diff --git a/arborist/cli.py b/arborist/cli.py
index fc88114..5882d45 100644
--- a/arborist/cli.py
+++ b/arborist/cli.py
@@ -7774,7 +7774,14 @@ def _session_repl(args: argparse.Namespace, sess) -> int:
     from arborist.qa.client import OpenAICompatibleClient
     client = OpenAICompatibleClient(base_url=endpoint)
 
-    qa_db = Path.home() / ".arborist" / "qa.db"
+    # Honor --shards-dir like other commands (cli line ~550-555). Without
+    # this, session-driven providence_cache writes land in ~/.arborist/
+    # qa.db while the viz reads <shards-dir>/qa.db — session cache_keys
+    # never surface in the Merkle Command Center.
+    if getattr(args, "global_shards_dir", None):
+        qa_db = Path(args.global_shards_dir) / "qa.db"
+    else:
+        qa_db = Path.home() / ".arborist" / "qa.db"
     qa_db.parent.mkdir(parents=True, exist_ok=True)
 
     policy = {"answer_mode": args.answer_mode}