diff --git a/app/api/v1/jobs.py b/app/api/v1/jobs.py
index 2f452b7..d2e80fa 100644
--- a/app/api/v1/jobs.py
+++ b/app/api/v1/jobs.py
@@ -13,6 +13,10 @@ async def upload_csv(
     file: UploadFile = File(...),
     service: JobService = Depends(get_job_service),
 ):
+    """
+    Accepts a CSV file upload. Validates it, creates a job record in the database
+    with status=pending, enqueues the processing task, and returns the job_id immediately.
+    """
     if not file.filename.endswith(".csv"):
         raise HTTPException(
             status_code=status.HTTP_400_BAD_REQUEST,
@@ -35,6 +39,10 @@ async def get_job_status(
     job_id: str,
     service: JobService = Depends(get_job_service),
 ):
+    """
+    Returns the current status of the job: pending, processing, completed, or failed.
+    If completed, also includes a summary field with high-level stats.
+    """
     try:
         job = await service.get_job_status(job_id)
         return job
@@ -50,6 +58,10 @@ async def get_job_result(
     job_id: str,
     service: JobService = Depends(get_job_service),
 ):
+    """
+    Returns the full structured output: cleaned transactions list, flagged anomalies,
+    per-category spend breakdown, and the LLM-generated narrative summary.
+    """
     try:
         job = await service.get_job_results(job_id)
         return job
@@ -65,4 +77,8 @@ async def get_all_jobs(
     status: Optional[str] = Query(None, description="Filter jobs by status"),
     service: JobService = Depends(get_job_service),
 ):
+    """
+    Lists all jobs with their status, filename, row count, and created_at timestamp.
+    Supports filtering via ?status= query parameter.
+    """
     return await service.list_jobs(status=status)
diff --git a/app/db/models/job.py b/app/db/models/job.py
index 5ed7da1..73dc2d2 100644
--- a/app/db/models/job.py
+++ b/app/db/models/job.py
@@ -33,6 +33,7 @@ class Job(Base):
         onupdate=func.now(),
         nullable=False,
     )
+    # JSON summaries and results
     summary: Mapped[Optional[Dict[str, Any]]] = mapped_column(
         JSON,
         nullable=True,
diff --git a/app/db/session.py b/app/db/session.py
index fa7cbc4..f0a14fc 100644
--- a/app/db/session.py
+++ b/app/db/session.py
@@ -2,6 +2,7 @@ from typing import AsyncGenerator
 from sqlalchemy.ext.asyncio import create_async_engine, async_sessionmaker, AsyncSession
 from app.core.config import settings
 
+# Create async database engine
 engine = create_async_engine(
     settings.DATABASE_URL,
     echo=False,
@@ -10,6 +11,7 @@ engine = create_async_engine(
     max_overflow=20,
 )
 
+# Async session factory
 AsyncSessionLocal = async_sessionmaker(
     bind=engine,
     class_=AsyncSession,
@@ -18,6 +20,7 @@ AsyncSessionLocal = async_sessionmaker(
 
 
 async def get_db() -> AsyncGenerator[AsyncSession, None]:
+    """Dependency for obtaining an asynchronous database session"""
     async with AsyncSessionLocal() as session:
         try:
             yield session
diff --git a/app/main.py b/app/main.py
index 61b9e88..84136df 100644
--- a/app/main.py
+++ b/app/main.py
@@ -9,16 +9,21 @@ from app.db.session import engine
 
 @asynccontextmanager
 async def lifespan(app: FastAPI):
+    # Startup: Create tables if they don't exist
     async with engine.begin() as conn:
         await conn.run_sync(Base.metadata.create_all)
     yield
     # Shutdown: Clean up pool
     await engine.dispose()
+
+
 app = FastAPI(
     title=settings.PROJECT_NAME,
     openapi_url=f"{settings.API_V1_STR}/openapi.json",
     lifespan=lifespan,
 )
+
+# CORS Middleware
 app.add_middleware(
     CORSMiddleware,
     allow_origins=["*"],
@@ -26,7 +31,12 @@ app.add_middleware(
     allow_methods=["*"],
     allow_headers=["*"],
 )
+
+# Include API Router
 app.include_router(jobs_router, prefix=settings.API_V1_STR)
+
+
+# Root healthcheck endpoint
 @app.get("/health", tags=["health"])
 def health_check():
     return {"status": "ok", "project": settings.PROJECT_NAME}