diff --git a/src/tools/background-task/create-background-output.ts b/src/tools/background-task/create-background-output.ts
index 78593a88..82ecb23e 100644
--- a/src/tools/background-task/create-background-output.ts
+++ b/src/tools/background-task/create-background-output.ts
@@ -106,6 +106,47 @@ export function createBackgroundOutput(manager: BackgroundOutputManager, client:
         }
 
         const isActive = resolvedTask.status === "pending" || resolvedTask.status === "running"
+=======
+        const shouldBlock = args.block === true
+        const timeoutMs = Math.min(args.timeout ?? 60000, 600000)
+
+        if (task.status === "completed") {
+          return await formatTaskResult(task, client)
+        }
+
+        if (task.status === "error" || task.status === "cancelled" || task.status === "interrupt") {
+          return formatTaskStatus(task)
+        }
+
+        if (shouldBlock) {
+          const startTime = Date.now()
+          while (Date.now() - startTime < timeoutMs) {
+            await delay(1000)
+
+            const currentTask = manager.getTask(args.task_id)
+            if (!currentTask) {
+              return `Task was deleted: ${args.task_id}`
+            }
+
+            if (currentTask.status === "completed") {
+              return await formatTaskResult(currentTask, client)
+            }
+
+            if (currentTask.status === "error" || currentTask.status === "cancelled" || currentTask.status === "interrupt") {
+              return formatTaskStatus(currentTask)
+            }
+          }
+
+          const finalTask = manager.getTask(args.task_id)
+          if (!finalTask) {
+            return `Task was deleted: ${args.task_id}`
+          }
+          return `Timeout exceeded (${timeoutMs}ms). Task still ${finalTask.status}.\n\n${formatTaskStatus(finalTask)}`
+        }
+
+        const isActive = task.status === "pending" || task.status === "running"
+        const fullSession = args.full_session ?? isActive
+>>>>>>> 20a1af47 (fix(background-output): prioritize block=true over fullSession auto-detection)
         const includeThinking = isActive || (args.include_thinking ?? false)
         const includeToolResults = isActive || (args.include_tool_results ?? false)