CUST-WP-0074-T02: task wait qualifiers in the hub read model

Adds tasks.decision_id and workplan_dependencies.from_task_id (migration
e8f9a0b1c2d3). A from_task_id column is needed rather than
from_workplan_id plus description: the partial unique indexes key on
(from_workplan_id, target, relationship_type), so two tasks in one
workplan waiting on the same target could not both be indexed, and the
derived wait_kind needs per-task attribution. The two existing unique
indexes are narrowed to frontmatter edges (from_task_id IS NULL) and two
task-origin counterparts are added; downgrade deletes task-origin rows
before restoring the old indexes.

POST /workplans/{id}/dependencies/ accepts from_task_id (must belong to
the from workplan; a task cannot depend on itself). TaskCreate/Update/Read
carry decision_id.

Derived read-model fields, no new write routes (rule 5):
- TaskRead.wait_kind: external | human | both | unqualified, null unless
  status is wait (dependency rows from this task / needs_human).
- WorkplanRead.blocked_kind: human | external | none, null unless status
  is blocked. Human wins over external.
Both come from api/services/wait_kind.py, applied on GET /tasks/,
GET /tasks/{id}, GET /workplans/ and GET /workplans/{id}.

The identifier-migration reference-count proof now includes from_task_id
(FK count guard 22 -> 23).

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

Assistant: claude-code
Assistant-Model: sonnet
Assistant-Process: 237582@bnt-lap001
Assistant-Session: f2b3d9f1-8fb9-4b9c-bc2b-837ec5dfc826

api/routers/tasks.py

@@ -20,6 +20,7 @@ from api.schemas.task import (
 )
 from api.services.legacy_compat import meter_legacy_body_from_model, meter_legacy_query_param
 from api.services.lifecycle import status_value, transition_task_status
+from api.services.wait_kind import annotate_tasks
 from api.task_status import normalize_task_status
 
 router = APIRouter(prefix="/tasks", tags=["tasks"])
@@ -69,7 +70,7 @@ async def list_tasks(
     if limit is not None:
         q = q.limit(limit)
     result = await session.execute(q)
-    return list(result.scalars().all())
+    return list(await annotate_tasks(session, list(result.scalars().all())))
 
 
 @router.get("/counts", response_model=list[TaskCountRead])
@@ -248,6 +249,7 @@ async def get_task(
     task = await session.get(Task, task_id)
     if task is None:
         raise HTTPException(status_code=404, detail="Task not found")
+    await annotate_tasks(session, [task])
     return task
 
 

api/routers/workstream_dependencies.py

@@ -36,9 +36,16 @@ async def _create_dependency(
         raise HTTPException(status_code=404, detail="target task not found")
     if workplan_id == body.to_workplan_id:
         raise HTTPException(status_code=422, detail="a workplan cannot depend on itself")
+    if body.from_task_id is not None:
+        from_task = await session.get(Task, body.from_task_id)
+        if from_task is None or from_task.workplan_id != workplan_id:
+            raise HTTPException(status_code=404, detail="from task not found in this workplan")
+        if body.from_task_id == body.to_task_id:
+            raise HTTPException(status_code=422, detail="a task cannot depend on itself")
 
     dep = WorkplanDependency(
         from_workplan_id=workplan_id,
+        from_task_id=body.from_task_id,
         to_workplan_id=body.to_workplan_id,
         to_task_id=body.to_task_id,
         relationship_type=body.relationship_type,

api/routers/workstreams.py

@@ -24,6 +24,7 @@ from api.schemas.workplan import (
 )
 from api.services.lifecycle import transition_workplan_status
 from api.services.legacy_compat import retire_legacy_route
+from api.services.wait_kind import annotate_workplans
 from api.work_record_flavor import (
     RESIDUAL_FLAVOR,
     WORK_RECORD_FLAVORS,
@@ -389,7 +390,7 @@ async def list_workplans(
     include_residuals: bool = Query(True),
     session: AsyncSession = Depends(get_session),
 ) -> list[Workplan]:
-    return await _list_workplans(
+    workplans = await _list_workplans(
         topic_id=topic_id,
         repo_id=repo_id,
         repo_goal_id=repo_goal_id,
@@ -400,6 +401,7 @@ async def list_workplans(
         include_residuals=include_residuals,
         session=session,
     )
+    return list(await annotate_workplans(session, workplans))
 
 
 @router.get("/workplan-index", status_code=status.HTTP_410_GONE)
@@ -499,7 +501,9 @@ async def get_workplan(
     workplan_id: uuid.UUID,
     session: AsyncSession = Depends(get_session),
 ) -> Workplan:
-    return await _get_workplan(workplan_id=workplan_id, session=session)
+    wp = await _get_workplan(workplan_id=workplan_id, session=session)
+    await annotate_workplans(session, [wp])
+    return wp
 
 
 @router.patch("/{workstream_id}", status_code=status.HTTP_410_GONE)