A folder's board can be embedded in a note

• Supersedes: the rejection of embedded blocks in ADR-0057

Context

ADR-0057 made database views a route and rejected an embedded block, because a React grid inside ProseMirror would pull cross-note projections into the editing path and need a document schema change.

The route alone works badly as a first impression. The starter workspace sent a first browser visit to the Books board, a full-width grid without the sidebar or any explanation, so a new visitor met a property board before they met the editor. A board shown inside a note can be introduced by the text around it, and it shows that notes and their properties are the same thing.

Decision

A database_view block shows one folder's notes as a board inside a note.

• Markdown is a fence. The block is written as a fenced code block with the language database whose first non-empty line is the folder's path from the workspace root, for example Projects/Books. Other editors show it as a short code block. An empty fence is a block that asks for a folder.
• The block stores a path, not an ID. The path survives export, import and copying between workspaces. Titles are compared case-insensitively. A path that names no live folder, including one that was renamed, shows a folder picker instead of a board, and choosing a folder rewrites the path.
• One source of truth. The block reads the same rows selector and the same device-local layout scope as #/database/<folderId>, always as a board. It writes only through the existing cell and note operations. It never changes the stored layout, so it has no toolbar.
• Off the editing path. The block is an atom with its own React root. ProseMirror never sees events inside it, and it subscribes only to its own folder's rows, so typing elsewhere in the note does not render it. Board groups keep the 50-card cap.
• Entry points. Database board in the / menu inserts an empty block, and pasting or importing the fence creates a filled one. The block links to the full view.

The database route also gains the notes sidebar. Opening a note from the sidebar leaves the board for that note.

Consequences

• The document schema has one more node type. Documents written before it parse the fence as the block, and documents with the block open in older builds as a database code block, because the markdown is unchanged.
• Renaming or moving a folder breaks the paths that name it until a folder is chosen again. Resolving by ID would survive renames but not export.
• The starter workspace opens on the Welcome note, which embeds the Books board, instead of on the database route.
• Deferred: embedding a table, per-block layouts, filters chosen in the block, and updating paths when a folder is renamed.