fix(retrieval): scope search_decisions by domain — derive from case, block only on undeterminable case (GAP-12, INV-RET1)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

mcp-server/tests/test_search_domain_scope.py

@@ -0,0 +1,144 @@
+"""Domain-scope tests for search_decisions (GAP-12 / INV-RET1).
+
+Policy under test (see CLAUDE.md + tools/search.py):
+  1. explicit practice_area  -> used as-is, search runs;
+  2. case_number + case.practice_area set       -> use case value, runs;
+  3. case_number + empty case.practice_area but derivable prefix (8xxx)
+                                                  -> derive domain, runs;
+  4. case_number present but UNDETERMINABLE (case.practice_area empty AND
+     prefix not 1/8/9)        -> BLOCK (return Hebrew error, hybrid search
+                                  NEVER called);
+  5. no case_number, no practice_area            -> warn + proceed (runs).
+
+All DB / embedding / hybrid-search / telemetry calls are monkeypatched so
+the test runs fully offline with no live Postgres or model.
+"""
+
+from __future__ import annotations
+
+import asyncio
+import json
+from uuid import uuid4
+
+import pytest
+
+from legal_mcp.services import db, embeddings, hybrid_search, telemetry
+from legal_mcp.tools import search as search_tool
+
+
+def _run(coro):
+    return asyncio.run(coro)
+
+
+@pytest.fixture()
+def patched(monkeypatch: pytest.MonkeyPatch) -> dict:
+    """Patch all I/O boundaries. Record what hybrid_search received.
+
+    ``calls["hybrid"]`` is appended to ONLY when the real search runs, so
+    asserting ``calls["hybrid"] == []`` proves the search was blocked.
+    """
+    calls: dict = {"hybrid": [], "cases": {}}
+
+    async def _embed_query(query: str):
+        return [0.0] * 8
+
+    async def _search_documents_hybrid(**kwargs):
+        calls["hybrid"].append(kwargs)
+        # one synthetic hit so the formatting path is exercised
+        return [
+            {
+                "score": 0.9,
+                "case_number": "X",
+                "document_title": "doc",
+                "section_type": "facts",
+                "page_number": 1,
+                "content": "hit",
+                "match_type": "text",
+                "image_thumbnail_path": None,
+            }
+        ]
+
+    async def _get_case_by_number(case_number: str):
+        return calls["cases"].get(case_number)
+
+    def _log_search_bg(**kwargs):
+        return None
+
+    monkeypatch.setattr(embeddings, "embed_query", _embed_query)
+    monkeypatch.setattr(
+        hybrid_search, "search_documents_hybrid", _search_documents_hybrid
+    )
+    monkeypatch.setattr(db, "get_case_by_number", _get_case_by_number)
+    monkeypatch.setattr(telemetry, "log_search_bg", _log_search_bg)
+    return calls
+
+
+def test_explicit_practice_area_used(patched: dict) -> None:
+    out = _run(
+        search_tool.search_decisions(
+            query="זכויות בנייה", practice_area="betterment_levy"
+        )
+    )
+    assert len(patched["hybrid"]) == 1
+    assert patched["hybrid"][0]["practice_area"] == "betterment_levy"
+    # explicit value must not trigger a case lookup
+    assert patched["cases"] == {}
+    # ran -> JSON result, not an error string
+    assert json.loads(out)[0]["content"] == "hit"
+
+
+def test_case_practice_area_used(patched: dict) -> None:
+    patched["cases"]["8126/25"] = {
+        "id": str(uuid4()),
+        "practice_area": "betterment_levy",
+        "appeal_subtype": "betterment_levy",
+    }
+    out = _run(
+        search_tool.search_decisions(query="היטל", case_number="8126/25")
+    )
+    assert len(patched["hybrid"]) == 1
+    assert patched["hybrid"][0]["practice_area"] == "betterment_levy"
+    assert json.loads(out)[0]["content"] == "hit"
+
+
+def test_case_empty_practice_area_derived_from_prefix(patched: dict) -> None:
+    # case row exists but practice_area is empty -> derive from 8xxx prefix
+    patched["cases"]["8126/25"] = {
+        "id": str(uuid4()),
+        "practice_area": "",
+        "appeal_subtype": "",
+    }
+    out = _run(
+        search_tool.search_decisions(query="היטל", case_number="8126/25")
+    )
+    assert len(patched["hybrid"]) == 1
+    assert patched["hybrid"][0]["practice_area"] == "betterment_levy"
+    assert json.loads(out)[0]["content"] == "hit"
+
+
+def test_case_undeterminable_is_blocked(patched: dict) -> None:
+    # case exists, empty practice_area, and prefix is NOT 1/8/9 -> block
+    patched["cases"]["7777/25"] = {
+        "id": str(uuid4()),
+        "practice_area": "",
+        "appeal_subtype": "",
+    }
+    out = _run(
+        search_tool.search_decisions(query="משהו", case_number="7777/25")
+    )
+    # hybrid search must NOT have been called
+    assert patched["hybrid"] == []
+    # returns a Hebrew error string, not JSON
+    assert out.startswith("שגיאה")
+    assert "7777/25" in out
+    with pytest.raises(json.JSONDecodeError):
+        json.loads(out)
+
+
+def test_no_case_no_practice_area_proceeds(patched: dict) -> None:
+    # exploratory / chat search: cross-domain, must NOT be blocked
+    out = _run(search_tool.search_decisions(query="חיפוש חופשי"))
+    assert len(patched["hybrid"]) == 1
+    assert patched["hybrid"][0]["practice_area"] is None
+    assert patched["cases"] == {}
+    assert json.loads(out)[0]["content"] == "hit"