Cut a long file into chunks a hosted request can outlive

An hour and a half of speech came back as "OpenRouter: HTTP 502: The
operation was aborted due to timeout", every time. The upload limit was
the only thing deciding where the file was cut, and mp3 at 48 kbps
reaches 24 MB after an hour, so a 90 minute file became two chunks and
the first one was 63 minutes of audio in a single request. Nothing
between here and the model stays on the line that long.

A chunk is capped at fifteen minutes now, whatever it weighs, and the
call is finally handed a timeout of its own: it was going out on the 300
second default sized for a dictation, which the same chunk would have
hit first anyway.

The other half is not throwing the run away when one request fails.
ApiError carries whether a second try can fix it, which is true of the
statuses a gateway raises itself and of a dropped connection, and false
of a rejected key. A chunk is asked for three times, waiting five then
ten seconds, with the Stop button still able to get through. If it does
fail in the end, what was already heard goes to the output box rather
than the bin, with the status line saying where it stops.

tests/test_filetranscribe.py

@@ -214,10 +214,22 @@ class ChunkSeconds(DikteTest):
         self.assertEqual(ft.chunk_seconds(self.file(1024), 600), 0.0)
 
     def test_a_file_over_the_limit_is_cut_by_what_it_measured(self):
-        # Twice the limit over an hour, so a little under half an hour fits.
-        seconds = ft.chunk_seconds(self.file(ft.UPLOAD_LIMIT * 2), 3600)
-        self.assertGreater(seconds, 1500)
-        self.assertLess(seconds, 1800)
+        # Twice the limit over twenty minutes, so a little under ten fits.
+        seconds = ft.chunk_seconds(self.file(ft.UPLOAD_LIMIT * 2), 1200)
+        self.assertGreater(seconds, 500)
+        self.assertLess(seconds, 600)
+
+    def test_a_chunk_is_never_more_audio_than_a_request_can_outlive(self):
+        """An hour in one request is a 502 from the gateway, whatever it weighs."""
+        self.assertEqual(ft.chunk_seconds(self.file(ft.UPLOAD_LIMIT * 2), 3600),
+                         ft.MAX_CHUNK_SECONDS)
+
+    def test_a_small_file_that_is_still_hours_long_is_cut_on_the_clock(self):
+        self.assertEqual(ft.chunk_seconds(self.file(1024), 7200),
+                         ft.MAX_CHUNK_SECONDS)
+
+    def test_a_file_short_enough_on_both_counts_is_not_cut(self):
+        self.assertEqual(ft.chunk_seconds(self.file(1024), ft.MAX_CHUNK_SECONDS), 0.0)
 
     def test_a_file_with_no_length_is_left_whole(self):
         self.assertEqual(ft.chunk_seconds(self.file(ft.UPLOAD_LIMIT * 2), 0), 0.0)
@@ -378,6 +390,58 @@ class Transcriber(DikteTest):
         worker.stop()
         self.assertTrue(worker._abort.aborted)
 
+    def test_a_chunk_is_given_longer_to_answer_than_a_dictation(self):
+        """A quarter hour of audio is not a sentence: the default would cut it off."""
+        worker = ft.FileTranscriber(self.conf)
+        with mock.patch.object(ft, "_to_wav", side_effect=lambda *a: self.source), \
+                mock.patch.object(ft, "_to_mp3",
+                                  side_effect=lambda path, *a, **k: path), \
+                mock.patch.object(ft.shutil, "which", return_value="/usr/bin/ffmpeg"), \
+                mock.patch.object(api, "transcribe", return_value="text") as call:
+            worker._work(self.source, False, False)
+        self.assertEqual(call.call_args.kwargs["timeout"], ft.HOSTED_TIMEOUT)
+
+    def test_a_gateway_having_a_bad_moment_is_asked_again(self):
+        with mock.patch.object(ft.FileTranscriber, "_wait"):
+            done, failures, progress, _ = self.run_chain(
+                fail=[api.ApiError("HTTP 502: timeout", 502), "raw text"])
+        self.assertEqual(failures, [])
+        self.assertEqual(done[0][0], "raw text")
+        self.assertTrue(any("Trying again" in message for message in progress))
+
+    def test_a_rejected_key_is_not_asked_again(self):
+        """Trying again with the same key is only a slower way to fail."""
+        call = mock.Mock(side_effect=api.ApiError("rejected the API key", 401))
+        with mock.patch.object(ft.FileTranscriber, "_wait"):
+            _, failures, _, _ = self.run_chain(fail=call)
+        self.assertEqual(call.call_count, 1)
+        self.assertIn("rejected", failures[0])
+
+    def test_a_chunk_is_given_up_on_after_the_last_try(self):
+        call = mock.Mock(side_effect=api.ApiError("HTTP 502: timeout", 502))
+        with mock.patch.object(ft.FileTranscriber, "_wait"):
+            _, failures, _, _ = self.run_chain(fail=call)
+        self.assertEqual(call.call_count, ft.RETRIES)
+        self.assertIn("502", failures[0])
+
+    def test_what_was_heard_before_the_failure_is_still_handed_over(self):
+        """An hour already transcribed is not thrown away over the chunk after it."""
+        boom = api.ApiError("HTTP 502: timeout", 502)
+        with mock.patch.object(ft.FileTranscriber, "_wait"), \
+                mock.patch.object(ft.FileTranscriber, "_chunks",
+                                  side_effect=lambda wav, *a: [(wav, 0.0), (wav, 10.0)]):
+            done, failures, _, _ = self.run_chain(
+                fail=["first half"] + [boom] * ft.RETRIES)
+        self.assertEqual(done[0][0], "first half")
+        self.assertIn("502", failures[0])
+
+    def test_nothing_heard_at_all_is_a_plain_failure(self):
+        call = mock.Mock(side_effect=api.ApiError("rejected the API key", 401))
+        with mock.patch.object(ft.FileTranscriber, "_wait"):
+            done, failures, _, _ = self.run_chain(fail=call)
+        self.assertEqual(done, [])
+        self.assertEqual(failures[0], "rejected the API key")
+
     def test_a_second_start_while_one_is_running_is_ignored(self):
         worker = ft.FileTranscriber(self.conf)
         worker._thread = mock.Mock(is_alive=lambda: True)