feat: Stage A finalizers + #35/#36/#37 — critical-gap closure

Four parallel sub-agents closed the remaining critical gaps from the
26/05 Stage A/B sprint. Each block independently tested; aggregated here.

## #30/#31 finalizers (sub-agent A)
* Auto-derive practice_area in case_create from case_number prefix
  (1xxx→rishuy_uvniya, 8xxx→betterment_levy, 9xxx→compensation_197);
  default for CaseCreateRequest is now "" (the DB constraint catches
  any stray "appeals_committee").
* practice_area.py: derive_subtype now handles axis-B domain values
  (rishuy_uvniya/betterment_levy/compensation_197) without parsing the
  case number; new helper derive_domain_practice_area().
* Halacha re-extraction verified unnecessary — all 6 reclassified
  records already had is_binding=false and approved halachot.
* Regression tests: 6 cases in tests/test_corpus_constraints.py
  covering practice_area enum, internal-committee chair/district,
  external-upload arar prefix, MCP guard.
* UI: district input → Select dropdown (7 districts) in
  precedent-edit-sheet.tsx, preserving legacy free-text values.

## #37 בל"מ subtypes (sub-agent B)
* 3 new appeal_subtypes: extension_request_{building_permit,
  betterment_levy,compensation}. APPEALS_COMMITTEE_SUBTYPES extended,
  SUBTYPES_BY_AREA mappings added.
* New helpers: is_blam_subject(), is_blam_subtype(),
  derive_subtype_with_blam(case_number, subject, practice_area).
  case_create now uses it to auto-detect "בקשה להארכת מועד" subjects.
* 3 methodology templates under docs/methodology/extension-request-*.md.
* paperclip_client.py mapping updated for the 3 new subtypes
  (extension_request_building_permit→CMP, the other two→CMPA).
* Frontend: bilingual "בל"מ" badge + filter dropdown on cases list +
  detail header; appeal-type-bars collapseBlam() merges בל"מ into its
  parent domain for aggregate bars.
* Wizard auto-detects בל"מ from subject during case creation.
* 3 Berlinger cases (1017/1018/1019-03-26) migrated to
  appeal_subtype=extension_request_building_permit via psql.

## #35 missing_precedents feature (sub-agent C)
* Schema V13: missing_precedents table (citation, case_id, party,
  legal_topic, status, linked_case_law_id, claim_quote, ...) +
  FK constraints + 3 indexes. Applied via psql + idempotent migration.
* 6 db.py service functions, 3 MCP tools, 6 FastAPI endpoints
  (POST/GET/PATCH/DELETE/upload — upload routes by citation prefix
  to ingest_internal_decision or ingest_precedent).
* Next.js page /missing-precedents with 5 status tabs + filters +
  sidebar badge counter + detail drawer with metadata edit + smart
  upload form that switches fields per committee/court.
* Bootstrap: 7 rows imported from the JSON file
  (3 citations × cases, all status=closed with linked_case_law_id).
* legal-researcher.md: new §2ב.5 with missing_precedent_create
  usage + dedup semantics + tool grant.

## #36 legal_arguments aggregation (sub-agent D)
* Schema V14: legal_arguments + legal_argument_propositions M:M.
  Applied via psql.
* New service argument_aggregator.py with two functions —
  aggregate_claims_to_arguments() (Claude CLI / claude_session) and
  get_legal_arguments(). Graceful llm_unavailable handling when CLI
  is missing (containers).
* 2 MCP tools + 2 API endpoints (POST .../aggregate-arguments as
  BackgroundTask, GET .../legal-arguments).
* Frontend: shadcn Accordion + new legal-arguments-panel.tsx with
  hierarchical (party → priority badge → arguments) display, "טיעונים"
  tab on the case page, "חשב/חשב מחדש" buttons.
* scripts/backfill_legal_arguments.py + SCRIPTS.md entry — dry-run
  found 8 candidate cases including 1017/1018/1019.

