fix(scheduling): reject stale invitation actions

src/govoplan_scheduling/backend/service.py

@@ -2866,6 +2866,19 @@ def _participant_for_invitation_action(
     return participant
 
 
+def _require_current_invitation_participant_revision(
+    participant: SchedulingParticipant,
+    *,
+    participant_revision: str,
+) -> None:
+    """Reject a stale invitation command while the participant row is locked."""
+
+    if participant_revision != scheduling_participant_revision(participant):
+        raise SchedulingConflictError(
+            "Scheduling participant invitation changed; reload and try again"
+        )
+
+
 def _new_public_invitation_expiry(
     request: SchedulingRequest,
 ) -> datetime | None:
@@ -2904,6 +2917,7 @@ def issue_scheduling_participant_invitation(
     tenant_id: str,
     request_id: str,
     participant_id: str,
+    participant_revision: str,
     action: str,
 ) -> SchedulingInvitationActionResult:
     """Rotate one bearer link for explicit copy or immediate delivery.
@@ -2925,6 +2939,10 @@ def issue_scheduling_participant_invitation(
         request,
         participant_id=participant_id,
     )
+    _require_current_invitation_participant_revision(
+        participant,
+        participant_revision=participant_revision,
+    )
     if request.poll_id is None:
         raise SchedulingError("Scheduling invitation action is unavailable")
     participation_provider = _poll_participation_provider()
@@ -3016,8 +3034,9 @@ def revoke_scheduling_participant_invitation(
     tenant_id: str,
     request_id: str,
     participant_id: str,
+    participant_revision: str,
 ) -> SchedulingInvitationActionResult:
-    """Immediately revoke the current link; exact repeats are safe no-ops."""
+    """Revoke the current link; refreshed no-link projections replay safely."""
 
     request = _lock_scheduling_request(
         session,
@@ -3029,6 +3048,10 @@ def revoke_scheduling_participant_invitation(
         request,
         participant_id=participant_id,
     )
+    _require_current_invitation_participant_revision(
+        participant,
+        participant_revision=participant_revision,
+    )
     invitation_id = participant.poll_invitation_id
     replayed = invitation_id is None
     if invitation_id is not None: