diff --git a/apps/x/apps/renderer/src/components/sidebar-content.tsx b/apps/x/apps/renderer/src/components/sidebar-content.tsx
index 2207a856..5bccd41e 100644
--- a/apps/x/apps/renderer/src/components/sidebar-content.tsx
+++ b/apps/x/apps/renderer/src/components/sidebar-content.tsx
@@ -1056,21 +1056,23 @@ function TasksSection({
                       ) : null}
                       <span className="min-w-0 flex-1 truncate text-sm">{run.title || '(Untitled chat)'}</span>
                       {run.createdAt ? (
-                        <span className="shrink-0 text-[10px] text-muted-foreground group-hover/chat-item:hidden">
+                        <span className={`shrink-0 text-[10px] text-muted-foreground${processingRunIds?.has(run.id) ? '' : ' group-hover/chat-item:hidden'}`}>
                           {formatRunTime(run.createdAt)}
                         </span>
                       ) : null}
-                      <button
-                        type="button"
-                        className="shrink-0 hidden group-hover/chat-item:flex items-center justify-center text-muted-foreground hover:text-destructive transition-colors"
-                        onClick={(e) => {
-                          e.stopPropagation()
-                          actions?.onDeleteRun(run.id)
-                        }}
-                        aria-label="Delete chat"
-                      >
-                        <Trash2 className="size-3.5" />
-                      </button>
+                      {!processingRunIds?.has(run.id) && (
+                        <button
+                          type="button"
+                          className="shrink-0 hidden group-hover/chat-item:flex items-center justify-center text-muted-foreground hover:text-destructive transition-colors"
+                          onClick={(e) => {
+                            e.stopPropagation()
+                            actions?.onDeleteRun(run.id)
+                          }}
+                          aria-label="Delete chat"
+                        >
+                          <Trash2 className="size-3.5" />
+                        </button>
+                      )}
                     </div>
                   </SidebarMenuButton>
                 </SidebarMenuItem>
diff --git a/apps/x/packages/core/src/runs/runs.ts b/apps/x/packages/core/src/runs/runs.ts
index d15144c4..490e935f 100644
--- a/apps/x/packages/core/src/runs/runs.ts
+++ b/apps/x/packages/core/src/runs/runs.ts
@@ -6,6 +6,7 @@ import { IRunsRepo } from "./repo.js";
 import { IAgentRuntime } from "../agents/runtime.js";
 import { IBus } from "../application/lib/bus.js";
 import { IAbortRegistry } from "./abort-registry.js";
+import { IRunsLock } from "./lock.js";
 import { forceCloseAllMcpClients } from "../mcp/mcp.js";
 
 export async function createRun(opts: z.infer<typeof CreateRunOptions>): Promise<z.infer<typeof Run>> {
@@ -66,8 +67,16 @@ export async function stop(runId: string, force: boolean = false): Promise<void>
 }
 
 export async function deleteRun(runId: string): Promise<void> {
-    const repo = container.resolve<IRunsRepo>('runsRepo');
-    await repo.delete(runId);
+    const runsLock = container.resolve<IRunsLock>('runsLock');
+    if (!await runsLock.lock(runId)) {
+        throw new Error(`Cannot delete run ${runId}: run is currently active`);
+    }
+    try {
+        const repo = container.resolve<IRunsRepo>('runsRepo');
+        await repo.delete(runId);
+    } finally {
+        await runsLock.release(runId);
+    }
 }
 
 export async function fetchRun(runId: string): Promise<z.infer<typeof Run>> {