## What changed
Add an optional `NetworkPolicyMetadataProvider` to the MCP runtime. Advertise `codex/network-policy-meta` only to trusted ChatGPT origins when a provider is available, and attach policy metadata only when the sending session also advertises support.
Strip caller-supplied policy metadata and derive restrictions from the call's captured permission profile and server environment. Resolve metadata against each session's capabilities, including after recovery, while retaining one policy snapshot per call. Fail the call before sending if policy resolution fails. Existing runtime callers leave the provider unset.
## Testing
Add tests for capability negotiation, trusted-origin restrictions, forged metadata removal, both tool dispatch paths, and policy snapshot reuse. Add HTTP session-recovery coverage for changing capabilities and policy-resolution failures while preserving caller metadata and read-only restrictions.
GitOrigin-RevId: 4b978f986abc0475fc67659be98fc01a2d6ce7cd
## Why
MCP requests pass through background transport queues, so HTTP requests need the caller's trace context carried explicitly to preserve trace ancestry.
## What changed
- Capture W3C trace context in request metadata for tool and resource operations, custom requests, and event streams.
- Restore that context in an `mcp.http.request` span around HTTP POSTs, linking outgoing HTTP traces to the originating request.
- Preserve application metadata while replacing trace fields with the current caller's context and removing stale `tracestate`. Read the SDK's merged metadata so extension fields retain precedence over parameter metadata.
## Testing
Add a unit test for metadata merge precedence and an integration test covering concurrent paginated requests, tool calls, custom requests, and tool-call continuations across legacy and `2026-07-28` protocol modes. Verify HTTP trace ancestry, metadata preservation, and removal of stale `tracestate`.
GitOrigin-RevId: 0b22cd75f31f9fcb855b27fa8d34ecdffd6e3549