feat(halachot): Phase 5 — canonical panel UI + instances accordion (V41)

UI changes to halacha-review-panel.tsx:
- instance_type badge (עיקרון מקורי / ציטוט / יישום) in meta row
- "מוזכר ב-N פסיקות" pill when instance_count > 1
- CanonicalSection component: canonical_statement (view + edit), instances accordion

Backend:
- list_halachot SQL: adds canonical_id, instance_type, canonical_statement,
  instance_count via LEFT JOIN canonical_halachot
- list_canonical_instances(canonical_id) → compact rows for accordion
- GET /api/canonical-halachot/{canonical_id}/instances endpoint
- PATCH /api/halachot/{id}: canonical_statement propagates to canonical_halachot
- HalachaUpdateRequest: canonical_statement field
- useCanonicalInstances hook + CanonicalInstance type in precedent-library.ts

INV-G10 (chair gate): only the chair can edit canonical_statement (same
flow as rule_statement — PATCH /api/halachot/{id} with reviewer="דפנה").
G2: canonical data flows through canonical_halachot, not a parallel store.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

mcp-server/src/legal_mcp/services/db.py

@@ -5494,12 +5494,15 @@ async def list_halachot(
                h.cites, h.confidence, h.quote_verified, h.quality_flags,
                h.review_status,
                h.reviewer, h.reviewed_at, h.created_at, h.updated_at,
+               h.canonical_id, h.instance_type,
+               ch.canonical_statement, ch.instance_count,
                cl.case_number, cl.case_name, cl.court, cl.date AS decision_date,
                cl.precedent_level,
                COALESCE(cor.corroboration_count, 0)::int AS corroboration_count,
                COALESCE(cor.corroboration_negative, false) AS corroboration_negative,
                pr.verdict AS panel_verdict
         FROM halachot h
+        LEFT JOIN canonical_halachot ch ON ch.id = h.canonical_id
         LEFT JOIN case_law cl ON cl.id = h.case_law_id
         LEFT JOIN (
             SELECT halacha_id,
@@ -6144,6 +6147,21 @@ async def update_canonical_statement(
     return result.split()[-1] != "0"
 
 
+async def list_canonical_instances(canonical_id: "UUID") -> list[dict]:
+    """List all halachot (instances) sharing a canonical_id — used by the UI accordion."""
+    pool = await get_pool()
+    rows = await pool.fetch(
+        """SELECT h.id, h.instance_type, h.confidence, h.rule_statement,
+                  cl.case_number, cl.case_name
+           FROM halachot h
+           LEFT JOIN case_law cl ON cl.id = h.case_law_id
+           WHERE h.canonical_id = $1
+           ORDER BY h.instance_type, cl.case_number""",
+        canonical_id,
+    )
+    return [dict(r) for r in rows]
+
+
 async def _annotate_equivalents(pool, out: list[dict]) -> None:
     """Attach an `equivalents` list to each row (#84.2) — parallel-authority links.
 

web-ui/src/components/precedents/halacha-review-panel.tsx

@@ -11,7 +11,8 @@ import { CorroborationBadge } from "./corroboration-badge";
 import { practiceAreaLabel } from "./practice-area";
 import {
   useHalachotPending, useHalachotByStatus, useUpdateHalacha, useBatchReviewHalachot,
-  useLibraryStats, isExtractionFixItem, type Halacha,
+  useLibraryStats, isExtractionFixItem, useCanonicalInstances,
+  type Halacha, type CanonicalInstance,
 } from "@/lib/api/precedent-library";
 import { AuthorityBadge, ruleTypeLabel } from "./halacha-meta";
 
@@ -135,6 +136,131 @@ function PanelDeliberation({ round }: { round: NonNullable<Halacha["panel_round"
   );
 }
 
