Update Database Migration

Database-Migration.md

@@ -1 +1,21 @@
-- Migrate from TinyDB to something else
+# Migrations from TinyDB to MongoDB Atlas
+Steps to include in migration:
+
+1. Migration script should be created to migrate TinyDB json files to mongo
+2. The mongo uri string is in environment variable MONGO_URI
+3. Refactor from TinyDB should use a minimal set of changes
+4. try to reuse function names
+5. handle unit test with `mongomock` when possible
+6. for integration tests run a local docker container
+7. for end to end playwright tests, use a dedicated isolated test db (chore_db_e2e) - the connection string resides in .env.test.  wipe test db between tests
+8. keep in mind multi-worker gunicorn. do not initialize MongoClient globally at the module root level. Initialize MongoClient lazily within Flask's app factory or use Gunicorn’s post_fork hook
+9. Make sure your migration script or application startup routine explicitly creates unique and secondary indexes on fields that are queried often
+10. configure mongo to fail fast when developing:
+```
+client = MongoClient(
+    os.getenv("MONGO_URI"),
+    serverSelectionTimeoutMS=5000,  # 5-second timeout instead of 30s
+    connectTimeoutMS=5000,          # 5-second connection handshake limit
+    maxPoolSize=20                   # Prevents hitting Atlas free-tier limits
+) 
+```