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Phase 3 UI Migration Milestones (Streamlit → React + FastAPI)

This document is the execution checklist for migrating the Testo UI from the Streamlit prototype (testo_ui/streamlit_app.py) to a decoupled React SPA (frontend/) backed by FastAPI (testo_api/), while keeping testo_core as the single source of truth for orchestration and preserving CI/NDJSON contracts.

References: - docs/Architecture/Deep Dive - Execution Logic.md - docs/CLI Commands/Troubleshooting and Error Codes.md - docs/Processes & Guides/Streamlit to React Migration Guide.md

Phase 0 — Contracts locked (no UI changes)

  • Execution model: standardize on plan/cycle execution (testo run lifecycle) as the primary web contract.
  • Streaming transport: standardize on SSE from backend → frontend.
  • Event schema: SSE data: payloads are the same objects as NDJSON events.ndjson lines (top-level event field and documented payload shapes).

Exit criteria: - A single written contract for: plan_started, stage_started, stage_finished, plan_finished, plan_aborted, cycle_trigger, error.

Rollback: - Keep Streamlit runnable.

Phase 1 — Backend: plan/cycle execution API (headless)

Deliverables: - POST /api/v1/cycles/{cycle}/executions to start a cycle run. - GET /api/v1/cycle-executions/{id} for execution status. - GET /api/v1/cycle-executions/{id}/events SSE stream that tails artifacts/<cycle>/events.ndjson.

Exit criteria: - A cycle run can be started and observed end-to-end via SSE. - Durable artifacts are written under artifacts/<cycle>/ (events.ndjson, plan_result.json).

Rollback: - Continue using the existing headless execution endpoints (/api/v1/executions) for legacy UI paths.

Phase 2 — Frontend: React scaffold + contract mapping

Deliverables: - Vite + TypeScript app under frontend/. - Routes/pages: - DashboardHome: uses /api/v1/dashboard/overview - Runner/LiveExecutionConsole: uses new cycle execution endpoints + SSE - History/ReportViewer: uses /api/v1/runs / /api/v1/runs/{id} / /api/v1/runs/{id}/reports

Exit criteria: - The SPA loads, navigates, and can start a cycle run with live event streaming.

Rollback: - Streamlit remains available for the same user journeys.

Phase 3 — Runner UX hardening (logs + artifacts + reports)

Deliverables: - Runner view shows: - stage timeline and final exit classification - direct links to run.log (per stage) and events.ndjson / plan_result.json - History links open the right report surfaces: - Allure Server per run_id when configured - static report mirrors (Allure/Extent) where available

Exit criteria: - Feature parity with Streamlit “Execution + Analytics + History” journeys.

Rollback: - Streamlit stays as fallback while production traffic is gradually shifted.

Phase 4 — Production readiness (multi-user + isolation)

Deliverables: - Concurrency control per cycle and/or per execution workspace. - Optional cancellation endpoint(s) and cleanup. - AuthN/AuthZ if required. - Better SSE resilience: reconnection with offset semantics (server can support Last-Event-ID or explicit offset).

Exit criteria: - Stable operations under concurrent users, with predictable resource usage and clean teardown.

[!note] Superseded in part (2026-07-04) The Phase 3 route map (/runner, /history, /execution) was reorganized by the Phase 5 UI redesign: cycles-first navigation, cycle discovery endpoints, and a consolidated Run panel. Old routes redirect. See Phase 5 UI Redesign - Cycles-First Navigation.