Architecture - FlowState DAW

🌐 High-Level Architecture

┌──────────────────────────────────────────────────────────────────────────────────┐ │ CLOUDFLARE EDGE (300+ Locations) │ ├──────────────────────────────────────────────────────────────────────────────────┤ │ │ │ ┌─────────────────┐ ┌─────────────────┐ ┌─────────────────┐ ┌─────────────┐ │ │ │ PAGES │ │ WORKERS │ │ AI GATEWAY │ │ CALLS │ │ │ │ React SPA │ │ API Routes │ │ Cache/Route │ │ WebRTC │ │ │ │ FREE │ │ $5/mo │ │ FREE │ │ $0.05/GB │ │ │ └────────┬────────┘ └────────┬────────┘ └────────┬────────┘ └──────┬──────┘ │ │ │ │ │ │ │ │ ┌────────┴────────────────────┴────────────────────┴───────────────────┴──────┐ │ │ │ WORKERS AI MODELS │ │ │ │ ┌──────────┐ ┌──────────┐ ┌──────────┐ ┌──────────┐ ┌────────────────┐ │ │ │ │ │ Whisper │ │ MeloTTS │ │ Llama 4 │ │ BGE │ │ Stable Diff │ │ │ │ │ │$0.0005/m │ │ included │ │ Scout │ │Embeddings│ │ (album art) │ │ │ │ │ └──────────┘ └──────────┘ └──────────┘ └──────────┘ └────────────────┘ │ │ │ └──────────────────────────────────────────────────────────────────────────────┘ │ │ │ │ ┌─────────────────┐ ┌─────────────────┐ ┌─────────────────┐ ┌─────────────┐ │ │ │ R2 │ │ D1 │ │ VECTORIZE │ │ DURABLE │ │ │ │ Audio Storage │ │ Database │ │ Sample Search │ │ OBJECTS │ │ │ │ 10GB FREE │ │ 5GB FREE │ │ 5M FREE │ │ Collab │ │ │ └─────────────────┘ └─────────────────┘ └─────────────────┘ └─────────────┘ │ └──────────────────────────────────────────────────────────────────────────────────┘ │ ▼ ┌──────────────────────────────────────────────────────────────────────────────────┐ │ FLY.IO COMPUTE (Multi-Region) │ ├──────────────────────────────────────────────────────────────────────────────────┤ │ ┌─────────────────────┐ ┌─────────────────────┐ ┌───────────────────────────┐ │ │ │ SHUSH BRAIN │ │ TTS ENGINE │ │ GPU WORKERS │ │ │ │ Intent Router │ │ Chatterbox/Fish │ │ HTDemucs (stems) │ │ │ │ Model Selector │ │ Viseme Mapping │ │ Stable Audio (gen) │ │ │ │ $3/mo │ │ $2/mo │ │ MusicGen │ │ │ │ 12ms avg │ │ 75-150ms │ │ ~$0.05/job │ │ │ └─────────────────────┘ └─────────────────────┘ └───────────────────────────┘ │ └──────────────────────────────────────────────────────────────────────────────────┘ │ ▼ ┌──────────────────────────────────────────────────────────────────────────────────┐ │ PREMIUM AI (Gemini - Non-Negotiable) │ ├──────────────────────────────────────────────────────────────────────────────────┤ │ ┌─────────────────────────────────┐ ┌─────────────────────────────────────────┐│ │ │ GEMINI 3 FLASH │ │ GEMINI 2.5 FLASH ││ │ │ • Native audio understanding │ │ • Native audio OUTPUT ││ │ │ • 1M token context │ │ • Real-time conversation ││ │ │ • Thinking levels (LOW-HIGH) │ │ • 30 HD voices, 24 languages ││ │ │ • Agentic multi-step tasks │ │ • Emotional expression ││ │ │ • Complex music analysis │ │ • Avatar voice responses ││ │ │ $0.075-0.30/1M tokens │ │ $0.15-0.60/1M tokens ││ │ └─────────────────────────────────┘ └─────────────────────────────────────────┘│ └──────────────────────────────────────────────────────────────────────────────────┘

📦 Cloudflare Products Mapping

Product	DAW Feature	Cost	Free Tier
Pages	Frontend hosting, React SPA	FREE	Unlimited
Workers	API routes, business logic	$5/mo paid	100K req/day
Workers AI	Whisper, Llama, embeddings	$0.011/1K neurons	10K neurons/day
R2	Audio files, waveforms	$0.015/GB-mo	10GB storage
D1	Projects, users, metadata	$0.75/1M reads	5GB storage
Vectorize	Semantic sample search	$0.01/1M queries	5M vectors
Durable Objects	Real-time collaboration	$0.15/M requests	Included w/Workers
Calls	WebRTC for avatar battles	$0.05/GB	-
AI Gateway	Cache Gemini responses	FREE	Unlimited
KV	Sessions, cache	$0.50/M reads	100K reads/day

🔄 Request Flow

Voice Command Flow

User speaks → Microphone capture → Workers AI Whisper → Text ↓ Llama 4 Scout (classify intent) ↓ Execute DAW command locally ↓ Visual feedback to user Total latency: ~200ms

AI Assistant Flow

User types/speaks → (Optional: Whisper) → AI Gateway cache check ↓ (cache miss) Gemini 3 Flash API ↓ Stream response to UI ↓ Cache response (AI Gateway) Total latency: 200-2000ms (depending on complexity)

Sample Search Flow

User searches "dark trap hi-hat" → Workers AI BGE embedding ↓ ┌────────────┴────────────┐ ↓ ↓ D1 keyword Vectorize semantic search search ↓ ↓ └────────────┬────────────┘ ↓ RRF Fusion ranking ↓ Return top 20 results Total latency: ~100ms

