Block Editor: support inline contentlet references inside paragraphs

[fmontes]

Summary

Today the Block Editor only supports contentlets as full block-level elements. Users want to embed a contentlet inline within a paragraph — similar to Notion's inline mentions — so the contentlet's title (or other display field) renders as a live, linked reference inside the surrounding text.

block-editor-inline.mp4

Use case

A content contributor writes a paragraph and wants to reference another contentlet (e.g. a product, page, or "MMC link") inline within the sentence. Today they can only:

• Type a static link (loses single source of truth — breaks if the target's URL/title changes), or
• Drop a full block-level contentlet (breaks the paragraph flow).

The inline contentlet would resolve both:

• Live reference: title/label updates automatically when the source contentlet changes
• Single source of truth: links and metadata stay in sync
• Inline rendering: the reference sits within the paragraph, not as a standalone block

Behavior

• User types / (or similar trigger) inside a paragraph
• Selects "Inline contentlet" (or similar)
• Picks a contentlet via the existing selector
• The contentlet renders inline, showing the title (configurable display field) as a linked reference
• The reference stays bound to the contentlet ID, not to the title text — so renames propagate

Scope notes

This is not a breaking change but it touches multiple layers:

• Block Editor UI (new inline node type)
• Stored JSON schema (inline content node)
• VTL rendering (must render inline, not as a block)
• SDK rendering (consumer must be able to provide a custom inline component)
• Documentation

Tiptap (the underlying library) has a community extension for inline mentions/references that we should evaluate as a starting point rather than building from scratch.

v1 scope

Inline contentlet reference (Notion-style mention) only. Other inline cases (buttons, custom blocks) deferred.

Open questions

• Display field configuration: per content type, or global default?
• Rendering API for SDK consumers — how do they register a component for the inline node?
• VTL fallback rendering — what does the default look like?