Migrate backend from Node.js/TypeScript/Express to Java Spring Boot

[Copilot]

Replaces the entire backend/ with a Java 17 + Spring Boot 3.4 application, preserving all existing API contracts so the React frontend requires no changes.

Replaced stack

• Runtime: Node.js + TypeScript → Java 17
• Framework: Express → Spring Boot (Spring Web, Spring Security)
• ODM/ORM: Mongoose → Spring Data MongoDB
• JWT: jsonwebtoken → JJWT 0.12.6
• Validation: Zod → Jakarta Bean Validation
• Password hashing: bcrypt npm → BCryptPasswordEncoder
• Build: package.json / tsc → Maven (pom.xml)

Project structure

backend/
├── pom.xml
└── src/main/java/com/secondbrain/
    ├── SecondBrainApplication.java
    ├── config/SecurityConfig.java          # CORS, stateless JWT, route auth rules
    ├── security/{JwtUtil,JwtAuthFilter}.java
    ├── model/{User,Content,Link}.java      # @Document mapped to existing collections
    ├── repository/*Repository.java         # Spring Data MongoRepository interfaces
    ├── dto/{Signup,Signin,Content,Share}Request.java
    ├── controller/{User,Content,Share,Root}Controller.java
    └── util/RandomUtil.java                # Same char set as original utils.ts

API compatibility preserved

All endpoints and response shapes are identical. Intentional backward-compat decisions:

• authorization header read as a bare token (no `****** prefix) — matches existing frontend
• Env var JWT_SECREAT (original typo) kept to avoid breaking deployed configurations
• contenetId (typo) preserved in DELETE /api/v1/content request body
• HTTP 411 responses on share lookup failures match original behavior

Security note

CSRF protection is disabled — correct for this stateless JWT/Authorization-header API (no cookies). CodeQL flags this; it is a false positive in this context.

Configuration

spring.data.mongodb.uri=${MONGODB_URI:mongodb://localhost:27017/secondbrain}
server.port=${PORT:3000}
jwt.secret=${JWT_SECREAT:change-this-secret-in-production}

Same environment variables as the original .env.

Original prompt

hey can you change this code base from node ts express to java spring boot completely

Created from VS Code.

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Project	Deployment	Actions	Updated (UTC)
second-brain	Error		Mar 23, 2026 6:18pm
second-brain-dkkx	Ready	Preview, Comment	Mar 23, 2026 6:18pm