🎹 Audio Engine Architecture

┌─────────────────────────────────────────────────────────────────┐ │ AUDIO ENGINE │ ├─────────────────────────────────────────────────────────────────┤ │ │ │ ┌─────────────────┐ ┌─────────────────┐ │ │ │ Tone.js │ │ AudioContext │ │ │ │ Transport │───▶│ (singleton) │ │ │ └─────────────────┘ └────────┬────────┘ │ │ │ │ │ ┌───────────────────────────────┼───────────────────────────┐ │ │ │ AUDIO GRAPH │ │ │ │ │ │ │ │ │ ┌─────────┐ ┌─────────┐ │ ┌─────────┐ │ │ │ │ │ Track 1 │ │ Track 2 │ │ │ Track N │ │ │ │ │ │ GainNode│ │ GainNode│ ... │ GainNode│ │ │ │ │ │ PanNode │ │ PanNode │ │ PanNode │ │ │ │ │ └────┬────┘ └────┬────┘ └────┬────┘ │ │ │ │ └─────────────┴─────────────────┘ │ │ │ │ │ │ │ │ │ ┌───────┴───────┐ │ │ │ │ │ Master Bus │ │ │ │ │ │ GainNode │ │ │ │ │ │ Compressor │ │ │ │ │ └───────┬───────┘ │ │ │ │ │ │ │ │ │ ┌───────┴───────┐ │ │ │ │ │ AnalyserNode │ ◀── VU Meters │ │ │ │ └───────┬───────┘ │ │ │ │ │ │ │ │ │ ┌───────┴───────┐ │ │ │ │ │ Destination │ ◀── Speakers │ │ │ │ └───────────────┘ │ │ │ └────────────────────────────────────────────────────────────┘ │ │ │ │ ┌─────────────────────────────────────────────────────────┐ │ │ │ AUDIO WORKLET (DSP Thread) │ │ │ │ ┌────────────┐ ┌────────────┐ ┌────────────┐ │ │ │ │ │ Waveform │ │ Meter │ │ Custom │ │ │ │ │ │ Generator │ │ Processor │ │ Effects │ │ │ │ │ └────────────┘ └────────────┘ └────────────┘ │ │ │ └─────────────────────────────────────────────────────────┘ │ └─────────────────────────────────────────────────────────────────┘

💾 Data Models

D1 Schema

-- Users
CREATE TABLE users (
  id TEXT PRIMARY KEY,
  email TEXT UNIQUE NOT NULL,
  name TEXT,
  tier TEXT DEFAULT 'free',
  created_at DATETIME DEFAULT CURRENT_TIMESTAMP
);

-- Projects
CREATE TABLE projects (
  id TEXT PRIMARY KEY,
  user_id TEXT NOT NULL,
  name TEXT NOT NULL,
  tempo INTEGER DEFAULT 120,
  time_signature TEXT DEFAULT '4/4',
  data_url TEXT,  -- R2 reference
  created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
  updated_at DATETIME DEFAULT CURRENT_TIMESTAMP,
  FOREIGN KEY (user_id) REFERENCES users(id)
);

-- Samples (metadata)
CREATE TABLE samples (
  id TEXT PRIMARY KEY,
  name TEXT NOT NULL,
  path TEXT NOT NULL,  -- R2 path
  category TEXT,
  bpm REAL,
  key TEXT,
  duration_ms INTEGER,
  tags TEXT,  -- JSON array
  waveform_url TEXT,
  embedding_id TEXT,  -- Vectorize reference
  created_at DATETIME DEFAULT CURRENT_TIMESTAMP
);

-- User Favorites
CREATE TABLE favorites (
  user_id TEXT,
  sample_id TEXT,
  created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (user_id, sample_id)
);

R2 Structure

r2://flowstate-audio/
├── system/                    # System samples (10K)
│   ├── drums/
│   │   ├── kicks/
│   │   ├── snares/
│   │   └── hihats/
│   ├── bass/
│   ├── fx/
│   └── loops/
├── users/{userId}/           # User uploads
│   ├── uploads/
│   ├── recordings/
│   └── projects/
└── cache/                    # Generated assets
    ├── waveforms/
    └── previews/

🔌 API Endpoints

Endpoint	Method	Description
`/api/auth/*`	POST	OAuth login/logout
`/api/projects`	GET/POST	List/create projects
`/api/projects/:id`	GET/PUT/DELETE	Project CRUD
`/api/samples/search`	POST	Hybrid sample search
`/api/samples/upload`	POST	Upload user sample
`/api/ai/transcribe`	POST	Whisper transcription
`/api/ai/chat`	POST	AI assistant (streaming)
`/api/ai/command`	POST	Voice command execution
`/api/export`	POST	Trigger audio export

🔒 Security Architecture

Authentication: OAuth 2.0 (Google, Discord, Apple)
Sessions: JWT in HttpOnly cookies, KV storage
API Security: Rate limiting, CORS, request validation
Data Encryption: TLS 1.3 in transit, AES-256 at rest (R2)
File Access: Presigned URLs with expiry

📈 Scaling Strategy

Horizontal Scaling (Automatic)

Cloudflare Workers: Auto-scale to millions of requests
R2: Unlimited storage, global replication
D1: Read replicas for query distribution

Scaling Triggers

Users	Action Required
0-1K	Stay on free tiers where possible
1K-10K	Upgrade to Workers Paid ($5/mo)
10K-50K	Add D1 read replicas, increase Fly.io
50K+	Consider Cloudflare Enterprise contract