diff --git a/guarddog_nexus/database.py b/guarddog_nexus/database.py
index 95fa759..ebab461 100644
--- a/guarddog_nexus/database.py
+++ b/guarddog_nexus/database.py
@@ -1,9 +1,12 @@
 """Async SQLite database setup via SQLAlchemy."""
 
+
+from sqlalchemy import inspect, text
 from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
 from sqlalchemy.orm import DeclarativeBase
 
 from guarddog_nexus.config import config
+from guarddog_nexus.logging_setup import log
 
 DATABASE_URL = f"sqlite+aiosqlite:///{config.database_path}"
 
@@ -15,11 +18,56 @@ class Base(DeclarativeBase):
     pass
 
 
+async def _migrate():
+    """Add any missing columns from model definitions to existing SQLite tables."""
+    import guarddog_nexus.models  # noqa: F401
+
+    async with _engine.connect() as conn:
+        for table in Base.metadata.sorted_tables:
+            # Get existing columns in DB
+            col_names = []
+            try:
+                existing = await conn.run_sync(
+                    lambda c: [col["name"] for col in inspect(c).get_columns(table.name)]
+                )
+                col_names = existing
+            except Exception:
+                continue
+
+            # Add missing model columns
+            for col in table.columns:
+                if col.name not in col_names:
+                    col_type = col.type.compile(_engine.dialect)
+                    nullable = "" if col.nullable else " NOT NULL"
+                    default = ""
+                    if col.default and col.default.arg is not None:
+                        default_val = col.default.arg
+                        if isinstance(default_val, str):
+                            default = f" DEFAULT '{default_val}'"
+                        else:
+                            default = f" DEFAULT {default_val}"
+                    if col.server_default:
+                        # Skip — func.now() etc. not trivially stringable
+                        pass
+
+                    sql = (
+                        f"ALTER TABLE {table.name} ADD COLUMN "
+                        f"{col.name} {col_type}{nullable}{default}"
+                    )
+                    log.info("Migration: %s", sql)
+                    try:
+                        await conn.execute(text(sql))
+                        await conn.commit()
+                    except Exception as e:
+                        log.warning("Migration skipped (may already exist): %s", e)
+
+
 async def init_db():
     import guarddog_nexus.models  # noqa: F401
 
     async with _engine.begin() as conn:
         await conn.run_sync(Base.metadata.create_all)
+    await _migrate()
 
 
 async def get_session() -> AsyncSession: