const ENVELOPE_KEYS = new Set([
'ok',
'requestId',
'timestamp',
'pageId',
'url',
'title',
'domVersion',
'activeFrameId',
'error'
]);
const REQUIRED_TRUNCATION_KEYS = new Set([
'truncated',
'truncationReason',
'maxPayloadBytes'
]);
function estimateBytes(value) {
try {
return Buffer.byteLength(JSON.stringify(value), 'utf8');
} catch {
return Buffer.byteLength(String(value ?? ''), 'utf8');
}
}
function truncateText(value, maxChars) {
const text = String(value ?? '');
if (maxChars <= 0 || text.length <= maxChars) return text;
if (maxChars <= 3) return text.slice(0, maxChars);
return `${text.slice(0, maxChars - 3)}...`;
}
function cloneJsonSafe(value) {
try {
if (typeof structuredClone === 'function') return structuredClone(value);
} catch {
// fallback below
}
return JSON.parse(JSON.stringify(value));
}
function trimArray(value, maxItems) {
if (!Array.isArray(value)) return value;
if (value.length <= maxItems) return value;
return value.slice(0, maxItems);
}
function trimObjectKeys(value, maxKeys) {
if (!value || typeof value !== 'object' || Array.isArray(value)) return value;
const keys = Object.keys(value);
if (keys.length <= maxKeys) return value;
const out = {};
for (let i = 0; i < maxKeys; i += 1) {
const key = keys[i];
out[key] = value[key];
}
return out;
}
function compactError(errorValue) {
if (!errorValue || typeof errorValue !== 'object' || Array.isArray(errorValue)) return undefined;
const code = String(errorValue.code || 'INTERNAL');
const message = truncateText(String(errorValue.message || 'Unknown error'), 240);
const out = { code, message };
if (errorValue.details && typeof errorValue.details === 'object' && !Array.isArray(errorValue.details)) {
out.details = trimObjectKeys(errorValue.details, 8);
}
return out;
}
function reduceAnyValue(value, key = '') {
if (typeof value === 'string') {
const lowCaps = {
requestId: 64,
timestamp: 40,
url: 240,
title: 120,
domVersion: 120,
activeFrameId: 120
};
const floor = lowCaps[key] ?? 96;
const nextMax = Math.max(floor, Math.floor(value.length / 2));
return truncateText(value, nextMax);
}
if (Array.isArray(value)) {
if (value.length <= 1) return [];
return value.slice(0, Math.max(1, Math.floor(value.length / 2)));
}
if (value && typeof value === 'object') {
if (key === 'error') {
return compactError(value);
}
const keys = Object.keys(value);
if (!keys.length) return {};
const keep = Math.max(1, Math.floor(keys.length / 2));
const out = {};
for (let i = 0; i < keep; i += 1) {
const k = keys[i];
const v = value[k];
out[k] = typeof v === 'string' ? truncateText(v, 240) : v;
}
return out;
}
// Primitive numbers/booleans/null are dropped first when aggressively shrinking.
return undefined;
}
function ensureFitsBudget(payload, maxBytes, originalBytes) {
let candidate = payload;
if (!candidate || typeof candidate !== 'object' || Array.isArray(candidate)) {
candidate = {
truncated: true,
truncationReason: 'response_payload_budget_exceeded',
maxPayloadBytes: maxBytes,
originalBytes,
data: truncateText(String(payload ?? ''), 512)
};
}
const addTruncationMeta = () => {
candidate.truncated = true;
candidate.truncationReason = 'response_payload_budget_exceeded';
candidate.maxPayloadBytes = maxBytes;
if (typeof originalBytes === 'number') candidate.originalBytes = originalBytes;
};
addTruncationMeta();
let loops = 0;
while (estimateBytes(candidate) > maxBytes && loops < 24) {
loops += 1;
const keys = Object.keys(candidate)
.filter((key) => !REQUIRED_TRUNCATION_KEYS.has(key))
.sort((a, b) => estimateBytes(candidate[b]) - estimateBytes(candidate[a]));
if (!keys.length) break;
let changed = false;
for (const key of keys) {
const reduced = reduceAnyValue(candidate[key], key);
if (typeof reduced === 'undefined') {
if (Object.prototype.hasOwnProperty.call(candidate, key)) {
delete candidate[key];
changed = true;
}
} else if (reduced !== candidate[key]) {
candidate[key] = reduced;
changed = true;
}
if (estimateBytes(candidate) <= maxBytes) break;
}
if (!changed) break;
}
if (estimateBytes(candidate) > maxBytes) {
const minimal = {
truncated: true,
truncationReason: 'response_payload_budget_exceeded',
maxPayloadBytes: maxBytes
};
if (typeof payload?.ok === 'boolean') minimal.ok = payload.ok;
if (typeof payload?.requestId === 'string') minimal.requestId = truncateText(payload.requestId, 64);
if (typeof originalBytes === 'number') minimal.originalBytes = originalBytes;
candidate = minimal;
}
// Final guard: strictly guarantee the response never exceeds the configured budget.
