Technology
Open source.
Free tier. Public data only.
The EMERGENZ Meridian stack is built entirely from free-tier infrastructure, open-source components, and public government data. Every cost must tie to a documented funding source before it is incurred. The platform is designed to run at zero ongoing cost in Phase 1.
Technology Stack
Proven components.
Free-tier architecture.
Frontend
React + TypeScript
Geospatial map UI with Mapbox GL JS for census block group score overlays and NCS coverage gap mapping.
Open Source
Frontend Deployment
Vercel
Static site hosting with edge CDN. Free tier sufficient for Phase 1 traffic. Automatic deploy from GitHub.
Free Tier
API / Backend
FastAPI (Python)
REST API with JWT auth for credentialed endpoints. Mandatory signal_disclaimer injected at the middleware layer into every response object.
Open Source
Backend Deployment
Railway
FastAPI deployment. Free tier sufficient for Phase 1. Scales with funding as access expands.
Free Tier
Database
PostgreSQL + PostGIS
Geospatial database with PostGIS extension for CBG spatial queries, coverage radius calculations, and score storage with full versioning.
Open Source
Database Hosting
Supabase
PostgreSQL + PostGIS + Auth + Storage. Free tier: 500MB database, 2GB storage. Built-in JWT auth for credentialed access tier.
Free Tier
Version Control
GitHub
Code repository, ETL pipeline management, issue tracking. Open source repository under Apache License 2.0.
Apache 2.0
Mapping
Mapbox GL JS
Interactive geospatial visualization for score layers and NCS access point overlays. Free tier sufficient for Phase 1.
Free Tier
ETL / Data Pipeline
Python (16 scheduled jobs)
16 ETL jobs on scheduled cycles. Each logs source URL, timestamp, row count, and validation status. No external data broker or proprietary feed.
Open Source
Data Sources
16 public sources.
Zero proprietary data.
Every source is a public government dataset with a documented URL, public license, and automated API or download endpoint. No personal health information. No individually identifiable records.
Daily/real-time
Weekly
Monthly/quarterly
Annual/biennial
Build Roadmap
Three phases.
Clear milestones.
Phase 1 — Active Build
Foundation
6–8 weeks from build start
- Database schema + PostGIS setup (15 tables)
- 16 ETL ingestion jobs for all public data sources
- ACS scoring engine + CBG computation
- NCS coverage gap calculation + 400m radius analysis
- Public map UI with score overlays (Mapbox GL JS)
- FastAPI backend with signal_disclaimer middleware
- JWT authentication for credentialed access tier
- STI Tiers 2–3 alert pipeline
Phase 2 — Expansion
Intelligence Layer
3–6 months post Phase 1
- EMS Effectiveness Score with agency preview protocol
- PSH Community Signal Score with pre-publication review
- Social media signal monitoring integration
- STI Tier 1 — DPH wastewater partnership
- Credentialed dashboard with CSV export and API access
Phase 3 — Validation
Empirical Foundation
6–12 months post Phase 1
- ML forecasting layer (LASSO / random forest)
- Retrospective validation: 2023 ACS vs. 2024 OCME data
- Columbus 311 weights SF-specific calibration
- SRO multiplier temporal revalidation
- Peer-reviewed publication submission
- Methodology v1.1 release
Architecture Constraints
Non-negotiable design decisions.
These constraints were established before architecture began. They are not preferences — they govern every component choice.
C.01
Free tier only — no cost without funding
Every infrastructure component must have a free-tier option sufficient for Phase 1. No component may incur recurring cost without a documented funding source. This is why Vercel, Railway, and Supabase were selected over AWS, GCP, or dedicated hosting.
C.02
Cache-first — no live computation on user requests
Score computation happens on scheduled batch cycles, not in response to user requests. API endpoints serve pre-computed cached scores only. Every score response includes a vintage timestamp so users know the computation date.
C.03
Public data only — no PHI, no individually identifiable records
Every data source must be publicly accessible via a documented URL. No data integration requires a data use agreement or MOU for Phase 1. Aggregate, geocoded government data only. This makes the platform fully replicable by any third party without legal barriers.
C.04
Signal disclaimer is non-removable at the API layer
The signal_disclaimer object is injected by FastAPI middleware before any response is returned. It cannot be filtered or suppressed by query parameters. Present in JSON, CSV, and all response formats. Governance by architecture, not policy.
C.05
PCSS pre-publication review enforced at endpoint layer
PCSS endpoints return
pending_review status until a 30-day review window has elapsed and review completion is logged in the database. No PCSS output reaches any user before review completion regardless of access tier.
C.06
Okta and enterprise identity management — future state
Phase 1 uses Supabase JWT authentication. Enterprise identity management is planned but not yet deployed. Device-organization separation is a documented open item. This is disclosed as a pre-deployment compliance gap in the risk assessment.
Open Source
Built to be replicated.
Platform code under Apache License 2.0. Methodology under CC BY 4.0. Any jurisdiction with standard open data infrastructure can build a local instance. Attribution required. Adaptation encouraged.