feat(seance): predecessor by-case לצריכת-סוכן דרך ה-plugin (#220 המשך)

מוסיף get_predecessor_for_case(case_number) — האח case-scoped של
get_predecessor_context (by-issue). סוכנים חושבים ב-case_number (לא issue-UUID),
לכן זהו הנתיב שכלי-ה-plugin legal_predecessor_context (PR נפרד ב-plugin-legal-ai)
יקרא. מחזיר מסקנות (summary) של ריצות-heartbeat שהסתיימו על-פני issues של התיק,
newest-first, עם summary בלבד (ריצות cancelled ריקות מסוננות).

- shaper משותף _shape_predecessor_run (G2 — נתיב-shaping יחיד ל-by-issue+by-case).
- join בטוח i.id::text = payload->>'issueId' (לא cast של payload חופשי ל-uuid).
- Port pc_get_predecessor_for_case (read-only); endpoint
  GET /api/operations/cases/{case_number}/predecessor.
- 2 בדיקות (shaping+identifier, case-לא-נמצא). אומת חי: 1043-02-26/8125-09-24
  מחזירים מסקנות-דיספוזיציה אמיתיות.

Invariants: G12 (fetch מהמעטפת, המגע מהשער; הכלי יחיה ב-plugin=מעטפת מוצהרת, לא
ב-mcp-server), G2 (shaper יחיד). המשך: PR ב-plugin-legal-ai (כלי) + הוראת-HEARTBEAT.

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

web/tests/test_agent_health.py

@@ -198,3 +198,54 @@ def test_get_recent_escalations_defaults_severity_when_untagged(monkeypatch):
     (item,) = asyncio.run(pc.get_recent_escalations())["items"]
     assert item["severity"] == "medium"  # fallback
     assert item["created_at"] is None
+
+
+# ── predecessor by case (#220 agent-facing) — resolve project then shape runs ──
+class _ProjectRunsConn:
+    def __init__(self, project, runs):
+        self._project, self._runs = project, runs
+
+    async def fetchrow(self, query, *args):
+        return self._project
+
+    async def fetch(self, query, *args):
+        return self._runs
+
+    async def close(self):
+        pass
+
+
+def test_get_predecessor_for_case_shapes_runs(monkeypatch):
+    from datetime import datetime
+
+    runs = [
+        {
+            "id": "run-1", "status": "succeeded",
+            "started_at": datetime(2026, 7, 5, 10, 0, 0),
+            "finished_at": datetime(2026, 7, 5, 10, 5, 0),
+            "summary": "הלולאה נסגרה כראוי", "error_code": None,
+            "session_id_after": "sess-9", "agent_name": "עוזר משפטי",
+            "identifier": "CMP-141",
+        },
+    ]
+
+    async def _connect(_url):
+        return _ProjectRunsConn({"id": "proj-1"}, runs)
+
+    monkeypatch.setattr(pc.asyncpg, "connect", _connect)
+    result = asyncio.run(pc.get_predecessor_for_case("1043-02-26"))
+    assert result["ok"] is True and result["case_number"] == "1043-02-26"
+    (run,) = result["runs"]
+    assert run["run_id"] == "run-1"
+    assert run["identifier"] == "CMP-141"  # by-case adds which issue
+    assert run["started_at"] == "2026-07-05T10:00:00"
+    assert "הלולאה" in run["summary"]
+
+
+def test_get_predecessor_for_case_unknown_case_is_empty(monkeypatch):
+    async def _connect(_url):
+        return _ProjectRunsConn(None, [])  # no project row
+
+    monkeypatch.setattr(pc.asyncpg, "connect", _connect)
+    result = asyncio.run(pc.get_predecessor_for_case("9999-99-99"))
+    assert result == {"ok": True, "case_number": "9999-99-99", "runs": []}