fix(office): sanitize LibreOffice failures + resolve binary via shutil.which

converters/office_converter.py

@@ -13,6 +13,7 @@ soffice first-run lock hang).
 """
 import logging
 import re
+import shutil
 import subprocess
 from pathlib import Path
 
@@ -33,17 +34,22 @@ def _run_office(src: Path, work: Path) -> bytes:
     Satisfies: spec render RICH_RENDER.
     """
     work.mkdir(parents=True, exist_ok=True)
+    binary = shutil.which("libreoffice") or "/usr/bin/libreoffice"
     try:
         subprocess.run(
-            ["/usr/bin/libreoffice", "--headless", "--convert-to", "pdf",
+            [binary, "--headless", "--convert-to", "pdf",
              "--outdir", str(work), str(src)],
             check=True, timeout=LIBREOFFICE_TIMEOUT,
             stdout=subprocess.PIPE, stderr=subprocess.PIPE,
         )
     except FileNotFoundError as exc:
-        raise ValueError(
+        raise ValueError("LibreOffice is not installed. Install it to enable Rich mode.") from exc
-            "LibreOffice is not installed. Install it to enable Rich mode."
+    except subprocess.CalledProcessError as exc:
-        ) from exc
+        # Read the captured stderr (already on exc) into a clean, actionable message
+        detail = exc.stderr.decode(errors="replace").strip() or f"exit status {exc.returncode}"
+        raise ValueError(f"LibreOffice could not render the document ({detail})") from exc
+    except subprocess.TimeoutExpired as exc:
+        raise ValueError("LibreOffice timed out rendering the document (600s)") from exc
     # LibreOffice names its output after the ON-DISK input basename (e.g. the
     # web job path job-abc123.docx -> job-abc123.pdf), NOT the original upload
     # name, so locate the PDF there rather than by the source stem.