fix: Improve cross-database compatibility and defensive checks in DCR migrations

- Replace server_default='1' with sa.true() for PostgreSQL compatibility
- Add table existence checks before ALTER operations
- Handle fresh database installations gracefully
- Follow existing migration patterns for conditional upgrades

Author: crivetimihai

mcpgateway/alembic/versions/2f67b12600b4_add_registered_oauth_clients_table_for_.py

@@ -39,7 +39,7 @@ def upgrade() -> None:
         sa.Column("registration_access_token_encrypted", sa.Text, nullable=True),
         sa.Column("created_at", sa.DateTime(timezone=True), nullable=False),
         sa.Column("expires_at", sa.DateTime(timezone=True), nullable=True),
-        sa.Column("is_active", sa.Boolean, server_default="1"),
+        sa.Column("is_active", sa.Boolean, server_default=sa.true()),
     )
 
     # Create unique index on (gateway_id, issuer)

mcpgateway/alembic/versions/61ee11c482d6_add_code_verifier_to_oauth_states_for_.py

@@ -22,11 +22,27 @@
 
 def upgrade() -> None:
     """Upgrade schema."""
+    # Check if oauth_states table exists before adding column
+    conn = op.get_bind()
+    inspector = sa.inspect(conn)
+
+    if "oauth_states" not in inspector.get_table_names():
+        print("oauth_states table not found. Skipping PKCE code_verifier migration.")
+        return
+
     # Add code_verifier column to oauth_states for PKCE support (RFC 7636)
     op.add_column("oauth_states", sa.Column("code_verifier", sa.String(128), nullable=True))
 
 
 def downgrade() -> None:
     """Downgrade schema."""
+    # Check if oauth_states table exists before dropping column
+    conn = op.get_bind()
+    inspector = sa.inspect(conn)
+
+    if "oauth_states" not in inspector.get_table_names():
+        print("oauth_states table not found. Skipping PKCE code_verifier downgrade.")
+        return
+
     # Remove code_verifier column from oauth_states
     op.drop_column("oauth_states", "code_verifier")