[cppla]

Summary

• Bridge safe declared request trailers from the inbound body at successful EOF, preserving streamed HTTP forward-proxy uploads without buffering.
• Filter forbidden trailer fields, proxy credentials and initial/late Connection nominations; preserve ordinary origin Authorization and body Read/Close errors.
• Add real TCP streaming, filtering and visitor-cancellation regressions plus ownership/framing/EOF unit coverage.

Validation

• Original controlled baseline: direct upload 200, proxied upload 422, identical complete 65,536-byte body; only safe trailers lost.
• Fixed real-wire controls: direct/proxy 200 with complete body/digest and first-body-before-EOF witness.
• Full make check and make race; Go 1.27.1 focused race x10; Go 1.25.13 focused race x3; offline Linux/arm64 Docker Go 1.25.13 race x3.

Boundary

A nomination received only at EOF filters values but cannot retract a declaration already streamed upstream. No dependency, protocol, default, version, release/tag or registry changes. This is upload compatibility evidence, not traffic-identification evidence.

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.