This pass hardens the interactive UX instead of chasing feature breadth.
It preserves raw REPL input whitespace, honors the configured editorMode
for vim-oriented sessions, improves slash-command help readability, and
turns unknown slash commands into actionable guidance instead of noisy
stderr output.
Constraint: Keep the existing slash-command surface and avoid new dependencies
Rejected: Full TUI/input rewrite | too broad for a polish-and-reliability pass
Confidence: high
Scope-risk: moderate
Reversibility: clean
Directive: Preserve user prompt text exactly in the REPL path; do not reintroduce blanket trimming before runtime submission
Tested: cargo check
Tested: cargo test
Tested: Manual QA of /help, /status, /statu suggestion flow, and editorMode=vim banner/help/status behavior
Not-tested: Live network-backed assistant turns against a real provider
