Extend View Render For Editor Preview

Goal

Make view.render sufficient for a client to render the complete Markdown view document around a backend-recognized content mount.

Sources

• architecture/editor-extension-adapter-contract
• architecture/forma-view-query-model
• design/editor-extension-mvp-design

In Scope

• Extend ViewRenderResult with a document payload containing Markdown body source and structured content-mount source locations.
• Keep mount recognition and validation in Forma Core.
• Preserve current list, table, kanban, and graph projection outputs.
• Return diagnostics for missing or multiple mounts with actionable locations.
• Align the implementation with the accepted behavior for content before and after the mount.
• Update RPC serialization, CLI JSON, shared TypeScript types, operation API documentation, and fixtures.
• Preserve compatibility for existing WebApp callers that ignore the new optional payload.

Out Of Scope

• HTML styling or editor theme behavior.
• Unsaved transient view rendering.
• Graph renderer changes.
• Writable view actions.

Acceptance Criteria

• Tests cover Markdown before, at, and after one mount plus missing and multiple mount cases.
• The serialized body and source locations are stable and workspace safe.
• Existing View query and projection tests continue to pass.
• WebApp shared-client type checks pass without requiring it to adopt the new payload.
• Canonical product and architecture wording no longer conflicts about missing-mount behavior.