fix(scheduling): repair missing participation gateway column

src/govoplan_scheduling/backend/migrations/versions/be8f4d2c1a70_v0110_scheduling_participation_gateway_repair.py

@@ -0,0 +1,65 @@
+"""v0.1.10 scheduling participation gateway schema repair
+
+Revision ID: be8f4d2c1a70
+Revises: ad7e3c9b2f10
+Create Date: 2026-07-22 00:00:00.000000
+
+Some development databases were stamped at ``ad7e3c9b2f10`` before the
+``scheduling_participants.participation_gateway`` column was present.  A
+forward repair is required because Alembic correctly does not replay an
+already-recorded revision.  The column is nullable, so adding it preserves all
+existing participant rows without inventing gateway ownership for legacy
+invitations.
+"""
+from __future__ import annotations
+
+from alembic import op
+import sqlalchemy as sa
+
+
+revision = "be8f4d2c1a70"
+down_revision = "ad7e3c9b2f10"
+branch_labels = None
+depends_on = None
+
+
+def _require_compatible_column(column: dict[str, object]) -> None:
+    column_type = column["type"]
+    if (
+        not column.get("nullable")
+        or not isinstance(column_type, sa.String)
+        or column_type.length != 40
+    ):
+        raise RuntimeError(
+            "Cannot adopt scheduling_participants.participation_gateway "
+            "because its schema is unexpected"
+        )
+
+
+def upgrade() -> None:
+    inspector = sa.inspect(op.get_bind())
+    if "scheduling_participants" not in inspector.get_table_names():
+        raise RuntimeError(
+            "Cannot repair Scheduling participation gateways because "
+            "scheduling_participants is missing"
+        )
+
+    columns = {
+        item["name"]: item
+        for item in inspector.get_columns("scheduling_participants")
+    }
+    existing = columns.get("participation_gateway")
+    if existing is not None:
+        _require_compatible_column(existing)
+        return
+
+    op.add_column(
+        "scheduling_participants",
+        sa.Column("participation_gateway", sa.String(length=40), nullable=True),
+    )
+
+
+def downgrade() -> None:
+    # ad7e3c9b2f10 already owns this column in the canonical schema.  The repair
+    # revision must therefore not remove it when returning to that revision.
+    pass