| { type: "thinking"; thinking: string }

| { type: "text"; text: string };

const THINKING_TAG_NAME_PATTERN = String.raw`(?:(?:antml:)?(?:think(?:ing)?|thought)|antthinking)`;

const THINKING_TAG_OPEN_RE = new RegExp(String.raw`<\s*${THINKING_TAG_NAME_PATTERN}\s*>`, "i");

const THINKING_TAG_CLOSE_RE = new RegExp(

String.raw`<\s*\/\s*${THINKING_TAG_NAME_PATTERN}\s*>`,

"i",

);

const THINKING_TAG_OPEN_GLOBAL_RE = new RegExp(

String.raw`<\s*${THINKING_TAG_NAME_PATTERN}\s*>`,

"gi",

);

const THINKING_TAG_CLOSE_GLOBAL_RE = new RegExp(

String.raw`<\s*\/\s*${THINKING_TAG_NAME_PATTERN}\s*>`,

"gi",

);

export const THINKING_TAG_SCAN_RE = new RegExp(

String.raw`<\s*(\/?)\s*${THINKING_TAG_NAME_PATTERN}\s*>`,

"gi",

);

export function splitThinkingTaggedText(text: string): ThinkTaggedSplitBlock[] | null {

const trimmedStart = text.trimStart();

// Avoid false positives: only treat it as structured thinking when it begins

if (!trimmedStart.startsWith("<")) {

return null;

}

const openRe = /<\s*(?:(?:antml:)?(?:think(?:ing)?|thought)|antthinking)\s*>/i;

const closeRe = /<\s*\/\s*(?:(?:antml:)?(?:think(?:ing)?|thought)|antthinking)\s*>/i;

if (!openRe.test(trimmedStart)) {

if (!THINKING_TAG_OPEN_RE.test(trimmedStart)) {

return null;

}

if (!closeRe.test(text)) {

if (!THINKING_TAG_CLOSE_RE.test(text)) {

return null;

}

const scanRe = /<\s*(\/?)\s*(?:(?:antml:)?(?:think(?:ing)?|thought)|antthinking)\s*>/gi;

let inThinking = false;

let cursor = 0;

let thinkingStart = 0;

blocks.push({ type: "thinking", thinking: cleaned });

};

for (const match of text.matchAll(scanRe)) {

for (const match of text.matchAll(THINKING_TAG_SCAN_RE)) {

const index = match.index ?? 0;

const isClose = match[1]?.includes("/") ?? false;

if (!text) {

return "";

}

const scanRe = /<\s*(\/?)\s*(?:(?:antml:)?(?:think(?:ing)?|thought)|antthinking)\s*>/gi;

let result = "";

let lastIndex = 0;

let inThinking = false;

for (const match of text.matchAll(scanRe)) {

for (const match of text.matchAll(THINKING_TAG_SCAN_RE)) {

const idx = match.index ?? 0;

if (inThinking) {

result += text.slice(lastIndex, idx);

return closed;

}

const openRe = /<\s*(?:(?:antml:)?(?:think(?:ing)?|thought)|antthinking)\s*>/gi;

const closeRe = /<\s*\/\s*(?:(?:antml:)?(?:think(?:ing)?|thought)|antthinking)\s*>/gi;

const openMatches = [...text.matchAll(openRe)];

const openMatches = [...text.matchAll(THINKING_TAG_OPEN_GLOBAL_RE)];

if (openMatches.length === 0) {

return "";

}

const closeMatches = [...text.matchAll(closeRe)];

const closeMatches = [...text.matchAll(THINKING_TAG_CLOSE_GLOBAL_RE)];

const lastOpen = openMatches[openMatches.length - 1];

const lastClose = closeMatches[closeMatches.length - 1];

if (lastClose && (lastClose.index ?? -1) > (lastOpen.index ?? -1)) {