feat: implement AI legal assistant system MVP

Core modules:
- Laws: CRUD, search, AI-powered QA
- Analysis: legal research and case management
- Contracts: lifecycle management with templates
- Signatures: electronic signature workflow

Infrastructure:
- FastAPI + SQLite + async SQLAlchemy
- Docker deployment support
- 54 unit tests passing

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.env.example

@@ -0,0 +1,21 @@
+# API Keys
+LLM_API_KEY=your-api-key-here
+LLM_API_BASE=https://api.openai.com/v1
+LLM_MODEL=gpt-4o-mini
+
+EMBEDDING_API_KEY=your-api-key-here
+EMBEDDING_API_BASE=https://api.openai.com/v1
+EMBEDDING_MODEL=text-embedding-3-small
+EMBEDDING_DIMENSION=1536
+
+# Database
+DATABASE_URL=sqlite+aiosqlite:///./data/legal_assistant.db
+
+# JWT
+JWT_SECRET_KEY=your-secret-key-change-in-production
+JWT_ALGORITHM=HS256
+JWT_ACCESS_TOKEN_EXPIRE_MINUTES=1440
+
+# Application
+DEBUG=false
+UPLOAD_DIR=./uploads

.gitignore

@@ -39,3 +39,4 @@ QWEN.md
 .codex/
 .gemini/
 .qwen/
+venv/

backend/Dockerfile

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+FROM python:3.11-slim
+
+WORKDIR /app
+
+# Install system dependencies
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    gcc \
+    && rm -rf /var/lib/apt/lists/*
+
+# Copy requirements and install Python dependencies
+COPY requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+
+# Copy application code
+COPY . .
+
+# Create data directory
+RUN mkdir -p /app/data /app/uploads
+
+# Expose port
+EXPOSE 8000
+
+# Run the application
+CMD ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "8000"]

backend/app/__init__.py

@@ -0,0 +1 @@
+# Backend package

backend/app/api/__init__.py

@@ -0,0 +1 @@
+# API v1 package

backend/app/api/v1/__init__.py

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+# API v1 endpoints

backend/app/api/v1/analyses.py

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+"""Analysis API endpoints."""
+from typing import Optional
+from fastapi import APIRouter, Depends, HTTPException, Query
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.core.database import get_db
+from app.schemas.analysis import (
+    LegalAnalysisCreate,
+    LegalAnalysisUpdate,
+    LegalAnalysisResponse,
+    CaseCreate,
+    CaseResponse,
+    GenerateAnalysisRequest,
+    GenerateAnalysisResponse,
+)
+from app.services.analysis_service import AnalysisService, CaseService
+from app.services.llm_service import llm_service
+
+router = APIRouter(prefix="/analyses", tags=["analyses"])
+
+
+@router.post("", response_model=LegalAnalysisResponse)
+async def create_analysis(
+    analysis_data: LegalAnalysisCreate,
+    user_id: int = 1,  # TODO: Get from auth
+    db: AsyncSession = Depends(get_db),
+):
+    """Create a new legal analysis."""
+    service = AnalysisService(db)
+    analysis = await service.create_analysis(
+        user_id=user_id,
+        title=analysis_data.title,
+        case_description=analysis_data.case_description,
+        legal_basis=analysis_data.legal_basis,
+    )
+    return analysis
+
+
+@router.get("", response_model=list[LegalAnalysisResponse])
+async def list_analyses(
+    skip: int = Query(0, ge=0),
+    limit: int = Query(20, ge=1, le=100),
+    user_id: int = 1,  # TODO: Get from auth
+    db: AsyncSession = Depends(get_db),
+):
+    """List analyses for current user."""
+    service = AnalysisService(db)
+    analyses = await service.get_analyses_by_user(user_id, skip, limit)
+    return analyses
+
+
+@router.get("/{analysis_id}", response_model=LegalAnalysisResponse)
+async def get_analysis(
+    analysis_id: int,
+    db: AsyncSession = Depends(get_db),
+):
+    """Get an analysis by ID."""
+    service = AnalysisService(db)
+    analysis = await service.get_analysis_by_id(analysis_id)
+
+    if not analysis:
+        raise HTTPException(status_code=404, detail="Analysis not found")
+
+    return analysis
+
+
+@router.put("/{analysis_id}", response_model=LegalAnalysisResponse)
+async def update_analysis(
+    analysis_id: int,
+    analysis_data: LegalAnalysisUpdate,
+    db: AsyncSession = Depends(get_db),
+):
+    """Update an analysis."""
+    service = AnalysisService(db)
+    analysis = await service.update_analysis(
+        analysis_id,
+        **analysis_data.model_dump(exclude_unset=True)
+    )
+
+    if not analysis:
+        raise HTTPException(status_code=404, detail="Analysis not found")
+
+    return analysis
+
+
+@router.delete("/{analysis_id}")
+async def delete_analysis(
+    analysis_id: int,
+    db: AsyncSession = Depends(get_db),
+):
+    """Delete an analysis."""
+    service = AnalysisService(db)
+    success = await service.delete_analysis(analysis_id)
+
+    if not success:
+        raise HTTPException(status_code=404, detail="Analysis not found")
+
+    return {"message": "Analysis deleted successfully"}
+
+
+@router.post("/generate", response_model=GenerateAnalysisResponse)
+async def generate_analysis(
+    request: GenerateAnalysisRequest,
+):
+    """Generate legal analysis using AI."""
+    result = await llm_service.analyze_legal_issue(
+        issue_description=request.case_description,
+        relevant_laws=request.relevant_laws,
+    )
+
+    return GenerateAnalysisResponse(
+        analysis_content=result,
+        legal_basis=request.relevant_laws or [],
+        conclusion=result,
+    )
+
+
+# Case endpoints
+@router.post("/cases", response_model=CaseResponse)
+async def create_case(
+    case_data: CaseCreate,
+    db: AsyncSession = Depends(get_db),
+):
+    """Create a new case."""
+    service = CaseService(db)
+    case = await service.create_case(**case_data.model_dump())
+    return case
+
+
+@router.get("/cases", response_model=list[CaseResponse])
+async def list_cases(
+    skip: int = Query(0, ge=0),
+    limit: int = Query(20, ge=1, le=100),
+    case_type: Optional[str] = Query(None),
+    db: AsyncSession = Depends(get_db),
+):
+    """List cases."""
+    service = CaseService(db)
+    cases = await service.get_cases_list(skip, limit, case_type)
+    return cases

backend/app/api/v1/contracts.py

@@ -0,0 +1,180 @@
+"""Contract API endpoints."""
+from typing import Optional
+from fastapi import APIRouter, Depends, HTTPException, Query
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.core.database import get_db
+from app.models.contract import ContractStatus
+from app.schemas.contract import (
+    ContractCreate,
+    ContractUpdate,
+    ContractResponse,
+    ContractTemplateCreate,
+    ContractTemplateResponse,
+    ApprovalRequest,
+    ApprovalResponse,
+    ContractReviewRequest,
+    ContractReviewResponse,
+)
+from app.services.contract_service import ContractService, ContractTemplateService
+from app.services.llm_service import llm_service
+
+router = APIRouter(prefix="/contracts", tags=["contracts"])
+
+
+@router.post("", response_model=ContractResponse)
+async def create_contract(
+    contract_data: ContractCreate,
+    user_id: int = 1,  # TODO: Get from auth
+    db: AsyncSession = Depends(get_db),
+):
+    """Create a new contract."""
+    service = ContractService(db)
+    contract = await service.create_contract(
+        created_by=user_id,
+        **contract_data.model_dump(exclude={"template_id"}),
+        template_id=contract_data.template_id,
+    )
+    return contract
+
+
+@router.get("", response_model=list[ContractResponse])
+async def list_contracts(
+    skip: int = Query(0, ge=0),
+    limit: int = Query(20, ge=1, le=100),
+    status: Optional[str] = Query(None),
+    user_id: int = 1,  # TODO: Get from auth
+    db: AsyncSession = Depends(get_db),
+):
+    """List contracts."""
+    service = ContractService(db)
+    status_filter = ContractStatus(status) if status else None
+    contracts = await service.get_contracts_list(skip, limit, status_filter, user_id)
+    return contracts
+
+
+@router.get("/{contract_id}", response_model=ContractResponse)
+async def get_contract(
+    contract_id: int,
+    db: AsyncSession = Depends(get_db),
+):
+    """Get a contract by ID."""
+    service = ContractService(db)
+    contract = await service.get_contract_by_id(contract_id)
+
+    if not contract:
+        raise HTTPException(status_code=404, detail="Contract not found")
+
+    return contract
+
+
+@router.put("/{contract_id}", response_model=ContractResponse)
+async def update_contract(
+    contract_id: int,
+    contract_data: ContractUpdate,
+    db: AsyncSession = Depends(get_db),
+):
+    """Update a contract."""
+    service = ContractService(db)
+    contract = await service.update_contract(
+        contract_id,
+        **contract_data.model_dump(exclude_unset=True)
+    )
+
+    if not contract:
+        raise HTTPException(status_code=404, detail="Contract not found")
+
+    return contract
+
+
+@router.post("/{contract_id}/submit", response_model=ContractResponse)
+async def submit_contract(
+    contract_id: int,
+    db: AsyncSession = Depends(get_db),
+):
+    """Submit a contract for approval."""
+    service = ContractService(db)
+    contract = await service.submit_for_approval(contract_id)
+
+    if not contract:
+        raise HTTPException(status_code=404, detail="Contract not found")
+
+    return contract
+
+
+@router.post("/{contract_id}/approve", response_model=ApprovalResponse)
+async def approve_contract(
+    contract_id: int,
+    approval_data: ApprovalRequest,
+    user_id: int = 1,  # TODO: Get from auth
+    db: AsyncSession = Depends(get_db),
+):
+    """Approve a contract."""
+    service = ContractService(db)
+    approval = await service.approve_contract(
+        contract_id,
+        user_id,
+        approval_data.comment,
+    )
+    return approval
+
+
+@router.post("/{contract_id}/reject", response_model=ApprovalResponse)
+async def reject_contract(
+    contract_id: int,
+    approval_data: ApprovalRequest,
+    user_id: int = 1,  # TODO: Get from auth
+    db: AsyncSession = Depends(get_db),
+):
+    """Reject a contract."""
+    service = ContractService(db)
+    approval = await service.reject_contract(
+        contract_id,
+        user_id,
+        approval_data.comment,
+    )
+    return approval
+
+
+@router.post("/review", response_model=ContractReviewResponse)
+async def review_contract(
+    review_data: ContractReviewRequest,
+):
+    """Review a contract using AI."""
+    result = await llm_service.review_contract(
+        contract_content=review_data.contract_content,
+        contract_type=review_data.contract_type,
+    )
+    return ContractReviewResponse(
+        review_result=result,
+        risks=[],
+        suggestions=[],
+    )
+
+
+# Template endpoints
+@router.post("/templates", response_model=ContractTemplateResponse)
+async def create_template(
+    template_data: ContractTemplateCreate,
+    user_id: int = 1,  # TODO: Get from auth
+    db: AsyncSession = Depends(get_db),
+):
+    """Create a contract template."""
+    service = ContractTemplateService(db)
+    template = await service.create_template(
+        created_by=user_id,
+        **template_data.model_dump(),
+    )
+    return template
+
+
+@router.get("/templates", response_model=list[ContractTemplateResponse])
+async def list_templates(
+    skip: int = Query(0, ge=0),
+    limit: int = Query(20, ge=1, le=100),
+    db: AsyncSession = Depends(get_db),
+):
+    """List contract templates."""
+    service = ContractTemplateService(db)
+    templates = await service.get_templates_list(skip, limit)
+    return templates

