From 7ac373179b438247b551a7f24cc98be2994a64e4 Mon Sep 17 00:00:00 2001
From: Leo Vasanko <git@vasanko.com>
Date: Thu, 13 Aug 2026 05:19:50 +0000
Subject: [PATCH] Shorter short error messages.

---
 mediapreview/exceptions.py | 10 +++++++++-
 tests/test_office.py       |  9 +++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/mediapreview/exceptions.py b/mediapreview/exceptions.py
index 6fa5821..e5cf2b3 100644
--- a/mediapreview/exceptions.py
+++ b/mediapreview/exceptions.py
@@ -154,7 +154,15 @@ def onlyoffice_no_fileurl_error(snippet: str | None = None) -> OnlyOfficeError:
 
 
 def backend_error(backend: str, message: str) -> PreviewBackendError:
-    short = message.splitlines()[0][:60]
+    short = message.splitlines()[0]
+    # Many backend messages look like "source: summary: detail ...".
+    # Drop the source prefix and any trailing detail so the short label
+    # is usable in UIs with limited space.
+    if ": " in short:
+        short = short.split(": ", 1)[1]
+    if ": " in short:
+        short = short.split(": ", 1)[0]
+    short = short[:60]
     return PreviewBackendError(
         f"[{backend}] preview failed: {message}",
         short,
diff --git a/tests/test_office.py b/tests/test_office.py
index de0bee0..99e055f 100644
--- a/tests/test_office.py
+++ b/tests/test_office.py
@@ -72,6 +72,15 @@ def test_backend_error_pipeline_backend():
     assert isinstance(err, PreviewBackendError)
 
 
+def test_backend_error_short_message_strips_source_and_detail():
+    """Backend messages like "source: summary: detail" become just the summary."""
+    err = backend_error(
+        "vips",
+        "pyvips: cannot decode image: unable to load from file b'/mnt/c/Users...",
+    )
+    assert err.short == "cannot decode image"
+
+
 def test_error_pickle_round_trip():
     """Exceptions survive pickling (the worker pool wire) intact."""
     err = onlyoffice_error_from_code("-8")