Feature Request: Shell Completions for OpenSpec CLI

[ndrwstn]

Feature Request: Add Shell Completions for OpenSpec CLI

Use Case

As a new OpenSpec user, I'd love to have shell completions to improve my daily workflow. Currently, I find myself:

• Typing openspec show <change-name> and having to remember exact change identifiers
• Forgetting available options like --specs for the list command
• Making typos in command names that require re-typing the full command
• Wanting to quickly discover what commands are available without reaching for --help

Proposed Feature

It would be incredibly helpful if OpenSpec provided shell completions for bash, zsh, and/or fish that could:

1. Complete command names - openspec <tab> shows available commands
2. Complete options - openspec list <tab> shows --specs and other options
3. Complete change names - openspec show <tab> shows actual changes in my project
4. Complete spec names - When working with specs, complete existing spec identifiers

Why This Matters

Shell completions would make OpenSpec feel more polished and professional, while significantly reducing friction in daily use. It's especially valuable when:

• Working with multiple changes and needing to reference specific change IDs
• Onboarding new team members who are learning the CLI
• Using OpenSpec frequently throughout the day
• Working in different projects with different change/spec names

[noameron]

That sounds actually very useful, i'd love to give it a go @TabishB

[TabishB]

Go for it @noameron! Feel free to reach out on discord if you have questiond :)

[noameron]

Opened first PR for zsh completions #289 @TabishB