calls: false	limited: only the first tool call of the answer was kept.
x-plugboard-opencode-tools	The app runs OpenCode tools, not streamed	The number of OpenCode tool calls that ran.
x-plugboard-structured-fallback	Structured output came from plain text	text: the model answered in text that matched the schema instead of calling respond.
x-plugboard-user-dropped	The end user name was not usable	1: the user value was not kept for usage.

Errors from plugboard-owned routes (/plugboard/*) use application/problem+json. Model routes answer errors in their own API's shape. See Errors.