The moths die because several forms of intelligence cooperate: Isaac's improvisational science, Derkhan's networks, Yagharek's courage, the Council's computation, and the Weaver's perception of the worldweb. No participant could have solved the crisis alone. The victory validates solidarity without pretending solidarity makes its members morally identical or permanently allied.
Lin survives biologically but loses part of the mind that made her the person Isaac knew. The injury refuses a familiar rescue ending. Isaac can remove her from Motley's warehouse, but he cannot restore the stolen consciousness or undo the decisions that placed her there. Their departure is escape, not recovery.
Yagharek's revelation reinterprets the entire commission. The mutilation that appeared to make him a victim was imposed for his violation of another person's agency. Garuda justice treats individual choice as sacred; taking sexual choice justified removing the wings through which Yagharek defined himself. Isaac refuses to become the outsider who cancels that sentence because he sympathizes with the punished man. The decision is ethically understandable and emotionally brutal, especially after Yagharek risked his life to save the city.
The final image does not redeem Yagharek. By tearing out his feathers and entering the crowd, he accepts that he cannot return to the identity that preceded his crime. He remains alive, capable of change, and unable to demand that change be recognized as innocence. New Crobuzon, which remakes bodies as punishment and absorbs every kind of exile, becomes the only available place for that unresolved life.
Most importantly, saving New Crobuzon does not transform New Crobuzon. Rudgutter's government survives, Motley survives, the militia remains, and the systems that produced the moths continue. The novel's heroes avert apocalypse while losing the people and communities that made the city home. Miéville's politics allow collective action to matter without turning one victory into historical completion.