Add case_precedents: attached legal support for the compose phase

New self-contained table + MCP tools + FastAPI endpoints for letting
the chair attach external case-law quotes (quote + citation מראה מקום,
optional chair note, optional archived PDF) to either a specific
threshold_claim / issue or the case as a whole.

Data model
  - case_precedents (SCHEMA_V5_SQL) — case_id, section_id NULL/
    "threshold_N"/"issue_N", quote, citation (free-text), chair_note,
    pdf_document_id FK to documents, denormalized practice_area for
    cross-case library filtering.
  - Deliberately NOT linked to the existing case_law table — that one
    has UNIQUE(case_number) which would force parsing the free-text
    citation into a structured key. A backfill pass into case_law is
    a later follow-up once the UI stabilizes.
  - db.py gains 4 helpers: create_case_precedent, list_case_precedents,
    delete_case_precedent, search_precedent_library. The last uses
    DISTINCT ON (citation) for the cross-case typeahead so each
    precedent appears once even if reused across many cases.

MCP tools (legal_mcp/tools/precedents.py)
  - precedent_attach, precedent_list, precedent_remove,
    precedent_search_library — registered in server.py.

FastAPI (web/app.py)
  - POST /api/cases/{n}/precedents — create, with PrecedentCreateRequest
  - POST /api/cases/{n}/precedents/upload-pdf — one-shot PDF upload to
    a dedicated documents/precedents/ subdirectory, creates a
    documents row with doc_type="precedent_archive" and no text
    extraction (archive only)
  - GET /api/cases/{n}/precedents — list
  - DELETE /api/precedents/{id} — uses path param since precedent_id
    is a UUID (slash-safe, unlike case numbers)
  - GET /api/precedents/search?q=...&practice_area=... — library
    typeahead

Block-writer integration into _build_precedents_context is a deferred
follow-up — Phase 1 surfaces the feature in the compose UI only.

Plan: ~/.claude/plans/woolly-cooking-graham.md

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

web/app.py

@@ -29,7 +29,7 @@ import asyncpg
 
 from legal_mcp import config
 from legal_mcp.services import chunker, db, embeddings, extractor, processor, proofreader, research_md
-from legal_mcp.tools import cases as cases_tools, search as search_tools, workflow as workflow_tools, drafting as drafting_tools
+from legal_mcp.tools import cases as cases_tools, search as search_tools, workflow as workflow_tools, drafting as drafting_tools, precedents as precedents_tools
 
 # Import integration clients (same directory)
 _web_dir = Path(__file__).resolve().parent
@@ -1643,6 +1643,120 @@ async def api_research_chair_position(case_number: str, req: ChairPositionReques
         raise HTTPException(500, f"שגיאה בשמירה: {e}")
 
 
+# ── Precedents API — attached case-law quotes for the compose phase ──
+
+
+class PrecedentCreateRequest(BaseModel):
+    quote: str
+    citation: str
+    section_id: str = ""            # empty = case-level / general discussion
+    chair_note: str = ""
+    pdf_document_id: str = ""       # UUID string, empty = no PDF
+
+
+@app.post("/api/cases/{case_number}/precedents")
+async def api_precedent_attach(case_number: str, req: PrecedentCreateRequest):
+    """Attach a legal precedent (quote + citation) to a case, optionally
+    scoped to a specific threshold_claim / issue section. Cross-case
+    library reuse happens at the search endpoint — this one always
+    inserts a new row."""
+    if req.section_id and not re.match(r"^(threshold|issue)_\d+$", req.section_id):
+        raise HTTPException(400, "section_id לא תקין")
+    if not req.quote.strip() or not req.citation.strip():
+        raise HTTPException(400, "quote ו-citation חובה")
+
+    result = await precedents_tools.precedent_attach(
+        case_number=case_number,
+        quote=req.quote,
+        citation=req.citation,
+        section_id=req.section_id,
+        chair_note=req.chair_note,
+        pdf_document_id=req.pdf_document_id,
+    )
+    data = json.loads(result)
+    if data.get("error"):
+        raise HTTPException(404, data["error"])
+    return data
+
+
+@app.post("/api/cases/{case_number}/precedents/upload-pdf")
+async def api_precedent_upload_pdf(
+    case_number: str,
+    file: UploadFile = File(...),
+):
+    """One-shot PDF upload for a precedent attachment. Stores the file
+    on disk alongside other case documents and creates a `documents`
+    row with doc_type='precedent_archive'. Returns {document_id} so the
+    frontend can pass it into POST /precedents. No SSE / background
+    processing — archive only, no text extraction."""
+    case = await db.get_case_by_number(case_number)
+    if not case:
+        raise HTTPException(404, f"תיק {case_number} לא נמצא")
+
+    if not file.filename:
+        raise HTTPException(400, "No filename provided")
+
+    ext = Path(file.filename).suffix.lower()
+    if ext not in {".pdf", ".docx", ".doc"}:
+        raise HTTPException(400, f"סוג קובץ לא נתמך לפסיקה: {ext}")
+
+    content = await file.read()
+    if len(content) > MAX_FILE_SIZE:
+        raise HTTPException(400, f"קובץ גדול מדי. מקסימום: {MAX_FILE_SIZE // (1024*1024)}MB")
+
+    # Save under a dedicated precedents/ subdirectory so they don't mix
+    # with extracted originals.
+    case_dir = config.find_case_dir(case_number) / "documents" / "precedents"
+    case_dir.mkdir(parents=True, exist_ok=True)
+    safe_name = re.sub(r"[^\w\u0590-\u05FF\s.\-()]", "", Path(file.filename).stem).strip()
+    dest = case_dir / f"{safe_name or 'precedent'}{ext}"
+    counter = 1
+    while dest.exists():
+        dest = case_dir / f"{safe_name or 'precedent'}-{counter}{ext}"
+        counter += 1
+    dest.write_bytes(content)
+
+    case_id = UUID(case["id"])
+    doc = await db.create_document(
+        case_id=case_id,
+        doc_type="precedent_archive",
+        title=safe_name or "precedent",
+        file_path=str(dest),
+    )
+    return {"document_id": doc["id"], "filename": dest.name}
+
+
+@app.get("/api/cases/{case_number}/precedents")
+async def api_precedent_list(case_number: str):
+    """List all precedents attached to a case, grouped client-side by section_id."""
+    result = await precedents_tools.precedent_list(case_number)
+    data = json.loads(result)
+    if isinstance(data, dict) and data.get("error"):
+        raise HTTPException(404, data["error"])
+    return data
+
+
+@app.delete("/api/precedents/{precedent_id}")
+async def api_precedent_delete(precedent_id: str):
+    """Delete a precedent attachment. The archived PDF (if any) stays
+    in the documents table — orphaned references nullify via FK
+    ON DELETE SET NULL — so we keep the audit trail of the file."""
+    result = await precedents_tools.precedent_remove(precedent_id)
+    data = json.loads(result)
+    if data.get("error"):
+        raise HTTPException(400, data["error"])
+    if not data.get("deleted"):
+        raise HTTPException(404, "לא נמצא")
+    return data
+
+
+@app.get("/api/precedents/search")
+async def api_precedent_search(q: str, practice_area: str = "", limit: int = 10):
+    """Cross-case library typeahead. Returns one row per distinct citation."""
+    result = await precedents_tools.precedent_search_library(q, practice_area, limit)
+    return json.loads(result)
+
+
 # ── Exports API — drafts, versions, download, upload, mark-final ──