backend/app/api/v1/laws.py

@@ -0,0 +1,184 @@
+"""Law API endpoints."""
+from typing import Optional
+from fastapi import APIRouter, Depends, HTTPException, Query
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.core.database import get_db
+from app.models.law import LawType, LawStatus
+from app.schemas.law import (
+    LawCreate,
+    LawUpdate,
+    LawResponse,
+    LawListResponse,
+    LawArticleCreate,
+    LawArticleResponse,
+    LawSearchRequest,
+    LegalQARequest,
+    LegalQAResponse,
+)
+from app.services.law_service import LawService
+from app.services.llm_service import llm_service
+
+router = APIRouter(prefix="/laws", tags=["laws"])
+
+
+@router.post("", response_model=LawResponse)
+async def create_law(
+    law_data: LawCreate,
+    db: AsyncSession = Depends(get_db),
+):
+    """Create a new law."""
+    service = LawService(db)
+    law = await service.create_law(
+        title=law_data.title,
+        law_type=LawType(law_data.law_type.value),
+        promulgation_date=law_data.promulgation_date,
+        effective_date=law_data.effective_date,
+        issuing_authority=law_data.issuing_authority,
+        content=law_data.content,
+        status=LawStatus(law_data.status.value),
+        document_number=law_data.document_number,
+    )
+    return law
+
+
+@router.get("", response_model=LawListResponse)
+async def list_laws(
+    skip: int = Query(0, ge=0),
+    limit: int = Query(20, ge=1, le=100),
+    law_type: Optional[str] = Query(None),
+    status: Optional[str] = Query(None),
+    db: AsyncSession = Depends(get_db),
+):
+    """List laws with optional filters."""
+    service = LawService(db)
+
+    law_type_filter = LawType(law_type) if law_type else None
+    status_filter = LawStatus(status) if status else None
+
+    laws = await service.get_laws_list(
+        skip=skip,
+        limit=limit,
+        law_type=law_type_filter,
+        status=status_filter,
+    )
+
+    return LawListResponse(
+        items=laws,
+        total=len(laws),
+        skip=skip,
+        limit=limit,
+    )
+
+
+@router.get("/{law_id}", response_model=LawResponse)
+async def get_law(
+    law_id: int,
+    db: AsyncSession = Depends(get_db),
+):
+    """Get a law by ID."""
+    service = LawService(db)
+    law = await service.get_law_by_id(law_id)
+
+    if not law:
+        raise HTTPException(status_code=404, detail="Law not found")
+
+    return law
+
+
+@router.put("/{law_id}", response_model=LawResponse)
+async def update_law(
+    law_id: int,
+    law_data: LawUpdate,
+    db: AsyncSession = Depends(get_db),
+):
+    """Update a law."""
+    service = LawService(db)
+
+    update_dict = law_data.model_dump(exclude_unset=True)
+    if "law_type" in update_dict:
+        update_dict["law_type"] = LawType(update_dict["law_type"].value)
+    if "status" in update_dict:
+        update_dict["status"] = LawStatus(update_dict["status"].value)
+
+    law = await service.update_law(law_id, **update_dict)
+
+    if not law:
+        raise HTTPException(status_code=404, detail="Law not found")
+
+    return law
+
+
+@router.delete("/{law_id}")
+async def delete_law(
+    law_id: int,
+    db: AsyncSession = Depends(get_db),
+):
+    """Delete a law."""
+    service = LawService(db)
+    success = await service.delete_law(law_id)
+
+    if not success:
+        raise HTTPException(status_code=404, detail="Law not found")
+
+    return {"message": "Law deleted successfully"}
+
+
+@router.post("/search", response_model=LawListResponse)
+async def search_laws(
+    search_data: LawSearchRequest,
+    db: AsyncSession = Depends(get_db),
+):
+    """Search laws by keyword."""
+    service = LawService(db)
+    laws = await service.search_laws_by_keyword(
+        keyword=search_data.keyword,
+        limit=search_data.limit,
+    )
+
+    return LawListResponse(
+        items=laws,
+        total=len(laws),
+        skip=0,
+        limit=search_data.limit,
+    )
+
+
+@router.post("/qa", response_model=LegalQAResponse)
+async def legal_qa(
+    qa_data: LegalQARequest,
+):
+    """Ask a legal question and get AI-powered answer."""
+    answer = await llm_service.legal_qa(
+        question=qa_data.question,
+        context=qa_data.context,
+    )
+
+    return LegalQAResponse(
+        question=qa_data.question,
+        answer=answer,
+        references=[],
+    )
+
+
+@router.post("/{law_id}/articles", response_model=LawArticleResponse)
+async def create_article(
+    law_id: int,
+    article_data: LawArticleCreate,
+    db: AsyncSession = Depends(get_db),
+):
+    """Create a law article."""
+    service = LawService(db)
+
+    # Verify law exists
+    law = await service.get_law_by_id(law_id)
+    if not law:
+        raise HTTPException(status_code=404, detail="Law not found")
+
+    article = await service.create_article(
+        law_id=law_id,
+        article_number=article_data.article_number,
+        content=article_data.content,
+    )
+
+    return article

backend/app/api/v1/signatures.py

@@ -0,0 +1,96 @@
+"""Signature API endpoints."""
+from fastapi import APIRouter, Depends, HTTPException, Request
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.core.database import get_db
+from app.schemas.signature import (
+    SignatureRequestCreate,
+    SignatureRequestResponse,
+    SignatureSignRequest,
+    SignatureResponse,
+    SignatureVerifyResponse,
+)
+from app.services.signature_service import SignatureService
+
+router = APIRouter(prefix="/signatures", tags=["signatures"])
+
+
+@router.post("/request", response_model=SignatureRequestResponse)
+async def create_signature_request(
+    request_data: SignatureRequestCreate,
+    user_id: int = 1,  # TODO: Get from auth
+    db: AsyncSession = Depends(get_db),
+):
+    """Create a signature request."""
+    service = SignatureService(db)
+    sig_request = await service.create_signature_request(
+        contract_id=request_data.contract_id,
+        requester_id=user_id,
+        signer_name=request_data.signer_name,
+        signer_email=request_data.signer_email,
+        expire_hours=request_data.expire_hours,
+    )
+    return sig_request
+
+
+@router.get("/{token}", response_model=SignatureRequestResponse)
+async def get_signature_request(
+    token: str,
+    db: AsyncSession = Depends(get_db),
+):
+    """Get a signature request by token."""
+    service = SignatureService(db)
+    sig_request = await service.get_signature_request_by_token(token)
+
+    if not sig_request:
+        raise HTTPException(status_code=404, detail="Signature request not found")
+
+    return sig_request
+
+
+@router.post("/{token}/sign", response_model=SignatureResponse)
+async def sign_document(
+    token: str,
+    sign_data: SignatureSignRequest,
+    request: Request,
+    db: AsyncSession = Depends(get_db),
+):
+    """Sign a document."""
+    service = SignatureService(db)
+    sig_request = await service.get_signature_request_by_token(token)
+
+    if not sig_request:
+        raise HTTPException(status_code=404, detail="Signature request not found")
+
+    if not await service.is_request_valid(sig_request):
+        raise HTTPException(status_code=400, detail="Signature request is not valid")
+
+    # Get client info
+    ip_address = request.client.host if request.client else None
+    user_agent = request.headers.get("user-agent")
+
+    signature = await service.sign_document(
+        request=sig_request,
+        signature_data=sign_data.signature_data,
+        ip_address=ip_address,
+        user_agent=user_agent,
+    )
+
+    return signature
+
+
+@router.get("/{signature_id}/verify", response_model=SignatureVerifyResponse)
+async def verify_signature(
+    signature_id: int,
+    content_hash: str,
+    db: AsyncSession = Depends(get_db),
+):
+    """Verify a signature."""
+    service = SignatureService(db)
+    # Note: In production, you would verify against stored content
+    # This is a simplified version
+    return SignatureVerifyResponse(
+        valid=True,
+        signed_at=None,
+        signer_name=None,
+    )

backend/app/core/__init__.py

@@ -0,0 +1 @@
+# Core package

backend/app/core/config.py

@@ -0,0 +1,47 @@
+"""Core application configuration."""
+from typing import Optional
+from pydantic_settings import BaseSettings
+
+
+class Settings(BaseSettings):
+    """Application settings."""
+
+    # Application
+    APP_NAME: str = "AI Legal Assistant"
+    APP_VERSION: str = "1.0.0"
+    DEBUG: bool = False
+
+    # Database
+    DATABASE_URL: str = "sqlite+aiosqlite:///./data/legal_assistant.db"
+
+    # LLM Configuration
+    LLM_API_KEY: Optional[str] = None
+    LLM_API_BASE: str = "https://api.openai.com/v1"
+    LLM_MODEL: str = "gpt-4o-mini"
+
+    # Embedding Configuration
+    EMBEDDING_API_KEY: Optional[str] = None
+    EMBEDDING_API_BASE: str = "https://api.openai.com/v1"
+    EMBEDDING_MODEL: str = "text-embedding-3-small"
+    EMBEDDING_DIMENSION: int = 1536
+
+    # JWT Configuration
+    JWT_SECRET_KEY: str = "your-secret-key-change-in-production"
+    JWT_ALGORITHM: str = "HS256"
+    JWT_ACCESS_TOKEN_EXPIRE_MINUTES: int = 1440  # 24 hours
+    JWT_REFRESH_TOKEN_EXPIRE_DAYS: int = 7
+
+    # File Storage
+    UPLOAD_DIR: str = "./uploads"
+    MAX_UPLOAD_SIZE: int = 10 * 1024 * 1024  # 10MB
+
+    # Signature
+    SIGNATURE_TOKEN_EXPIRE_HOURS: int = 72  # 3 days
+
+    class Config:
+        env_file = ".env"
+        env_file_encoding = "utf-8"
+        case_sensitive = True
+
+
+settings = Settings()

backend/app/core/database.py

@@ -0,0 +1,47 @@
+"""Database configuration and session management."""
+from typing import AsyncGenerator
+from sqlalchemy.ext.asyncio import (
+    AsyncSession,
+    create_async_engine,
+    async_sessionmaker,
+)
+from sqlalchemy.orm import DeclarativeBase
+
+from app.core.config import settings
+
+
+class Base(DeclarativeBase):
+    """Base class for all database models."""
+    pass
+
+
+# Create async engine
+engine = create_async_engine(
+    settings.DATABASE_URL,
+    echo=settings.DEBUG,
+    future=True,
+)
+
+# Create async session factory
+async_session_maker = async_sessionmaker(
+    engine,
+    class_=AsyncSession,
+    expire_on_commit=False,
+)
+
+
+async def get_db() -> AsyncGenerator[AsyncSession, None]:
+    """Dependency for getting async database sessions."""
+    async with async_session_maker() as session:
+        try:
+            yield session
+            await session.commit()
+        except Exception:
+            await session.rollback()
+            raise
+
+
+async def init_db() -> None:
+    """Initialize database tables."""
+    async with engine.begin() as conn:
+        await conn.run_sync(Base.metadata.create_all)

backend/app/core/security.py

@@ -0,0 +1,61 @@
+"""Security utilities for authentication and authorization."""
+from datetime import datetime, timedelta
+from typing import Optional, Dict, Any
+
+import bcrypt
+from jose import jwt, JWTError
+
+from app.core.config import settings
+
+
+def get_password_hash(password: str) -> str:
+    """Hash a password using bcrypt."""
+    salt = bcrypt.gensalt()
+    hashed = bcrypt.hashpw(password.encode('utf-8'), salt)
+    return hashed.decode('utf-8')
+
+
+def verify_password(plain_password: str, hashed_password: str) -> bool:
+    """Verify a password against its hash."""
+    return bcrypt.checkpw(
+        plain_password.encode('utf-8'),
+        hashed_password.encode('utf-8')
+    )
+
+
+def create_access_token(
+    data: Dict[str, Any],
+    expires_delta: Optional[timedelta] = None
+) -> str:
+    """Create a JWT access token."""
+    to_encode = data.copy()
+
+    if expires_delta:
+        expire = datetime.utcnow() + expires_delta
+    else:
+        expire = datetime.utcnow() + timedelta(
+            minutes=settings.JWT_ACCESS_TOKEN_EXPIRE_MINUTES
+        )
+
+    to_encode.update({"exp": expire})
+
+    encoded_jwt = jwt.encode(
+        to_encode,
+        settings.JWT_SECRET_KEY,
+        algorithm=settings.JWT_ALGORITHM
+    )
+
+    return encoded_jwt
+
+
+def decode_access_token(token: str) -> Optional[Dict[str, Any]]:
+    """Decode and validate a JWT access token."""
+    try:
+        payload = jwt.decode(
+            token,
+            settings.JWT_SECRET_KEY,
+            algorithms=[settings.JWT_ALGORITHM]
+        )
+        return payload
+    except JWTError:
+        return None

backend/app/main.py

@@ -0,0 +1,56 @@
+"""Main FastAPI application."""
+from contextlib import asynccontextmanager
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+
+from app.core.config import settings
+from app.core.database import init_db
+from app.api.v1 import laws, analyses, contracts, signatures
+
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    """Application lifespan handler."""
+    # Startup
+    await init_db()
+    yield
+    # Shutdown
+    pass
+
+
+app = FastAPI(
+    title=settings.APP_NAME,
+    version=settings.APP_VERSION,
+    lifespan=lifespan,
+)
+
+# CORS middleware
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],  # Configure in production
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+# Include routers
+app.include_router(laws.router, prefix="/api/v1")
+app.include_router(analyses.router, prefix="/api/v1")
+app.include_router(contracts.router, prefix="/api/v1")
+app.include_router(signatures.router, prefix="/api/v1")
+
+
+@app.get("/")
+async def root():
+    """Root endpoint."""
+    return {
+        "name": settings.APP_NAME,
+        "version": settings.APP_VERSION,
+        "status": "running"
+    }
+
+
+@app.get("/health")
+async def health_check():
+    """Health check endpoint."""
+    return {"status": "healthy"}

backend/app/models/__init__.py

@@ -0,0 +1 @@
+# Models package

backend/app/models/analysis.py

@@ -0,0 +1,96 @@
+"""Analysis model for legal research."""
+import enum
+from datetime import date, datetime
+from typing import Optional, List
+
+from sqlalchemy import String, Text, Date, DateTime, Enum as SQLEnum, Integer, ForeignKey, JSON
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.core.database import Base
+
+
+class AnalysisStatus(str, enum.Enum):
+    """Analysis status enumeration."""
+    DRAFT = "draft"
+    IN_PROGRESS = "in_progress"
+    COMPLETED = "completed"
+
+
+class LegalAnalysis(Base):
+    """Legal analysis model."""
+
+    __tablename__ = "legal_analyses"
+
+    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
+    user_id: Mapped[int] = mapped_column(Integer, ForeignKey("users.id"), index=True)
+    title: Mapped[str] = mapped_column(String(200))
+    case_description: Mapped[str] = mapped_column(Text)
+    legal_basis: Mapped[Optional[dict]] = mapped_column(JSON, nullable=True)
+    analysis_content: Mapped[Optional[str]] = mapped_column(Text, nullable=True)
+    conclusion: Mapped[Optional[str]] = mapped_column(Text, nullable=True)
+    status: Mapped[AnalysisStatus] = mapped_column(
+        SQLEnum(AnalysisStatus),
+        default=AnalysisStatus.DRAFT
+    )
+    created_at: Mapped[datetime] = mapped_column(DateTime, nullable=False)
+    updated_at: Mapped[datetime] = mapped_column(DateTime, nullable=False)
+
+    def __init__(
+        self,
+        user_id: int,
+        title: str,
+        case_description: str,
+        legal_basis: Optional[dict] = None,
+        analysis_content: Optional[str] = None,
+        conclusion: Optional[str] = None,
+        status: AnalysisStatus = AnalysisStatus.DRAFT,
+        **kwargs
+    ):
+        self.user_id = user_id
+        self.title = title
+        self.case_description = case_description
+        self.legal_basis = legal_basis
+        self.analysis_content = analysis_content
+        self.conclusion = conclusion
+        self.status = status
+        self.created_at = datetime.utcnow()
+        self.updated_at = datetime.utcnow()
+
+
+class Case(Base):
+    """Case model for case database."""
+
+    __tablename__ = "cases"
+
+    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
+    title: Mapped[str] = mapped_column(String(200), index=True)
+    case_number: Mapped[Optional[str]] = mapped_column(String(50), nullable=True)
+    court: Mapped[Optional[str]] = mapped_column(String(100), nullable=True)
+    case_type: Mapped[Optional[str]] = mapped_column(String(100), nullable=True)
+    judgment_date: Mapped[Optional[date]] = mapped_column(Date, nullable=True)
+    facts: Mapped[Optional[str]] = mapped_column(Text, nullable=True)
+    judgment: Mapped[Optional[str]] = mapped_column(Text, nullable=True)
+    reasoning: Mapped[Optional[str]] = mapped_column(Text, nullable=True)
+    created_at: Mapped[datetime] = mapped_column(DateTime, nullable=False)
+
+    def __init__(
+        self,
+        title: str,
+        case_number: Optional[str] = None,
+        court: Optional[str] = None,
+        case_type: Optional[str] = None,
+        judgment_date: Optional[date] = None,
+        facts: Optional[str] = None,
+        judgment: Optional[str] = None,
+        reasoning: Optional[str] = None,
+        **kwargs
+    ):
+        self.title = title
+        self.case_number = case_number
+        self.court = court
+        self.case_type = case_type
+        self.judgment_date = judgment_date
+        self.facts = facts
+        self.judgment = judgment
+        self.reasoning = reasoning
+        self.created_at = datetime.utcnow()

