return MESSAGE_NOT_FOUND_RE.test(extractErrorText(err));

}

function isIncompleteFinalPreviewPrefix(previewText: string, finalText: string): boolean {

const preview = previewText.trimEnd();

const final = finalText.trimEnd();

return preview.length > 0 && preview.length < final.length && final.startsWith(preview);

}

export type LaneName = "answer" | "reasoning";

export type DraftLaneState = {

lane: DraftLaneState;

finalTextAlreadyLanded: boolean;

retainAlternatePreviewOnMissingTarget: boolean;

targetPreviewText: string;

}): Promise<PreviewEditResult> => {

try {

await params.editPreview({

);

return "fallback";

}

// Default: ambiguous error — prefer incomplete over duplicate

if (isIncompleteFinalPreviewPrefix(args.targetPreviewText, args.text)) {

params.log(

`telegram: ${args.laneName} preview final edit failed and existing preview is an incomplete prefix; falling back to standard send (${String(err)})`,

);

return "fallback";

}

// Default: ambiguous error — retain when fallback may duplicate a final

// edit that already landed or when the preview is not known-incomplete.

params.log(

`telegram: ${args.laneName} preview final edit failed with ambiguous error; keeping existing preview to avoid duplicate (${String(err)})`,

);

messageId: number,

finalTextAlreadyLanded: boolean,

retainAlternatePreviewOnMissingTarget: boolean,

targetPreviewText: string,

) =>

tryEditPreviewMessage({

laneName,

lane,

finalTextAlreadyLanded,

retainAlternatePreviewOnMissingTarget,

targetPreviewText,

});

const finalizePreview = (

previewMessageId: number,

previewMessageId,

finalTextAlreadyLanded,

retainAlternatePreviewOnMissingTarget,

currentPreviewText,

);

};

if (!lane.stream) {