Give appended Chat system messages their own cards and suppress the following initial or same-step update header card. Preserve replacement/header ownership and conservative unknown surface ordering. Trajectory uses prompt-only presentation when no request header is loaded, never fabricated provider, model, or tools; prepend deduplicates against real request changes. Test-first regressions showed missing Chat cards and missing trajectory prompt data; 148 focused tests and affected client project typechecks pass.
Tianyi Cui
cea0aff474