backend/app/models/case.py

@@ -0,0 +1,60 @@
+"""Case review model."""
+import enum
+from datetime import datetime
+from typing import Optional
+
+from sqlalchemy import String, Text, DateTime, Enum as SQLEnum, Integer, ForeignKey
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.core.database import Base
+
+
+class ReviewStatus(str, enum.Enum):
+    """Review status enumeration."""
+    PENDING = "pending"
+    APPROVED = "approved"
+    REJECTED = "rejected"
+
+
+class ReviewType(str, enum.Enum):
+    """Review type enumeration."""
+    INITIAL = "initial"
+    SECONDARY = "secondary"
+    FINAL = "final"
+
+
+class CaseReview(Base):
+    """Case review model."""
+
+    __tablename__ = "case_reviews"
+
+    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
+    case_id: Mapped[int] = mapped_column(Integer, ForeignKey("cases.id"), index=True)
+    reviewer_id: Mapped[int] = mapped_column(Integer, ForeignKey("users.id"), index=True)
+    review_type: Mapped[ReviewType] = mapped_column(SQLEnum(ReviewType))
+    opinion: Mapped[Optional[str]] = mapped_column(Text, nullable=True)
+    score: Mapped[Optional[int]] = mapped_column(Integer, nullable=True)
+    status: Mapped[ReviewStatus] = mapped_column(
+        SQLEnum(ReviewStatus),
+        default=ReviewStatus.PENDING
+    )
+    created_at: Mapped[datetime] = mapped_column(DateTime, nullable=False)
+    reviewed_at: Mapped[Optional[datetime]] = mapped_column(DateTime, nullable=True)
+
+    def __init__(
+        self,
+        case_id: int,
+        reviewer_id: int,
+        review_type: ReviewType,
+        opinion: Optional[str] = None,
+        score: Optional[int] = None,
+        status: ReviewStatus = ReviewStatus.PENDING,
+        **kwargs
+    ):
+        self.case_id = case_id
+        self.reviewer_id = reviewer_id
+        self.review_type = review_type
+        self.opinion = opinion
+        self.score = score
+        self.status = status
+        self.created_at = datetime.utcnow()

backend/app/models/contract.py

@@ -0,0 +1,131 @@
+"""Contract model."""
+import enum
+from datetime import date, datetime
+from typing import Optional
+
+from sqlalchemy import String, Text, Date, DateTime, Enum as SQLEnum, Integer, ForeignKey
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.core.database import Base
+
+
+class ContractStatus(str, enum.Enum):
+    """Contract status enumeration."""
+    DRAFT = "draft"
+    PENDING_APPROVAL = "pending_approval"
+    APPROVED = "approved"
+    PENDING_SIGNATURE = "pending_signature"
+    SIGNED = "signed"
+    ARCHIVED = "archived"
+    REJECTED = "rejected"
+
+
+class Contract(Base):
+    """Contract model."""
+
+    __tablename__ = "contracts"
+
+    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
+    template_id: Mapped[Optional[int]] = mapped_column(Integer, ForeignKey("contract_templates.id"), nullable=True)
+    title: Mapped[str] = mapped_column(String(200), index=True)
+    contract_number: Mapped[Optional[str]] = mapped_column(String(50), nullable=True)
+    party_a: Mapped[str] = mapped_column(String(100))
+    party_b: Mapped[str] = mapped_column(String(100))
+    content: Mapped[str] = mapped_column(Text)
+    status: Mapped[ContractStatus] = mapped_column(
+        SQLEnum(ContractStatus),
+        default=ContractStatus.DRAFT
+    )
+    effective_date: Mapped[Optional[date]] = mapped_column(Date, nullable=True)
+    expiry_date: Mapped[Optional[date]] = mapped_column(Date, nullable=True)
+    file_path: Mapped[Optional[str]] = mapped_column(String(255), nullable=True)
+    created_by: Mapped[int] = mapped_column(Integer, ForeignKey("users.id"))
+    created_at: Mapped[datetime] = mapped_column(DateTime, nullable=False)
+    updated_at: Mapped[datetime] = mapped_column(DateTime, nullable=False)
+
+    def __init__(
+        self,
+        title: str,
+        party_a: str,
+        party_b: str,
+        content: str,
+        created_by: int,
+        template_id: Optional[int] = None,
+        contract_number: Optional[str] = None,
+        status: ContractStatus = ContractStatus.DRAFT,
+        effective_date: Optional[date] = None,
+        expiry_date: Optional[date] = None,
+        file_path: Optional[str] = None,
+        **kwargs
+    ):
+        self.title = title
+        self.party_a = party_a
+        self.party_b = party_b
+        self.content = content
+        self.created_by = created_by
+        self.template_id = template_id
+        self.contract_number = contract_number
+        self.status = status
+        self.effective_date = effective_date
+        self.expiry_date = expiry_date
+        self.file_path = file_path
+        self.created_at = datetime.utcnow()
+        self.updated_at = datetime.utcnow()
+
+
+class ContractTemplate(Base):
+    """Contract template model."""
+
+    __tablename__ = "contract_templates"
+
+    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
+    name: Mapped[str] = mapped_column(String(100))
+    contract_type: Mapped[Optional[str]] = mapped_column(String(50), nullable=True)
+    content: Mapped[str] = mapped_column(Text)
+    variables: Mapped[Optional[dict]] = mapped_column(String, nullable=True)  # JSON string
+    created_by: Mapped[int] = mapped_column(Integer, ForeignKey("users.id"))
+    created_at: Mapped[datetime] = mapped_column(DateTime, nullable=False)
+
+    def __init__(
+        self,
+        name: str,
+        content: str,
+        created_by: int,
+        contract_type: Optional[str] = None,
+        variables: Optional[dict] = None,
+        **kwargs
+    ):
+        self.name = name
+        self.content = content
+        self.created_by = created_by
+        self.contract_type = contract_type
+        self.variables = variables
+        self.created_at = datetime.utcnow()
+
+
+class ContractApproval(Base):
+    """Contract approval model."""
+
+    __tablename__ = "contract_approvals"
+
+    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
+    contract_id: Mapped[int] = mapped_column(Integer, ForeignKey("contracts.id"), index=True)
+    approver_id: Mapped[int] = mapped_column(Integer, ForeignKey("users.id"), index=True)
+    status: Mapped[ContractStatus] = mapped_column(SQLEnum(ContractStatus))
+    comment: Mapped[Optional[str]] = mapped_column(Text, nullable=True)
+    created_at: Mapped[datetime] = mapped_column(DateTime, nullable=False)
+    approved_at: Mapped[Optional[datetime]] = mapped_column(DateTime, nullable=True)
+
+    def __init__(
+        self,
+        contract_id: int,
+        approver_id: int,
+        status: ContractStatus,
+        comment: Optional[str] = None,
+        **kwargs
+    ):
+        self.contract_id = contract_id
+        self.approver_id = approver_id
+        self.status = status
+        self.comment = comment
+        self.created_at = datetime.utcnow()

backend/app/models/law.py

@@ -0,0 +1,106 @@
+"""Law model for legal regulations."""
+import enum
+from datetime import date, datetime
+from typing import Optional, List
+
+from sqlalchemy import String, Text, Date, DateTime, Enum as SQLEnum, Integer, ForeignKey
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.core.database import Base
+
+
+class LawType(str, enum.Enum):
+    """Law type enumeration."""
+    LAW = "law"                              # 法律
+    REGULATION = "regulation"                # 法规
+    RULE = "rule"                            # 规章
+    JUDICIAL_INTERPRETATION = "judicial_interpretation"  # 司法解释
+
+
+class LawStatus(str, enum.Enum):
+    """Law status enumeration."""
+    EFFECTIVE = "effective"    # 有效
+    REVOKED = "revoked"        # 废止
+    AMENDED = "amended"        # 修订
+
+
+class Law(Base):
+    """Law model for legal regulations."""
+
+    __tablename__ = "laws"
+
+    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
+    title: Mapped[str] = mapped_column(String(200), index=True)
+    law_type: Mapped[LawType] = mapped_column(SQLEnum(LawType), nullable=False)
+    promulgation_date: Mapped[date] = mapped_column(Date, nullable=False)
+    effective_date: Mapped[date] = mapped_column(Date, nullable=False)
+    status: Mapped[LawStatus] = mapped_column(
+        SQLEnum(LawStatus),
+        nullable=False
+    )
+    issuing_authority: Mapped[str] = mapped_column(String(100))
+    content: Mapped[str] = mapped_column(Text)
+    document_number: Mapped[Optional[str]] = mapped_column(String(50), nullable=True)
+    created_at: Mapped[datetime] = mapped_column(DateTime, nullable=False)
+    updated_at: Mapped[datetime] = mapped_column(DateTime, nullable=False)
+
+    # Relationships
+    articles: Mapped[List["LawArticle"]] = relationship(
+        back_populates="law", cascade="all, delete-orphan"
+    )
+
+    def __init__(
+        self,
+        title: str,
+        law_type: LawType,
+        promulgation_date: date,
+        effective_date: date,
+        issuing_authority: str,
+        content: str,
+        status: LawStatus = LawStatus.EFFECTIVE,
+        document_number: Optional[str] = None,
+        **kwargs
+    ):
+        self.title = title
+        self.law_type = law_type
+        self.promulgation_date = promulgation_date
+        self.effective_date = effective_date
+        self.status = status
+        self.issuing_authority = issuing_authority
+        self.content = content
+        self.document_number = document_number
+        self.created_at = datetime.utcnow()
+        self.updated_at = datetime.utcnow()
+
+    def __repr__(self) -> str:
+        return f"<Law(id={self.id}, title={self.title})>"
+
+
+class LawArticle(Base):
+    """Law article model for individual articles."""
+
+    __tablename__ = "law_articles"
+
+    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
+    law_id: Mapped[int] = mapped_column(Integer, ForeignKey("laws.id"), index=True)
+    article_number: Mapped[str] = mapped_column(String(20))
+    content: Mapped[str] = mapped_column(Text)
+    created_at: Mapped[datetime] = mapped_column(DateTime, nullable=False)
+
+    # Relationships
+    law: Mapped["Law"] = relationship(back_populates="articles")
+
+    def __init__(
+        self,
+        law_id: int,
+        article_number: str,
+        content: str,
+        **kwargs
+    ):
+        self.law_id = law_id
+        self.article_number = article_number
+        self.content = content
+        self.created_at = datetime.utcnow()
+
+    def __repr__(self) -> str:
+        return f"<LawArticle(id={self.id}, article_number={self.article_number})>"

backend/app/models/signature.py

@@ -0,0 +1,119 @@
+"""Signature model for electronic signatures."""
+import enum
+from datetime import datetime
+from typing import Optional
+
+from sqlalchemy import String, Text, DateTime, Enum as SQLEnum, Integer, ForeignKey, JSON
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.core.database import Base
+
+
+class SignatureStatus(str, enum.Enum):
+    """Signature status enumeration."""
+    PENDING = "pending"
+    SIGNED = "signed"
+    REJECTED = "rejected"
+    EXPIRED = "expired"
+
+
+class SignatureRequest(Base):
+    """Signature request model."""
+
+    __tablename__ = "signature_requests"
+
+    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
+    contract_id: Mapped[int] = mapped_column(Integer, ForeignKey("contracts.id"), index=True)
+    requester_id: Mapped[int] = mapped_column(Integer, ForeignKey("users.id"), index=True)
+    signer_name: Mapped[str] = mapped_column(String(100))
+    signer_email: Mapped[str] = mapped_column(String(100))
+    status: Mapped[SignatureStatus] = mapped_column(
+        SQLEnum(SignatureStatus),
+        default=SignatureStatus.PENDING
+    )
+    token: Mapped[str] = mapped_column(String(64), unique=True, index=True)
+    expires_at: Mapped[datetime] = mapped_column(DateTime, nullable=False)
+    created_at: Mapped[datetime] = mapped_column(DateTime, nullable=False)
+
+    def __init__(
+        self,
+        contract_id: int,
+        requester_id: int,
+        signer_name: str,
+        signer_email: str,
+        token: str,
+        expires_at: datetime,
+        status: SignatureStatus = SignatureStatus.PENDING,
+        **kwargs
+    ):
+        self.contract_id = contract_id
+        self.requester_id = requester_id
+        self.signer_name = signer_name
+        self.signer_email = signer_email
+        self.token = token
+        self.expires_at = expires_at
+        self.status = status
+        self.created_at = datetime.utcnow()
+
+
+class Signature(Base):
+    """Signature record model."""
+
+    __tablename__ = "signatures"
+
+    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
+    request_id: Mapped[int] = mapped_column(Integer, ForeignKey("signature_requests.id"), index=True)
+    signer_name: Mapped[str] = mapped_column(String(100))
+    signature_data: Mapped[str] = mapped_column(Text)  # Base64 image or coordinates
+    ip_address: Mapped[Optional[str]] = mapped_column(String(50), nullable=True)
+    user_agent: Mapped[Optional[str]] = mapped_column(String(255), nullable=True)
+    verification_hash: Mapped[str] = mapped_column(String(64))  # Document fingerprint
+    signed_at: Mapped[datetime] = mapped_column(DateTime, nullable=False)
+
+    def __init__(
+        self,
+        request_id: int,
+        signer_name: str,
+        signature_data: str,
+        verification_hash: str,
+        ip_address: Optional[str] = None,
+        user_agent: Optional[str] = None,
+        **kwargs
+    ):
+        self.request_id = request_id
+        self.signer_name = signer_name
+        self.signature_data = signature_data
+        self.verification_hash = verification_hash
+        self.ip_address = ip_address
+        self.user_agent = user_agent
+        self.signed_at = datetime.utcnow()
+
+
+class SignatureAudit(Base):
+    """Signature audit log model."""
+
+    __tablename__ = "signature_audits"
+
+    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
+    signature_id: Mapped[Optional[int]] = mapped_column(Integer, ForeignKey("signatures.id"), nullable=True)
+    request_id: Mapped[Optional[int]] = mapped_column(Integer, ForeignKey("signature_requests.id"), nullable=True)
+    action: Mapped[str] = mapped_column(String(50))
+    details: Mapped[Optional[dict]] = mapped_column(JSON, nullable=True)
+    ip_address: Mapped[Optional[str]] = mapped_column(String(50), nullable=True)
+    created_at: Mapped[datetime] = mapped_column(DateTime, nullable=False)
+
+    def __init__(
+        self,
+        action: str,
+        signature_id: Optional[int] = None,
+        request_id: Optional[int] = None,
+        details: Optional[dict] = None,
+        ip_address: Optional[str] = None,
+        **kwargs
+    ):
+        self.action = action
+        self.signature_id = signature_id
+        self.request_id = request_id
+        self.details = details
+        self.ip_address = ip_address
+        self.created_at = datetime.utcnow()

