feat(precedents): citation_formatted דטרמיניסטי בקוד — Gemini מחלץ רכיבים, לא מעצב (#145)

הבעיה (#145): מחלץ-המטא ביקש מ-Gemini Flash *לעצב* את מראה-המקום המלא
(citation_formatted). ב-JSON-mode חופשי (ללא responseSchema) המודל החזיר JSON
תקין ומלא אך **השמיט בעקביות** דווקא את השדה הזה — אומת על 8070-05-25,
1194-12-25, 1200-12-25 (וגם כשהצדדים זוהו). השדה הקשה ביותר (עיצוב מחרוזת) +
היתר-בפרומפט להשאיר ריק → Flash מפיל אותו.

הפתרון: citation_formatted הוא **שדה-תצוגה נגזר** (X1 §3 / INV-ID2) — מורכב
דטרמיניסטית מרכיבים מובְנים, לא מעוצב ע"י LLM. תפקיד ה-LLM מצטמצם לחילוץ
רכיבים אמינים (שורת-הצדדים, קידומת-ההליך לפסקי-בית-משפט).

- db.format_precedent_citation(record) — מרכיב לפי כללי-הציטוט-האחיד:
  ועדת-ערר (מחוזית/ארצית/בל"מ) מ-proceeding_type+district+source_kind;
  פסקי-בית-משפט מ-court_prefix(LLM)+district-abbrev. מוציא docket נקי
  מ-case_number מזוהם ("עע\"מ 683/13"→"683/13"). נמנע ('') כשחסר רכיב
  (צדדים/docket/תאריך/קידומת) — abstention על המצאה (INV-AH).
- case_law.parties (V39) — שורת "עורר נ' משיב" כבסיס re-derivable.
- מחלץ-המטא: הפרומפט מחלץ parties+citation_prefix (לא citation_formatted);
  apply_to_record מרכיב דטרמיניסטית מהרשומה-האפקטיבית וממלא רק שדה ריק
  (עריכות-יו"ר נשמרות).
- scripts/backfill_precedent_citations.py — backfill 2-מעברים (דטרמיניסטי→LLM),
  מדווח שורות-נמנעות, idempotent.

אומת: 3 הרשומות הידניות משוחזרות תו-בתו; פסק עליון אמיתי מולא end-to-end
(עע"מ 683/13 ... נבו 3.9.2015). test_fu2b_reconcile ✓.

Invariants: INV-ID2/X1§3 (ציטוט=תצוגה נגזר, לא מפתח) · INV-AH (abstention,
אפס המצאה) · G1 (docket נקי) · G2 (מסלול-יחיד — מחליף את נתיב-ה-LLM, לא מקביל).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

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

@@ -1560,6 +1560,18 @@ CREATE INDEX IF NOT EXISTS idx_plans_meta_tsv ON plans USING gin(meta_tsv);
 """
 
 
+# ── V39: case_law.parties ──────────────────────────────────────────
+# The "עורר נ' משיב" line, extracted from the caption as a structured component.
+# It is the re-derivable BASIS for the deterministic citation_formatted
+# (format_precedent_citation) — the LLM extracts the party line (a reliable caption
+# read) instead of formatting the whole Markdown citation, which it dropped outright
+# (#145). citation_formatted stays a DERIVED display field (X1 §3 / INV-ID2); this
+# column is its irreducible bold component.
+SCHEMA_V39_SQL = """
+ALTER TABLE case_law ADD COLUMN IF NOT EXISTS parties TEXT DEFAULT '';
+"""
+
+
 # Stable, arbitrary key for the session-level advisory lock that serialises
 # schema DDL across processes. Every short-lived process (cron drains, services)
 # re-runs the idempotent migrations on startup; without this lock two processes
@@ -1620,6 +1632,7 @@ async def _apply_schema_ddl(conn: asyncpg.Connection) -> None:
         await conn.execute(SCHEMA_V36_SQL)
         await conn.execute(SCHEMA_V37_SQL)
         await conn.execute(SCHEMA_V38_SQL)
+        await conn.execute(SCHEMA_V39_SQL)
 
 
 async def init_schema() -> None:
@@ -3502,6 +3515,88 @@ def format_plan_citation(plan: dict) -> str:
     return sentence
 
