fix(reader_xlsx): add missing import subprocess (recalc silently disabled)

[Anai-Guo]

Problem

plugins/tools/_reader_xlsx.py calls subprocess.run(...) in _x_recalc_copy (lines 133 and 149), but the module never imports subprocess:

import datetime as _dt
import os
import re
import shutil
import tempfile
import xml.etree.ElementTree as _ET
import zipfile

Because the entire body of _x_recalc_copy is wrapped in try: ... except Exception: return None, the NameError: name 'subprocess' is not defined is swallowed silently rather than crashing.

Impact

_x_recalc_copy first checks if not shutil.which("soffice"): return None, so the subprocess.run calls are only reached when LibreOffice is installed. In exactly that case, the call raises NameError, is caught, and returns None. The caller then does:

new = _x_recalc_copy(path)
if new:
    ... # recalc done
else:
    mark_uncached = True
    head.append("`recalc: soffice unavailable; empty formula caches marked uncached`")

So on any machine where soffice is available, the formula-recalc feature silently reports "soffice unavailable" and never recalculates empty formula caches — the feature is effectively dead.

Fix

Add the missing import subprocess. One line, no behavior change beyond letting the recalc path run as intended.

🤖 Generated with Claude Code

[zhanghanduo]

This conclusion is not correct. _reader_xlsx.py is not loaded as an independent Python module; _doc_reader.reader_src() concatenates the reader fragments into one script in a fixed order, with _reader_core.py placed before _reader_xlsx.py. _reader_core.py already executes import subprocess, so by the time _x_recalc_copy() runs, subprocess exists in the shared global namespace. The alleged NameError therefore does not occur, and the LibreOffice recalculation path is not broken for this reason.
Adding import subprocess directly to _reader_xlsx.py would be harmless and could improve the fragment’s self-containment and readability. However, it would be a defensive cleanup rather than a bug fix. Calling this a feature-breaking issue overlooks the project’s bundled execution model.
The more relevant issue is the error message: any recalculation failure is currently reported as “soffice unavailable,” which can obscure other LibreOffice execution failures.