refactor

src/usecase/purchase/get_placement.py

@@ -0,0 +1,35 @@
+import logging
+from typing import TYPE_CHECKING
+
+from src import domain, dto
+
+from .create_placements import _build_placement_output
+
+if TYPE_CHECKING:
+    from .. import Usecase
+
+log = logging.getLogger(__name__)
+
+
+async def get_placement_user(self: 'Usecase', input: dto.GetPlacementInput) -> dto.PlacementOutput:
+    """Get single placement by ID (user-managed)"""
+    context = await self.ensure_workspace_permission(
+        input.workspace_id, input.user_id, domain.PermissionKey.PLACEMENTS_READ
+    )
+
+    project = await self.database.get_project(input.workspace_id, project_id=input.project_id)
+    if not project:
+        raise domain.ProjectNotFound(input.project_id)
+
+    context.ensure_project_permission(domain.PermissionKey.PLACEMENTS_READ, project.id)
+
+    placement = await self.database.get_placement(input.workspace_id, input.placement_id)
+    if not placement or placement.project_id != project.id:
+        raise domain.PlacementNotFound(input.placement_id)
+
+    # Prefetch channel for output building
+    if placement.channel is None:
+        channel = await self.database.get_channel(channel_id=placement.channel_id)
+        placement.channel = channel
+
+    return _build_placement_output(placement)