fix(cli): warn when jieba is unavailable for readable SRT splitting (#3726)

Report the punctuation-only subtitle fallback once per process without changing subtitle output.

Signed-off-by: LauraGPT <zhifu.gzf@alibaba-inc.com>

Author: Linxiushen

funasr/cli.py

@@ -2,6 +2,7 @@
 
 import argparse
 import json
+import logging
 import os
 import re
 import sys
@@ -184,13 +185,28 @@ def _timestamps_are_ordered(timestamps):
     )
 
 
+_SUBTITLE_WORD_BOUNDARY_FALLBACK_WARNED = False
+
+
+def _warn_subtitle_word_boundary_fallback(error):
+    """Report once that subtitle splitting lost its word-boundary scoring."""
+    global _SUBTITLE_WORD_BOUNDARY_FALLBACK_WARNED
+    if _SUBTITLE_WORD_BOUNDARY_FALLBACK_WARNED:
+        return
+    _SUBTITLE_WORD_BOUNDARY_FALLBACK_WARNED = True
+    logging.warning(
+        f"jieba word segmentation is unavailable ({error}); readable subtitles "
+        "fall back to punctuation-only boundaries and can split words across "
+        "cues. Install jieba to restore word-aware subtitle splitting."
+    )
+
+
 def _subtitle_break_weights(text, token_spans):
     """Map token-boundary indices to lexical and punctuation preferences."""
     boundary_to_token = {span[1]: index + 1 for index, span in enumerate(token_spans)}
     breaks = {len(token_spans): 0.0}
 
     try:
-        import logging
         import warnings
 
         with warnings.catch_warnings():
@@ -222,8 +238,8 @@ def _subtitle_break_weights(text, token_spans):
                     breaks[token_index] = max(
                         breaks.get(token_index, 0.0), strength
                     )
-    except (ImportError, RuntimeError, ValueError):
-        pass
+    except (ImportError, RuntimeError, ValueError) as error:
+        _warn_subtitle_word_boundary_fallback(error)
 
     for index, span in enumerate(token_spans[:-1], 1):
         boundary = span[1]

tests/test_cli.py

@@ -609,3 +609,20 @@ def test_merge_subtitle_segments_avoids_single_character_phrase_breaks():
             for boundary in boundary_offsets
         )
         search_from = phrase_start + 1
+
+
+def test_subtitle_break_weights_warns_once_without_jieba(monkeypatch):
+    text = "钟书成为朴家保姆后他轻易的偷偷扭了一下儿子的耳朵"
+    token_spans = [[index, index + 1] for index in range(len(text))]
+    monkeypatch.setattr(cli, "_SUBTITLE_WORD_BOUNDARY_FALLBACK_WARNED", False, raising=False)
+
+    with (
+        patch.dict(sys.modules, {"jieba": None}),
+        patch("logging.warning") as warning,
+    ):
+        first = cli._subtitle_break_weights(text, token_spans)
+        second = cli._subtitle_break_weights(text, token_spans)
+
+    assert first == second == {len(token_spans): 0.0}
+    assert warning.call_count == 1
+    assert "jieba" in warning.call_args[0][0]