Add "listing" flag support to theme commands

[chrisberthe]

Follow up to #6002.

WHY are these changes introduced?

Shopify introduced new requirements for the Shopify Theme Store that require themes with multiple presets to include a /listings directory in their theme zip submissions. However, developers need a way to preview and test these specific theme presets during development and deployment.

WHAT is this pull request doing?

• Added --listing flag to shopify theme dev, shopify theme push, and shopify theme share commands
• Implemented "file overlay" to serve listing-specific templates and sections when available
• Updated theme file watching to monitor the active listing directories during development
• Added config/settings_data.json preset switching, i.e. "current" key, based on listing name

How to test your changes?

1. Create a theme with a listings/ directory:

   theme/
   ├── listings/
   │   ├── preset-name-one/
   │   │   ├── templates/
   │   │   │   └── *.json
   │   │   └── sections/ (optional)
   │   │       └── *.json
   │   └── another-preset-name/
   │       ├── templates/
   │       │   └── *.json
   │       └── sections/ (optional)
   │           └── *.json
   

2. Test development with listing:

   shopify theme dev --listing preset-name-one

3. Test push with listing:

   shopify theme push --listing another-preset-name

4. Test share with listing:

   shopify theme share --listing preset-name-one

5. Verify that listing-specific files are served when they exist, and base theme files are used as fallbacks when they don't

Measuring impact

How do we know this change was effective? Please choose one:

• n/a - this doesn't need measurement, e.g. a linting rule or a bug-fix
• Existing analytics will cater for this addition
• PR includes analytics changes to measure impact

Checklist

• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've considered possible documentation changes

[graygilmore]

Testing this out with theme dev worked well! Very neat! Couple of pieces of feedback and I'll ping the rest of the team to get one more set of eyes because I'm not too familiar with some of the pieces in here.

[karreiro]

Thank you for this PR, @chrisberthe! Excellent work! 🚀

I’ve tested it, and most workflows are working quite reliably. However, one workflow isn’t behaving as expected:

shopify theme dev --listing example --theme-editor-sync

When we run the command with the --theme-editor-sync flag, we expect that changes made in the theme editor are automatically downloaded. Currently, with the new flag, those changes seem to be lost.

If supporting these flags together turns out to be too challenging, we could consider throwing an early error when both are used at the same time. Ideally, though, it would be great to make them work together if possible. Please let me know your thoughts.

Thanks again for all your work on this PR!

[chrisberthe]

Thanks @karreiro. I'm taking vacation so I'll look into this once I'm back in a week or so. Could you share some thoughts on this point?

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[anastis]

Commenting so that this won't get closed automatically.
It's still relevant and needed for theme development, waiting feedback from @chrisberthe and @karreiro

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[anastis]

Any progress on this?

[chrisberthe]

Any progress on this?

This fell by the wayside. Will look into the remaining feedback and address.

[chrisberthe]

@karreiro Going to need your input on --theme-editor-sync with --listing. Thinking of two options here:

• Always sync JSON files to listings/<preset>/.... This keeps things isolated per preset but also generates lots of, potentially unwanted, files per preset.
• If a JSON file exists in listings/<preset>/..., sync to that folder, otherwise sync to the theme's base templates/ or sections/ folders. Example: if listings/<preset>/templates/index.json exists, sync to this folder, but if that file didn't exist, sync to templates/index.json.

Personally, leaning towards the latter. What do you think?

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[anastis]

Still relevant.
@chrisberthe waiting feedback from @karreiro

[chrisberthe]

Can't say when this will be merged @anastis, but I can say that having to repeatedly rebase this is getting annoying 😛

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[chrisberthe]

Still relevant.