test(transcribe): rebuild Text from segments so a split word is not broken (red)

Found by comparing the first real one-hour transcript against pianissimo:
whisper.cpp wraps at ~60 chars and can wrap INSIDE a word. The continuation
segment has no leading space, the text field joins segments with newlines, and
a segment can be a lone '.'. Measured 2026-10-01: 7% of segments (96/1332) in a
synthetic hour, 42/1302 lines in the real one. My earlier tests used short
sentences and could not see it. berget's segments are whole sentences with no
leading space, so the two backends need different joins.

Red: Text still joins by newline.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

internal/adapters/transcribe/gateway_test.go

@@ -121,7 +121,7 @@ func TestGateway_NormalisesTheVerboseJSONResponse(t *testing.T) {
 	got, err := g.Transcribe(context.Background(), wavFile(t, "x"))
 
 	require.NoError(t, err)
-	assert.Equal(t, "God morgon allihopa.\n Vi går igenom läget.", got.Text)
+	assert.Equal(t, "God morgon allihopa. Vi går igenom läget.", got.Text)
 	assert.Equal(t, "iguana/kb-whisper", got.Endpoint, "the serving endpoint is part of the result")
 	assert.InDelta(t, 4.25, got.AudioSeconds, 1e-9)
 	assert.Equal(t, []domain.Segment{
@@ -172,3 +172,61 @@ func TestGateway_MissingAudioFileIsAnError(t *testing.T) {
 
 	assert.Error(t, err)
 }
+
+// whisper.cpp wraps its output at ~60 characters, and a wrap can land INSIDE a word:
+// the continuation segment has no leading space, the `text` field joins segments
+// with newlines, and a segment can be a lone ".". Measured on real gateway output
+// 2026-10-01: 7% of a one-hour recording's segments were such fragments. Joining by
+// newline hands the chat model broken words ("nyt\nt"), so Text is rebuilt from the
+// segments: a segment that begins with a space starts a new word, one that does not
+// continues the previous one.
+func TestGateway_RejoinsWordsWhisperCppSplitAcrossSegments(t *testing.T) {
+	reply := `{
+	  "text": " Vi ligger just nu 12 procent över den ursprungliga kalkylen\n.\n Det kräver ett nyt\nt godkännande från beställaren.\n Framförallt på arbetspl\natsen.\n",
+	  "language": "swedish", "duration": 20,
+	  "segments": [
+	    {"start": 0, "end": 4, "text": " Vi ligger just nu 12 procent över den ursprungliga kalkylen"},
+	    {"start": 4, "end": 5, "text": "."},
+	    {"start": 5, "end": 8, "text": " Det kräver ett nyt"},
+	    {"start": 8, "end": 11, "text": "t godkännande från beställaren."},
+	    {"start": 11, "end": 14, "text": " Framförallt på arbetspl"},
+	    {"start": 14, "end": 16, "text": "atsen."}
+	  ]}`
+	srv := serve(t, 200, reply, nil)
+	g := transcribe.NewGateway(srv.URL+"/v1", "k", "iguana/kb-whisper", srv.Client())
+
+	got, err := g.Transcribe(context.Background(), wavFile(t, "x"))
+
+	require.NoError(t, err)
+	assert.Equal(t, "Vi ligger just nu 12 procent över den ursprungliga kalkylen. "+
+		"Det kräver ett nytt godkännande från beställaren. Framförallt på arbetsplatsen.", got.Text)
+	assert.Len(t, got.Segments, 6, "the timed segments are kept as the backend gave them (trimmed)")
+	assert.Equal(t, ".", got.Segments[1].Text)
+}
+
+func TestGateway_SentenceLevelSegmentsWithNoLeadingSpaceAreJoinedWithASpace(t *testing.T) {
+	// berget/kb-whisper returns whole sentences with no leading space; rebuilding by
+	// concatenation would glue them ("allihopa!Vi").
+	reply := `{"text": "God morgon allihopa!\nVi går igenom läget.", "language": "sv", "duration": 5,
+	  "segments": [
+	    {"start": 0.05, "end": 1.2, "text": "God morgon allihopa!"},
+	    {"start": 1.6, "end": 4.2, "text": "Vi går igenom läget."}
+	  ]}`
+	srv := serve(t, 200, reply, nil)
+	g := transcribe.NewGateway(srv.URL+"/v1", "k", "berget/kb-whisper", srv.Client())
+
+	got, err := g.Transcribe(context.Background(), wavFile(t, "x"))
+
+	require.NoError(t, err)
+	assert.Equal(t, "God morgon allihopa! Vi går igenom läget.", got.Text)
+}
+
+func TestGateway_WithNoSegmentsTheTextFieldIsUsedWithWhitespaceCollapsed(t *testing.T) {
+	srv := serve(t, 200, `{"text": "  Hej  allihopa.\n Vi börjar.  ", "duration": 3, "segments": []}`, nil)
+	g := transcribe.NewGateway(srv.URL+"/v1", "k", "m", srv.Client())
+
+	got, err := g.Transcribe(context.Background(), wavFile(t, "x"))
+
+	require.NoError(t, err)
+	assert.Equal(t, "Hej allihopa. Vi börjar.", got.Text)
+}