UX: Tab completion for file paths and commands

[evansenter]

Summary

Add tab completion in the REPL for:

• File paths
• Slash commands (/help, /clear, etc.)
• Shell escape commands (!git, !cargo, etc.)

Current State

rustyline supports custom completers via the Completer trait. Clemini currently uses DefaultEditor without custom completion.

Proposed Completions

Slash commands

> /cl<TAB>  →  /clear
> /st<TAB>  →  /stats (or cycle: /stats, /status)

File paths (when context suggests a path)

> read src/too<TAB>  →  read src/tools/
> read src/tools/<TAB>  →  (shows: bash.rs, edit.rs, ...)

Shell escapes

> !car<TAB>  →  !cargo
> !cargo bu<TAB>  →  !cargo build

Implementation Notes

use rustyline::completion::{Completer, Pair};

struct CleminiCompleter {
    cwd: PathBuf,
}

impl Completer for CleminiCompleter {
    fn complete(&self, line: &str, pos: usize) -> Result<(usize, Vec<Pair>)> {
        if line.starts_with('/') {
            // Complete slash commands
        } else if line.starts_with('!') {
            // Complete shell commands  
        } else {
            // Could do path completion for quoted strings
        }
    }
}

Related

• rustyline Helper trait combines Completer, Highlighter, Hinter, Validator

[evansenter]

Related but distinct from #29

This issue (#25) uses rustyline's Completer trait to complete what you're currently typing - file paths, slash commands, shell escapes.

#29 uses the Hinter trait to suggest what to type next via ghost text based on context.

Both share the rustyline Helper trait infrastructure and could be implemented together, but they're separate UX features.

[evansenter]

Note: We've since migrated from rustyline to reedline (#37). The implementation will use reedline::Completer trait instead.

Starting work on this now.

[evansenter]

Slash command completion ✅

Commit c6f4212 adds tab completion for slash commands:

• Implemented CleminiCompleter with reedline's Completer trait
• Completions: /quit, /exit, /q, /clear, /c, /version, /v, /model, /m, /pwd, /cwd, /diff, /d, /status, /s, /log, /l, /branch, /b, /tokens, /t, /stats, /help, /h, /?
• Added /? as alias for /help

Still pending

• File path completion (when context suggests a path)
• Shell escape completion (!git, !cargo, etc.)