Read a comma before the fractional seconds of a log timestamp

README.md

@@ -59,6 +59,8 @@ Messages may be empty. Timestamps are timezone-naive: `Z` and UTC offsets are no
 supported. Invalid lines, including blank lines and stack-trace continuations,
 are skipped.
 
+The fractional seconds may follow a dot or a comma, so the default output of Python's `logging` module (`2026-10-10 12:00:00,123 ERROR Disk full`) is read too. A matching line is printed exactly as it was written, comma included. The `--since` and `--until` values still use a dot.
+
 Read one or more files in argument order:
 
 ```sh

src/logslice/parser.py

@@ -29,23 +29,23 @@ class Record:
 
 _LINE_RE = re.compile(
     r"(?P<timestamp>[0-9]{4}-[0-9]{2}-[0-9]{2}[ T]"
-    r"[0-9]{2}:[0-9]{2}:[0-9]{2}(?:\.[0-9]+)?)"
+    r"[0-9]{2}:[0-9]{2}:[0-9]{2}(?:[.,][0-9]+)?)"
     r"[ \t]+(?P<level>[A-Za-z]+)(?:[ \t]+(?P<message>.*))?"
 )
 
 
 def parse_line(line: str) -> Record | None:
     """Return a record, or None for invalid dates, levels, or line formats.
 
-    Accept space or T timestamp separators and optional fractional seconds.
+    Accept space or T timestamp separators and optional fractional seconds after a dot or comma.
     Levels are case-insensitive. Timezone suffixes are not accepted.
     """
     raw = line.rstrip("\r\n")
     match = _LINE_RE.fullmatch(raw)
     if match is None:
         return None
     try:
-        timestamp = datetime.fromisoformat(match["timestamp"])
+        timestamp = datetime.fromisoformat(match["timestamp"].replace(",", "."))
         level = Level[match["level"].upper()]
     except (ValueError, KeyError):
         return None

tests/test_comma_fraction.py

@@ -0,0 +1,106 @@
+"""Tests for comma fractional seconds in log timestamps."""
+
+from datetime import datetime
+
+import pytest
+
+from logslice.cli import main
+from logslice.parser import Level, Record, parse_line
+
+
+@pytest.mark.parametrize("separator", [" ", "T"])
+def test_comma_fraction_is_read_like_a_dot(separator):
+    line = f"2026-10-10{separator}12:00:00,123 ERROR Disk full"
+
+    assert parse_line(line) == Record(
+        datetime(2026, 10, 10, 12, 0, 0, 123000), Level.ERROR, "Disk full", raw=line
+    )
+
+
+def test_comma_and_dot_give_the_same_timestamp():
+    comma_record = parse_line("2026-10-10 12:00:00,5 ERROR Disk full")
+    dot_record = parse_line("2026-10-10 12:00:00.5 ERROR Disk full")
+
+    assert comma_record is not None
+    assert dot_record is not None
+    assert comma_record.timestamp == dot_record.timestamp
+    assert comma_record.timestamp.microsecond == 500000
+
+
+@pytest.mark.parametrize(
+    "line",
+    [
+        "2026-10-10 12:00:00, INFO x",
+        "2026-10-10 12:00:00,,5 INFO x",
+        "2026-10-10 12:00:00,5,6 INFO x",
+        "2026-10-10,12:00:00 INFO x",
+        "2026-10-10 12:00,00 INFO x",
+        "2026-10-10 12:00:00,5Z INFO x",
+    ],
+)
+def test_other_commas_are_still_rejected(line):
+    assert parse_line(line) is None
+
+
+def test_the_original_text_keeps_its_comma():
+    line = "2026-10-10 12:00:00,123\tWARN\tSlow\r\n"
+
+    record = parse_line(line)
+
+    assert record is not None
+    assert record.raw == "2026-10-10 12:00:00,123\tWARN\tSlow"
+    assert record.level == Level.WARNING
+
+
+def test_cli_filters_and_prints_comma_lines(tmp_path, capsys):
+    lines = (
+        "2026-10-10 12:00:00,100 INFO Started\n"
+        "2026-10-10 12:00:00,900 ERROR Disk full\n"
+        "2026-10-10 12:00:01,000 ERROR Timeout\n"
+    )
+    path = tmp_path / "app.log"
+    path.write_text(lines, encoding="utf-8")
+
+    exit_code = main([str(path), "--since", "2026-10-10 12:00:00.5", "--level", "error"])
+    captured = capsys.readouterr()
+
+    assert exit_code == 0
+    assert captured.out == (
+        "2026-10-10 12:00:00,900 ERROR Disk full\n2026-10-10 12:00:01,000 ERROR Timeout\n"
+    )
+    assert captured.err == ""
+
+
+def test_cli_summary_counts_comma_lines_and_skips_bad_ones(tmp_path, capsys):
+    contents = (
+        "2026-10-10 12:00:00,100 ERROR Disk full\n"
+        "2026-10-10 12:00:00,900 ERROR Disk full\n"
+        "2026-10-10 12:00:00, ERROR Broken\n"
+    )
+    path = tmp_path / "app.log"
+    path.write_text(contents, encoding="utf-8")
+
+    exit_code = main([str(path), "--summary"])
+    captured = capsys.readouterr()
+
+    assert exit_code == 0
+    assert "ERROR: 2\n" in captured.out
+    assert "  2  Disk full\n" in captured.out
+    assert captured.out.endswith("Skipped lines: 1\n")
+    assert captured.err == ""
+
+
+def test_since_and_until_still_need_a_dot(tmp_path, capsys):
+    path = tmp_path / "app.log"
+    path.write_text("", encoding="utf-8")
+
+    with pytest.raises(SystemExit) as exc_info:
+        main([str(path), "--since", "2026-10-10 12:00:00,5"])
+    captured = capsys.readouterr()
+
+    assert exc_info.value.code == 2
+    assert captured.out == ""
+    assert (
+        "argument --since: invalid datetime '2026-10-10 12:00:00,5': expected "
+        "YYYY-MM-DD or YYYY-MM-DD[ T]HH:MM:SS[.fraction] without a timezone"
+    ) in captured.err