backend/app/models/user.py

@@ -0,0 +1,64 @@
+"""User model for authentication and authorization."""
+import enum
+from datetime import datetime
+from typing import Optional
+
+from sqlalchemy import String, Boolean, DateTime, Enum as SQLEnum
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.core.database import Base
+
+
+class UserRole(str, enum.Enum):
+    """User role enumeration."""
+    ADMIN = "admin"
+    LAWYER = "lawyer"
+    REVIEWER = "reviewer"
+    CLIENT = "client"
+
+
+class User(Base):
+    """User model for authentication."""
+
+    __tablename__ = "users"
+
+    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
+    username: Mapped[str] = mapped_column(String(50), unique=True, index=True)
+    email: Mapped[str] = mapped_column(String(100), unique=True, index=True)
+    hashed_password: Mapped[str] = mapped_column(String(255))
+    full_name: Mapped[Optional[str]] = mapped_column(String(100), nullable=True)
+    role: Mapped[UserRole] = mapped_column(
+        SQLEnum(UserRole),
+        nullable=False
+    )
+    is_active: Mapped[bool] = mapped_column(Boolean, nullable=False)
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime,
+        nullable=False
+    )
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime,
+        nullable=False
+    )
+
+    def __init__(
+        self,
+        username: str,
+        email: str,
+        hashed_password: str,
+        full_name: Optional[str] = None,
+        role: UserRole = UserRole.CLIENT,
+        is_active: bool = True,
+        **kwargs
+    ):
+        self.username = username
+        self.email = email
+        self.hashed_password = hashed_password
+        self.full_name = full_name
+        self.role = role
+        self.is_active = is_active
+        self.created_at = datetime.utcnow()
+        self.updated_at = datetime.utcnow()
+
+    def __repr__(self) -> str:
+        return f"<User(id={self.id}, username={self.username}, role={self.role})>"

backend/app/schemas/__init__.py

@@ -0,0 +1 @@
+# Schemas package

backend/app/schemas/analysis.py

@@ -0,0 +1,87 @@
+"""Schemas for Analysis module."""
+from datetime import date, datetime
+from typing import List, Optional
+from enum import Enum
+
+from pydantic import BaseModel, Field
+
+
+class AnalysisStatusEnum(str, Enum):
+    DRAFT = "draft"
+    IN_PROGRESS = "in_progress"
+    COMPLETED = "completed"
+
+
+class LegalAnalysisBase(BaseModel):
+    """Base schema for LegalAnalysis."""
+    title: str = Field(..., max_length=200)
+    case_description: str
+
+
+class LegalAnalysisCreate(LegalAnalysisBase):
+    """Schema for creating a legal analysis."""
+    legal_basis: Optional[dict] = None
+
+
+class LegalAnalysisUpdate(BaseModel):
+    """Schema for updating a legal analysis."""
+    title: Optional[str] = Field(None, max_length=200)
+    case_description: Optional[str] = None
+    legal_basis: Optional[dict] = None
+    analysis_content: Optional[str] = None
+    conclusion: Optional[str] = None
+    status: Optional[AnalysisStatusEnum] = None
+
+
+class LegalAnalysisResponse(LegalAnalysisBase):
+    """Schema for legal analysis response."""
+    id: int
+    user_id: int
+    legal_basis: Optional[dict] = None
+    analysis_content: Optional[str] = None
+    conclusion: Optional[str] = None
+    status: AnalysisStatusEnum
+    created_at: datetime
+    updated_at: datetime
+
+    class Config:
+        from_attributes = True
+
+
+class CaseBase(BaseModel):
+    """Base schema for Case."""
+    title: str = Field(..., max_length=200)
+    case_number: Optional[str] = Field(None, max_length=50)
+    court: Optional[str] = Field(None, max_length=100)
+    case_type: Optional[str] = Field(None, max_length=100)
+    judgment_date: Optional[date] = None
+    facts: Optional[str] = None
+    judgment: Optional[str] = None
+    reasoning: Optional[str] = None
+
+
+class CaseCreate(CaseBase):
+    """Schema for creating a case."""
+    pass
+
+
+class CaseResponse(CaseBase):
+    """Schema for case response."""
+    id: int
+    created_at: datetime
+
+    class Config:
+        from_attributes = True
+
+
+class GenerateAnalysisRequest(BaseModel):
+    """Schema for generating analysis with AI."""
+    case_description: str
+    relevant_laws: Optional[List[str]] = None
+
+
+class GenerateAnalysisResponse(BaseModel):
+    """Schema for generated analysis response."""
+    analysis_content: str
+    legal_basis: List[str] = []
+    conclusion: str

backend/app/schemas/contract.py

@@ -0,0 +1,112 @@
+"""Schemas for Contract module."""
+from datetime import date, datetime
+from typing import Optional
+from enum import Enum
+
+from pydantic import BaseModel, Field
+
+
+class ContractStatusEnum(str, Enum):
+    DRAFT = "draft"
+    PENDING_APPROVAL = "pending_approval"
+    APPROVED = "approved"
+    PENDING_SIGNATURE = "pending_signature"
+    SIGNED = "signed"
+    ARCHIVED = "archived"
+    REJECTED = "rejected"
+
+
+class ContractBase(BaseModel):
+    """Base schema for Contract."""
+    title: str = Field(..., max_length=200)
+    party_a: str = Field(..., max_length=100)
+    party_b: str = Field(..., max_length=100)
+    content: str
+    contract_number: Optional[str] = Field(None, max_length=50)
+    effective_date: Optional[date] = None
+    expiry_date: Optional[date] = None
+
+
+class ContractCreate(ContractBase):
+    """Schema for creating a contract."""
+    template_id: Optional[int] = None
+
+
+class ContractUpdate(BaseModel):
+    """Schema for updating a contract."""
+    title: Optional[str] = Field(None, max_length=200)
+    party_a: Optional[str] = Field(None, max_length=100)
+    party_b: Optional[str] = Field(None, max_length=100)
+    content: Optional[str] = None
+    contract_number: Optional[str] = Field(None, max_length=50)
+    effective_date: Optional[date] = None
+    expiry_date: Optional[date] = None
+    status: Optional[ContractStatusEnum] = None
+
+
+class ContractResponse(ContractBase):
+    """Schema for contract response."""
+    id: int
+    template_id: Optional[int] = None
+    status: ContractStatusEnum
+    file_path: Optional[str] = None
+    created_by: int
+    created_at: datetime
+    updated_at: datetime
+
+    class Config:
+        from_attributes = True
+
+
+class ContractTemplateBase(BaseModel):
+    """Base schema for ContractTemplate."""
+    name: str = Field(..., max_length=100)
+    content: str
+    contract_type: Optional[str] = Field(None, max_length=50)
+
+
+class ContractTemplateCreate(ContractTemplateBase):
+    """Schema for creating a contract template."""
+    pass
+
+
+class ContractTemplateResponse(ContractTemplateBase):
+    """Schema for contract template response."""
+    id: int
+    created_by: int
+    created_at: datetime
+
+    class Config:
+        from_attributes = True
+
+
+class ApprovalRequest(BaseModel):
+    """Schema for approval request."""
+    comment: Optional[str] = None
+
+
+class ApprovalResponse(BaseModel):
+    """Schema for approval response."""
+    id: int
+    contract_id: int
+    approver_id: int
+    status: ContractStatusEnum
+    comment: Optional[str] = None
+    created_at: datetime
+    approved_at: Optional[datetime] = None
+
+    class Config:
+        from_attributes = True
+
+
+class ContractReviewRequest(BaseModel):
+    """Schema for AI contract review request."""
+    contract_content: str
+    contract_type: Optional[str] = None
+
+
+class ContractReviewResponse(BaseModel):
+    """Schema for AI contract review response."""
+    review_result: str
+    risks: list = []
+    suggestions: list = []

backend/app/schemas/law.py

@@ -0,0 +1,107 @@
+"""Schemas for Law module."""
+from datetime import date, datetime
+from typing import List, Optional
+from enum import Enum
+
+from pydantic import BaseModel, Field
+
+
+class LawTypeEnum(str, Enum):
+    LAW = "law"
+    REGULATION = "regulation"
+    RULE = "rule"
+    JUDICIAL_INTERPRETATION = "judicial_interpretation"
+
+
+class LawStatusEnum(str, Enum):
+    EFFECTIVE = "effective"
+    REVOKED = "revoked"
+    AMENDED = "amended"
+
+
+class LawBase(BaseModel):
+    """Base schema for Law."""
+    title: str = Field(..., max_length=200)
+    law_type: LawTypeEnum
+    promulgation_date: date
+    effective_date: date
+    issuing_authority: str = Field(..., max_length=100)
+    content: str
+    status: LawStatusEnum = LawStatusEnum.EFFECTIVE
+    document_number: Optional[str] = Field(None, max_length=50)
+
+
+class LawCreate(LawBase):
+    """Schema for creating a law."""
+    pass
+
+
+class LawUpdate(BaseModel):
+    """Schema for updating a law."""
+    title: Optional[str] = Field(None, max_length=200)
+    law_type: Optional[LawTypeEnum] = None
+    promulgation_date: Optional[date] = None
+    effective_date: Optional[date] = None
+    status: Optional[LawStatusEnum] = None
+    issuing_authority: Optional[str] = Field(None, max_length=100)
+    content: Optional[str] = None
+    document_number: Optional[str] = Field(None, max_length=50)
+
+
+class LawArticleBase(BaseModel):
+    """Base schema for LawArticle."""
+    article_number: str = Field(..., max_length=20)
+    content: str
+
+
+class LawArticleCreate(LawArticleBase):
+    """Schema for creating a law article."""
+    law_id: int
+
+
+class LawArticleResponse(LawArticleBase):
+    """Schema for law article response."""
+    id: int
+    law_id: int
+    created_at: datetime
+
+    class Config:
+        from_attributes = True
+
+
+class LawResponse(LawBase):
+    """Schema for law response."""
+    id: int
+    created_at: datetime
+    updated_at: datetime
+    articles: List[LawArticleResponse] = []
+
+    class Config:
+        from_attributes = True
+
+
+class LawListResponse(BaseModel):
+    """Schema for law list response."""
+    items: List[LawResponse]
+    total: int
+    skip: int
+    limit: int
+
+
+class LawSearchRequest(BaseModel):
+    """Schema for law search request."""
+    keyword: str = Field(..., min_length=1)
+    limit: int = Field(10, ge=1, le=50)
+
+
+class LegalQARequest(BaseModel):
+    """Schema for legal QA request."""
+    question: str = Field(..., min_length=1)
+    context: Optional[str] = None
+
+
+class LegalQAResponse(BaseModel):
+    """Schema for legal QA response."""
+    question: str
+    answer: str
+    references: List[str] = []

backend/app/schemas/signature.py

@@ -0,0 +1,61 @@
+"""Schemas for Signature module."""
+from datetime import datetime
+from typing import Optional
+from enum import Enum
+
+from pydantic import BaseModel, Field
+
+
+class SignatureStatusEnum(str, Enum):
+    PENDING = "pending"
+    SIGNED = "signed"
+    REJECTED = "rejected"
+    EXPIRED = "expired"
+
+
+class SignatureRequestCreate(BaseModel):
+    """Schema for creating a signature request."""
+    contract_id: int
+    signer_name: str = Field(..., max_length=100)
+    signer_email: str = Field(..., max_length=100)
+    expire_hours: Optional[int] = None
+
+
+class SignatureRequestResponse(BaseModel):
+    """Schema for signature request response."""
+    id: int
+    contract_id: int
+    requester_id: int
+    signer_name: str
+    signer_email: str
+    status: SignatureStatusEnum
+    token: str
+    expires_at: datetime
+    created_at: datetime
+
+    class Config:
+        from_attributes = True
+
+
+class SignatureSignRequest(BaseModel):
+    """Schema for signing a document."""
+    signature_data: str  # Base64 image or coordinates
+
+
+class SignatureResponse(BaseModel):
+    """Schema for signature response."""
+    id: int
+    request_id: int
+    signer_name: str
+    signed_at: datetime
+    verification_hash: str
+
+    class Config:
+        from_attributes = True
+
+
+class SignatureVerifyResponse(BaseModel):
+    """Schema for signature verification response."""
+    valid: bool
+    signed_at: Optional[datetime] = None
+    signer_name: Optional[str] = None

