Reference
Headers Reference
Arc adds a small set of request and response headers on top of the OpenAI-compatible request body.
Request Headers
Authorization
Bearer Arc key, for example Bearer arc_live_...
Content-Type
Standard JSON request body.
X-Arc-Route
Route key to apply route-level configuration.
X-Arc-No-Inject
Skip route system prompt injection for one request.
X-Arc-Client-ID
Client ID for memory lookup and injection.
X-Arc-Workflow
Workflow slug for trace-aware execution.
X-Arc-Trace-Id
Trace identifier for grouped execution.
X-Arc-Span-Name
Optional current span name within a trace.
X-Arc-Parent-Span-Id
Optional parent span reference.
X-Arc-Trace-Status
Optional terminal trace state.
X-Forwarded-For
End-user IP for geolocation logging.
Response Headers
X-Arc-Trace-Id
Returned when workflow mode is active and a trace is present.
X-Arc-Budget-Remaining
Remaining workflow budget after budget enforcement is evaluated.
X-Arc-Budget-Warning
Warning string when the trace is nearing its budget cap.
X-Arc-Downgraded
Returned when Arc downgraded the request to a cheaper model due to budget policy.
X-Arc-Rate-Limit-Warning
Present when a warn-mode rate limit allowed the request through.
X-Arc-Latency-Breakdown
Optional compact JSON stage timing breakdown when debug latency mode is enabled.