RootShellBackend

ShellBackend backed by libsu — runs commands as the root UID. Strictly more powerful than Shizuku's ShizukuShellBackend: writes to /system, freezes apps via pm hide, reads /data/data/<pkg>, etc.

Output model. libsu's Shell.Result.out is List<String> (UTF-8 line-decoded). exec joins those lines back into a byte stream via UTF-8 re-encoding which is lossy for binary stdout (the PNG signature 89 50 4E 47 ... is invalid UTF-8, so the round-trip mangles it). Tools whose stdout is raw bytes — screencap -p, anything streaming non-UTF-8 — must call execBinary, which uses a temp-file roundtrip via SuFileInputStream to read raw bytes.

Host responsibility — do not override libsu's default builder to a non-root config. requestAccess calls Shell.getShell which uses whatever default builder is configured. If your host has called Shell.setDefaultBuilder(...) with non-root flags before any droid-mcp code runs, the prompt will never fire and root tools will silently fail with shell_unavailable. libsu's untouched default prefers root, which is the configuration droid-mcp expects.

Command parsing. libsu writes each Shell.cmd(String) invocation to the stdin of a long-running interactive shell process — it is NOT a sh -c <string> wrap. The shell still parses each line per sh syntax, so argv quoting via ShellUtils.escapedString is required for any value that could contain shell metacharacters.