+// ─── V41: Canonical section (principle statement + instances accordion) ──────
+
+const INSTANCE_TYPE_LABELS: Record<string, string> = {
+  original: "עיקרון מקורי",
+  citation: "ציטוט",
+  application: "יישום",
+};
+const INSTANCE_TYPE_CLS: Record<string, string> = {
+  original: "bg-navy text-parchment",
+  citation: "bg-info text-white",
+  application: "bg-ink-muted text-white",
+};
+
+function CanonicalSection({
+  h, onSaveCanonical,
+}: {
+  h: Halacha;
+  onSaveCanonical: (stmt: string) => Promise<void>;
+}) {
+  const [editingCanon, setEditingCanon] = useState(false);
+  const [canonDraft, setCanonDraft] = useState(h.canonical_statement ?? "");
+  const [showInstances, setShowInstances] = useState(false);
+  const { data: instances, isLoading: instLoading } = useCanonicalInstances(
+    showInstances ? h.canonical_id : null,
+  );
+
+  useEffect(() => {
+    // eslint-disable-next-line react-hooks/set-state-in-effect
+    setCanonDraft(h.canonical_statement ?? "");
+  }, [h.canonical_id, h.canonical_statement]);
+
+  const handleSave = async () => {
+    await onSaveCanonical(canonDraft);
+    setEditingCanon(false);
+  };
+
+  const instanceCount = h.instance_count ?? 1;
+
+  return (
+    <div className="rounded-lg border border-[#d4cdef] bg-[#f0ecfb] p-3 space-y-2">
+      <div className="flex items-center gap-2 flex-wrap">
+        <span className="w-4 h-4 rounded-sm bg-[#6d5fa6] text-white text-[0.6rem] font-bold flex items-center justify-center flex-shrink-0">כ</span>
+        <span className="text-[0.7rem] font-bold text-[#6d5fa6]">ניסוח קנוני — העיקרון הרחב (V41)</span>
+        <span className="text-[0.65rem] text-[#9089b8] ms-auto">
+          {instanceCount > 1 ? `מאחד ${instanceCount} פסיקות` : "instance יחיד"}
+          {h.review_status && ` · ${h.review_status}`}
+        </span>
+      </div>
+
+      {editingCanon ? (
+        <>
+          <Textarea
+            value={canonDraft}
+            onChange={(e) => setCanonDraft(e.target.value)}
+            rows={3}
+            dir="rtl"
+            className="bg-white/85 border-[#6d5fa6]/50 text-[0.82rem]"
+          />
+          <div className="flex items-center gap-2 justify-end">
+            <button
+              type="button"
+              onClick={() => setEditingCanon(false)}
+              className="text-[0.72rem] text-ink-muted hover:text-navy"
+            >
+              ביטול
+            </button>
+            <button
+              type="button"
+              onClick={handleSave}
+              className="rounded-md bg-[#6d5fa6] text-white text-[0.72rem] font-semibold px-3 py-1"
+            >
+              שמור ניסוח קנוני
+            </button>
+          </div>
+        </>
+      ) : (
+        <div className="flex items-start gap-2">
+          <p className="text-[0.82rem] text-ink font-medium leading-relaxed flex-1 bg-white/65 rounded px-2 py-1.5 border border-[#d4cdef]" dir="rtl">
+            {h.canonical_statement || <span className="text-ink-muted italic">— pending synthesis —</span>}
+          </p>
+          <button
+            type="button"
+            onClick={() => setEditingCanon(true)}
+            className="text-[0.65rem] text-[#6d5fa6] hover:underline flex-shrink-0 mt-1"
+          >
+            ערוך
+          </button>
+        </div>
+      )}
+
+      {instanceCount > 1 && (
+        <div className="rounded-md border border-[#d4cdef] overflow-hidden">
+          <button
+            type="button"
+            onClick={() => setShowInstances((v) => !v)}
+            className="w-full flex items-center gap-2 px-3 py-2 text-[0.7rem] text-[#6d5fa6] font-medium hover:bg-[#e9e4f8] transition-colors"
+            aria-expanded={showInstances}
+          >
+            {showInstances ? <ChevronDown className="w-3 h-3" /> : <ChevronLeft className="w-3 h-3" />}
+            <span>אינסטנסים — {instanceCount} פסיקות שמאזכרות עיקרון זה</span>
+          </button>
+          {showInstances && (
+            <div className="bg-white p-2 space-y-1">
+              {instLoading && <p className="text-[0.7rem] text-ink-muted px-2">טוען...</p>}
+              {instances?.map((inst: CanonicalInstance) => (
+                <div key={inst.id}
+                  className="flex items-center gap-2 rounded px-2 py-1.5 border border-rule-soft text-[0.72rem]">
+                  <span className="font-semibold text-navy min-w-[80px]">{inst.case_number}</span>
+                  <span className="text-ink-soft flex-1 truncate">{inst.case_name}</span>
+                  <Badge className={`text-[0.6rem] font-bold border-0 rounded-full px-2 ${INSTANCE_TYPE_CLS[inst.instance_type] ?? "bg-rule text-ink"}`}>
+                    {INSTANCE_TYPE_LABELS[inst.instance_type] ?? inst.instance_type}
+                  </Badge>
+                  {inst.confidence > 0 && (
+                    <span className="text-ink-muted tabular-nums">{inst.confidence.toFixed(2)}</span>
+                  )}
+                </div>
+              ))}
+            </div>
+          )}
+        </div>
+      )}
+    </div>
+  );
+}
+
 // ─── Pending-queue card (full interactions) ───────────────────────────────────
 
