fix(gate-b): fresh-db install path - conditional guards on plugin-table migrations + dual-path convergence migrations

alembic/versions/0119_ai_provider_compliance_fields.py

@@ -18,7 +18,26 @@ branch_labels = None
 depends_on = None
 
 
+def _table_exists(conn, table_name: str) -> bool:
+    """True when the table exists (dual-path convergence, Gate B).
+
+    On a fresh install the ai_assistant plugin SQL migration has not run
+    yet when Alembic reaches this revision — skip instead of failing.
+    The plugin-side migration adds the same columns idempotently.
+    """
+    row = conn.execute(
+        sa.text("SELECT to_regclass(:tname) IS NOT NULL"),
+        {"tname": f"public.{table_name}"},
+    ).scalar()
+    return bool(row)
+
+
 def upgrade() -> None:
+    conn = op.get_bind()
+    if not _table_exists(conn, "ai_providers"):
+        # Fresh-install path: table arrives with the ai_assistant plugin
+        # migration, which includes these columns.
+        return
     op.add_column("ai_providers", sa.Column("region", sa.String(20), nullable=False, server_default="unknown"))
     op.add_column("ai_providers", sa.Column("hosting_type", sa.String(30), nullable=False, server_default="cloud"))
     op.add_column("ai_providers", sa.Column("dpa_status", sa.String(20), nullable=False, server_default="none"))
@@ -29,6 +48,9 @@ def upgrade() -> None:
 
 
 def downgrade() -> None:
+    conn = op.get_bind()
+    if not _table_exists(conn, "ai_providers"):
+        return
     op.drop_column("ai_providers", "allowed_data_classes")
     op.drop_column("ai_providers", "transfer_notice")
     op.drop_column("ai_providers", "training_on_customer_data")