Oversized tool results are archived to disk and replaced in-context with a
'Full output saved to: <path>' reference. Until now the write was trusted
blind: a partially-flushed host file (ENOSPC/quota races) or a lossy sandbox
write (API-body truncation on payload backends) still produced the archive
reference, so the model was told the full result was recoverable when bytes
had silently vanished.
Both persistence paths now round-trip-verify size before building the
reference and fail closed to the bounded inline truncation otherwise:
- _write_to_spillover: byte-count check via os.stat after write; mismatched
archives are deleted and the caller falls through to inline truncation.
- _write_to_sandbox: wc -c probe after the cat; heredoc-mode backends get a
+1 byte tolerance (wrap_modal_stdin_heredoc appends one newline by
construction), unprobeable backends stay best-effort success.
Regression tests fail without the fix (verified by stashing the source
change: 4 failed). E2E-verified against a temp HERMES_HOME with real file
I/O including multibyte content and a simulated short write.
Teknium
fc93a1b55a