Reject invalid page positions before input I/O and keep diagnostic stderr
failures from overriding rendering, text errors or MCP startup. Preserve
real file and protocol output failures and upstream compact MCP behavior.
Co-authored-by: sanyamsingh001 <314051937+sanyamsingh001@users.noreply.github.com>
Co-authored-by: Codex <codex@openai.com>
Co-authored-by: Brandon Thomas <echelon@gmail.com>