import Foundation struct CodexExecutableResolution: Sendable {    let executable: String    let loginPATH: [String]?} typealias CodexExecutableResolver = @Sendable (    _ environment: [String: String],    _ executable: String) -> CodexExecutableResolution? private func executableIsScript(_ path: String) -> Bool {    guard let handle = FileHandle(forReadingAtPath: path) else { return true }    defer { try? handle.close() }    return (try? handle.read(upToCount: 2)) == Data("#!".utf8)} func resolveCodexExecutableForRPC(    environment: [String: String],    executable: String,    captureLoginPATH: () -> [String]?) -> CodexExecutableResolution?{    if let override = environment["CODEX_CLI_PATH"],       FileManager.default.isExecutableFile(atPath: override)    {        // Native overrides can launch directly. Script overrides can depend on a        // login-shell PATH through `#!/usr/bin/env node` or helper commands.        let loginPATH = executableIsScript(override) ? captureLoginPATH() : nil        return CodexExecutableResolution(executable: override, loginPATH: loginPATH)    }     // Capture before the general resolver to preserve login-shell PATH precedence    // over bundled fallbacks and to make `/usr/bin/env node` launchers usable.    let loginPATH = captureLoginPATH()    guard let resolved = BinaryLocator.resolveCodexBinary(env: environment, loginPATH: loginPATH)        ?? TTYCommandRunner.which(executable)    else { return nil }    return CodexExecutableResolution(executable: resolved, loginPATH: loginPATH)} let defaultCodexExecutableResolver: CodexExecutableResolver = { environment, executable in    // Resolve the login-shell PATH at the actual RPC launch boundary. Warming it    // from UsageFetcher.init was both racy for env-based launchers and unsafe for    // short-lived CLI hosts because the fire-and-forget probe could outlive them.    resolveCodexExecutableForRPC(        environment: environment,        executable: executable,        captureLoginPATH: {            LoginShellPathCache.shared.currentOrCapture(shell: environment["SHELL"])        })}