## Open follow-ups (intentionally deferred)
* npm run api:types in web-ui (CLAUDE.md flow) — recommended before
  the next UI commit; not required for backend deployment.
* Run backfill_legal_arguments.py --apply once the container picks up
  the new aggregator service.
* webhook on missing-precedents upload-close to Paperclip (optional).

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

web-ui/src/lib/practice-area.ts

@@ -18,6 +18,10 @@ export type AppealSubtype =
   | "building_permit"
   | "betterment_levy"
   | "compensation_197"
+  /* בל"מ — בקשה להארכת מועד להגשת ערר. שלושה מסלולים נפרדים. */
+  | "extension_request_building_permit"
+  | "extension_request_betterment_levy"
+  | "extension_request_compensation"
   | "unknown";
 
 export const PRACTICE_AREAS: ReadonlyArray<{
@@ -34,12 +38,26 @@ export const APPEAL_SUBTYPES: ReadonlyArray<{
   value: AppealSubtype;
   label: string;
 }> = [
-  { value: "building_permit",  label: "רישוי ובנייה"      },
-  { value: "betterment_levy",  label: "היטל השבחה"        },
-  { value: "compensation_197", label: "פיצויים (ס' 197)"  },
-  { value: "unknown",          label: "לא ידוע"           },
+  { value: "building_permit",                  label: "רישוי ובנייה"       },
+  { value: "betterment_levy",                  label: "היטל השבחה"         },
+  { value: "compensation_197",                 label: "פיצויים (ס' 197)"   },
+  { value: "extension_request_building_permit", label: "בל\"מ — רישוי"      },
+  { value: "extension_request_betterment_levy", label: "בל\"מ — היטל השבחה" },
+  { value: "extension_request_compensation",    label: "בל\"מ — פיצויים"    },
+  { value: "unknown",                          label: "לא ידוע"            },
 ];
 
+/* בל"מ subtypes — תת-קבוצה. שימוש: badges, filters */
+export const BLAM_SUBTYPES: ReadonlySet<AppealSubtype> = new Set([
+  "extension_request_building_permit",
+  "extension_request_betterment_levy",
+  "extension_request_compensation",
+]);
+
+export function isBlamSubtype(s?: AppealSubtype | null): boolean {
+  return s != null && BLAM_SUBTYPES.has(s);
+}
+
 export const PRACTICE_AREA_LABELS: Record<PracticeArea, string> =
   Object.fromEntries(PRACTICE_AREAS.map((p) => [p.value, p.label])) as Record<
     PracticeArea,
@@ -70,3 +88,30 @@ export function deriveSubtype(
   if (first === "9") return "compensation_197";
   return "unknown";
 }
+
+/*
+ * Detect a בל"מ subject (בקשה להארכת מועד). Mirrors the Python
+ * `is_blam_subject` in practice_area.py. Accepts common variants.
+ */
+const BLAM_SUBJECT_RE = /(?:בקשה\s+להארכת\s+מועד|בל["״]מ|הארכת\s+מועד\s+להגשת)/i;
+
+export function isBlamSubject(subject: string): boolean {
+  return Boolean(subject) && BLAM_SUBJECT_RE.test(subject);
+}
+
+/*
+ * Like deriveSubtype() but also detects בל"מ from the subject. Mirrors
+ * `derive_subtype_with_blam()` in practice_area.py.
+ */
+export function deriveSubtypeWithBlam(
+  caseNumber: string,
+  subject: string = "",
+  practiceArea: PracticeArea = "appeals_committee",
+): AppealSubtype {
+  const base = deriveSubtype(caseNumber, practiceArea);
+  if (!isBlamSubject(subject)) return base;
+  if (base === "building_permit")  return "extension_request_building_permit";
+  if (base === "betterment_levy")  return "extension_request_betterment_levy";
+  if (base === "compensation_197") return "extension_request_compensation";
+  return base;
+}