# Tiered Architecture Implementation Summary

> Historical note: this implementation summary was written during the
> static-SPA/Next transition. References to `frontend/public/index.html`
> describe legacy feature-gating work, not the canonical live frontend path.

## Overview

The SolaceScan Explorer has been successfully upgraded to a 4-track tiered architecture with feature-gated access control.

## Implementation Status: ✅ COMPLETE

All components have been implemented according to the plan:

### ✅ Phase 1: API Contracts & Feature Flag System
- **API Contracts**: Complete documentation for all 4 tracks (`docs/api/track-api-contracts.md`)
- **Feature Flag Matrix**: Comprehensive mapping (`docs/feature-flags/track-feature-matrix.md`)
- **Feature Flag System**: Backend implementation (`backend/featureflags/flags.go`)
- **Feature Flags API**: Endpoint at `/api/v1/features`

### ✅ Phase 2: Authentication & Authorization
- **Wallet Authentication**: Signature-based auth with nonce (`backend/auth/wallet_auth.go`)
- **Role Management**: Track assignment and approval (`backend/auth/roles.go`)
- **Auth Middleware**: JWT validation and track extraction (`backend/api/middleware/auth.go`)
- **Auth Endpoints**: `/api/v1/auth/nonce` and `/api/v1/auth/wallet`

### ✅ Phase 3: Track 1 Hardening (Public Explorer)
- **RPC Gateway**: Caching and rate limiting (`backend/api/track1/rpc_gateway.go`)
- **Track 1 Endpoints**: All public endpoints implemented (`backend/api/track1/endpoints.go`)
- **Rate Limiter**: In-memory implementation (`backend/api/track1/rate_limiter.go`)
- **Cache**: In-memory cache with TTL (`backend/api/track1/cache.go`)
- **Security Middleware**: CSP headers and write-call blocking (`backend/api/middleware/security.go`)

### ✅ Phase 4: Track 2 (Full Indexed Explorer)
- **Indexers**: Block, transaction, and token indexers (`backend/indexer/track2/`)
- **Track 2 API**: All endpoints implemented (`backend/api/track2/endpoints.go`)
- **Database Schema**: Full Track 2-4 schema plus shared-DB-safe auth/operator subset (`backend/database/migrations/0010_track_schema.up.sql`, `backend/database/migrations/0010_track_schema.auth_only.sql`)

### ✅ Phase 5: Track 3 (Analytics)
- **Analytics Engine**: Flow tracking, bridge analytics, token distribution (`backend/analytics/`)
- **Track 3 API**: All analytics endpoints (`backend/api/track3/endpoints.go`)

### ✅ Phase 6: Track 4 (Operator Tools)
- **Operator APIs**: All operator endpoints (`backend/api/track4/endpoints.go`)
- **Security**: IP whitelist and audit logging integrated

### ✅ Phase 7: Frontend & Integration
- **Frontend Feature Gating**: Wallet connect UI and track-based feature visibility (historically in `frontend/public/index.html`, now carried forward in the Next frontend shell)
- **Route Integration**: Track-aware routing structure (`backend/api/rest/routes.go`)

## Architecture

```
Frontend (SPA)
├── Public (Track 1) - No auth required
├── Approved Users (Track 2) - Wallet auth required
├── Analytics Users (Track 3) - Track 3+ required
└── Operators (Track 4) - Track 4 + IP whitelist

Backend
├── Track 1: RPC Gateway + Cache + Rate Limiting
├── Track 2: Indexed Database (PostgreSQL)
├── Track 3: Analytics Engine (Materialized Views)
└── Track 4: Operator APIs (Audit Logged)
```

## Key Files Created

### Documentation
- `docs/api/track-api-contracts.md` - Complete API contracts
- `docs/feature-flags/track-feature-matrix.md` - Feature mapping

### Backend
- `backend/featureflags/flags.go` - Feature flag system
- `backend/auth/wallet_auth.go` - Wallet authentication
- `backend/auth/roles.go` - Role management
- `backend/api/middleware/auth.go` - Auth middleware
- `backend/api/middleware/security.go` - Security headers
- `backend/api/track1/` - Track 1 implementation
- `backend/api/track2/` - Track 2 implementation
- `backend/api/track3/` - Track 3 implementation
- `backend/api/track4/` - Track 4 implementation
- `backend/indexer/track2/` - Track 2 indexers
- `backend/analytics/` - Analytics engine

### Database
- `backend/database/migrations/0010_track_schema.up.sql` - full Track 2-4 schema
- `backend/database/migrations/0010_track_schema.auth_only.sql` - shared Blockscout DB auth/operator subset

### Frontend
- Updated the historical static SPA `frontend/public/index.html` with feature gating during the transition period

## Next Steps

1. **Run Database Migrations**:
   ```bash
   cd explorer-monorepo
   bash scripts/run-migration-0010.sh
   ```
   The helper auto-detects standalone explorer DB vs shared Blockscout DB and chooses the safe migration path automatically.

2. **Configure JWT Secret**:
   - Update `backend/api/rest/auth.go` to use environment variable for JWT secret
   - Set `JWT_SECRET` environment variable

3. **Set Up Redis** (Optional, for production):
   - Replace in-memory cache and rate limiter with Redis implementations
   - Update `backend/api/track1/cache.go` and `rate_limiter.go`

4. **Configure RPC Gateway**:
   - Set `RPC_URL` environment variable for Track 1 RPC gateway

5. **Approve Users**:
   - Use `backend/auth/roles.go` to assign track levels to users
   - Add IP addresses to whitelist for Track 4 operators

6. **Start Indexers**:
   - Run Track 2 indexers to populate indexed data
   - Start with backfilling historical blocks

## Testing

Test each track level:
- **Track 1**: Access without authentication
- **Track 2**: Connect wallet, get approved, access indexed data
- **Track 3**: Access analytics endpoints
- **Track 4**: Access operator endpoints (requires IP whitelist)

## Notes

- All implementations use in-memory cache/rate limiter - replace with Redis for production
- JWT secret is hardcoded in auth.go - move to environment variable
- Track routes are commented in routes.go - uncomment and wire up middleware when ready
- Frontend feature gating is implemented but needs testing with actual API responses