 
+# Clean court docket inside a possibly citation-shaped case_number
+# ("עע\"מ 683/13" → "683/13"). Legacy court-ruling rows stored the full citation
+# in the identity field (X1 §4 known violation); pull the docket out so the
+# assembled citation never doubles the prefix.
+_CITATION_DOCKET_RE = re.compile(r"\d{1,6}(?:[-/]\d{1,4}){1,2}")
+
+# District → administrative-court abbreviation as it appears in citations
+# (`עת"מ (י-ם) 1234/56 ...`). Empty/unknown → the abbrev parenthetical is omitted
+# rather than guessed.
+_DISTRICT_COURT_ABBREV = {
+    "ירושלים": "י-ם",
+    "תל אביב": 'ת"א',
+    "מרכז": "מרכז",
+    "חיפה": "חי'",
+    "צפון": "נצ'",
+    "דרום": 'ב"ש',
+}
+
+
+def _citation_docket(case_number: str) -> str:
+    s = (case_number or "").strip()
+    if not s:
+        return ""
+    m = _CITATION_DOCKET_RE.search(s)
+    return m.group(0) if m else s
+
+
+def format_precedent_citation(
+    record: dict, *, parties: str | None = None, court_prefix: str = "",
+) -> str:
+    """Deterministically render a precedent's unified-rules citation (מראה מקום).
+
+    DERIVED display field (X1 §3 / INV-ID2) assembled from stored components — NEVER
+    formatted by an LLM, which proved to drop the field outright (#145). The LLM's job
+    shrinks to extracting reliable COMPONENTS (the ``parties`` line and, for court
+    rulings, the caption ``court_prefix``); the formatted string is built here.
+
+      • ועדת-ערר family — prefix from ``proceeding_type`` ('ערר'/'בל"מ'), forum from
+        ``district``, national level → 'ערר ארצי'. Reporter: our own decisions
+        (``source_kind='internal_committee'``) are unpublished → date only; external /
+        Nevo rows → 'נבו '.
+      • court rulings (עליון/מנהלי) — prefix from the caption (``court_prefix``, e.g.
+        'ע"א'/'עת"מ'/'ת"א'); admin-court district abbrev when known; reporter 'נבו '.
+
+    Abstains (returns '') when an essential component is missing — parties, docket, date,
+    or an indeterminate court prefix — never inventing one (INV-AH).
+    """
+    parties = (parties if parties is not None else (record.get("parties") or "")).strip()
+    docket = _citation_docket(record.get("case_number") or "")
+    d = _coerce_plan_date(record.get("date"))
+    if not (parties and docket and d):
+        return ""
+    date_str = f"{d.day}.{d.month}.{d.year}"
+
+    level = (record.get("precedent_level") or "").strip()
+    source_type = (record.get("source_type") or "").strip()
+    is_committee = level.startswith("ועדת_ערר") or source_type == "appeals_committee"
+
+    if is_committee:
+        reporter = "" if record.get("source_kind") == "internal_committee" else "נבו "
+        if level == "ועדת_ערר_ארצית":
+            head = f"ערר ארצי {docket}"
+        else:
+            prefix = 'בל"מ' if (record.get("proceeding_type") or "").strip() == 'בל"מ' else "ערר"
+            district = (record.get("district") or "").strip()
+            if not district:
+                return ""
+            head = f"{prefix} (ועדות ערר - מחוז {district}) {docket}"
+    else:
+        prefix = (court_prefix or "").strip()
+        if not prefix:
+            return ""  # court-ruling prefix is not derivable from structured fields
+        reporter = "נבו "
+        if level == "מנהלי":
+            abbrev = _DISTRICT_COURT_ABBREV.get((record.get("district") or "").strip(), "")
+            head = f"{prefix} ({abbrev}) {docket}" if abbrev else f"{prefix} {docket}"
+        else:
+            head = f"{prefix} {docket}"
+
+    return f"{head} **{parties}** ({reporter}{date_str})"
+
+
 def _plan_row_to_dict(row) -> dict | None:
     if row is None:
         return None
@@ -4248,7 +4343,7 @@ async def update_case_law(case_law_id: UUID, **fields) -> dict | None:
         "case_number", "case_name", "court", "date", "practice_area", "appeal_subtype",
         "subject_tags", "summary", "headnote", "nevo_ratio", "key_quote", "source_url",
         "source_type", "precedent_level", "is_binding", "district", "chair_name",
-        "proceeding_type", "citation_formatted",
+        "proceeding_type", "citation_formatted", "parties",
     }
     updates = {k: v for k, v in fields.items() if k in allowed}
     if not updates: