fix(family): a decision read as precedent says its reason once - to_brief for precedents and idea history; the decision log keeps the full row (#5131)

Each decision stored its reason three times (reason, before.reason, after.reason)
and a promotion carried the whole criteria reasoning in evidence. Precedents
(assess, promote, get_family_adoption, get_family_idea) and get_family_idea's
history now serve FamilyDecision.to_brief(): reason once, before/after as status,
canon_version and platforms, evidence as the cited list. list_family_decisions
and the decision echoed back by a write keep to_dict. The precedent count was
already bounded at five.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/scribe/mcp/tools/family.py

@@ -33,7 +33,8 @@ async def list_family_ideas(
 
 async def get_family_idea(note_id: int) -> dict:
     """One family idea with what an evaluation needs: its state, platforms,
-    full decision history, ledger counts, THE THREE CRITERIA, the `ledger`
+    decision history (brief — each reason once; list_family_decisions has
+    the full rows), ledger counts, THE THREE CRITERIA, the `ledger`
     (every project's answer, with `needs_recheck`), and the `precedents` —
     the decisions on the ideas nearest this one by meaning.
     Read the precedents before deciding, and decide consistently with them

src/scribe/models/family.py

@@ -357,3 +357,37 @@ class FamilyDecision(Base, CreatedAtMixin):
             "user_id": self.user_id,
             "created_at": iso(self.created_at),
         }
+
+    def to_brief(self) -> dict:
+        """The decision as a reader WEIGHING it needs it: what was decided,
+        why — once — and the state it moved between.
+
+        Precedents and an idea's history are read in bulk, a handful per
+        call, and the full row repeats itself: an assessment's reason is
+        stored again inside `after` (and the prior one inside `before`), and
+        a promotion's evidence carries the whole criteria reasoning. So a
+        state here is its status, version and platforms only, and evidence is
+        the cited list alone (#5131). The full row is `to_dict`, which the
+        decision log serves.
+        """
+        return {
+            "id": self.id,
+            "idea_id": self.idea_id,
+            "project_id": self.project_id,
+            "action": self.action,
+            "reason": self.reason,
+            "before": _brief_state(self.before),
+            "after": _brief_state(self.after),
+            "evidence": list((self.evidence or {}).get("evidence") or []),
+            "created_at": iso(self.created_at),
+        }
+
+
+# What a decision's before/after keeps in its brief: the state, not the prose.
+_BRIEF_STATE_KEYS = ("status", "canon_version", "platforms")
+
+
+def _brief_state(state: dict | None) -> dict | None:
+    if state is None:
+        return None
+    return {k: state[k] for k in _BRIEF_STATE_KEYS if k in state}

src/scribe/services/family.py

@@ -211,7 +211,8 @@ async def get_idea(user_id: int, note_id: int) -> dict | None:
             "platforms": await _platform_slugs(session, note_id),
             "topic": await _topic(session, user_id, idea.topic_id, rules=True),
             "adoptions": counts,
-            "decisions": [_decision_dict(d) for d in decisions],
+            # Brief: the history is read in bulk; the full rows are list_decisions (#5131).
+            "decisions": [d.to_brief() for d in decisions],
             "undoable_decision_id": _undoable_id(decisions),
         })
     out["criteria"] = list(CRITERIA)
@@ -383,8 +384,8 @@ async def precedents(user_id: int, note_id: int, limit: int = 5) -> list[dict]:
     for score, n in ranked:
         d = decisions.get(latest.get(n.id))
         if d is not None:
-            item = _decision_dict(d, n.title)
-            item["similarity"] = round(float(score), 3)
+            item = {**d.to_brief(), "idea_title": n.title,
+                    "similarity": round(float(score), 3)}
             out.append(item)
     return out
 

src/scribe/services/family_adoption.py

@@ -545,8 +545,7 @@ async def assessment_precedents(user_id: int, project_id: int, idea_id: int,
     for d, idea_title, project_title in rows:
         if not await access.can_read_project(user_id, d.project_id):
             continue
-        item = d.to_dict()
-        item.update({"idea_title": idea_title, "project_title": project_title})
+        item = {**d.to_brief(), "idea_title": idea_title, "project_title": project_title}
         if d.idea_id == idea_id:
             item["relation"] = "same idea, another project"
             out_same.append(item)