Proposal: interactive mindmap view for search spaces

[mvanhorn]

NotebookLM's 2025 release added a mindmap view showing how documents and ideas relate. Open-Notebook tracks it as #706. SurfSense doesn't have one today — the dashboard shows documents as a list in DocumentsSidebar.tsx and chats as a separate log, with no visual of how they connect.

I'd like to add a mindmap tab at /dashboard/[search_space_id]/mindmap rendering a reactflow graph with three node types: connector groups (one per Notion, Slack, Drive, etc.), documents (children of their connector), and chat sessions (separate cluster, edges drawn to cited documents using existing citation data). Read-only in v1, no backend change, no AI clustering. Dagre for initial layout, node positions persisted in localStorage.

Scope estimate: ~300–400 LOC pure frontend. Adds reactflow + dagre (~63KB gzipped, both MIT) — dynamic-imported so the main bundle is unaffected.

If this lands well, v2 additions in scope: AI-generated topic clustering (using existing chunk embeddings + pairwise similarity), drag-to-relate edges, mobile support.

Happy to target dev and follow the branch workflow. Would you like the mindmap to live as a tab inside the existing search-space layout, or as a separate route at the top level? And is reactflow OK (vs. a lighter custom SVG canvas) given the bundle impact?

Reference: I've shipped 3 frontend PRs here already (#1215 TanStack Query migration, #1220 dashboard-scoped error boundary, #1233 scroll-timer cleanup) so I'm familiar with the dashboard scaffolding and the surfsense_web/ build/lint setup.