# EVS-TAP & GCVWP System Architecture & Passenger Common Core Reuse

## 1. Architectural Philosophy: Not a Snowflake
Rather than building an isolated, costly bespoke silo, the EVS-TAP / Guam-CNMI ETA system is architected as modular extensions atop **CBP Passenger Common Core Services (PCCS)** and **Advanced Targeting System (ATS)** infrastructure.

```
+-----------------------------------------------------------------------------------------+
|                                PUBLIC INTAKE LAYER                                      |
|  +-----------------------------------+     +-----------------------------------------+  |
|  | GCVWP Standard Visa-Exempt Intake |     | EVS-TAP Restricted Track (PRC Parole)  |  |
|  | - 508 WCAG 2.1 AA Compliant       |     | - Enhanced Question Flow                |  |
|  | - Multi-Lingual (EN/ZH/JA/KO)     |     | - Intended Island Verification          |  |
|  | - Mobile Passport OCR Engine      |     | - Discretionary Parole Rule Engine      |  |
|  +-----------------------------------+     +-----------------------------------------+  |
+--------------------------------------------|--------------------------------------------+
                                             | (Encrypted TLS 1.3 / mTLS API)
+--------------------------------------------v--------------------------------------------+
|                             API GATEWAY & SECURITY ENCLAVE                              |
|  - Zero Trust Architecture (ZTA) & FIPS 140-3 Encryption                                |
|  - Attribute-Based Access Control (ABAC) & Cryptographic Data Segmentation             |
+--------------------------------------------|--------------------------------------------+
                                             |
+--------------------------------------------v--------------------------------------------+
|                          PASSENGER COMMON CORE SERVICES (PCCS)                          |
|  +---------------------------+  +--------------------------+  +----------------------+  |
|  | Travel Auth Datastore     |  | Officer Adjudication     |  | Recurrent Vetting    |  |
|  | (Event-Sourced Ledger)    |  | Portal (TASPD/PSPD)      |  | Engine (Real-Time)   |  |
|  +---------------------------+  +--------------------------+  +----------------------+  |
|  +---------------------------+  +--------------------------+  +----------------------+  |
|  | Carrier PDS Board/NoBoard |  | Lookouts / NCIC / Nlets  |  | Simplified Arrival   |  |
|  | Integration (sub-500ms)   |  | Bi-Directional Adapter   |  | TVS Biometric Sync   |  |
|  +---------------------------+  +--------------------------+  +----------------------+  |
+-----------------------------------------------------------------------------------------+
```

## 2. Component Specifications

### A. Public-Facing Intake Microservice
- **Multi-lingual Support**: English, Simplified Chinese, Traditional Chinese, Japanese, Korean.
- **Section 508 / WCAG 2.1 AA Accessibility**: High-contrast modes, ARIA-labeled dynamic form fields, screen-reader live announcements, keyboard-only tab navigation.
- **Passport MRZ / OCR Processing**: Client-side image validation and MRZ extraction with zero unencrypted data caching.
- **Restricted Group Branching**: Self-identification dynamically activates EVS-TAP supplemental questionnaire without exposing internal targeting logic.

### B. Officer Adjudication Portal
- **Automated Rules Engine**: Cleared, low-risk applications without derogatory matches are auto-adjudicated within 15 minutes.
- **TASPD / PSPD Compliant Queue**: Tiered analyst queues for applications requiring manual officer review.
- **Integrated Lookouts / NCIC / Nlets**: Single-pane lookup preventing duplicate manual searches across legacy systems.

### C. Recurrent Vetting Engine
- **Continuous Stream Matching**: Event-driven streaming comparing active authorisations against continuous watchlist deltas (TSDB, TECS, INTERPOL Red Notices).
- **Sub-Second Token Revocation**: Automatically invalidates authorization tokens and updates APIS/PDS manifests in real time.

### D. Carrier PDS & Simplified Arrival Integration
- **Pre-Departure Screening (PDS)**: Interactive API returning `BOARD` / `NO_BOARD` status during carrier check-in (sub-500ms response time).
- **Graceful Degradation / Safe Mode**: Local cached authorization hashes and encrypted offline tokens ensure carrier operations never stall during transient network partition.
- **Simplified Arrival (TVS)**: Biometric match templates at Guam/Saipan air and sea ports linked directly to active EVS-TAP authorization status.