{"version":"2.1.277","anchor":"tool-calls-can-now-be-detached-to-background-mid-flight-to","canonical_anchor":"long-running-tool-calls-can-now-detach-to-the-background-whe","heading":"Long-running tool calls can now detach to the background instead of blocking new messages","tier":"notice","area":"Background Tasks","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.277\/e\/tool-calls-can-now-be-detached-to-background-mid-flight-to","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.277","markdown":"### Long-running tool calls can now detach to the background instead of blocking new messages\n\nA slow tool call can now move to the background so a new message gets through, with its result delivered later\n\n**What**\n\nIf a tool call is still running when the user sends a new message, Claude Code can now move that call to the background ('detach' it) instead of making the new message wait for the tool to finish.\n\n- The model is told via an injected note that the call 'was not interrupted' and that its result 'will be delivered to you on its own, in a later tool_result carrying this tool_use_id'.\n\n- When the detached call eventually finishes, completes, fails, times out, or is stopped, its result is delivered as a task notification.\n\n- Detachment is capped: a detached call is force-aborted after 5 minutes if it hasn't finished.\n\n- The event `tengu_tool_call_detached` is emitted for telemetry.\n\n**Why**\n\nThis stops a single slow tool call from blocking the whole conversation. A new message can get through immediately while the original tool keeps running in the background, with its result delivered whenever it's ready.\n\n- Flag `tengu_tool_detach`: Not enough to say (read for one account on one subscription tier against v2.1.277; this account: no value returned, anonymous baseline: no value returned, compiled default: on) These values were read against a different version of Claude Code, so treat them as the nearest reading available instead of one taken on this release.\n- Area: Background Tasks\n- Tier: You'll notice\n- Useful: 5\/5\n- Signal: 4\/5"}