commit f45619

Commit `f45619`

2025-10-06 11:44:54 Meenakshi: uploading LLD

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`Projects/HireGenius/LLD.md` ..
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	# LLD
+	# AI-Powered Recruitment Automation System
+	## Low-Level Design Document (LLD)
+
+	### 📘 Table of Contents
+	1. [System Overview](#1-system-overview)
+	2. [Module Breakdown](#2-module-breakdown)
+	3. [API Design](#3-api-design)
+	4. [Database Design](#4-database-design)
+	5. [Business Workflow](#5-business-workflow)
+	6. [AI Integration Points](#6-ai-integration-points)
+	7. [System Architecture](#7-system-architecture)
+
+	## 1. System Overview
+
+	### 1.1 🎯 Purpose
+	Automate the recruitment pipeline from resume ingestion to candidate ranking using NLP-based parsing, vector embeddings, and AI-powered re-ranking.
+
+	---
+
+	### 1.2 ⚙️ Key Capabilities
+	- Incremental Resume Ingestion: Fetch new resumes from Gmail on schedule
+	- Automated Resume Parsing: Extract structured data (skills, experience, education, contact)
+	- Semantic Matching: Use embeddings to find similar candidates to job descriptions
+	- AI Re-Ranking: Re-rank top candidates using GPT-4o-mini for better precision
+	- Dashboard: HR views ranked candidates with explainability
+
+	---
+
+	### 1.3 🧰 Technology Stack
+	\| Layer \| Technology \|
+	\|--------\|-------------\|
+	\| Frontend \| React.js + Tailwind CSS \|
+	\| Backend \| Node.js + Express.js \|
+	\| Database \| PostgreSQL 15+ with pgvector extension \|
+	\| AI/ML \| OpenAI GPT-4o-mini \|
+	\| Embeddings \| OpenAI `text-embedding-3-small` \|
+	\| Email Integration \| Gmail API with OAuth 2.0 \|
+	\| Scheduler \| node-cron \|
+	### 🧠 Additional Components
+
+	\| Component \| Technology \|
+	\|------------\|-------------\|
+	\| AI/ML \| OpenAI GPT-4o-mini \|
+	\| Vector Embeddings \| OpenAI text-embedding-3-small \|
+	\| Email Integration \| Gmail API with OAuth 2.0 \|
+	\| Scheduler \| node-cron \|
+
+
+	## Module Breakdown
+
+	### 2.1 Module Architecture
+	┌─────────────────────────────────────────────────────────┐
+	│ Frontend Layer (React) │
+	│ - Job Dashboard - Candidate Pipeline - Analytics │
+	└────────────────────┬────────────────────────────────────┘
+	│ REST API
+	┌────────────────────▼────────────────────────────────────┐
+	│ Backend Layer (Node.js/Express) │
+	├──────────────────────────────────────────────────────────┤
+	│ 1. Gmail Module - Email fetching & OAuth │
+	│ 2. Resume Parser Module - NLP extraction │
+	│ 3. Embedding Module - Vector generation │
+	│ 4. Database Module - Data persistence │
+	│ 5. Job Description Mod - JD management │
+	│ 6. Ranking Module - AI re-ranking │
+	│ 7. Application Control - Orchestration │
+	│ 8. HR UI Module - Dashboard APIs │
+	└────────────────────┬────────────────────────────────────┘
+	│
+	┌────────────────────▼────────────────────────────────────┐
+	│ Data Layer (PostgreSQL + pgvector) │
+
+
+	## 2.2 Detailed Module Specifications
+
+	### Module 1: Gmail Module
+	Responsibility: Email integration and resume fetching
+
+	Functions:
+	- Authenticate with Gmail API using OAuth 2.0
+	- Fetch emails with attachments based on filters (date, keywords, labels)
+	- Download resume attachments (PDF, DOCX)
+	- Track last fetch timestamp for incremental processing
+
+	Key Operations:
+	- `fetchNewEmails(afterDate, filters)` → Returns array of email objects with attachments
+	- `downloadAttachment(messageId, attachmentId)` → Returns file buffer
+	- `getLastFetchTime(jobId)` → Returns timestamp of last successful fetch
+
+	External Dependencies: Gmail API, Google OAuth 2.0
+
+	---
+
+	### Module 2: Resume Parser Module
+	Responsibility: Extract structured data from resume text
+
+	Parsing Strategy: Rule-based NLP with regex patterns
+
+	Extraction Details:
+	- Name: First line heuristics, capitalization patterns
+	- Email: Regex pattern `[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}`
+	- Phone: Regex for various formats (`+1-XXX-XXX-XXXX`, `(XXX) XXX-XXXX`)
+	- Skills: Keyword matching against predefined skill database
+	- Experience: Section detection (keywords: "experience", "work history") + date parsing
+	- Education: Section detection + degree/institution extraction
+
+	Functions:
+	- `extractText(fileBuffer, format)` → Returns plain text from PDF/DOCX
+	- `parseResume(resumeText)` → Returns structured JSON object
+	- `validateParsedData(data)` → Returns boolean + error messages
+	- `normalizeSkills(skillArray)` → Returns deduplicated, lowercase skills
+
+	Output Format (JSON):
+	```json
+	{
+	"name": "John Doe",
+	"email": "john@example.com",
+	"phone": "+1-555-0123",
+	"skills": ["javascript", "python", "sql"],
+	"experience": [
+	{
+	"title": "Software Engineer",
+	"company": "Tech Corp",
+	"duration": "2020-2023",
+	"description": "Built REST APIs..."
+	}
+	],
+	"education": [
+	{
+	"degree": "B.S. Computer Science",
+	"institution": "MIT",
+	"year": 2018
+	}
+	],
+	"total_experience_years": 5
+	}

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