Architecture Overview

AB Test Research Designer is a local-first FastAPI and React application for designing, running, reviewing, and exporting A/B-test plans. The backend owns deterministic calculations and persistence; the frontend owns the wizard, dashboard, and review workflows.

Experiment runner

app/backend/app/routes/analysis.py converts project inputs into calculation payloads, experiment reports, LLM-advice requests, sensitivity tables, SRM checks, and observed-result analyses.

Stats engine

app/backend/app/stats/* contains binary, continuous, Bayesian, sequential, SRM, duration, and Student-t routines used by services and tests.

Slack notifier

app/backend/app/routes/slack.py and app/backend/app/slack/* implement install, OAuth callback, slash command, interactivity, and event endpoints.

Postgres schema

ProjectRepository switches from SQLite to Postgres when AB_DATABASE_URL is set, creating project, audit, API-key, webhook, template, Slack, and analysis-history tables.

Dashboard

app/frontend/src contains the wizard, comparison dashboard, results panels, project store, draft store, API client, and locale bundles.

Experiment Lifecycle

flowchart TD
  A[Wizard input] --> B[POST /api/v1/analyze or /api/v1/design]
  B --> C[Normalize ExperimentInput]
  C --> D[calculate_experiment_metrics]
  D --> E[build_experiment_report]
  E --> F{Optional advice?}
  F -->|local orchestrator| G[LocalOrchestratorAdapter]
  F -->|OpenAI header token| H[OpenAIAdapter]
  F -->|Anthropic header token| I[AnthropicAdapter]
  G --> J[AnalysisResponse]
  H --> J
  I --> J
  E --> K[ProjectRepository save/history/export]
  J --> L[Dashboard results panels]
  K --> M[Webhook and Slack status surfaces]

Data Stores

Store	Default	Optional production path	Owned data
Workspace database	SQLite at app/backend/data/projects.sqlite3	Postgres through AB_DATABASE_URL	Projects, analysis runs, exports, audit events, templates, API keys, webhooks, Slack installs
Frontend build	app/frontend/dist	Docker image or external static host	Vite bundle served by FastAPI when AB_SERVE_FRONTEND_DIST=true
Snapshot dataset	Disabled	Legacy optional AB_HF_* code remains in-repo but is unsupported	Not a publication or production backup path
Generated docs	docs-site/src/content/docs	GitHub Pages artifact	Synced markdown, route catalog, experiment catalog, configuration matrix