Function bindFirstUsableSocket

src/mcp/daemon.ts:673–697

(
  candidates: string[],
  listen: (socketPath: string) => Promise<net.Server>,
  opts: { onRelocate?: (from: string, to: string, code: string) => void } = {},
)

 * direct mode (#974). Exported for testing.
 */
export async function bindFirstUsableSocket(
  candidates: string[],
  listen: (socketPath: string) => Promise<net.Server>,
  opts: { onRelocate?: (from: string, to: string, code: string) => void } = {},
): Promise<{ server: net.Server; socketPath: string }> {
  let lastErr: unknown;
  for (let i = 0; i < candidates.length; i++) {
    const socketPath = candidates[i]!; // i < length, so always defined
    const isLast = i === candidates.length - 1;
    try {
      const server = await listen(socketPath);
      return { server, socketPath };
    } catch (err) {
      lastErr = err;
      const code = (err as NodeJS.ErrnoException).code;
      if (!isLast && code !== SOCKET_BIND_CONFLICT_CODE) {
        opts.onRelocate?.(socketPath, candidates[i + 1]!, code ?? ''); // !isLast ⇒ i+1 in range
        continue;
      }
      throw err;
    }
  }
  // Only reachable with an empty candidate list — a programmer error.
  throw lastErr ?? new Error('no socket candidates to bind');
}

function resolveIdleTimeoutMs(): number {
  const raw = process.env.CODEGRAPH_DAEMON_IDLE_TIMEOUT_MS;