JuliusBrussee/caveman · error · Error

caveman-mcp ${compatible.probe.version} lacks current mcp_re

Error message

caveman-mcp ${compatible.probe.version} lacks current mcp_recovery capability; run `caveman setup --install`

What it means

nativeMcpBinaryRequired() throws before any native MCP wiring when probeMcpBinary() found a caveman-mcp binary whose probe reports current=false — the installed binary predates the mcp_recovery capability the runtime requires.

Source

Thrown at packages/cli/src/index.ts:6873

  try {
    unlinkSync(path);
    fsyncParentDirectory(path);
  } catch (error) {
    if ((error as NodeJS.ErrnoException).code !== "ENOENT") throw error;
  }
}

function parseJsonFileObject(path: string, bytes: Buffer | null): Record<string, unknown> {
  if (!bytes || bytes.length === 0) return {};
  const parsed = JSON.parse(bytes.toString("utf8"));
  if (!parsed || typeof parsed !== "object" || Array.isArray(parsed)) throw new Error(`${path} is not a JSON object`);
  return parsed as Record<string, unknown>;
}

function nativeMcpBinaryRequired(): string {
  const compatible = probeMcpBinary();
  if (!compatible) throw new Error("caveman-mcp not found; run `caveman setup --install`");
  if (!compatible.probe.current) throw new Error(`caveman-mcp ${compatible.probe.version} lacks current mcp_recovery capability; run \`caveman setup --install\``);
  return compatible.binary;
}

function nativeProxyBinaryRequired(gw: string): void {
  if (wrapMode(gw) !== "local") return;
  const binary = resolveGoBin("caveman-proxy", "CAVEMAN_PROXY_BIN");
  if (!binary) throw new Error("caveman-proxy not found; run `caveman setup --install`");
  const probe = probeVersionedBinary(binary, "native_runtime_v1");
  if (!probe.current) throw new Error(`caveman-proxy ${probe.version} lacks current native_runtime_v1 capability; run \`caveman setup --install\``);
}

function nativeHostProbe(agent: AgentProfile): { binary: string | null; launchable: boolean; version: string | null; error: string | null } {
  const binary = which(binOf(agent));
  if (!binary) return { binary: null, launchable: false, version: null, error: "binary_not_found" };
  try {
    const invocation = portableInvocation(binary, ["--version"]);
    const out = spawnSync(invocation.command, invocation.args, { encoding: "utf8", timeout: 3000 });
    if (out.error) return { binary, launchable: false, version: null, error: boundedHookString(out.error.message, 240) ?? "version_probe_failed" };

View on GitHub (pinned to 5184b3d11a)

Solutions

1. Run `caveman setup --install` to replace caveman-mcp with a current build
2. Check `caveman-mcp --version` and update the CLI package if setup reports already-current but stale binaries persist

When it happens

Trigger: Thrown at packages/cli/src/index.ts:6298 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of JuliusBrussee/caveman@5184b3d11a (2026-08-18). Data as JSON: /api/errors/4dab3c35cfcabece. Report an issue: GitHub.