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src/bot/directAddressConfidence.ts

export const DEFAULT_DIRECT_ADDRESS_CONFIDENCE_THRESHOLD = 0.62; // English-token fallback only; the model-driven decider remains primary for ambiguous addressing. const EN_GENERIC_NAME_TOKENS = new Set(["bot", "assistant", "ai", "the"]);

export function hasBotNameCue({ transcript = "", botName = "" }: { transcript?: string; botName?: string; }) { const primary = pickPrimaryBotToken(tokenize(botName)); if (!primary) return false; const transcriptTokens = tokenize(transcript); if (!transcriptTokens.length) return false; for (const token of transcriptTokens) { if (isLikelyNameCueToken(token, primary)) return true; } return false; }

function pickPrimaryBotToken(tokens: string[] = []) { if (!Array.isArray(tokens) || !tokens.length) return ""; const filtered = tokens.filter((token) => token.length >= 4 && !EN_GENERIC_NAME_TOKENS.has(token)); const candidates = filtered.length ? filtered : tokens.filter((token) => token.length >= 4); if (!candidates.length) return ""; return [...candidates].sort((left, right) => right.length - left.length)[0] || ""; }

function isLikelyNameCueToken(token = "", primary = "") { const normalizedToken = String(token || "").trim().toLowerCase(); const normalizedPrimary = String(primary || "").trim().toLowerCase(); if (!normalizedToken || !normalizedPrimary) return false; if (normalizedToken.length < 4 || normalizedPrimary.length < 4) return false; if (normalizedToken === normalizedPrimary) return true;

const tokenPrefix = normalizedToken.slice(0, 3); const primaryPrefix = normalizedPrimary.slice(0, 3); if (tokenPrefix === primaryPrefix) return true; const shortTokenPrefix = normalizedToken.slice(0, 2); const shortPrimaryPrefix = normalizedPrimary.slice(0, 2); if ( shortTokenPrefix.length === 2 && shortTokenPrefix === shortPrimaryPrefix && sharedConsonantCount(normalizedToken, normalizedPrimary) >= 2 ) { return true; } const distance = levenshteinDistance(normalizedToken, normalizedPrimary); const maxLen = Math.max(normalizedToken.length, normalizedPrimary.length); const normalizedSimilarity = maxLen > 0 ? 1 - distance / maxLen : 0; if (normalizedSimilarity >= 0.58 && sharedConsonantCount(normalizedToken, normalizedPrimary) >= 2) { return true; }

return false; }

function sharedConsonantCount(left = "", right = "") { const leftSet = new Set(consonants(left)); const rightSet = new Set(consonants(right)); let count = 0; for (const char of leftSet) { if (rightSet.has(char)) count += 1; } return count; }

function consonants(value = "") { const letters = String(value || "").toLowerCase().replace(/[^a-z]/g, ""); const out = []; for (const char of letters) { if ("aeiou".includes(char)) continue; out.push(char); } return out; }

function levenshteinDistance(left = "", right = "") { const a = String(left || ""); const b = String(right || ""); const rows = a.length + 1; const cols = b.length + 1; const matrix = Array.from( { length: rows }, (, row) => Array.from({ length: cols }, (, col) => (row === 0 ? col : col === 0 ? row : 0)) );

for (let row = 1; row < rows; row += 1) { for (let col = 1; col < cols; col += 1) { const cost = a[row - 1] === b[col - 1] ? 0 : 1; const deletion = matrix[row - 1][col] + 1; const insertion = matrix[row][col - 1] + 1; const substitution = matrix[row - 1][col - 1] + cost; matrix[row][col] = Math.min(deletion, insertion, substitution); } }

return matrix[rows - 1][cols - 1]; }