diff --git a/.yoi/tickets/00001KXDWAXTS/item.md b/.yoi/tickets/00001KXDWAXTS/item.md
index 78206adc..26b4c2f2 100644
--- a/.yoi/tickets/00001KXDWAXTS/item.md
+++ b/.yoi/tickets/00001KXDWAXTS/item.md
@@ -1,8 +1,8 @@
 ---
 title: 'Stop Worker before cleanup deletion'
-state: 'inprogress'
+state: 'done'
 created_at: '2026-07-13T13:58:15Z'
-updated_at: '2026-07-13T13:58:54Z'
+updated_at: '2026-07-13T14:05:35Z'
 assignee: null
 queued_by: 'yoi ticket'
 queued_at: '2026-07-13T13:58:54Z'
diff --git a/.yoi/tickets/00001KXDWAXTS/thread.md b/.yoi/tickets/00001KXDWAXTS/thread.md
index 82d4dc9e..05b460f9 100644
--- a/.yoi/tickets/00001KXDWAXTS/thread.md
+++ b/.yoi/tickets/00001KXDWAXTS/thread.md
@@ -39,4 +39,45 @@ Ticket を `yoi ticket` が queued にしました。
 State changed to `inprogress`.
 
 
+---
+
+<!-- event: implementation_report author: hare at: 2026-07-13T14:05:35Z -->
+
+## Implementation report
+
+Changed Worker cleanup execution to stop the selected Worker before Runtime deletion.
+
+Root cause:
+- Runtime `delete_worker` rejects active Workers with `worker <id> is running and must be stopped before deletion`.
+- The cleanup plan can present a Worker as cleanup-eligible when the browser-facing projected state is not `running` (for example execution rejected/unconnected) while Runtime status is still active.
+- Cleanup execution previously called Runtime delete directly, causing `workspace_cleanup_worker_runtime_delete_rejected`.
+
+Changes:
+- `cleanup_runtime_worker_for_execution` now calls `stop_worker` first with a cleanup reason.
+- If stop is rejected, the cleanup fails with `workspace_cleanup_worker_runtime_stop_rejected` and preserves Runtime diagnostics.
+- Only after accepted stop does cleanup call Runtime delete and then delete the Backend registry row.
+- Unknown-worker during stop/delete remains idempotent for stale Backend registry cleanup.
+
+Manual observation:
+- Direct Runtime DELETE for worker 1 returned HTTP 400: `worker 1 is running and must be stopped before deletion`.
+- Direct Runtime stop followed by delete succeeded, confirming the required operation sequence.
+
+Validation:
+- `cargo fmt --check`
+- `git diff --check`
+- `cargo check -q`
+- `cargo test -q -p yoi-workspace-server`
+- targeted cleanup execution test
+- `nix build .#yoi --no-link`
+
+
+---
+
+<!-- event: state_changed author: "yoi ticket" at: 2026-07-13T14:05:35Z from: inprogress to: done reason: cli_state field: state -->
+
+## State changed
+
+State changed to `done`.
+
+
 ---
diff --git a/crates/workspace-server/src/server.rs b/crates/workspace-server/src/server.rs
index 1c767bd9..dbfd0a12 100644
--- a/crates/workspace-server/src/server.rs
+++ b/crates/workspace-server/src/server.rs
@@ -2024,6 +2024,28 @@ fn cleanup_runtime_worker_for_execution(
     runtime_id: &str,
     candidate: &CleanupWorkerCandidate,
 ) -> ApiResult<()> {
+    match api.runtime.stop_worker(
+        runtime_id,
+        candidate.runtime_worker_id.as_str(),
+        WorkerLifecycleRequest {
+            reason: Some("cleanup worker before deletion".to_string()),
+        },
+    ) {
+        Ok(result) if result.state == WorkerOperationState::Accepted => {}
+        Ok(result) => {
+            return Err(ApiError::with_diagnostics(
+                Error::RuntimeOperationFailed {
+                    runtime_id: runtime_id.to_string(),
+                    code: "workspace_cleanup_worker_runtime_stop_rejected".to_string(),
+                    message: "Runtime did not stop selected Worker before deletion".to_string(),
+                },
+                result.diagnostics,
+            ));
+        }
+        Err(RuntimeRegistryError::UnknownWorker { .. }) => return Ok(()),
+        Err(error) => return Err(error.into_error().into()),
+    }
+
     match api
         .runtime
         .delete_worker(runtime_id, candidate.runtime_worker_id.as_str())
@@ -2033,7 +2055,7 @@ fn cleanup_runtime_worker_for_execution(
             Error::RuntimeOperationFailed {
                 runtime_id: runtime_id.to_string(),
                 code: "workspace_cleanup_worker_runtime_delete_rejected".to_string(),
-                message: "Runtime did not delete selected Worker".to_string(),
+                message: "Runtime did not delete selected Worker after stopping it".to_string(),
             },
             result.diagnostics,
         )),