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14.18 Architecture Decision Records (ADR Log)
This log records every major architectural and technical decision made across the 21-BIS-Compliance-Engine, documenting the chosen approach, alternatives evaluated, trade-offs accepted, and triggers to revisit.
Master Architecture Decisions Table
| Decision | Chosen Option | Alternatives Considered | Deciding Factors | Trade-off Accepted | Revisit When |
|---|---|---|---|---|---|
| Backend Web Framework | FastAPI (Python 3.11) | Express.js, Flask, Django, Go Gin, Spring Boot | Direct in-memory zero-copy pointer sharing with Python ML/NumPy arrays; async ASGI; Pydantic v2 validation | Python GIL limits single-process thread concurrency | Backend logic separates into high-throughput I/O gateway requiring Go/Rust |
| Vector Embedding Model | FastEmbed ONNX (bge-small-en-v1.5) | OpenAI text-embedding-3-small, PyTorch SentenceTransformers, HuggingFace API | Strips away 1.2GB PyTorch dependency; cuts RAM to 60MB; runs in 14ms on CPU; zero cloud token costs | CPU-bound computation at high concurrency bursts | Queries exceed 1,000 RPS, requiring dedicated GPU/TensorRT inference sidecars |
| Vector Search Engine | FAISS CPU (IndexFlatIP) | Pinecone, pgvector, Weaviate, Qdrant, Milvus, ChromaDB | 100% exact cosine recall (no approximation loss); <0.2ms search latency; operates 100% in RAM with zero cloud fees | Flat scan scales as $O(N)$ linearly with corpus size | Corpus grows beyond 50,000 standards, requiring HNSW or IVF index quantization |
| Department Classifier | Scikit-Learn Serialized Pipeline (v3.pkl) | Fine-tuned BERT, LLM few-shot prompting, Zero-shot NLI | Sub-0.1ms inference; deterministic closed-set routing; zero neural network compute | Cannot easily predict novel, unseen ministry categories | Dynamic multi-level hierarchical ministerial taxonomies are introduced |
| Domain Safety Guardrail | 4-Tier Deterministic Rules (guardrail.py) | LLM moderator prompt, Llama Guard, OpenAI Moderation API | Sub-0.05ms execution; zero API dependencies; 100% accuracy on adversarial test suites | Requires manual maintenance of commercial keyword blacklists | Unregulated product categories become too vast for keyword lists |
| Readiness Scoring Engine | Rule-Based Weighted Checklists (gap_engine.py) | LLM compliance estimation, Fuzzy neural scoring | 100% mathematically reproducible and auditable in legal/court proceedings | Fixed criteria weights cannot capture subjective auditor nuances | Dynamic clause-level severity scoring is required per product |
| Audit Pack Export Format | RFC 4180 CSV Stream | PDF generation (Puppeteer/WeasyPrint), Excel .xlsx | Lightweight native Python generation with zero headless browser dependencies; directly importable into ERP/Excel | Plain text layout without visual certificate branding | Enterprise customers mandate cryptographically signed, branded PDF certificates |
| Conversational Intent Handling | Prefix & Substring Short-Circuit | LLM intent routing, Rasa NLU, Dialogflow | Sub-microsecond execution; prevents misinterpreting greetings as product queries | Limited flexibility for ambiguous user phrasing | Multi-turn conversational dialog and context memory are added |
| Frontend Architecture | React 19 SPA + Vite 8 | Next.js (App Router), Vue 3, Svelte 5, Angular | Fast HMR (<50ms); 140KB production bundle; internal tool does not require public SEO | Client-rendered (no initial server-side HTML rendering) | Public SEO-indexed consumer standard search portal is launched |
| UI Styling Strategy | Inline Vanilla CSS Objects | Tailwind CSS, Material UI, styled-components | Zero build-step dependencies; zero class-name collisions; self-contained in App.jsx | Styles cannot be extracted into external cached CSS files | Application expands beyond a single dashboard into a multi-page portal |
| Master Knowledge Base Storage | Static JSON File (model2_corpus.json) | MongoDB, PostgreSQL, SQLite, Redis | Immutable, read-only dataset; loads into RAM in 0.5ms; zero database connection overhead | Modifying standards requires running rebuild scripts and restarting process | Multi-tenant dynamic standard uploads by external contributors |
| Containerization Strategy | Python 3.11-slim Single Container | Multi-container Docker Compose, Alpine base | Debian slim provides pre-compiled glibc wheels for FAISS and NumPy without compiler bloat | 280MB image is slightly larger than Alpine (which frequently fails building FAISS) | Microservices decoupling splits frontend and backend containers |
| API Versioning | Unversioned Root Routes (/chat) | URI versioning (/v1/chat), Header versioning | Simple MVP demonstration interface | Breaking changes to JSON schemas could affect existing clients | Public developer APIs and third-party partner integrations are exposed |