[META] Production-ready client-side data model + internal HTTP API

🐛 Empty slot placeholder not rendering for content that has been published Active and 📌 [PP-1] Rename PropSourceComponent.field_data to propSources Postponed are in.

🐛 Component transforms need to be per sourceType, not per component prop Active and 📌 Define API URI naming conventions Active landed.

Oops. #3519992 is part of 📌 SdcController cleanup tasks Active .

Removed #3499352 from this meta and into 📌 Only run XbTwigExtension inside XBPreviewRenderer Active per #3499352-15: No XB-targeted HTML comments on the live site: only run XbTwigExtension inside XBPreviewRenderer → .

Added two missing things for the client-side data model:

1. Missing "node type" in docs/data-model.md's 3.4 UI Data Model: communicating a `component tree` to the front end: a node type for exposed ContentTemplate slots: #3519352-32: Content templates, part 3b: store exposed slot subtrees on individual entities →
2. Missing "node type" in docs/data-model.md's 3.4 UI Data Model: communicating a `component tree` to the front end: a node type for overrides/personalization variants

#20.2 is overkill, based on a call I just had with @effulgentsia and @penyaskito — thanks @effulgentsia for raising, as you heard, I'd already been thinking in the same direction 😊

So … adopting the same structure as we have for 🌱 [META] Production-ready ComponentSource plugins Active and others: beta vs stable vs post-stable.

Changes:

• Removed 🐛 Click publish shortly after making a change can lead to error Active , because there's multiple metas for auto-save: 📌 META: Conflict free concurrent editing Active + 🐛 [Meta] Selective Publishing and Reverting Active + 🌱 Research: Possible backend implementations of auto-save, drafts, and publishing Active .
• Moved 🐛 Handle adding page title to content Active under 🌱 [META] Production-ready ComponentSource plugins Active .

HTML fixes.

⚠️ a crucial piece here is access control/permissions, but that has its own meta: 📌 SdcController cleanup tasks Active .

Added 🐛 Duplicate alias results in a Drupal rendered error message Active to beta blockers and 📌 Implement `lookup_keys` in Component for optimized queries Active to stable blockers.

As you can see as of #22, IMHO all remaining HTTP API changes can happen after beta1 aka 🌱 Milestone 1.0.0-beta1: Start creating non-throwaway sites Active .

Observations:

• Back when I opened this at the end of April, we were being slammed with bug report after bug report. It was hard to pinpoint the cause of things. It felt like a lot of it was due to the internal HTTP API. It was on the server side, but actually almost entirely the individual ComponentSource plugins and their supporting infrastructure. 🌱 [META] Production-ready ComponentSource plugins Active handled that, and things are WAY better 👍
• The list of beta blocker-tagged issues is quite short → . 😊
• Note that ComponentSourceInterface is NOT a stable API yet at 🌱 Milestone 1.0.0-beta1: Start creating non-throwaway sites Active  — only the data storage is. XB basically has no public API at that point, only stable storage. Consequently, the client-side data model is also still free to change until 1.0.

That's why actually … I can signal this is "done for now", i.e. for 🌱 Milestone 1.0.0-beta1: Start creating non-throwaway sites Active but NOT for 🌱 Milestone 1.0.0: Production Sites Postponed , by marking this .