fix: await optional file database saves

test/e2e-obsidian/README.md

@@ -256,6 +256,8 @@ This proves in real Obsidian the plug-in behaviour shared by supported platforms
 
 The workflow also opens the Customisation Sync dialogue. `--case=visibility` checks that **Hide not applicable items** hides an identical snippet, preserves a different snippet and its source selector, and restores the identical snippet when cleared. `--case=mtime` gives the multi-file plug-in fixture modern millisecond timestamps and requires an older remote copy to remain labelled **Older** and unselected by **Select All Shiny**. With no case argument, both checks run before the existing apply, update, and deletion workflow.
 
+`test:e2e:obsidian:optional-file-save-completion` exercises Hidden File Sync and both Customisation Sync formats in one isolated real Obsidian Vault. It holds a local database write to verify that its event stays in the snapshot and that flush waits for the write, then checks unchanged notifications, subsequent edits, and repeated deletions. Injected save failures remain pending and must replay successfully before the next start reaches readiness. This local scenario disables replication and requires no remote service. It is outside `test:e2e:obsidian:local-suite`.
+
 `test:e2e:obsidian:received-change-readiness` uses two sequential real Obsidian sessions and isolated CouchDB databases. The source creates ordinary notes and their Chunks; the target starts continuous replication, resets readiness through the public lifecycle service, and receives those documents while its Vault files remain absent. Marking the target ready twice must emit one readiness event and reflect the queued content. A second note remains absent after readiness while database reflecting is explicitly suspended, then appears when that setting is resumed. This focused scenario is outside `test:e2e:obsidian:local-suite`.
 
 `test:e2e:obsidian:remote-feature-change` starts real Obsidian with continuous CouchDB replication, then changes the remote version document from generation 12 to generation 13 with an unknown feature. It waits for the control document to reach the local database and the active Replicator to retire, checks that another replication is refused, and verifies that an already accepted Vault note remains intact. After restarting the same Vault, the current remote declaration still blocks finite replication and the actual continuous connection attempt. No KV feature history is involved. It is a focused test outside `test:e2e:obsidian:local-suite`; recovery with a future compatible client remains a separate validation boundary.