Fix: save_block_content now writes draft file + writer must update status

Two issues that caused QA agent to fail:
1. save_block_content saved to DB only — now also rebuilds drafts/decision.md
2. legal-writer.md now has explicit mandatory step: case_update(status="drafted")

Without these, workflow_status reports has_draft=false and QA can't run.

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

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

@@ -685,7 +685,10 @@ async def get_block_context(case_id: UUID, block_id: str, instructions: str = ""
 
 
 async def save_block_content(case_id: UUID, block_id: str, content: str) -> dict:
-    """Save block content written by Claude Code (or any external writer)."""
+    """Save block content written by Claude Code (or any external writer).
+
+    Saves to DB and also writes/updates the draft file on disk.
+    """
     if block_id not in BLOCK_CONFIG:
         raise ValueError(f"Unknown block: {block_id}")
 
@@ -699,9 +702,37 @@ async def save_block_content(case_id: UUID, block_id: str, content: str) -> dict
     result["model_used"] = "claude-code"
 
     await store_block(UUID(decision["id"]), result)
+
+    # Also write/update the draft file on disk
+    await _update_draft_file(case_id, UUID(decision["id"]))
+
     return result
 
 
+async def _update_draft_file(case_id: UUID, decision_id: UUID) -> None:
+    """Rebuild drafts/decision.md from all blocks in DB."""
+    from pathlib import Path
+
+    case = await db.get_case(case_id)
+    if not case:
+        return
+
+    case_dir = config.find_case_dir(case["case_number"])
+    draft_dir = case_dir / "drafts"
+    draft_dir.mkdir(parents=True, exist_ok=True)
+
+    pool = await db.get_pool()
+    async with pool.acquire() as conn:
+        rows = await conn.fetch(
+            "SELECT content FROM decision_blocks WHERE decision_id = $1 AND content != '' ORDER BY block_index",
+            decision_id,
+        )
+
+    draft_path = draft_dir / "decision.md"
+    draft_path.write_text("\n\n".join(row["content"] for row in rows if row["content"]), encoding="utf-8")
+    logger.info("Draft file updated: %s (%d blocks)", draft_path, len(rows))
+
+
 # ── Renumbering ───────────────────────────────────────────────────
 
 async def renumber_all_blocks(decision_id: UUID) -> dict: