feat: refactor user configuration table

api/alembic/versions/91cc6ba3e1c7_add_key_to_user_configurations.py

@@ -0,0 +1,52 @@
+"""add key to user_configurations
+
+Turns user_configurations into a per-user keyed JSON store mirroring
+organization_configurations. Existing rows (the legacy v1 AI model
+configuration blob) are backfilled with key MODEL_CONFIGURATION.
+
+Revision ID: 91cc6ba3e1c7
+Revises: 384be6596b36
+Create Date: 2026-06-12 21:04:25.561529
+
+"""
+
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision: str = "91cc6ba3e1c7"
+down_revision: Union[str, None] = "384be6596b36"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    # Backfill existing rows (all legacy model-config blobs) via the server
+    # default, then drop the default — application code always supplies key.
+    op.add_column(
+        "user_configurations",
+        sa.Column(
+            "key",
+            sa.String(),
+            nullable=False,
+            server_default="MODEL_CONFIGURATION",
+        ),
+    )
+
+    op.create_unique_constraint(
+        "_user_configuration_key_uc", "user_configurations", ["user_id", "key"]
+    )
+    op.alter_column("user_configurations", "key", server_default=None)
+
+
+def downgrade() -> None:
+    op.drop_constraint(
+        "_user_configuration_key_uc", "user_configurations", type_="unique"
+    )
+    # Non-model-config rows (e.g. ONBOARDING) have no meaning in the old
+    # single-blob schema; the old code would read them as the user's model
+    # config, so they must not survive the downgrade.
+    op.execute("DELETE FROM user_configurations WHERE key != 'MODEL_CONFIGURATION'")
+    op.drop_column("user_configurations", "key")