Prevent status regression in case_update

CEO agent was reverting case status from "processing" to "new" when
updating metadata fields. Added ordered status list — case_update now
silently ignores status changes that would move backwards.

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

mcp-server/src/legal_mcp/tools/cases.py

@@ -277,13 +277,27 @@ async def case_update(
     """
     from datetime import date as date_type
 
+    # Ordered workflow statuses — regression protection
+    STATUS_ORDER = [
+        "new", "uploading", "processing", "documents_ready",
+        "analyst_verified", "research_complete", "outcome_set",
+        "brainstorming", "direction_approved", "analysis_enriched", "ready_for_writing",
+        "drafting", "qa_review", "drafted",
+        "exported", "reviewed", "final",
+    ]
+
     case = await db.get_case_by_number(case_number)
     if not case:
         return f"תיק {case_number} לא נמצא."
 
     fields = {}
     if status:
-        fields["status"] = status
+        current = case.get("status", "")
+        cur_idx = STATUS_ORDER.index(current) if current in STATUS_ORDER else -1
+        new_idx = STATUS_ORDER.index(status) if status in STATUS_ORDER else -1
+        # Only update if advancing or status is unknown to the order
+        if new_idx >= cur_idx or new_idx == -1:
+            fields["status"] = status
     if title:
         fields["title"] = title
     if subject: