Line-buffer remote fiwi output: stdbuf + reconfigure stdout/stderr.

SSH remote command uses stdbuf -oL -eL when available so libc-backed I/O
flushes on newlines; fiwi.py enables line_buffering on TextIO stdout/stderr
for Python prints over pipes.

Made-with: Cursor

fiwi.py

@@ -2,11 +2,27 @@
 """Fi-Wi test framework CLI — maps and SSH env files resolve to this file’s directory."""
 
 import os
+import sys
 
 import fiwi.paths as _paths
 
 _paths.configure(os.path.dirname(os.path.abspath(__file__)))
 
+
+def _prefer_line_buffered_stdio() -> None:
+    """Flush stdout/stderr after each newline when attached to a pipe (e.g. SSH capture)."""
+    for stream in (sys.stdout, sys.stderr):
+        reconf = getattr(stream, "reconfigure", None)
+        if reconf is None:
+            continue
+        try:
+            reconf(line_buffering=True)
+        except (OSError, ValueError, AttributeError):
+            pass
+
+
+_prefer_line_buffered_stdio()
+
 from fiwi.cli import main
 
 if __name__ == "__main__":

fiwi/ssh.py

@@ -553,13 +553,20 @@ class SshNode:
         Single remote command string for ``bash -lc`` so ``~/`` in ``FIWI_REMOTE_*`` paths expand
         on the *remote* host (quoted tilde literals would not).
 
-        ``-u`` forces unbuffered stdout/stderr so SSH pipe capture (no TTY) still receives
-        BrainStem and libc output from ``discover`` and similar commands.
+        ``-u`` makes the interpreter unbuffered. When ``stdbuf`` from GNU coreutils is on
+        ``PATH`` (typical on Pi / Fedora), ``stdbuf -oL -eL`` also sets **line-buffered**
+        libc streams so mixed Python + native (BrainStem) output flushes on newlines over
+        SSH pipes (no TTY). If ``stdbuf`` is missing, the command falls back to ``-u`` only.
         """
         py = cls.remote_path_bash_word(cfg.python)
         sc = cls.remote_path_bash_word(cfg.script)
         tail = " ".join(shlex.quote(p) for p in remote_args)
-        return f"{py} -u {sc}" + (f" {tail}" if tail else "")
+        core = f"{py} -u {sc}" + (f" {tail}" if tail else "")
+        return (
+            "if command -v stdbuf >/dev/null 2>&1; then "
+            f"stdbuf -oL -eL {core}; "
+            f"else {core}; fi"
+        )
 
     def _fiwi_cmd_argv(self, cfg: SshNodeConfig, remote_args: List[str]) -> List[str]:
         inner = self._fiwi_remote_shell_command(cfg, remote_args)