Investigate running reen via rvx (rv project)

[soumyaray]

Summary

Investigate whether reen can be run using rvx from the rv project — a fast Ruby version and gem manager built in Rust.

What is rvx?

rvx is a convenience command from rv that runs any gem CLI directly without permanent installation. For example, rvx rails new myapp downloads and runs the Rails gem in an ephemeral environment. This eliminates the need to gem install a tool globally before using it.

The rv project replaces rbenv + bundler + rubygems with a single fast CLI, and rvx specifically enables on-demand gem execution (similar to npx for Node).

Why this matters

If rvx reen works out of the box, users could rename files without installing the gem permanently:

rvx reen *.txt

This would lower the barrier to trying reen and fit well with modern Ruby tooling workflows.

Investigation items

• Does rvx reen correctly discover and run the gem's CLI entry point?
• Does reen's editor workflow (spawning $EDITOR with a temp file) work correctly in rvx's ephemeral environment?
• Are there any issues with temp file paths, signal handling, or TTY interaction?
• Does rvx reen --version and rvx reen --help behave as expected?
• Document any setup or compatibility notes if it works

[soumyaray]

Additional concern: gem name vs executable name mismatch

The gem is published as reenrb but the CLI executable is reen (declared via spec.executables << "reen" in the gemspec).

The rvx docs only show the simple case where gem and command names match (e.g., rvx rails). It's unclear how rvx handles this mismatch:

• rvx reen — would rvx know to install the reenrb gem?
• rvx reenrb — would rvx find the reen executable inside the gem?

This name mapping is a key part of the investigation. If rvx doesn't handle it automatically, we may need to check whether rv provides flags to specify the gem name separately from the command (e.g., something like rvx --gem reenrb reen).

[soumyaray]

Investigation Results: Running reen via rvx

Tested with rv 0.5.3 on macOS (Darwin 25.3.0), Ruby 4.0.1.

1. CLI Entry Point Discovery

The gem name (reenrb) differs from the executable (reen), so rvx cannot auto-discover it:

Command	Result
rvx reen	Fails — no gem named reen on rubygems
rvx reenrb	Installs gem, but fails looking for reenrb executable
rvx --from reenrb reen	Works

The --from flag is required because rvx defaults to matching gem name = executable name.

2. Editor Workflow

Works correctly. On Unix, rv uses exec() to replace itself with the child process, so reen gets full TTY ownership. Confirmed:

• Temp file creation works in rvx's isolated environment
• $VISUAL/$EDITOR env vars are forwarded
• Editor spawning and TTY interaction work (VS Code opened the temp file with numbered entries)
• Full round-trip confirmed: a.txt was successfully renamed to renamed_a.txt via mock editor

3. Temp File Paths / Signal Handling

No issues. rv creates no temp files of its own for execution — reen's Tempfile works as usual. Since rv exec()s into Ruby on Unix, signals (SIGINT, SIGTERM, SIGTSTP) go directly to the running process. No signal forwarding middleware.

4. --version and --help

Command	Result
rvx --from reenrb reen --version	reen 1.0.0 ✅
rvx --from reenrb reen --help	Shows usage correctly (exits code 1 from exit(false) — pre-existing)

5. Caching Behavior

rvx is cached, not ephemeral. First run installs Ruby + gem to ~/.local/share/rv/tools/reenrb@1.0.0/. Subsequent runs reuse the cache and execute near-instantly.

6. Issues Found During Testing

• -v/--visual flag crashes on Ruby 4.0: NameError: no member 'visual' in struct — caused by optparse.parse!(args, into: @options) trying to set :visual on the Options struct which only has :editor and :review. This is a reen bug (not rvx), exposed by Ruby 4.0's stricter Struct#[]=. Tracked separately.

Recommendation

Document rvx usage in README:

# Run reen without permanent installation (requires rv)
rvx --from reenrb reen *.txt

# With explicit editor
rvx --from reenrb reen -e vim *.txt

# Specific version
rvx --from reenrb@1.0.0 reen *.txt

Could also consider renaming the gem to reen on rubygems so rvx reen works directly, but that has namespace implications.

[soumyaray]

Next Step: Rename gem to reen

The reen gem name is available on rubygems. Renaming from reenrb to reen would allow:

rvx reen *.txt

instead of requiring rvx --from reenrb reen. This is the direction we want to go.