/**
 * The names to try for one command on this platform.
 *
 * ⚠ A command that ALREADY carries a known extension (`agy.exe`) is a complete name — appending
 * PATHEXT to it would look for `agy.exe.EXE` and find nothing. The membership test is
 * case-insensitive because Windows paths are.
 */
export declare function executableCandidates(command: string, env?: NodeJS.ProcessEnv, platform?: NodeJS.Platform): string[];
/**
 * Is `command` runnable from PATH?
 *
 * ⚠ **The `platform` argument governs the WHOLE lookup, not just the extension list.** PATH is
 * split and joined through `path.win32` or `path.posix` chosen by that argument, never through the
 * unqualified `node:path` bindings — those follow the REAL host, so a caller simulating win32 on a
 * POSIX host would split a `C:\a;C:\b` PATH on `:` and shred it into garbage segments while the
 * candidate list was correctly virtualized. Half-virtualized is worse than not virtualized: the
 * two halves disagree about which OS they are pretending to be, and the function returns a
 * confident wrong boolean. This is the Windows-versus-Linux-CI divergence class `CLAUDE.md`
 * repeatedly flags.
 *
 * ⚠ **A match must be a FILE.** `X_OK` has no effect on Windows — Node degrades it to `F_OK` — so
 * an `accessSync` check alone reports a *directory* named `codex` on PATH as an executable. The
 * `isFile()` test is what makes the Windows answer mean the same thing as the POSIX one.
 *
 * ⚠ Absence is the branch signal, not an exceptional condition — a missing entry is the normal
 * case and must never throw.
 */
export declare function executableOnPath(command: string, env?: NodeJS.ProcessEnv, platform?: NodeJS.Platform): string | undefined;
/** Is `command` runnable from PATH? Boolean compatibility surface over the one resolving walk. */
export declare function commandExistsOnPath(command: string, env?: NodeJS.ProcessEnv, platform?: NodeJS.Platform): boolean;