0003: slash prefix grammar

• Status: accepted
• Date: 2026-09-26

Context

slash is the primary interface of the OS, and most of its users already use Claude Code or Codex, which share a prefix convention.

Decision

• Bare text goes to the agent backend.
• / is a control command: handled by slash if recognised, otherwise passed to the backend.
• ! runs the rest of the line in a persistent zsh/bash session.
• @ inside a message references a file.

No heuristic routing of bare text to the shell. slash is not intended to replace zsh for people who want zsh; it is the interface for people who do not want a shell at all. ! is the escape hatch, not the daily path.

Consequences

• Zero learning curve for Claude Code and Codex users.
• Absolute paths starting with / are ambiguous; use !/path/to/bin.
• slash must exec the POSIX shell when invoked non-interactively so $SHELL -c keeps working.