backend/app/services/__init__.py

@@ -0,0 +1 @@
+# Services package

backend/app/services/analysis_service.py

@@ -0,0 +1,134 @@
+"""Analysis service for legal research."""
+from typing import List, Optional
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.models.analysis import LegalAnalysis, Case, AnalysisStatus
+
+
+class AnalysisService:
+    """Service for legal analysis operations."""
+
+    def __init__(self, db: AsyncSession):
+        self.db = db
+
+    async def create_analysis(
+        self,
+        user_id: int,
+        title: str,
+        case_description: str,
+        legal_basis: Optional[dict] = None,
+    ) -> LegalAnalysis:
+        """Create a new legal analysis."""
+        analysis = LegalAnalysis(
+            user_id=user_id,
+            title=title,
+            case_description=case_description,
+            legal_basis=legal_basis,
+        )
+        self.db.add(analysis)
+        await self.db.flush()
+        await self.db.refresh(analysis)
+        return analysis
+
+    async def get_analysis_by_id(self, analysis_id: int) -> Optional[LegalAnalysis]:
+        """Get an analysis by ID."""
+        result = await self.db.execute(
+            select(LegalAnalysis).where(LegalAnalysis.id == analysis_id)
+        )
+        return result.scalar_one_or_none()
+
+    async def get_analyses_by_user(
+        self,
+        user_id: int,
+        skip: int = 0,
+        limit: int = 20,
+    ) -> List[LegalAnalysis]:
+        """Get analyses by user ID."""
+        result = await self.db.execute(
+            select(LegalAnalysis)
+            .where(LegalAnalysis.user_id == user_id)
+            .offset(skip)
+            .limit(limit)
+            .order_by(LegalAnalysis.created_at.desc())
+        )
+        return list(result.scalars().all())
+
+    async def update_analysis(
+        self,
+        analysis_id: int,
+        **kwargs
+    ) -> Optional[LegalAnalysis]:
+        """Update an analysis."""
+        analysis = await self.get_analysis_by_id(analysis_id)
+        if not analysis:
+            return None
+
+        for key, value in kwargs.items():
+            if hasattr(analysis, key) and value is not None:
+                setattr(analysis, key, value)
+
+        await self.db.flush()
+        await self.db.refresh(analysis)
+        return analysis
+
+    async def delete_analysis(self, analysis_id: int) -> bool:
+        """Delete an analysis."""
+        analysis = await self.get_analysis_by_id(analysis_id)
+        if not analysis:
+            return False
+
+        await self.db.delete(analysis)
+        await self.db.flush()
+        return True
+
+
+class CaseService:
+    """Service for case operations."""
+
+    def __init__(self, db: AsyncSession):
+        self.db = db
+
+    async def create_case(
+        self,
+        title: str,
+        case_number: Optional[str] = None,
+        court: Optional[str] = None,
+        case_type: Optional[str] = None,
+        **kwargs
+    ) -> Case:
+        """Create a new case."""
+        case = Case(
+            title=title,
+            case_number=case_number,
+            court=court,
+            case_type=case_type,
+            **kwargs
+        )
+        self.db.add(case)
+        await self.db.flush()
+        await self.db.refresh(case)
+        return case
+
+    async def get_case_by_id(self, case_id: int) -> Optional[Case]:
+        """Get a case by ID."""
+        result = await self.db.execute(
+            select(Case).where(Case.id == case_id)
+        )
+        return result.scalar_one_or_none()
+
+    async def get_cases_list(
+        self,
+        skip: int = 0,
+        limit: int = 20,
+        case_type: Optional[str] = None,
+    ) -> List[Case]:
+        """Get list of cases."""
+        query = select(Case)
+
+        if case_type:
+            query = query.where(Case.case_type == case_type)
+
+        query = query.offset(skip).limit(limit).order_by(Case.created_at.desc())
+        result = await self.db.execute(query)
+        return list(result.scalars().all())

backend/app/services/contract_service.py

@@ -0,0 +1,171 @@
+"""Contract service for contract management."""
+from typing import List, Optional
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.models.contract import Contract, ContractTemplate, ContractApproval, ContractStatus
+
+
+class ContractService:
+    """Service for contract operations."""
+
+    def __init__(self, db: AsyncSession):
+        self.db = db
+
+    async def create_contract(
+        self,
+        title: str,
+        party_a: str,
+        party_b: str,
+        content: str,
+        created_by: int,
+        **kwargs
+    ) -> Contract:
+        """Create a new contract."""
+        contract = Contract(
+            title=title,
+            party_a=party_a,
+            party_b=party_b,
+            content=content,
+            created_by=created_by,
+            **kwargs
+        )
+        self.db.add(contract)
+        await self.db.flush()
+        await self.db.refresh(contract)
+        return contract
+
+    async def get_contract_by_id(self, contract_id: int) -> Optional[Contract]:
+        """Get a contract by ID."""
+        result = await self.db.execute(
+            select(Contract).where(Contract.id == contract_id)
+        )
+        return result.scalar_one_or_none()
+
+    async def get_contracts_list(
+        self,
+        skip: int = 0,
+        limit: int = 20,
+        status: Optional[ContractStatus] = None,
+        created_by: Optional[int] = None,
+    ) -> List[Contract]:
+        """Get list of contracts."""
+        query = select(Contract)
+
+        if status:
+            query = query.where(Contract.status == status)
+        if created_by:
+            query = query.where(Contract.created_by == created_by)
+
+        query = query.offset(skip).limit(limit).order_by(Contract.created_at.desc())
+        result = await self.db.execute(query)
+        return list(result.scalars().all())
+
+    async def update_contract(
+        self,
+        contract_id: int,
+        **kwargs
+    ) -> Optional[Contract]:
+        """Update a contract."""
+        contract = await self.get_contract_by_id(contract_id)
+        if not contract:
+            return None
+
+        for key, value in kwargs.items():
+            if hasattr(contract, key) and value is not None:
+                setattr(contract, key, value)
+
+        await self.db.flush()
+        await self.db.refresh(contract)
+        return contract
+
+    async def submit_for_approval(self, contract_id: int) -> Optional[Contract]:
+        """Submit a contract for approval."""
+        return await self.update_contract(
+            contract_id,
+            status=ContractStatus.PENDING_APPROVAL
+        )
+
+    async def approve_contract(
+        self,
+        contract_id: int,
+        approver_id: int,
+        comment: Optional[str] = None,
+    ) -> ContractApproval:
+        """Approve a contract."""
+        approval = ContractApproval(
+            contract_id=contract_id,
+            approver_id=approver_id,
+            status=ContractStatus.APPROVED,
+            comment=comment,
+        )
+        self.db.add(approval)
+
+        # Update contract status
+        await self.update_contract(contract_id, status=ContractStatus.APPROVED)
+
+        await self.db.flush()
+        await self.db.refresh(approval)
+        return approval
+
+    async def reject_contract(
+        self,
+        contract_id: int,
+        approver_id: int,
+        comment: Optional[str] = None,
+    ) -> ContractApproval:
+        """Reject a contract."""
+        approval = ContractApproval(
+            contract_id=contract_id,
+            approver_id=approver_id,
+            status=ContractStatus.REJECTED,
+            comment=comment,
+        )
+        self.db.add(approval)
+
+        # Update contract status
+        await self.update_contract(contract_id, status=ContractStatus.REJECTED)
+
+        await self.db.flush()
+        await self.db.refresh(approval)
+        return approval
+
+
+class ContractTemplateService:
+    """Service for contract template operations."""
+
+    def __init__(self, db: AsyncSession):
+        self.db = db
+
+    async def create_template(
+        self,
+        name: str,
+        content: str,
+        created_by: int,
+        contract_type: Optional[str] = None,
+    ) -> ContractTemplate:
+        """Create a contract template."""
+        template = ContractTemplate(
+            name=name,
+            content=content,
+            created_by=created_by,
+            contract_type=contract_type,
+        )
+        self.db.add(template)
+        await self.db.flush()
+        await self.db.refresh(template)
+        return template
+
+    async def get_templates_list(
+        self,
+        skip: int = 0,
+        limit: int = 20,
+    ) -> List[ContractTemplate]:
+        """Get list of templates."""
+        result = await self.db.execute(
+            select(ContractTemplate)
+            .offset(skip)
+            .limit(limit)
+            .order_by(ContractTemplate.created_at.desc())
+        )
+        return list(result.scalars().all())

backend/app/services/law_service.py

@@ -0,0 +1,137 @@
+"""Law service for CRUD operations."""
+from datetime import date
+from typing import List, Optional
+from sqlalchemy import select, or_
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.models.law import Law, LawArticle, LawType, LawStatus
+
+
+class LawService:
+    """Service for law CRUD operations."""
+
+    def __init__(self, db: AsyncSession):
+        self.db = db
+
+    async def create_law(
+        self,
+        title: str,
+        law_type: LawType,
+        promulgation_date: date,
+        effective_date: date,
+        issuing_authority: str,
+        content: str,
+        status: LawStatus = LawStatus.EFFECTIVE,
+        document_number: Optional[str] = None,
+    ) -> Law:
+        """Create a new law."""
+        law = Law(
+            title=title,
+            law_type=law_type,
+            promulgation_date=promulgation_date,
+            effective_date=effective_date,
+            status=status,
+            issuing_authority=issuing_authority,
+            content=content,
+            document_number=document_number,
+        )
+        self.db.add(law)
+        await self.db.flush()
+        await self.db.refresh(law)
+        return law
+
+    async def get_law_by_id(self, law_id: int) -> Optional[Law]:
+        """Get a law by ID."""
+        result = await self.db.execute(
+            select(Law).where(Law.id == law_id)
+        )
+        return result.scalar_one_or_none()
+
+    async def get_laws_list(
+        self,
+        skip: int = 0,
+        limit: int = 20,
+        law_type: Optional[LawType] = None,
+        status: Optional[LawStatus] = None,
+    ) -> List[Law]:
+        """Get list of laws with optional filters."""
+        query = select(Law)
+
+        if law_type:
+            query = query.where(Law.law_type == law_type)
+        if status:
+            query = query.where(Law.status == status)
+
+        query = query.offset(skip).limit(limit).order_by(Law.created_at.desc())
+        result = await self.db.execute(query)
+        return list(result.scalars().all())
+
+    async def update_law(
+        self,
+        law_id: int,
+        **kwargs
+    ) -> Optional[Law]:
+        """Update a law."""
+        law = await self.get_law_by_id(law_id)
+        if not law:
+            return None
+
+        for key, value in kwargs.items():
+            if hasattr(law, key) and value is not None:
+                setattr(law, key, value)
+
+        await self.db.flush()
+        await self.db.refresh(law)
+        return law
+
+    async def delete_law(self, law_id: int) -> bool:
+        """Delete a law."""
+        law = await self.get_law_by_id(law_id)
+        if not law:
+            return False
+
+        await self.db.delete(law)
+        await self.db.flush()
+        return True
+
+    async def search_laws_by_keyword(
+        self,
+        keyword: str,
+        limit: int = 10
+    ) -> List[Law]:
+        """Search laws by keyword in title or content."""
+        query = select(Law).where(
+            or_(
+                Law.title.contains(keyword),
+                Law.content.contains(keyword),
+            )
+        ).limit(limit)
+
+        result = await self.db.execute(query)
+        return list(result.scalars().all())
+
+    async def create_article(
+        self,
+        law_id: int,
+        article_number: str,
+        content: str,
+    ) -> LawArticle:
+        """Create a law article."""
+        article = LawArticle(
+            law_id=law_id,
+            article_number=article_number,
+            content=content,
+        )
+        self.db.add(article)
+        await self.db.flush()
+        await self.db.refresh(article)
+        return article
+
+    async def get_articles_by_law_id(self, law_id: int) -> List[LawArticle]:
+        """Get articles for a law."""
+        result = await self.db.execute(
+            select(LawArticle)
+            .where(LawArticle.law_id == law_id)
+            .order_by(LawArticle.id)
+        )
+        return list(result.scalars().all())

backend/app/services/llm_service.py

@@ -0,0 +1,123 @@
+"""LLM service for AI-powered features."""
+from typing import List, Dict, Any, Optional
+import httpx
+
+from app.core.config import settings
+
+
+class LLMService:
+    """Service for LLM API interactions."""
+
+    def __init__(self):
+        self.api_base = settings.LLM_API_BASE
+        self.api_key = settings.LLM_API_KEY
+        self.model = settings.LLM_MODEL
+
+    async def chat_completion(
+        self,
+        messages: List[Dict[str, str]],
+        temperature: float = 0.7,
+        max_tokens: int = 2000,
+    ) -> str:
+        """Get chat completion from LLM."""
+        if not self.api_key:
+            # Return mock response for testing
+            return "这是一个模拟的法律回复。"
+
+        async with httpx.AsyncClient() as client:
+            response = await client.post(
+                f"{self.api_base}/chat/completions",
+                headers={
+                    "Authorization": f"Bearer {self.api_key}",
+                    "Content-Type": "application/json",
+                },
+                json={
+                    "model": self.model,
+                    "messages": messages,
+                    "temperature": temperature,
+                    "max_tokens": max_tokens,
+                },
+                timeout=60.0,
+            )
+            response.raise_for_status()
+            data = response.json()
+            return data["choices"][0]["message"]["content"]
+
+    async def legal_qa(
+        self,
+        question: str,
+        context: Optional[str] = None,
+    ) -> str:
+        """Answer a legal question."""
+        system_prompt = """你是一个专业的法律助手。请根据以下原则回答问题：
+1. 准确引用相关法律条文
+2. 解释法律条文的含义和适用条件
+3. 提供实用的法律建议
+4. 如不确定，请明确说明"""
+
+        messages = [
+            {"role": "system", "content": system_prompt},
+        ]
+
+        if context:
+            messages.append({
+                "role": "user",
+                "content": f"参考以下法律内容：\n{context}\n\n问题：{question}"
+            })
+        else:
+            messages.append({"role": "user", "content": question})
+
+        return await self.chat_completion(messages)
+
+    async def analyze_legal_issue(
+        self,
+        issue_description: str,
+        relevant_laws: Optional[List[str]] = None,
+    ) -> str:
+        """Analyze a legal issue and provide insights."""
+        system_prompt = """你是一个专业的法律分析师。请根据以下结构分析法律问题：
+1. 问题定性
+2. 相关法律依据
+3. 法律分析
+4. 风险提示
+5. 建议"""
+
+        user_content = f"请分析以下法律问题：\n{issue_description}"
+
+        if relevant_laws:
+            user_content += f"\n\n相关法律：\n" + "\n".join(relevant_laws)
+
+        messages = [
+            {"role": "system", "content": system_prompt},
+            {"role": "user", "content": user_content},
+        ]
+
+        return await self.chat_completion(messages, temperature=0.5)
+
+    async def review_contract(
+        self,
+        contract_content: str,
+        contract_type: Optional[str] = None,
+    ) -> str:
+        """Review a contract and identify potential issues."""
+        system_prompt = """你是一个专业的合同审查专家。请审查合同并：
+1. 识别潜在风险条款
+2. 指出不明确的条款
+3. 提出修改建议
+4. 检查法律合规性"""
+
+        user_content = f"请审查以下合同内容：\n{contract_content}"
+
+        if contract_type:
+            user_content = f"合同类型：{contract_type}\n\n{user_content}"
+
+        messages = [
+            {"role": "system", "content": system_prompt},
+            {"role": "user", "content": user_content},
+        ]
+
+        return await self.chat_completion(messages, max_tokens=3000)
+
+
+# Singleton instance
+llm_service = LLMService()

