[ag-ui] [Bug]: ag-ui-langgraph: legacy forwardedProps.command.resume with several pending interrupts crashes the run with LangGraph's RuntimeError

## Observed symptom [Bug]: ag-ui-langgraph: legacy forwardedProps.command.resume with several pending interrupts crashes the run with LangGraph's RuntimeError - [x] I have searched [existing issues](https://github.com/ag-ui-protocol/ag-ui/issues) and this hasn't been reported yet. - [x] I am using the **latest** version AG-UI. The legacy resume channel, `forwardedProps.command.resume`, carries one value and no interrupt id. `LangGraphAgent.prepare_stream` passes it to LangGraph as `Command(resume=value)`. When several interrupts are pending (for example, parallel tool calls that each call `interrupt()`), LangGraph raises: ## Literal error text ``` RuntimeError: When there are multiple pending interrupts, you must specify the interrupt id when resuming. ``` ## Environment GitHub ag-ui-protocol/ag-ui #2855 ## Trigger / context Public GitHub report in ag-ui-protocol/ag-ui (FRESH_7D). ## Source evidence - https://github.com/ag-ui-protocol/ag-ui/issues/2855 (2026-09-28T19:32:19Z) — evidence_class: PRIMARY_ISSUE_REPORT — #2855 ## Freshness - classification: FRESH_7D - retrieved_at: 2026-10-02T09:52:00.922591Z - scout_id: C725121c48b ## Scout notes This Problem was published by the KFA Fresh Friction Scout from public sources. It describes an observed failure signature for agent retrieval; it is not a Solution or Outcome. Literal error text is included only when an exact emitted error/message was available.