BE-PR-008: add Proposal Accept tracking fields (source_proposal_id, source_essential_id)

- Add source_proposal_id and source_essential_id FK columns to Task model
- Populate tracking fields during Proposal Accept task generation
- Add generated_tasks relationship on Proposal model for reverse lookup
- Expose source_proposal_id/source_essential_id in TaskResponse schema
- Add GeneratedTaskBrief schema and include generated_tasks in ProposalDetailResponse
- Proposal detail endpoint now returns generated story tasks with status

app/api/routers/proposals.py

@@ -63,6 +63,26 @@ def _serialize_proposal(db: Session, proposal: Proposal, *, include_essentials:
             .all()
         )
         result["essentials"] = [_serialize_essential(e) for e in essentials]
+
+        # BE-PR-008: include tasks generated from this Proposal via Accept
+        gen_tasks = (
+            db.query(Task)
+            .filter(Task.source_proposal_id == proposal.id)
+            .order_by(Task.id.asc())
+            .all()
+        )
+        result["generated_tasks"] = [
+            {
+                "task_id": t.id,
+                "task_code": t.task_code,
+                "task_type": t.task_type or "story",
+                "task_subtype": t.task_subtype,
+                "title": t.title,
+                "status": t.status.value if hasattr(t.status, "value") else t.status,
+                "source_essential_id": t.source_essential_id,
+            }
+            for t in gen_tasks
+        ]
     return result
 
 
@@ -327,6 +347,9 @@ def accept_proposal(
             reporter_id=proposal.created_by_id or current_user.id,
             created_by_id=proposal.created_by_id or current_user.id,
             task_code=task_code,
+            # BE-PR-008: track which Proposal/Essential generated this task
+            source_proposal_id=proposal.id,
+            source_essential_id=essential.id,
         )
         db.add(task)
         db.flush()  # materialise task.id

app/models/proposal.py

@@ -78,6 +78,14 @@ class Proposal(Base):
         lazy="select",
     )
 
+    # BE-PR-008: reverse lookup — story tasks generated from this Proposal
+    generated_tasks = relationship(
+        "Task",
+        foreign_keys="Task.source_proposal_id",
+        lazy="select",
+        viewonly=True,
+    )
+
     # ---- convenience alias ------------------------------------------------
     @hybrid_property
     def proposal_code(self) -> str | None:

app/models/task.py

@@ -37,6 +37,17 @@ class Task(Base):
     assignee_id = Column(Integer, ForeignKey("users.id"), nullable=True)
     created_by_id = Column(Integer, ForeignKey("users.id"), nullable=True)
     
+    # Proposal Accept tracking (BE-PR-008)
+    # When a task is generated from Proposal Accept, these record the source.
+    source_proposal_id = Column(
+        Integer, ForeignKey("proposes.id"), nullable=True,
+        comment="Proposal that generated this task via accept (NULL if manually created)",
+    )
+    source_essential_id = Column(
+        Integer, ForeignKey("essentials.id"), nullable=True,
+        comment="Essential that generated this task via accept (NULL if manually created)",
+    )
+
     # Tags (comma-separated)
     tags = Column(String(500), nullable=True)
     

app/schemas/schemas.py

@@ -93,6 +93,9 @@ class TaskResponse(TaskBase):
     resolution_summary: Optional[str] = None
     positions: Optional[str] = None
     pending_matters: Optional[str] = None
+    # BE-PR-008: Proposal Accept tracking
+    source_proposal_id: Optional[int] = None
+    source_essential_id: Optional[int] = None
     created_at: datetime
     updated_at: Optional[datetime] = None
     
@@ -344,10 +347,22 @@ class EssentialResponse(EssentialBase):
         from_attributes = True
 
 
+class GeneratedTaskBrief(BaseModel):
+    """Brief info about a story task generated from Proposal Accept."""
+    task_id: int
+    task_code: Optional[str] = None
+    task_type: str
+    task_subtype: Optional[str] = None
+    title: str
+    status: Optional[str] = None
+    source_essential_id: Optional[int] = None
+
+
 class ProposalDetailResponse(ProposalResponse):
-    """Extended Proposal response that embeds its Essential list."""
+    """Extended Proposal response that embeds its Essential list and generated tasks."""
 
     essentials: List[EssentialResponse] = []
+    generated_tasks: List[GeneratedTaskBrief] = []
 
     class Config:
         from_attributes = True