 function HalachaCard({
@@ -195,6 +321,18 @@ function HalachaCard({
         <Badge className="rounded bg-gold text-white border-0 text-[0.62rem] font-bold tracking-wide">
           הלכה
         </Badge>
+        {/* V41: instance_type badge */}
+        {h.instance_type && (
+          <Badge className={`rounded border-0 text-[0.62rem] font-bold ${INSTANCE_TYPE_CLS[h.instance_type] ?? "bg-rule text-ink"}`}>
+            {INSTANCE_TYPE_LABELS[h.instance_type] ?? h.instance_type}
+          </Badge>
+        )}
+        {/* V41: instance count pill */}
+        {(h.instance_count ?? 0) > 1 && (
+          <Badge variant="outline" className="text-[0.62rem] border-[#d4cdef] text-[#6d5fa6] bg-[#f0ecfb]">
+            מוזכר ב-{h.instance_count} פסיקות
+          </Badge>
+        )}
         {h.page_reference && (
           <span className="text-[0.7rem]">{h.page_reference}</span>
         )}
@@ -372,6 +510,16 @@ function HalachaCard({
         </div>
       )}
 
+      {/* V41: canonical statement + instances accordion */}
+      {h.canonical_id && (
+        <CanonicalSection
+          h={h}
+          onSaveCanonical={async (stmt) => {
+            await onSave({ canonical_statement: stmt } as Parameters<typeof onSave>[0]);
+          }}
+        />
+      )}
+
       <div className="flex items-center gap-2 justify-end pt-1 border-t border-rule-soft">
         {editing ? (
           <>

web-ui/src/lib/api/precedent-library.ts

@@ -126,6 +126,11 @@ export type Halacha = {
       reason: string;
     }[];
   };
+  /* V41 — canonical halachot model: one principle, many instances. */
+  canonical_id?: string | null;
+  instance_type?: "original" | "citation" | "application" | null;
+  canonical_statement?: string | null;
+  instance_count?: number | null;
 };
 
 export type RelatedCase = {
@@ -671,8 +676,31 @@ export type HalachaPatch = Partial<{
   // #133 — editing the quote re-verifies it against the source server-side and
   // clears/sets the quote_unverified flag (extraction repair).
   supporting_quote: string;
+  // V41 — propagated to canonical_halachot.canonical_statement
+  canonical_statement: string;
 }>;
 
+export type CanonicalInstance = {
+  id: string;
+  instance_type: "original" | "citation" | "application";
+  confidence: number;
+  rule_statement: string;
+  case_number: string;
+  case_name: string;
+};
+
+export function useCanonicalInstances(canonical_id: string | null | undefined) {
+  return useQuery({
+    queryKey: ["canonical-instances", canonical_id],
+    queryFn: () =>
+      apiRequest<{ instances: CanonicalInstance[] }>(
+        `/api/canonical-halachot/${encodeURIComponent(canonical_id!)}/instances`,
+      ).then((r) => r.instances),
+    enabled: !!canonical_id,
+    staleTime: 60_000,
+  });
+}
+
 export function useUpdateHalacha() {
   const qc = useQueryClient();
   return useMutation({

web/app.py

@@ -6025,6 +6025,7 @@ class HalachaUpdateRequest(BaseModel):
     subject_tags: list[str] | None = None
     practice_areas: list[str] | None = None
     supporting_quote: str | None = None  # #133 — edited quote → re-verify + sync flag
+    canonical_statement: str | None = None  # V41 — updates canonical_halachot.canonical_statement
 
 
 class HalachaBatchReviewRequest(BaseModel):
@@ -7414,6 +7415,18 @@ async def halacha_equivalents_unlink(halacha_id: str, other_id: str):
     return {"ok": await db.unlink_equivalent_halachot(hid, oid)}
 
 
+# ── Canonical halachot — V41 ─────────────────────────────────────────────────
+
+@app.get("/api/canonical-halachot/{canonical_id}/instances")
+async def canonical_halacha_instances(canonical_id: str):
+    """All halachot instances sharing a canonical_id (V41 — used by the UI accordion)."""
+    try:
+        cid = UUID(canonical_id)
+    except ValueError:
+        raise HTTPException(400, "canonical_id לא תקין")
+    return {"instances": await db.list_canonical_instances(cid)}
+
+
 # ── Gold-set tagging (#81.7 / #81.8) ─────────────────────────────────────────
 
 class GoldsetSampleRequest(BaseModel):
@@ -7490,6 +7503,16 @@ async def halacha_update(halacha_id: str, req: HalachaUpdateRequest):
     )
     if not row:
         raise HTTPException(404, "הלכה לא נמצאה")
+    if req.canonical_statement is not None:
+        # V41: propagate to canonical_halachot; canonical_id not in RETURNING
+        # so we fetch it separately (one cheap indexed lookup).
+        _pool = await db.get_pool()
+        canon_id = await _pool.fetchval(
+            "SELECT canonical_id FROM halachot WHERE id=$1", hid
+        )
+        if canon_id:
+            from uuid import UUID as _UUID
+            await db.update_canonical_statement(_UUID(str(canon_id)), req.canonical_statement)
     return row