The TUI slash dispatcher started treating any unrecognized /command as handled before session.prompt() could resolve extension commands, prompt templates, or /skill:* inputs. That blocked valid non-builtin slash commands and also let /export swallow unrelated /export* prefixes.
Move unknown-command detection to the interactive entry points, allow only known builtins or session-resolved slash commands through, gate /skill:* on the skill-command setting, and tighten /export matching to exact command tokens.