Improved workplan dependency management facilities

api/routers/workstream_dependencies.py

@@ -5,6 +5,7 @@ from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from api.database import get_session
+from api.models.task import Task
 from api.models.workstream import Workstream
 from api.models.workstream_dependency import WorkstreamDependency
 from api.schemas.workstream_dependency import WorkstreamDependencyCreate, WorkstreamDependencyRead
@@ -22,17 +23,27 @@ async def create_dependency(
     body: WorkstreamDependencyCreate,
     session: AsyncSession = Depends(get_session),
 ) -> WorkstreamDependency:
-    """Record that workstream_id depends on body.to_workstream_id."""
+    """Record that workstream_id depends on another workstream or a task."""
     if await session.get(Workstream, workstream_id) is None:
         raise HTTPException(status_code=404, detail="from workstream not found")
-    if await session.get(Workstream, body.to_workstream_id) is None:
-        raise HTTPException(status_code=404, detail="to workstream not found")
+
+    has_workstream_target = body.to_workstream_id is not None
+    has_task_target = body.to_task_id is not None
+    if has_workstream_target == has_task_target:
+        raise HTTPException(status_code=422, detail="provide exactly one dependency target")
+
+    if body.to_workstream_id and await session.get(Workstream, body.to_workstream_id) is None:
+        raise HTTPException(status_code=404, detail="target workstream not found")
+    if body.to_task_id and await session.get(Task, body.to_task_id) is None:
+        raise HTTPException(status_code=404, detail="target task not found")
     if workstream_id == body.to_workstream_id:
         raise HTTPException(status_code=422, detail="a workstream cannot depend on itself")
 
     dep = WorkstreamDependency(
         from_workstream_id=workstream_id,
         to_workstream_id=body.to_workstream_id,
+        to_task_id=body.to_task_id,
+        relationship_type=body.relationship_type,
         description=body.description,
     )
     session.add(dep)