fix(responses): invalidate changed options safely

src/govoplan_poll/backend/service.py

@@ -732,6 +732,44 @@ def _lock_poll_for_response(session: Session, *, tenant_id: str, poll_id: str) -
     return poll
 
 
+def get_poll_response_for_respondents(
+    session: Session,
+    *,
+    tenant_id: str,
+    poll_id: str,
+    respondent_ids: tuple[str, ...],
+    invitation_id: str | None = None,
+) -> PollResponse | None:
+    """Resolve a response from server-trusted respondent identities."""
+
+    get_poll(session, tenant_id=tenant_id, poll_id=poll_id)
+    ids = tuple(dict.fromkeys(value for value in respondent_ids if value))
+    if ids:
+        response = (
+            session.query(PollResponse)
+            .filter(
+                PollResponse.tenant_id == tenant_id,
+                PollResponse.poll_id == poll_id,
+                PollResponse.respondent_id.in_(ids),
+                PollResponse.deleted_at.is_(None),
+            )
+            .order_by(PollResponse.submitted_at.desc(), PollResponse.id.desc())
+            .first()
+        )
+        if response is not None:
+            return response
+    if invitation_id is None:
+        return None
+    return next(
+        (
+            response
+            for response in reversed(list_poll_responses(session, tenant_id=tenant_id, poll_id=poll_id))
+            if (response.metadata_ or {}).get("invitation_id") == invitation_id
+        ),
+        None,
+    )
+
+
 def update_poll_option(
     session: Session,
     *,
@@ -793,6 +831,8 @@ def update_poll_option(
         .with_for_update()
         .all()
     )
+    if responses and not poll.allow_response_update:
+        raise PollError("Poll options cannot be edited after responses when response updates are disabled")
     option.label = label
     option.description = description
     option.value = normalized_value
@@ -805,6 +845,8 @@ def update_poll_option(
         ]
         if retained_answers != (response.answers or []):
             response.answers = retained_answers
+            if not retained_answers:
+                response.deleted_at = _now()
     session.flush()
     return option