backend/app/services/signature_service.py

@@ -0,0 +1,174 @@
+"""Signature service for electronic signatures."""
+import hashlib
+import secrets
+from datetime import datetime, timedelta
+from typing import Optional
+
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.core.config import settings
+from app.models.signature import (
+    SignatureRequest,
+    Signature,
+    SignatureAudit,
+    SignatureStatus,
+)
+from app.models.contract import Contract
+
+
+class SignatureService:
+    """Service for electronic signature operations."""
+
+    def __init__(self, db: AsyncSession):
+        self.db = db
+
+    def generate_token(self) -> str:
+        """Generate a secure random token."""
+        return secrets.token_urlsafe(32)
+
+    def generate_verification_hash(self, content: str) -> str:
+        """Generate a verification hash for document content."""
+        return hashlib.sha256(content.encode()).hexdigest()
+
+    async def create_signature_request(
+        self,
+        contract_id: int,
+        requester_id: int,
+        signer_name: str,
+        signer_email: str,
+        expire_hours: int = None,
+    ) -> SignatureRequest:
+        """Create a signature request."""
+        expire_hours = expire_hours or settings.SIGNATURE_TOKEN_EXPIRE_HOURS
+
+        request = SignatureRequest(
+            contract_id=contract_id,
+            requester_id=requester_id,
+            signer_name=signer_name,
+            signer_email=signer_email,
+            token=self.generate_token(),
+            expires_at=datetime.utcnow() + timedelta(hours=expire_hours),
+        )
+        self.db.add(request)
+
+        # Create audit log
+        await self.create_audit_log(
+            action="request_created",
+            request_id=request.id,
+            details={"signer_email": signer_email}
+        )
+
+        await self.db.flush()
+        await self.db.refresh(request)
+        return request
+
+    async def get_signature_request_by_token(
+        self,
+        token: str
+    ) -> Optional[SignatureRequest]:
+        """Get a signature request by token."""
+        result = await self.db.execute(
+            select(SignatureRequest).where(SignatureRequest.token == token)
+        )
+        return result.scalar_one_or_none()
+
+    async def get_signature_request_by_id(
+        self,
+        request_id: int
+    ) -> Optional[SignatureRequest]:
+        """Get a signature request by ID."""
+        result = await self.db.execute(
+            select(SignatureRequest).where(SignatureRequest.id == request_id)
+        )
+        return result.scalar_one_or_none()
+
+    async def is_request_valid(self, request: SignatureRequest) -> bool:
+        """Check if a signature request is valid."""
+        if request.status != SignatureStatus.PENDING:
+            return False
+        if request.expires_at < datetime.utcnow():
+            return False
+        return True
+
+    async def sign_document(
+        self,
+        request: SignatureRequest,
+        signature_data: str,
+        ip_address: Optional[str] = None,
+        user_agent: Optional[str] = None,
+    ) -> Signature:
+        """Sign a document."""
+        # Get contract content for hash
+        result = await self.db.execute(
+            select(Contract).where(Contract.id == request.contract_id)
+        )
+        contract = result.scalar_one_or_none()
+
+        if not contract:
+            raise ValueError("Contract not found")
+
+        verification_hash = self.generate_verification_hash(contract.content)
+
+        signature = Signature(
+            request_id=request.id,
+            signer_name=request.signer_name,
+            signature_data=signature_data,
+            verification_hash=verification_hash,
+            ip_address=ip_address,
+            user_agent=user_agent,
+        )
+        self.db.add(signature)
+
+        # Update request status
+        request.status = SignatureStatus.SIGNED
+
+        # Create audit log
+        await self.create_audit_log(
+            action="document_signed",
+            signature_id=signature.id,
+            request_id=request.id,
+            ip_address=ip_address
+        )
+
+        await self.db.flush()
+        await self.db.refresh(signature)
+        return signature
+
+    async def verify_signature(
+        self,
+        signature_id: int,
+        content: str
+    ) -> bool:
+        """Verify a signature against document content."""
+        result = await self.db.execute(
+            select(Signature).where(Signature.id == signature_id)
+        )
+        signature = result.scalar_one_or_none()
+
+        if not signature:
+            return False
+
+        current_hash = self.generate_verification_hash(content)
+        return current_hash == signature.verification_hash
+
+    async def create_audit_log(
+        self,
+        action: str,
+        signature_id: Optional[int] = None,
+        request_id: Optional[int] = None,
+        details: Optional[dict] = None,
+        ip_address: Optional[str] = None,
+    ) -> SignatureAudit:
+        """Create an audit log entry."""
+        audit = SignatureAudit(
+            action=action,
+            signature_id=signature_id,
+            request_id=request_id,
+            details=details,
+            ip_address=ip_address,
+        )
+        self.db.add(audit)
+        await self.db.flush()
+        await self.db.refresh(audit)
+        return audit

backend/app/services/vector_service.py

@@ -0,0 +1,107 @@
+"""Vector service for embedding and similarity search."""
+import numpy as np
+from typing import List, Dict, Any, Optional
+import httpx
+
+from app.core.config import settings
+
+
+class VectorService:
+    """Service for vector embeddings and similarity search."""
+
+    def __init__(self):
+        self.api_base = settings.EMBEDDING_API_BASE
+        self.api_key = settings.EMBEDDING_API_KEY or settings.LLM_API_KEY
+        self.model = settings.EMBEDDING_MODEL
+        self.dimension = settings.EMBEDDING_DIMENSION
+
+    async def get_embedding(self, text: str) -> List[float]:
+        """Get embedding for a text using external API."""
+        if not self.api_key:
+            # Return mock embedding for testing
+            return [0.0] * self.dimension
+
+        async with httpx.AsyncClient() as client:
+            response = await client.post(
+                f"{self.api_base}/embeddings",
+                headers={
+                    "Authorization": f"Bearer {self.api_key}",
+                    "Content-Type": "application/json",
+                },
+                json={
+                    "model": self.model,
+                    "input": text,
+                },
+                timeout=30.0,
+            )
+            response.raise_for_status()
+            data = response.json()
+            return data["data"][0]["embedding"]
+
+    async def get_embeddings(self, texts: List[str]) -> List[List[float]]:
+        """Get embeddings for multiple texts."""
+        if not self.api_key:
+            return [[0.0] * self.dimension for _ in texts]
+
+        async with httpx.AsyncClient() as client:
+            response = await client.post(
+                f"{self.api_base}/embeddings",
+                headers={
+                    "Authorization": f"Bearer {self.api_key}",
+                    "Content-Type": "application/json",
+                },
+                json={
+                    "model": self.model,
+                    "input": texts,
+                },
+                timeout=60.0,
+            )
+            response.raise_for_status()
+            data = response.json()
+            return [item["embedding"] for item in data["data"]]
+
+    def cosine_similarity(
+        self,
+        vec1: List[float],
+        vec2: List[float]
+    ) -> float:
+        """Calculate cosine similarity between two vectors."""
+        arr1 = np.array(vec1)
+        arr2 = np.array(vec2)
+
+        dot_product = np.dot(arr1, arr2)
+        norm1 = np.linalg.norm(arr1)
+        norm2 = np.linalg.norm(arr2)
+
+        if norm1 == 0 or norm2 == 0:
+            return 0.0
+
+        return float(dot_product / (norm1 * norm2))
+
+    def search_similar(
+        self,
+        query_embedding: List[float],
+        stored_vectors: List[Dict[str, Any]],
+        top_k: int = 5
+    ) -> List[Dict[str, Any]]:
+        """Search for similar vectors."""
+        results = []
+
+        for item in stored_vectors:
+            similarity = self.cosine_similarity(
+                query_embedding,
+                item["embedding"]
+            )
+            results.append({
+                "id": item["id"],
+                "similarity": similarity,
+            })
+
+        # Sort by similarity descending
+        results.sort(key=lambda x: x["similarity"], reverse=True)
+
+        return results[:top_k]
+
+
+# Singleton instance
+vector_service = VectorService()

backend/pytest.ini

@@ -0,0 +1,16 @@
+[tool:pytest]
+asyncio_mode = auto
+testpaths = tests
+python_files = test_*.py
+python_classes = Test*
+python_functions = test_*
+
+[coverage:run]
+source = app
+omit = app/__init__.py
+
+[coverage:report]
+exclude_lines =
+    pragma: no cover
+    def __repr__
+    raise NotImplementedError

backend/requirements.txt

@@ -0,0 +1,31 @@
+# FastAPI and dependencies
+fastapi==0.110.0
+uvicorn[standard]==0.27.1
+python-multipart==0.0.9
+
+# Database
+sqlalchemy==2.0.25
+aiosqlite==0.19.0
+
+# Vector search
+sqlite-vss==0.1.2
+
+# Pydantic
+pydantic==2.6.0
+pydantic-settings==2.1.0
+
+# Authentication
+python-jose[cryptography]==3.3.0
+bcrypt==4.0.1
+
+# HTTP client for external APIs
+httpx==0.26.0
+
+# Testing
+pytest==7.4.4
+pytest-asyncio==0.23.4
+pytest-cov==4.1.0
+
+# Utilities
+python-dotenv==1.0.1
+numpy==1.26.4

backend/tests/__init__.py

@@ -0,0 +1 @@
+# Tests package

backend/tests/conftest.py

@@ -0,0 +1,36 @@
+"""Pytest configuration and fixtures."""
+import asyncio
+import pytest
+import pytest_asyncio
+from typing import AsyncGenerator
+from sqlalchemy.ext.asyncio import (
+    AsyncSession,
+    create_async_engine,
+    async_sessionmaker,
+)
+
+from app.core.database import Base
+from app.models.user import User
+from app.models.law import Law, LawArticle
+
+
+@pytest_asyncio.fixture
+async def db_session(tmp_path) -> AsyncGenerator[AsyncSession, None]:
+    """Create a test database session."""
+    db_file = tmp_path / "test.db"
+    engine = create_async_engine(
+        f"sqlite+aiosqlite:///{db_file}",
+        echo=False,
+    )
+
+    async with engine.begin() as conn:
+        await conn.run_sync(Base.metadata.create_all)
+
+    async_session = async_sessionmaker(
+        engine, class_=AsyncSession, expire_on_commit=False
+    )
+
+    async with async_session() as session:
+        yield session
+
+    await engine.dispose()

backend/tests/unit/__init__.py

@@ -0,0 +1 @@
+# Unit tests package

backend/tests/unit/test_config.py

@@ -0,0 +1,60 @@
+"""Unit tests for core configuration."""
+import pytest
+from app.core.config import Settings
+
+
+class TestSettings:
+    """Test cases for Settings configuration."""
+
+    def test_default_settings(self):
+        """Test default configuration values."""
+        settings = Settings()
+
+        assert settings.APP_NAME == "AI Legal Assistant"
+        assert settings.APP_VERSION == "1.0.0"
+        assert settings.DEBUG is False
+        assert settings.DATABASE_URL == "sqlite+aiosqlite:///./data/legal_assistant.db"
+
+    def test_custom_settings_from_env(self, monkeypatch):
+        """Test configuration from environment variables."""
+        monkeypatch.setenv("DEBUG", "true")
+        monkeypatch.setenv("DATABASE_URL", "sqlite+aiosqlite:///./test.db")
+        monkeypatch.setenv("LLM_API_KEY", "test-key")
+
+        settings = Settings()
+
+        assert settings.DEBUG is True
+        assert settings.DATABASE_URL == "sqlite+aiosqlite:///./test.db"
+        assert settings.LLM_API_KEY == "test-key"
+
+    def test_llm_settings(self, monkeypatch):
+        """Test LLM configuration."""
+        monkeypatch.setenv("LLM_API_BASE", "https://api.example.com/v1")
+        monkeypatch.setenv("LLM_MODEL", "gpt-4")
+
+        settings = Settings()
+
+        assert settings.LLM_API_BASE == "https://api.example.com/v1"
+        assert settings.LLM_MODEL == "gpt-4"
+
+    def test_embedding_settings(self, monkeypatch):
+        """Test embedding configuration."""
+        monkeypatch.setenv("EMBEDDING_MODEL", "text-embedding-3-small")
+        monkeypatch.setenv("EMBEDDING_DIMENSION", "1536")
+
+        settings = Settings()
+
+        assert settings.EMBEDDING_MODEL == "text-embedding-3-small"
+        assert settings.EMBEDDING_DIMENSION == 1536
+
+    def test_jwt_settings(self, monkeypatch):
+        """Test JWT configuration."""
+        monkeypatch.setenv("JWT_SECRET_KEY", "test-secret-key")
+        monkeypatch.setenv("JWT_ALGORITHM", "HS256")
+        monkeypatch.setenv("JWT_ACCESS_TOKEN_EXPIRE_MINUTES", "60")
+
+        settings = Settings()
+
+        assert settings.JWT_SECRET_KEY == "test-secret-key"
+        assert settings.JWT_ALGORITHM == "HS256"
+        assert settings.JWT_ACCESS_TOKEN_EXPIRE_MINUTES == 60

backend/tests/unit/test_contract_service.py

@@ -0,0 +1,100 @@
+"""Unit tests for Contract service."""
+import pytest
+from datetime import date
+
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.models.contract import ContractStatus
+from app.services.contract_service import ContractService, ContractTemplateService
+
+
+class TestContractService:
+    """Test cases for Contract service."""
+
+    @pytest.mark.asyncio
+    async def test_create_contract(self, db_session: AsyncSession):
+        """Test creating a contract."""
+        service = ContractService(db_session)
+
+        contract = await service.create_contract(
+            title="测试合同",
+            party_a="甲方",
+            party_b="乙方",
+            content="合同内容",
+            created_by=1,
+        )
+
+        assert contract.id is not None
+        assert contract.title == "测试合同"
+        assert contract.status == ContractStatus.DRAFT
+
+    @pytest.mark.asyncio
+    async def test_get_contract_by_id(self, db_session: AsyncSession):
+        """Test getting a contract by ID."""
+        service = ContractService(db_session)
+
+        created = await service.create_contract(
+            title="测试合同",
+            party_a="甲方",
+            party_b="乙方",
+            content="合同内容",
+            created_by=1,
+        )
+
+        contract = await service.get_contract_by_id(created.id)
+
+        assert contract is not None
+        assert contract.title == "测试合同"
+
+    @pytest.mark.asyncio
+    async def test_submit_for_approval(self, db_session: AsyncSession):
+        """Test submitting a contract for approval."""
+        service = ContractService(db_session)
+
+        contract = await service.create_contract(
+            title="测试合同",
+            party_a="甲方",
+            party_b="乙方",
+            content="合同内容",
+            created_by=1,
+        )
+
+        updated = await service.submit_for_approval(contract.id)
+
+        assert updated.status == ContractStatus.PENDING_APPROVAL
+
+    @pytest.mark.asyncio
+    async def test_approve_contract(self, db_session: AsyncSession):
+        """Test approving a contract."""
+        service = ContractService(db_session)
+
+        contract = await service.create_contract(
+            title="测试合同",
+            party_a="甲方",
+            party_b="乙方",
+            content="合同内容",
+            created_by=1,
+        )
+
+        approval = await service.approve_contract(contract.id, 1, "同意")
+
+        assert approval.status == ContractStatus.APPROVED
+
+
+class TestContractTemplateService:
+    """Test cases for ContractTemplate service."""
+
+    @pytest.mark.asyncio
+    async def test_create_template(self, db_session: AsyncSession):
+        """Test creating a contract template."""
+        service = ContractTemplateService(db_session)
+
+        template = await service.create_template(
+            name="测试模板",
+            content="模板内容",
+            created_by=1,
+            contract_type="销售合同",
+        )
+
+        assert template.id is not None
+        assert template.name == "测试模板"

backend/tests/unit/test_database.py

@@ -0,0 +1,51 @@
+"""Unit tests for database configuration."""
+import pytest
+from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine, async_sessionmaker
+from sqlalchemy import text
+
+from app.core.database import Base, get_db, init_db
+
+
+class TestDatabase:
+    """Test cases for database configuration."""
+
+    @pytest.mark.asyncio
+    async def test_create_tables(self, tmp_path):
+        """Test creating database tables."""
+        db_path = tmp_path / "test.db"
+        engine = create_async_engine(
+            f"sqlite+aiosqlite:///{db_path}",
+            echo=False
+        )
+
+        async with engine.begin() as conn:
+            await conn.run_sync(Base.metadata.create_all)
+
+        # Verify tables exist
+        async with engine.begin() as conn:
+            result = await conn.execute(text(
+                "SELECT name FROM sqlite_master WHERE type='table'"
+            ))
+            tables = [row[0] for row in result.fetchall()]
+            # At minimum, alembic_version table should exist after migration
+            # For now, just verify the connection works
+            assert len(tables) >= 0
+
+        await engine.dispose()
+
+    @pytest.mark.asyncio
+    async def test_get_db_session(self, tmp_path):
+        """Test getting database session."""
+        db_path = tmp_path / "test.db"
+        engine = create_async_engine(
+            f"sqlite+aiosqlite:///{db_path}",
+            echo=False
+        )
+        async_session = async_sessionmaker(
+            engine, class_=AsyncSession, expire_on_commit=False
+        )
+
+        async with async_session() as session:
+            assert isinstance(session, AsyncSession)
+
+        await engine.dispose()

backend/tests/unit/test_law_model.py

@@ -0,0 +1,70 @@
+"""Unit tests for Law model."""
+import pytest
+from datetime import date
+
+from app.models.law import Law, LawArticle, LawType, LawStatus
+
+
+class TestLawModel:
+    """Test cases for Law model."""
+
+    def test_law_creation(self):
+        """Test creating a law instance."""
+        law = Law(
+            title="中华人民共和国民法典",
+            law_type=LawType.LAW,
+            promulgation_date=date(2020, 5, 28),
+            effective_date=date(2021, 1, 1),
+            status=LawStatus.EFFECTIVE,
+            issuing_authority="全国人民代表大会",
+            content="民法典全文...",
+        )
+
+        assert law.title == "中华人民共和国民法典"
+        assert law.law_type == LawType.LAW
+        assert law.promulgation_date == date(2020, 5, 28)
+        assert law.effective_date == date(2021, 1, 1)
+        assert law.status == LawStatus.EFFECTIVE
+        assert law.issuing_authority == "全国人民代表大会"
+
+    def test_law_type_enum(self):
+        """Test law type enum values."""
+        assert LawType.LAW.value == "law"
+        assert LawType.REGULATION.value == "regulation"
+        assert LawType.RULE.value == "rule"
+        assert LawType.JUDICIAL_INTERPRETATION.value == "judicial_interpretation"
+
+    def test_law_status_enum(self):
+        """Test law status enum values."""
+        assert LawStatus.EFFECTIVE.value == "effective"
+        assert LawStatus.REVOKED.value == "revoked"
+        assert LawStatus.AMENDED.value == "amended"
+
+    def test_law_default_values(self):
+        """Test law default values."""
+        law = Law(
+            title="测试法规",
+            law_type=LawType.REGULATION,
+            promulgation_date=date(2024, 1, 1),
+            effective_date=date(2024, 2, 1),
+            issuing_authority="测试机关",
+            content="测试内容",
+        )
+
+        assert law.status == LawStatus.EFFECTIVE
+
+
+class TestLawArticleModel:
+    """Test cases for LawArticle model."""
+
+    def test_article_creation(self):
+        """Test creating a law article instance."""
+        article = LawArticle(
+            law_id=1,
+            article_number="第一条",
+            content="为了保护民事主体的合法权益...",
+        )
+
+        assert article.law_id == 1
+        assert article.article_number == "第一条"
+        assert "民事主体" in article.content

backend/tests/unit/test_law_service.py

@@ -0,0 +1,144 @@
+"""Unit tests for Law service."""
+import pytest
+from datetime import date
+from unittest.mock import AsyncMock, patch, MagicMock
+
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.models.law import Law, LawArticle, LawType, LawStatus
+from app.services.law_service import LawService
+
+
+class TestLawService:
+    """Test cases for Law service."""
+
+    @pytest.mark.asyncio
+    async def test_create_law(self, db_session: AsyncSession):
+        """Test creating a law."""
+        service = LawService(db_session)
+
+        law = await service.create_law(
+            title="测试法律",
+            law_type=LawType.LAW,
+            promulgation_date=date(2024, 1, 1),
+            effective_date=date(2024, 2, 1),
+            issuing_authority="测试机关",
+            content="测试内容",
+        )
+
+        assert law.id is not None
+        assert law.title == "测试法律"
+        assert law.law_type == LawType.LAW
+
+    @pytest.mark.asyncio
+    async def test_get_law_by_id(self, db_session: AsyncSession):
+        """Test getting a law by ID."""
+        service = LawService(db_session)
+
+        # Create a law first
+        created = await service.create_law(
+            title="测试法律",
+            law_type=LawType.LAW,
+            promulgation_date=date(2024, 1, 1),
+            effective_date=date(2024, 2, 1),
+            issuing_authority="测试机关",
+            content="测试内容",
+        )
+
+        # Get the law
+        law = await service.get_law_by_id(created.id)
+
+        assert law is not None
+        assert law.title == "测试法律"
+
+    @pytest.mark.asyncio
+    async def test_get_laws_list(self, db_session: AsyncSession):
+        """Test getting list of laws."""
+        service = LawService(db_session)
+
+        # Create multiple laws
+        for i in range(3):
+            await service.create_law(
+                title=f"测试法律{i}",
+                law_type=LawType.LAW,
+                promulgation_date=date(2024, 1, 1),
+                effective_date=date(2024, 2, 1),
+                issuing_authority="测试机关",
+                content=f"测试内容{i}",
+            )
+
+        laws = await service.get_laws_list(skip=0, limit=10)
+
+        assert len(laws) == 3
+
+    @pytest.mark.asyncio
+    async def test_update_law(self, db_session: AsyncSession):
+        """Test updating a law."""
+        service = LawService(db_session)
+
+        # Create a law
+        law = await service.create_law(
+            title="原标题",
+            law_type=LawType.LAW,
+            promulgation_date=date(2024, 1, 1),
+            effective_date=date(2024, 2, 1),
+            issuing_authority="测试机关",
+            content="原内容",
+        )
+
+        # Update the law
+        updated = await service.update_law(law.id, title="新标题")
+
+        assert updated.title == "新标题"
+
+    @pytest.mark.asyncio
+    async def test_delete_law(self, db_session: AsyncSession):
+        """Test deleting a law."""
+        service = LawService(db_session)
+
+        # Create a law
+        law = await service.create_law(
+            title="待删除法律",
+            law_type=LawType.LAW,
+            promulgation_date=date(2024, 1, 1),
+            effective_date=date(2024, 2, 1),
+            issuing_authority="测试机关",
+            content="测试内容",
+        )
+
+        # Delete the law
+        result = await service.delete_law(law.id)
+
+        assert result is True
+
+        # Verify it's deleted
+        deleted = await service.get_law_by_id(law.id)
+        assert deleted is None
+
+    @pytest.mark.asyncio
+    async def test_search_laws_by_keyword(self, db_session: AsyncSession):
+        """Test searching laws by keyword."""
+        service = LawService(db_session)
+
+        # Create laws with different content
+        await service.create_law(
+            title="民法典",
+            law_type=LawType.LAW,
+            promulgation_date=date(2024, 1, 1),
+            effective_date=date(2024, 2, 1),
+            issuing_authority="全国人大",
+            content="民法典全文内容",
+        )
+        await service.create_law(
+            title="刑法",
+            law_type=LawType.LAW,
+            promulgation_date=date(2024, 1, 1),
+            effective_date=date(2024, 2, 1),
+            issuing_authority="全国人大",
+            content="刑法全文内容",
+        )
+
+        results = await service.search_laws_by_keyword("民法")
+
+        assert len(results) >= 1
+        assert any("民法典" in law.title for law in results)

backend/tests/unit/test_llm_service.py

@@ -0,0 +1,82 @@
+"""Unit tests for LLM service."""
+import pytest
+from unittest.mock import AsyncMock, patch, MagicMock
+
+from app.services.llm_service import LLMService
+
+
+class TestLLMService:
+    """Test cases for LLM service."""
+
+    @pytest.mark.asyncio
+    async def test_chat_completion_no_api_key(self):
+        """Test chat completion without API key returns mock."""
+        service = LLMService()
+        service.api_key = None  # Ensure no API key
+
+        response = await service.chat_completion(
+            messages=[{"role": "user", "content": "你好"}]
+        )
+
+        # Should return mock response
+        assert "模拟" in response or "法律" in response
+
+    @pytest.mark.asyncio
+    async def test_chat_completion_with_api_key(self):
+        """Test chat completion with API key."""
+        service = LLMService()
+        service.api_key = "test-key"
+
+        with patch('httpx.AsyncClient') as mock_client:
+            mock_response = MagicMock()
+            mock_response.json.return_value = {
+                "choices": [{
+                    "message": {
+                        "role": "assistant",
+                        "content": "这是测试回复"
+                    }
+                }]
+            }
+            mock_response.raise_for_status = MagicMock()
+
+            mock_client_instance = MagicMock()
+            mock_client_instance.post = AsyncMock(return_value=mock_response)
+            mock_client_instance.__aenter__ = AsyncMock(return_value=mock_client_instance)
+            mock_client_instance.__aexit__ = AsyncMock(return_value=None)
+            mock_client.return_value = mock_client_instance
+
+            response = await service.chat_completion(
+                messages=[{"role": "user", "content": "你好"}]
+            )
+
+            assert "这是测试回复" in response
+
+    @pytest.mark.asyncio
+    async def test_legal_qa(self):
+        """Test legal QA."""
+        service = LLMService()
+
+        with patch.object(service, 'chat_completion') as mock_chat:
+            mock_chat.return_value = "根据《民法典》第一条规定..."
+
+            response = await service.legal_qa(
+                question="民法典的立法目的是什么？",
+                context="《民法典》第一条 为了保护民事主体的合法权益..."
+            )
+
+            assert "民法典" in response
+
+    @pytest.mark.asyncio
+    async def test_analyze_legal_issue(self):
+        """Test legal issue analysis."""
+        service = LLMService()
+
+        with patch.object(service, 'chat_completion') as mock_chat:
+            mock_chat.return_value = "分析结果：该问题涉及..."
+
+            response = await service.analyze_legal_issue(
+                issue_description="甲方未按合同约定支付货款",
+                relevant_laws=["《民法典》第五百零九条"]
+            )
+
+            assert "分析结果" in response

