Summary
Cloudflare Workers observability now automatically records JavaScript RPC session spans, so a trace follows RPC calls across Worker boundaries and into Durable Objects instead of stopping at the RPC boundary. Traces show caller-side sessions, method invocations, nested calls, and callbacks, with visual cues for which Worker or Durable Object handled each hop.
What changed
Workers traces now include JavaScript RPC session spans, following RPC calls across Worker-to-Worker and Worker-to-Durable-Object boundaries and rendering the full call tree (sessions, methods, nested calls, callbacks) in the dashboard.
Why it matters
Multi-Worker and Durable Object architectures are common in agent and service-binding designs, where cross-boundary RPC previously went dark in traces. End-to-end RPC visibility makes latency and error attribution across distributed Workers tractable without custom instrumentation.
Evidence excerpt
Workers traces can now follow JavaScript RPC calls across Worker boundaries and into Durable Objects.