langgraph-api auto-copies the entire config.configurable dict into runtime.context. That dict
carries the CopilotKit-internal transport key `copilotkit_forwarded_headers`, populated solely
to drive the httpx header-forwarding hook (it is not user-visible state). The middleware's
before_agent step then rendered runtime.context into the LLM prompt as an "App Context" system
message, and the expose_state path could surface the same key via the state note — either path
leaks transport headers into the prompt body and, under strict fixture matching (D6/aimock),
changes the request payload and breaks the match.
Fix: hard-exclude `copilotkit_forwarded_headers` from both render paths. The App Context
renderer strips the reserved key before serialization, and the expose_state allowlist applies
the same exclusion so an explicit allow cannot reintroduce the leak. The httpx hook is
unchanged, so the key still reaches aimock as an HTTP header — pure conveyance, no body
pollution.
Adds red-green unit coverage for both paths (App Context strip, expose_state default + allowlist).
Add integration and edge-case coverage for the new
_extract_forwarded_headers_from_config flow: wrapper-dict and raw x-*
sources, context > configurable precedence, mixed-case key normalization,
RuntimeError early-return clears stale ContextVar, exception path clears
stale ContextVar, None and empty-config fallbacks, and a sync/async
parity check that both call paths run the extraction.
github-actions[bot]