backend/tests/unit/test_remaining_models.py

@@ -0,0 +1,115 @@
+"""Unit tests for remaining models and services."""
+import pytest
+from datetime import date, datetime
+
+from app.models.analysis import LegalAnalysis, Case, AnalysisStatus
+from app.models.case import CaseReview, ReviewStatus, ReviewType
+from app.models.contract import Contract, ContractTemplate, ContractStatus
+from app.models.signature import SignatureRequest, Signature, SignatureStatus
+
+
+class TestAnalysisModel:
+    """Test cases for Analysis model."""
+
+    def test_legal_analysis_creation(self):
+        """Test creating a legal analysis instance."""
+        analysis = LegalAnalysis(
+            user_id=1,
+            title="合同纠纷分析",
+            case_description="甲方未按合同约定支付货款...",
+        )
+
+        assert analysis.user_id == 1
+        assert analysis.title == "合同纠纷分析"
+        assert analysis.status == AnalysisStatus.DRAFT
+
+    def test_case_creation(self):
+        """Test creating a case instance."""
+        case = Case(
+            title="买卖合同纠纷案",
+            case_number="(2024)京01民初1号",
+            court="北京市第一中级人民法院",
+            case_type="买卖合同纠纷",
+        )
+
+        assert case.title == "买卖合同纠纷案"
+        assert case.case_number == "(2024)京01民初1号"
+
+
+class TestCaseReviewModel:
+    """Test cases for CaseReview model."""
+
+    def test_case_review_creation(self):
+        """Test creating a case review instance."""
+        review = CaseReview(
+            case_id=1,
+            reviewer_id=1,
+            review_type=ReviewType.INITIAL,
+            opinion="同意立案",
+            score=90,
+        )
+
+        assert review.case_id == 1
+        assert review.review_type == ReviewType.INITIAL
+        assert review.status == ReviewStatus.PENDING
+
+
+class TestContractModel:
+    """Test cases for Contract model."""
+
+    def test_contract_creation(self):
+        """Test creating a contract instance."""
+        contract = Contract(
+            title="销售合同",
+            party_a="甲方公司",
+            party_b="乙方公司",
+            content="合同内容...",
+            created_by=1,
+        )
+
+        assert contract.title == "销售合同"
+        assert contract.party_a == "甲方公司"
+        assert contract.status == ContractStatus.DRAFT
+
+    def test_contract_template_creation(self):
+        """Test creating a contract template instance."""
+        template = ContractTemplate(
+            name="标准销售合同模板",
+            content="模板内容...",
+            created_by=1,
+            contract_type="销售合同",
+        )
+
+        assert template.name == "标准销售合同模板"
+        assert template.contract_type == "销售合同"
+
+
+class TestSignatureModel:
+    """Test cases for Signature model."""
+
+    def test_signature_request_creation(self):
+        """Test creating a signature request instance."""
+        request = SignatureRequest(
+            contract_id=1,
+            requester_id=1,
+            signer_name="张三",
+            signer_email="zhangsan@example.com",
+            token="abc123token",
+            expires_at=datetime.utcnow(),
+        )
+
+        assert request.contract_id == 1
+        assert request.signer_name == "张三"
+        assert request.status == SignatureStatus.PENDING
+
+    def test_signature_creation(self):
+        """Test creating a signature instance."""
+        signature = Signature(
+            request_id=1,
+            signer_name="张三",
+            signature_data="base64encodedimage",
+            verification_hash="hash123",
+        )
+
+        assert signature.request_id == 1
+        assert signature.signer_name == "张三"

backend/tests/unit/test_security.py

@@ -0,0 +1,84 @@
+"""Unit tests for security module."""
+import pytest
+from datetime import datetime, timedelta
+
+from app.core.security import (
+    get_password_hash,
+    verify_password,
+    create_access_token,
+    decode_access_token,
+)
+
+
+class TestPasswordHashing:
+    """Test cases for password hashing."""
+
+    def test_password_hash(self):
+        """Test password hashing."""
+        password = "test_password_123"
+        hashed = get_password_hash(password)
+
+        assert hashed != password
+        assert len(hashed) > 0
+        assert hashed.startswith("$2b$")
+
+    def test_verify_password_correct(self):
+        """Test verifying correct password."""
+        password = "test_password_123"
+        hashed = get_password_hash(password)
+
+        assert verify_password(password, hashed) is True
+
+    def test_verify_password_incorrect(self):
+        """Test verifying incorrect password."""
+        password = "test_password_123"
+        hashed = get_password_hash(password)
+
+        assert verify_password("wrong_password", hashed) is False
+
+    def test_different_passwords_different_hashes(self):
+        """Test that same password produces different hashes."""
+        password = "test_password_123"
+        hash1 = get_password_hash(password)
+        hash2 = get_password_hash(password)
+
+        assert hash1 != hash2
+
+
+class TestJWTTokens:
+    """Test cases for JWT token handling."""
+
+    def test_create_access_token(self):
+        """Test creating access token."""
+        data = {"sub": "user123", "role": "lawyer"}
+        token = create_access_token(data)
+
+        assert token is not None
+        assert isinstance(token, str)
+        assert len(token) > 0
+
+    def test_decode_access_token(self):
+        """Test decoding access token."""
+        data = {"sub": "user123", "role": "lawyer"}
+        token = create_access_token(data)
+
+        decoded = decode_access_token(token)
+
+        assert decoded is not None
+        assert decoded["sub"] == "user123"
+        assert decoded["role"] == "lawyer"
+
+    def test_decode_invalid_token(self):
+        """Test decoding invalid token."""
+        decoded = decode_access_token("invalid.token.here")
+
+        assert decoded is None
+
+    def test_token_contains_exp(self):
+        """Test that token contains expiration."""
+        data = {"sub": "user123"}
+        token = create_access_token(data)
+
+        decoded = decode_access_token(token)
+
+        assert "exp" in decoded

backend/tests/unit/test_signature_service.py

@@ -0,0 +1,88 @@
+"""Unit tests for Signature service."""
+import pytest
+from datetime import datetime, timedelta
+
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.models.signature import SignatureStatus
+from app.models.contract import Contract
+from app.services.signature_service import SignatureService
+from app.services.contract_service import ContractService
+
+
+class TestSignatureService:
+    """Test cases for Signature service."""
+
+    @pytest.mark.asyncio
+    async def test_generate_token(self, db_session: AsyncSession):
+        """Test token generation."""
+        service = SignatureService(db_session)
+
+        token = service.generate_token()
+
+        assert token is not None
+        assert len(token) > 20
+
+    @pytest.mark.asyncio
+    async def test_generate_verification_hash(self, db_session: AsyncSession):
+        """Test verification hash generation."""
+        service = SignatureService(db_session)
+
+        hash1 = service.generate_verification_hash("test content")
+        hash2 = service.generate_verification_hash("test content")
+        hash3 = service.generate_verification_hash("different content")
+
+        assert hash1 == hash2
+        assert hash1 != hash3
+        assert len(hash1) == 64  # SHA-256 hex length
+
+    @pytest.mark.asyncio
+    async def test_create_signature_request(self, db_session: AsyncSession):
+        """Test creating a signature request."""
+        # First create a contract
+        contract_service = ContractService(db_session)
+        contract = await contract_service.create_contract(
+            title="测试合同",
+            party_a="甲方",
+            party_b="乙方",
+            content="合同内容",
+            created_by=1,
+        )
+
+        service = SignatureService(db_session)
+        request = await service.create_signature_request(
+            contract_id=contract.id,
+            requester_id=1,
+            signer_name="张三",
+            signer_email="zhangsan@example.com",
+        )
+
+        assert request.id is not None
+        assert request.signer_name == "张三"
+        assert request.status == SignatureStatus.PENDING
+        assert request.token is not None
+
+    @pytest.mark.asyncio
+    async def test_is_request_valid(self, db_session: AsyncSession):
+        """Test checking if request is valid."""
+        # Create a contract first
+        contract_service = ContractService(db_session)
+        contract = await contract_service.create_contract(
+            title="测试合同",
+            party_a="甲方",
+            party_b="乙方",
+            content="合同内容",
+            created_by=1,
+        )
+
+        service = SignatureService(db_session)
+        request = await service.create_signature_request(
+            contract_id=contract.id,
+            requester_id=1,
+            signer_name="张三",
+            signer_email="zhangsan@example.com",
+            expire_hours=72,
+        )
+
+        is_valid = await service.is_request_valid(request)
+        assert is_valid is True

backend/tests/unit/test_user_model.py

@@ -0,0 +1,52 @@
+"""Unit tests for User model."""
+import pytest
+from datetime import datetime
+
+from app.models.user import User, UserRole
+
+
+class TestUserModel:
+    """Test cases for User model."""
+
+    def test_user_creation(self):
+        """Test creating a user instance."""
+        user = User(
+            username="testuser",
+            email="test@example.com",
+            hashed_password="hashed_password",
+            role=UserRole.LAWYER,
+        )
+
+        assert user.username == "testuser"
+        assert user.email == "test@example.com"
+        assert user.hashed_password == "hashed_password"
+        assert user.role == UserRole.LAWYER
+        assert user.is_active is True
+
+    def test_user_role_enum(self):
+        """Test user role enum values."""
+        assert UserRole.ADMIN.value == "admin"
+        assert UserRole.LAWYER.value == "lawyer"
+        assert UserRole.REVIEWER.value == "reviewer"
+        assert UserRole.CLIENT.value == "client"
+
+    def test_user_default_values(self):
+        """Test user default values."""
+        user = User(
+            username="testuser",
+            email="test@example.com",
+            hashed_password="hashed_password",
+        )
+
+        assert user.role == UserRole.CLIENT
+        assert user.is_active is True
+
+    def test_user_repr(self):
+        """Test user string representation."""
+        user = User(
+            username="testuser",
+            email="test@example.com",
+            hashed_password="hashed_password",
+        )
+
+        assert "testuser" in repr(user)

backend/tests/unit/test_vector_service.py

@@ -0,0 +1,81 @@
+"""Unit tests for Vector service."""
+import pytest
+import numpy as np
+from unittest.mock import AsyncMock, patch, MagicMock
+
+from app.services.vector_service import VectorService
+
+
+class TestVectorService:
+    """Test cases for Vector service."""
+
+    @pytest.mark.asyncio
+    async def test_get_embedding_no_api_key(self):
+        """Test getting embedding without API key returns mock."""
+        service = VectorService()
+        service.api_key = None  # Ensure no API key
+
+        embedding = await service.get_embedding("测试文本")
+
+        # Should return mock embedding
+        assert len(embedding) == service.dimension
+        assert all(x == 0.0 for x in embedding)
+
+    @pytest.mark.asyncio
+    async def test_get_embedding_with_api_key(self):
+        """Test getting embedding with API key."""
+        service = VectorService()
+        service.api_key = "test-key"
+
+        with patch('httpx.AsyncClient') as mock_client:
+            mock_response = MagicMock()
+            mock_response.json.return_value = {
+                "data": [{"embedding": [0.1] * 1536}]
+            }
+            mock_response.raise_for_status = MagicMock()
+
+            mock_client_instance = MagicMock()
+            mock_client_instance.post = AsyncMock(return_value=mock_response)
+            mock_client_instance.__aenter__ = AsyncMock(return_value=mock_client_instance)
+            mock_client_instance.__aexit__ = AsyncMock(return_value=None)
+            mock_client.return_value = mock_client_instance
+
+            embedding = await service.get_embedding("测试文本")
+
+            assert len(embedding) == 1536
+            assert all(x == 0.1 for x in embedding)
+
+    @pytest.mark.asyncio
+    async def test_cosine_similarity(self):
+        """Test cosine similarity calculation."""
+        service = VectorService()
+
+        vec1 = [1.0, 0.0, 0.0]
+        vec2 = [1.0, 0.0, 0.0]
+        vec3 = [0.0, 1.0, 0.0]
+
+        # Same vectors should have similarity 1.0
+        sim1 = service.cosine_similarity(vec1, vec2)
+        assert abs(sim1 - 1.0) < 0.001
+
+        # Orthogonal vectors should have similarity 0.0
+        sim2 = service.cosine_similarity(vec1, vec3)
+        assert abs(sim2 - 0.0) < 0.001
+
+    @pytest.mark.asyncio
+    async def test_search_similar(self):
+        """Test searching similar vectors."""
+        service = VectorService()
+
+        # Mock vectors: first is similar, second is different
+        stored_vectors = [
+            {"id": 1, "embedding": [1.0, 0.0, 0.0]},
+            {"id": 2, "embedding": [0.0, 1.0, 0.0]},
+        ]
+
+        query_vec = [0.9, 0.1, 0.0]
+
+        results = service.search_similar(query_vec, stored_vectors, top_k=2)
+
+        assert len(results) == 2
+        assert results[0]["id"] == 1  # Most similar should be first

docker-compose.yml

@@ -0,0 +1,25 @@
+version: '3.8'
+
+services:
+  web:
+    build: ./backend
+    ports:
+      - "8000:8000"
+    volumes:
+      - ./data:/app/data
+      - ./uploads:/app/uploads
+    environment:
+      - DATABASE_URL=sqlite+aiosqlite:///./data/legal_assistant.db
+      - LLM_API_KEY=${LLM_API_KEY}
+      - LLM_API_BASE=${LLM_API_BASE:-https://api.openai.com/v1}
+      - LLM_MODEL=${LLM_MODEL:-gpt-4o-mini}
+      - EMBEDDING_API_KEY=${EMBEDDING_API_KEY}
+      - EMBEDDING_API_BASE=${EMBEDDING_API_BASE:-https://api.openai.com/v1}
+      - EMBEDDING_MODEL=${EMBEDDING_MODEL:-text-embedding-3-small}
+      - JWT_SECRET_KEY=${JWT_SECRET_KEY:-change-me-in-production}
+    restart: unless-stopped
+    healthcheck:
+      test: ["CMD", "curl", "-f", "http://localhost:8000/health"]
+      interval: 30s
+      timeout: 10s
+      retries: 3