fix: two error paths that made a failure worse than the thing that failed

/api/clip: _clip_wav/_clip_flac send audio headers and then stream frames.
A decode failure mid-stream unwound into _api_clip's handler, which called
_json_err(500) — writing a second status line and a JSON body into a
response that had already promised Content-Type: audio/wav and an exact
Content-Length. Under HTTP/1.1 keep-alive that desyncs the connection for
every subsequent request on it, so one bad clip corrupted unrelated
traffic. Track whether the headers went out; if they did, log and force
the connection closed instead, the same way _copy_to_response already
handles under-delivery.

config.ini: the int() coercion for split_minutes/max_retries/etc sat
outside the try that wraps recorder construction, so `split_minutes =
sixty` aborted the entire config load with an unhandled ValueError rather
than skipping that one section like every other config error. Moved
inside. split_duration is also clamped to >= 1 — 0 divided by zero in
get_next_split_time().

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tests/test_web.py

@@ -1,7 +1,10 @@
 """Tests for the adaptive loud-section detector in web.py."""
 
+import io
 import math
+import wave
 
+import web
 from web import _cut_filename, _loud_sections, _noise_floor_db, _recording_start
 
 WINDOW_DUR = 0.1  # 100 ms windows, as produced by WINDOW_SAMPLES at 48 kHz
@@ -160,3 +163,69 @@ def test_cut_filename_rolls_over_the_hour():
 def test_cut_filename_falls_back_for_nonstandard_name():
     name = _cut_filename("mixtape", ".mp3", 740, 750.4)
     assert name == "mixtape_cut_740s-750s.mp3"
+
+
+# ---------------------------------------------------------------------------
+# /api/clip error handling
+# ---------------------------------------------------------------------------
+
+class _OfflineHandler(web._Handler):
+    """A _Handler with no socket, for driving handler methods directly."""
+
+    def __init__(self, recordings_dir):
+        self.recordings_dir = str(recordings_dir)
+        self.analyses_dir = str(recordings_dir)
+        self.wfile = io.BytesIO()
+        self.close_connection = False
+        self.codes = []
+
+    def send_response(self, code):
+        self.codes.append(code)
+
+    def send_header(self, key, value):
+        pass
+
+    def end_headers(self):
+        pass
+
+
+def _write_wav(path, seconds=2, framerate=8000):
+    with wave.open(str(path), 'wb') as wf:
+        wf.setnchannels(1)
+        wf.setsampwidth(2)
+        wf.setframerate(framerate)
+        wf.writeframes(b'\x00\x00' * (seconds * framerate))
+
+
+def test_clip_failure_after_headers_closes_connection_instead_of_writing_json(tmp_path):
+    # Once the audio headers are out, an error body would be a second response
+    # on a keep-alive connection that already promised audio/wav plus an exact
+    # Content-Length — desyncing every later request on that connection.
+    _write_wav(tmp_path / 'rec.wav')
+    h = _OfflineHandler(tmp_path)
+
+    def boom(path, start, end):
+        h._send_clip_headers(b'HDR', 10, 1, 2)
+        raise RuntimeError('decode exploded')
+
+    h._clip_wav = boom
+    h._api_clip({'file': ['rec.wav'], 'start': ['0'], 'end': ['1']})
+
+    assert h.close_connection is True
+    assert h.codes == [200]                    # no second status line
+    assert b'error' not in h.wfile.getvalue()  # no JSON body
+
+
+def test_clip_failure_before_headers_still_reports_json(tmp_path):
+    _write_wav(tmp_path / 'rec.wav')
+    h = _OfflineHandler(tmp_path)
+
+    def boom(path, start, end):
+        raise RuntimeError('could not open')
+
+    h._clip_wav = boom
+    h._api_clip({'file': ['rec.wav'], 'start': ['0'], 'end': ['1']})
+
+    assert h.close_connection is False
+    assert h.codes == [500]
+    assert b'could not open' in h.wfile.getvalue()