captureCommandEdit

Captures a conditional-edit context from the selected authoritative shell producer. Returns null before start, during shutdown or output processing, while the writer has pending/active work, when editing is unavailable, or for a producer without atomic revision support (including the legacy StateFlow-only host factory).

Capture at request time, before asynchronous suggestion work. The host must publish unavailable editing state while its own pending input makes the model untrustworthy; queue idleness is not acknowledgement by a remote shell.