Vercel AI SDK 7.0.154 lets you steer a running agent with a queued message at the next step

Released Oct 26, experimental_createSteering() plugs into generateText, streamText and ToolLoopAgent, and steer(message) slips a user message in once the current step and its tools finish, resolving to delivered or a reason like finished or aborted. It never interrupts a running tool and doesn't work across processes yet; the same patch adds an onStepError callback for steps that fail before producing a result.