[FEATURE] Autocomplete for fish shell

[dsluo]

Use Case / Problem

Add completions for fish shell, which is supported by argcomplete.

Proposed Solution

https://github.com/kislyuk/argcomplete/tree/main/contrib#fish-support

In scripts/completion/fab_completion.fish:

register-python-argcomplete -s fish fab | source

Alternatives Considered

No response

Impact Assessment

• This would help me personally
• This would help my team/organization
• This would help the broader fabric-cli community
• This aligns with Microsoft Fabric roadmap items

Implementation Attestation

• I understand this feature should maintain backward compatibility with existing commands
• I confirm this feature request does not introduce performance regressions for existing workflows
• I acknowledge that new features must follow fabric-cli's established patterns and conventions

Implementation Notes

No response

[HasanAboShally]

/help-wanted

Hi @dsluo,

Thanks for the feature request! We appreciate you pointing out Fish shell support.

You're right that argcomplete does have Fish support via the register-python-argcomplete --shell fish command. However, I wanted to clarify a few things about the implementation:

While argcomplete provides native, built-in support for Bash and Zsh, both Fish and PowerShell require custom bridge scripts to work properly. We've already implemented this for PowerShell (you can see our custom script here), and we'd need to do something similar for Fish.

The good news is that argcomplete's Fish integration is well-documented, and based on their contribution guide, the implementation should be straightforward. We'd need to:

1. Create a fab_completion.fish script
2. Set up Fish in our testing environment to properly validate the implementation
3. Update our documentation to include Fish setup instructions

If you're interested in contributing this yourself, please take a look at our contribution guidelines first. The completion scripts are in the scripts/completion folder, and you can use our PowerShell implementation as a reference.

Looking forward to reviewing your PR 🙌.

Thanks again for the suggestion!

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