fix(node): an added root is served before it is scanned

Adding a large directory to a running group made the reload await the
scan of the new root before putting the new RootSet in the group's
context, holding _reload_lock the whole time. For the hours a large drive
takes to hash, the node served the old set:

- a file request under the new root got None from entry_abs_path and the
  handler died on None.exists() without replying;
- a writable/removable toggle answered with the live table, still the
  old one, so the directory vanished from the operator's settings;
- reconcile saw every file the scan had not reached as a missed event and
  hashed it again on the same executor, rewriting progress under the scan.

retarget now applies the set, the roots table and the watcher first, and
with wait=False scans the added roots in the background; the daemon swaps
ctx["roots"] before calling it. A scan lock shared by the initial scan,
added-root scans and reconcile makes the reconcile loop sit out a running
scan without backing off. Every transport site that resolves an entry
answers ROOT_NOT_SERVED instead of crashing, and a delete keeps the entry.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01T6jPTeocXA1BePekdsgPya

1 files changed, 8 insertions, 1 deletions

diff --git a/packages/meshbay-node/src/meshbay_node/daemon.py b/packages/meshbay-node/src/meshbay_node/daemon.py
index 518f221..c9c362a 100644
--- a/packages/meshbay-node/src/meshbay_node/daemon.py
+++ b/packages/meshbay-node/src/meshbay_node/daemon.py
@@ -805,8 +805,15 @@ class NodeDaemon:
                 continue
             log.info("Group %r roots changed: %s", group_cfg.name,
                      ", ".join(f"{r.name}={r.path}" for r in roots))
-            await indexer.retarget(roots)
+            # The new set is what the node serves from this moment, and the
+            # scan of an added root is not waited for. Awaiting it here held
+            # `_reload_lock` and the old set for as long as the scan ran —
+            # hours for a large drive — so every file request under the new
+            # root found no root to resolve against, and any op answering with
+            # the live table (a writable/removable toggle) showed the directory
+            # gone from the operator's settings.
             ctx["roots"] = roots
+            await indexer.retarget(roots, wait=False)
             changed += 1
 
         # ── Hot-load new groups ──────────────────────────────────────────