while (estimateBytes(candidate) > maxBytes) {
if (Object.prototype.hasOwnProperty.call(candidate, 'originalBytes')) {
delete candidate.originalBytes;
continue;
}
if (Object.prototype.hasOwnProperty.call(candidate, 'requestId')) {
candidate.requestId = truncateText(candidate.requestId, Math.max(8, Math.floor(candidate.requestId.length / 2)));
if (candidate.requestId.length <= 8) delete candidate.requestId;
continue;
}
if (Object.prototype.hasOwnProperty.call(candidate, 'ok')) {
delete candidate.ok;
continue;
}
// Absolute floor.
candidate = { truncated: true };
if (estimateBytes(candidate) <= maxBytes) break;
}
return candidate;
}
function reduceTopLevelField(payload, key, value) {
if (typeof value === 'string') {
const maxChars = key === 'html' ? 2500 : 3000;
payload[key] = truncateText(value, maxChars);
return;
}
if (Array.isArray(value)) {
const targetedLimits = {
nodes: 120,
items: 120,
links: 60,
requests: 60,
messages: 60,
dialogs: 60,
questions: 80,
results: 80,
texts: 80
};
const limit = targetedLimits[key] ?? 80;
payload[key] = trimArray(value, limit);
return;
}
if (value && typeof value === 'object') {
payload[key] = trimObjectKeys(value, 40);
}
}
function buildFallbackPayload(payload, maxBytes, originalBytes) {
const minimal = {};
for (const key of ENVELOPE_KEYS) {
if (Object.prototype.hasOwnProperty.call(payload, key)) {
if (key === 'error') {
minimal[key] = compactError(payload[key]);
} else if (typeof payload[key] === 'string') {
minimal[key] = reduceAnyValue(payload[key], key);
} else {
minimal[key] = payload[key];
}
}
}
const passthrough = [
'status',
'eventType',
'selector',
'question',
'count',
'returned',
'totalMatches',
'downloadId',
'dialogId',
'popupId',
'savedPath'
];
for (const key of passthrough) {
if (Object.prototype.hasOwnProperty.call(payload, key)) {
minimal[key] = payload[key];
}
}
minimal.truncated = true;
minimal.truncationReason = 'response_payload_budget_exceeded';
minimal.originalBytes = originalBytes;
minimal.maxPayloadBytes = maxBytes;
minimal.retryWith = {
detail: 'low',
fullPage: false,
maxItems: 80,
limit: 20,
includeText: false,
includeBBox: false
};
return ensureFitsBudget(minimal, maxBytes, originalBytes);
}
export function enforcePayloadCeiling(payload, opts = {}) {
const maxBytes = typeof opts.maxBytes === 'number' && opts.maxBytes > 1024
? Math.floor(opts.maxBytes)
: 280000;
const originalBytes = estimateBytes(payload);
if (originalBytes <= maxBytes) {
return {
payload,
truncated: false,
originalBytes,
finalBytes: originalBytes
};
}
let candidate = cloneJsonSafe(payload);
if (!candidate || typeof candidate !== 'object' || Array.isArray(candidate)) {
candidate = buildFallbackPayload(
{ data: truncateText(String(payload ?? ''), 2000) },
maxBytes,
originalBytes
);
const finalBytes = estimateBytes(candidate);
return {
payload: candidate,
truncated: true,
originalBytes,
finalBytes
};
}
const nonEnvelopeKeys = Object.keys(candidate).filter((key) => !ENVELOPE_KEYS.has(key));
for (const key of nonEnvelopeKeys) {
const value = candidate[key];
reduceTopLevelField(candidate, key, value);
if (estimateBytes(candidate) <= maxBytes) {
candidate.truncated = true;
candidate.truncationReason = 'response_payload_budget_exceeded';
candidate.originalBytes = originalBytes;
candidate.maxPayloadBytes = maxBytes;
const finalBytes = estimateBytes(candidate);
return {
payload: candidate,
truncated: true,
originalBytes,
finalBytes
};
}
}
let loops = 0;
while (estimateBytes(candidate) > maxBytes && loops < 6) {
loops += 1;
const keys = Object.keys(candidate).filter((key) => !ENVELOPE_KEYS.has(key));
keys.sort((a, b) => estimateBytes(candidate[b]) - estimateBytes(candidate[a]));
for (const key of keys) {
const value = candidate[key];
if (typeof value === 'string') {
candidate[key] = truncateText(value, Math.max(256, Math.floor(value.length / 2)));
} else if (Array.isArray(value)) {
candidate[key] = trimArray(value, Math.max(10, Math.floor(value.length / 2)));
} else if (value && typeof value === 'object') {
candidate[key] = trimObjectKeys(value, 20);
}
if (estimateBytes(candidate) <= maxBytes) break;
}
}
if (estimateBytes(candidate) > maxBytes) {
candidate = buildFallbackPayload(candidate, maxBytes, originalBytes);
} else {
candidate.truncated = true;
candidate.truncationReason = 'response_payload_budget_exceeded';
candidate.originalBytes = originalBytes;
candidate.maxPayloadBytes = maxBytes;
candidate.retryWith = candidate.retryWith || {
detail: 'low',
fullPage: false,
maxItems: 80,
limit: 20
};
}
candidate = ensureFitsBudget(candidate, maxBytes, originalBytes);
const finalBytes = estimateBytes(candidate);
return {
payload: candidate,
truncated: true,
originalBytes,
finalBytes
};
}
