Phase 5 — Real-time Progress & UX

[hypercompetent]

Part of the PyQt → Dash/Plotly migration. See cytoflowweb/PLAN.md for full context.

Estimated effort: 1–2 weeks
Depends on: Phase 1 (#1)

Tasks

• Add FastAPI WebSocket endpoint (/ws/{session_id})
• Integrate dash-extensions WebSocket client (or dcc.Interval polling as fallback)
• Status badges per pipeline step (valid / estimating / applying / error) using dbc.Badge
• Cancel running computation button

WebSocket message schema

{"type": "status",    "step": 3, "state": "estimating", "progress": 0.42}
{"type": "plot_ready","step": 3}
{"type": "error",     "step": 3, "message": "..."}

Milestone

Long-running operations (tSNE, SOM, Gaussian mixture) show live progress in the sidebar. Users can cancel a running computation without refreshing the page.