@sellable/install/lib/sellable-agent/fly-skills-bridge-exec.mjs

One-command installer for Sellable MCP in Claude Code, Codex, and Hermes

#!/usr/bin/env node

import { resolve } from "node:path";
import { fileURLToPath } from "node:url";

import {
  FlySkillsBridgeError,
  SKILLS_REQUEST_MAX_BYTES,
  executeExternalSkillsBridgeOperation,
} from "./fly-skills-bridge.mjs";

export const FLY_SKILLS_EXEC_ARGUMENT_MAX_BYTES = 96 * 1024;
export const FLY_SKILLS_EXEC_ARGUMENT_MAX_COUNT = 8;

const BASE64URL_CHUNK = /^[A-Za-z0-9_-]+$/;
const FLY_SKILLS_EXEC_ENCODED_MAX_BYTES =
  Math.ceil(SKILLS_REQUEST_MAX_BYTES / 3) * 4;

export function decodeFlySkillsExecArguments(args) {
  if (!Array.isArray(args) || args.length === 0) {
    throw new FlySkillsBridgeError("skills_request_rejected");
  }
  if (args.length > FLY_SKILLS_EXEC_ARGUMENT_MAX_COUNT) {
    throw new FlySkillsBridgeError("skills_request_too_large");
  }
  let encoded = "";
  for (const chunk of args) {
    if (typeof chunk !== "string" || !BASE64URL_CHUNK.test(chunk)) {
      throw new FlySkillsBridgeError("skills_request_rejected");
    }
    if (Buffer.byteLength(chunk, "utf8") > FLY_SKILLS_EXEC_ARGUMENT_MAX_BYTES) {
      throw new FlySkillsBridgeError("skills_request_too_large");
    }
    encoded += chunk;
    if (encoded.length > FLY_SKILLS_EXEC_ENCODED_MAX_BYTES) {
      throw new FlySkillsBridgeError("skills_request_too_large");
    }
  }
  let bytes;
  try {
    bytes = Buffer.from(encoded, "base64url");
  } catch {
    throw new FlySkillsBridgeError("skills_request_rejected");
  }
  if (bytes.toString("base64url") !== encoded) {
    throw new FlySkillsBridgeError("skills_request_rejected");
  }
  if (bytes.byteLength > SKILLS_REQUEST_MAX_BYTES) {
    throw new FlySkillsBridgeError("skills_request_too_large");
  }
  try {
    const json = new TextDecoder("utf-8", { fatal: true }).decode(bytes);
    return JSON.parse(json);
  } catch {
    throw new FlySkillsBridgeError("skills_request_rejected");
  }
}

export async function runFlySkillsBridgeExecCli() {
  try {
    const request = decodeFlySkillsExecArguments(process.argv.slice(2));
    const result = executeExternalSkillsBridgeOperation(request);
    process.stdout.write(`${JSON.stringify(result)}\n`);
    process.exitCode = result.ok ? 0 : 2;
  } catch (error) {
    process.stdout.write(
      `${JSON.stringify({ ok: false, code: error instanceof FlySkillsBridgeError ? error.code : "skills_bridge_failed" })}\n`
    );
    process.exitCode = 2;
  }
}

if (
  resolve(process.argv[1] ?? "") === resolve(fileURLToPath(import.meta.url))
) {
  await runFlySkillsBridgeExecCli();
}