File size: 4,358 Bytes
253e783 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 | import { isRecord } from "@openclaw/normalization-core/record-coerce";
import { boundedJsonUtf8Bytes, jsonUtf8BytesOrInfinity } from "../infra/json-utf8-bytes.js";
import { truncateUtf8Prefix } from "../utils/utf8-truncate.js";
const MCP_TEXT_CONTENT_MAX_BYTES = 1024 * 1024;
const MCP_TEXT_TRUNCATION_MARKER = "\n[truncated: MCP text content exceeded 1 MB]";
const MCP_INVOKE_PAYLOAD_MAX_BYTES = 20 * 1024 * 1024;
const MCP_PAYLOAD_TRUNCATION_MARKER = "[truncated: MCP result exceeded 20 MB]";
type McpInvokeContentBlock = Record<string, unknown>;
/** Bounds MCP result content before it crosses node.invoke. */
export function boundMcpToolResultPayload(result: {
content: readonly unknown[];
structuredContent?: Record<string, unknown>;
isError?: boolean;
}): {
content: McpInvokeContentBlock[];
structuredContent?: Record<string, unknown>;
isError?: true;
} {
const payloadMarker = { type: "text" as const, text: MCP_PAYLOAD_TRUNCATION_MARKER };
const reservedMarkerBytes = jsonUtf8BytesOrInfinity(payloadMarker) + 1;
const isError = result.isError === true;
let usedBytes = jsonUtf8BytesOrInfinity({ content: [], ...(isError ? { isError } : {}) });
let payloadTruncated = false;
let structuredContent: Record<string, unknown> | undefined;
if (result.structuredContent) {
const prefixBytes = Buffer.byteLength(',"structuredContent":');
const availableBytes = Math.max(
0,
MCP_INVOKE_PAYLOAD_MAX_BYTES - usedBytes - prefixBytes - reservedMarkerBytes,
);
const measured = boundedJsonUtf8Bytes(result.structuredContent, availableBytes);
if (measured.complete && measured.bytes <= availableBytes) {
structuredContent = result.structuredContent;
usedBytes += prefixBytes + measured.bytes;
} else {
payloadTruncated = true;
}
}
const mirroredStructuredContent = structuredContent
? JSON.stringify(structuredContent, null, 2)
: undefined;
const normalizedBlocks = result.content.filter(
(block): block is McpInvokeContentBlock =>
isRecord(block) &&
(mirroredStructuredContent === undefined ||
block.type !== "text" ||
block.text !== mirroredStructuredContent),
);
const totalTextBytes = normalizedBlocks.reduce<number>(
(total, block) =>
total +
(block.type === "text" && typeof block.text === "string" ? Buffer.byteLength(block.text) : 0),
0,
);
let remainingTextBytes =
totalTextBytes > MCP_TEXT_CONTENT_MAX_BYTES
? MCP_TEXT_CONTENT_MAX_BYTES - Buffer.byteLength(MCP_TEXT_TRUNCATION_MARKER)
: MCP_TEXT_CONTENT_MAX_BYTES;
let markedTruncated = false;
const textBoundedContent: McpInvokeContentBlock[] = [];
for (const block of normalizedBlocks) {
if (block.type !== "text" || typeof block.text !== "string") {
textBoundedContent.push(block);
continue;
}
if (totalTextBytes <= MCP_TEXT_CONTENT_MAX_BYTES) {
textBoundedContent.push(block);
continue;
}
if (markedTruncated) {
continue;
}
const text = truncateUtf8Prefix(block.text, remainingTextBytes);
remainingTextBytes -= Buffer.byteLength(text);
const blockWasTruncated = text.length < block.text.length;
if (text || blockWasTruncated) {
textBoundedContent.push({
...block,
text: blockWasTruncated ? `${text}${MCP_TEXT_TRUNCATION_MARKER}` : text,
});
}
if (blockWasTruncated || remainingTextBytes === 0) {
if (!blockWasTruncated) {
textBoundedContent.push({ type: "text", text: MCP_TEXT_TRUNCATION_MARKER.trimStart() });
}
markedTruncated = true;
}
}
const content: McpInvokeContentBlock[] = [];
for (const block of textBoundedContent) {
const separatorBytes = content.length > 0 ? 1 : 0;
const availableBytes = Math.max(
0,
MCP_INVOKE_PAYLOAD_MAX_BYTES - usedBytes - separatorBytes - reservedMarkerBytes,
);
const measured = boundedJsonUtf8Bytes(block, availableBytes);
if (!measured.complete || measured.bytes > availableBytes) {
payloadTruncated = true;
continue;
}
content.push(block);
usedBytes += measured.bytes + separatorBytes;
}
if (payloadTruncated) {
content.push(payloadMarker);
}
return {
content,
...(structuredContent ? { structuredContent } : {}),
...(isError ? { isError } : {}),
};
}
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