CUST-WP-0055 T06: workplan-first curate decision scope

Dual-write workplan_id and legacy workstream_id on State Hub decisions;
add --workplan-id CLI flag. Archive grandfather notes (T07).

session_memory/curate/decisions.py

@@ -28,15 +28,16 @@ def _now() -> str:
 
 
 def build_decision(candidate: dict, action: str, rationale: str,
-                   *, workstream_id: Optional[str] = None,
+                   *, workplan_id: Optional[str] = None,
+                   workstream_id: Optional[str] = None,
                    decided_by: str = "curator") -> dict:
     """Shape a curate decision as a State Hub ``record_decision`` payload."""
     key = candidate["key"]
     verb = "Promote" if action == "approve" else "Reject"
-    return {
+    scope_id = workplan_id or workstream_id
+    payload = {
         "title": f"{verb} pattern candidate {key}",
         "decision_type": "made",
-        "workstream_id": workstream_id,
         "rationale": rationale,
         "decided_by": decided_by,
         "description": json.dumps({
@@ -46,6 +47,10 @@ def build_decision(candidate: dict, action: str, rationale: str,
         }, sort_keys=True),
         "recorded_at": _now(),
     }
+    if scope_id:
+        payload["workplan_id"] = scope_id
+        payload["workstream_id"] = scope_id
+    return payload
 
 
 @dataclass
@@ -54,14 +59,21 @@ class DecisionRecorder:
 
     queue_path: str
     sink: Optional[Sink] = None
+    workplan_id: Optional[str] = None
     workstream_id: Optional[str] = None
     decided_by: str = "curator"
     _queued: int = field(default=0, init=False)
 
     def record(self, candidate: dict, action: str, rationale: str) -> bool:
         """Record one decision. Returns True if the sink accepted it, else queued."""
-        payload = build_decision(candidate, action, rationale,
-                                 workstream_id=self.workstream_id, decided_by=self.decided_by)
+        payload = build_decision(
+            candidate,
+            action,
+            rationale,
+            workplan_id=self.workplan_id,
+            workstream_id=self.workstream_id,
+            decided_by=self.decided_by,
+        )
         if self.sink is not None:
             try:
                 self.sink(payload)