Wire up the existing office document extractors in document.py to
ReadFileTool by adding an extension guard and _read_office_doc() method
that follows the established PDF pattern. Handles missing libraries,
corrupt files, empty documents, and 128K truncation consistently.
SessionManager.save() previously used bare open("w") which could
truncate the JSONL file if the process crashed mid-write. Now writes
to a .tmp file and atomically replaces via os.replace(), matching the
pattern already used in qq.py.
_load() now attempts _repair() before returning None, recovering
valid lines from partially-written files. 12 new tests cover atomic
save correctness, temp-file cleanup on failure, and repair of
truncated/corrupt JSONL.
cowork-with:opencode(glm-5.1)