workspace: show backend error details

.yoi/tickets/00001KXDHAWEF/item.md

@@ -1,8 +1,8 @@
 ---
 title: 'Show backend operation error details'
-state: 'inprogress'
+state: 'done'
 created_at: '2026-07-13T10:45:59Z'
-updated_at: '2026-07-13T10:46:30Z'
+updated_at: '2026-07-13T10:51:20Z'
 assignee: null
 queued_by: 'yoi ticket'
 queued_at: '2026-07-13T10:46:30Z'

.yoi/tickets/00001KXDHAWEF/thread.md

@@ -39,4 +39,31 @@ Ticket を `yoi ticket` が queued にしました。
 State changed to `inprogress`.
 
 
+---
+
+<!-- event: implementation_report author: hare at: 2026-07-13T10:51:20Z -->
+
+## Implementation report
+
+Changed workspace-server backend operation error reporting to preserve backend messages instead of replacing them with the fixed `backend-private details were omitted` text.
+
+- `sanitize_backend_error` now returns the original message.
+- Updated the existing test to assert backend operation details are preserved.
+
+Validation:
+- `cargo fmt --check`
+- `git diff --check`
+- `cargo test -q -p yoi-workspace-server`
+- `nix build .#yoi --no-link`
+
+
+---
+
+<!-- event: state_changed author: "yoi ticket" at: 2026-07-13T10:51:20Z from: inprogress to: done reason: cli_state field: state -->
+
+## State changed
+
+State changed to `done`.
+
+
 ---