Capture mode: run a command like time, multiplexing its stdout, stderr, and exit code into a single ordered JSONL stream on stdout
Split mode (-s): read that JSONL stream on stdin and demultiplex it back into real stdout and stderr, mirroring the recorded return code so monopipe stays transparent in a pipeline
One JSONL record per output line, or per 512 bytes when a line is longer, emitted through a single serialised writer — readable line-by-line, well-formed, streamed in real time, bounded memory for large output
Output kept as human-readable text when valid UTF-8, with byte-exact base64 fallback (stdout_b64 / stderr_b64) for arbitrary binary output
Incomplete trailing UTF-8 sequences are carried across read boundaries, so multi-byte runes never spuriously trigger the base64 fallback
Child stdin is forwarded in capture mode, so interactive programs and filters work
Lenient split parsing: ignores unrecognised keys, applies multiple recognised keys per line, and skips lines carrying none
Signal-terminated children report a POSIX 128+signal exit code (Unix)
Written in Go with zero external dependencies — stdlib only
Distributed as platform-specific Python wheels via bin2whl (pip install monopipe)
Cross-compiled for macOS (arm64/amd64), Linux (arm64/amd64), Windows (arm64/amd64)
Statically linked single binary — no Python runtime needed at execution time