fix(fuse): never adopt a node we trashed as an unanswered create's twin (B162)

A folder removed and made again met the old folder while its trash was on
the wire and adopted it, so the new folder's contents went into the old
one and were trashed with it. The twin search now skips hidden nodes, as
listings do.

The fake Drive can hold a trash (hold_next_trash).

docs/BUGS.md

@@ -12,6 +12,32 @@ Conventions:
 
 ---
 
+## B162 — A folder removed and made again at once loses what goes into it
+
+**Status:** Fixed.
+**Found:** 2026-10-04, by the simulation's slow-link profile (`one_client_on_a_slow_link`,
+seed 4). The client removed folder `z` and made `z` again, with `z/x` and `z/x/y` inside. All
+three stayed in the mount but never reached Drive. The log showed the new `z` "adopting" the old
+one.
+
+**Where:** `Core::adoptable_twin` in `crates/pdfs-fuse/src/drain.rs`.
+
+**Cause.** A create that finds its name taken looks for a node an earlier, unanswered attempt
+of its own made (B127), and adopts it. The old folder's trash was still on the wire, so Drive
+refused the new folder's name, and the listing showed the old folder, not in the tree any more
+and made a moment ago. The new folder took it for its own twin. What went into the new folder
+was created in the old one, and the trash then took it all along.
+
+**Fix.** The twin search skips nodes this mount trashed (its `hidden` set), as listings already
+do. The create then waits for the trash to free the name (`name_is_held`), or takes the name
+at once if the trash has landed (B144).
+
+**Test:** simulation test `a_folder_made_again_while_the_old_one_is_trashed_is_a_new_folder`
+(failed before the fix: Drive ended up empty). The fake Drive can now hold a trash
+(`FakeClient::hold_next_trash`).
+
+---
+
 ## B161 — A file moved while it was being created shows up under its old name
 
 **Status:** Fixed.