怎生行事 Then How Will You Manage It
金聖宮高擎玉掌，叫聲：「神僧。」行者嚶嚶的應道：「我是神僧變的。」那娘娘方才信了。悄悄的道：「我去請那妖王來時，你卻怎生行事？」金圣宫高擎玉掌，叫声：「神僧。」行者嘤嘤的应道：「我是神僧变的。」那娘娘方才信了。悄悄的道：「我去请那妖王来时，你却怎生行事？」
逐句解 Line by line
The Golden Sage Queen raised her jade palm high and called, "Divine monk!"
She lifts him up to eye level to check. 擎 is qíng, to hold something up on a flat hand, the word for offering a cup or a tray. This is the second of the two 玉掌 in the chapter; the first was 40 characters back, when he landed on it.
Pilgrim answered in a tiny buzz, "I am the divine monk, transformed."
The automatic reading gives this character the level tone, which is the ought-to sense; 應 here is yìng, to answer. Sealed work in this edition takes that split from 康熙, which files 答也 and 物相應也 in the falling-tone band. 嚶嚶 is a doubled word for a very small sound — birdsong in the classics, an insect here.
Only then did the Queen believe.
Seven characters to close the whole test. 方才 is only then, not until now — the phrase measures how much convincing it took. 了 is the neutral le.
She said quietly, "When I go and fetch the fiend king here, how will you manage it?"
She has accepted the plan and gone straight to logistics. 悄 is qiǎo twice again, the same reading as in the previous passage. 怎生 is the vernacular how, and 行 is xíng in 行事, to act.
The proof finishes the way stage business does. She holds him up, calls out, he answers in a buzz small enough to need the doubled word 嚶嚶 to describe it, and seven characters later she believes. The narrator spends no time at all on what it must be like to have a talking fly on your hand.
方才信了 is doing quiet work. Only then — after the voice, the offer, the open hand, the descent, four lines of flower imagery, and a buzzed reply — does she accept it. That is a long way to bring a reader who was told the truth in the first sentence, and the length of it is the point: she is being careful because being wrong would kill her.
Her first question afterwards is not who are you or how did you get in. It is 怎生行事 — then how will you manage it. She has moved from victim to accomplice in the space of one passage, and she is the one asking for the operational detail.