internal/stt/http.go

@@ -0,0 +1,92 @@
+package stt
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+	"strconv"
+	"time"
+
+	"github.com/kami/maven/internal/audio"
+)
+
+// HTTPTranscriber — speech-to-text on another host, over HTTP.
+//
+// mavsttd is whisper.cpp linked into a Go daemon and reached over a unix
+// socket. CrisperWhisper 2.0 cannot be reached that way: whisper.cpp derives
+// its language count from the vocabulary size, and CW2's 51897 tokens shift
+// seven special token ids. It runs under transformers instead, as a service
+// beside the model on workpc. See docs/evals/2026-08-09-crisperwhisper2-russian-wer.md.
+//
+// So this is the second transport for the same seam, not a second seam. The
+// caller still sees stt.Transcriber and one method.
+type HTTPTranscriber struct {
+	url   string
+	token string
+	lang  string
+	http  *http.Client
+}
+
+// NewHTTPTranscriber builds the remote client. token may be empty for a
+// service on a trusted socket, but audio is the most sensitive thing that
+// crosses this seam, so a LAN deployment should always set one.
+func NewHTTPTranscriber(url, token, lang string, timeout time.Duration) *HTTPTranscriber {
+	return &HTTPTranscriber{
+		url:   url,
+		token: token,
+		lang:  lang,
+		http:  &http.Client{Timeout: timeout},
+	}
+}
+
+// ErrFormat — the audio is not the one canonical shape. Refused at the seam
+// rather than sent to a model that expects something else.
+var ErrFormat = errors.New("stt: audio is not 16kHz mono pcm_s16le")
+
+type httpTranscript struct {
+	Text       string  `json:"text"`
+	Confidence float64 `json:"confidence"`
+}
+
+// Transcribe posts the raw PCM and reads back the text.
+//
+// The body is the PCM bytes themselves rather than JSON. A minute of 16kHz
+// mono is under 2MB raw and about 2.6MB base64, and the format is fixed by
+// audio.PCM16kMono, so a header carries it more cheaply than an envelope.
+func (t *HTTPTranscriber) Transcribe(ctx context.Context, a audio.Audio) (string, float64, error) {
+	if !a.Format.IsValid() {
+		return "", 0, ErrFormat
+	}
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, t.url, bytes.NewReader(a.Bytes))
+	if err != nil {
+		return "", 0, fmt.Errorf("stt: build request: %w", err)
+	}
+	req.Header.Set("Content-Type", "application/octet-stream")
+	req.Header.Set("X-Sample-Rate", strconv.Itoa(a.Format.SampleRate))
+	req.Header.Set("X-Channels", strconv.Itoa(a.Format.Channels))
+	req.Header.Set("X-Sample-Bits", strconv.Itoa(a.Format.SampleBits))
+	req.Header.Set("X-Language", t.lang)
+	if t.token != "" {
+		req.Header.Set("Authorization", "Bearer "+t.token)
+	}
+
+	resp, err := t.http.Do(req)
+	if err != nil {
+		return "", 0, fmt.Errorf("stt: post audio: %w", err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		return "", 0, fmt.Errorf("stt: remote returned %d", resp.StatusCode)
+	}
+
+	var out httpTranscript
+	if err := json.NewDecoder(resp.Body).Decode(&out); err != nil {
+		return "", 0, fmt.Errorf("stt: decode transcript: %w", err)
+	}
+	return out.Text, out.Confidence, nil
+}
+
+var _ Transcriber = (*HTTPTranscriber)(nil)

internal/stt/http_test.go

@@ -0,0 +1,89 @@
+package stt
+
+import (
+	"context"
+	"errors"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"strconv"
+	"testing"
+	"time"
+
+	"github.com/kami/maven/internal/audio"
+)
+
+func TestHTTPTranscriberSendsRawPCM(t *testing.T) {
+	t.Parallel()
+	var gotBody []byte
+	var gotHeader http.Header
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		gotBody, _ = io.ReadAll(r.Body)
+		gotHeader = r.Header.Clone()
+		w.Header().Set("Content-Type", "application/json")
+		_, _ = io.WriteString(w, `{"text":"привет","confidence":0.82}`)
+	}))
+	defer srv.Close()
+
+	a := audio.Audio{Format: audio.PCM16kMono, Bytes: []byte("pcm-bytes")}
+	tr := NewHTTPTranscriber(srv.URL, "s3cret", "ru", 2*time.Second)
+	text, conf, err := tr.Transcribe(context.Background(), a)
+	if err != nil {
+		t.Fatalf("Transcribe: %v", err)
+	}
+	if text != "привет" || conf != 0.82 {
+		t.Fatalf("got %q %v", text, conf)
+	}
+	if string(gotBody) != "pcm-bytes" {
+		t.Fatalf("body should be the PCM itself, got %q", gotBody)
+	}
+	if got := gotHeader.Get("X-Sample-Rate"); got != strconv.Itoa(audio.PCM16kMono.SampleRate) {
+		t.Fatalf("X-Sample-Rate = %q", got)
+	}
+	if got := gotHeader.Get("X-Language"); got != "ru" {
+		t.Fatalf("X-Language = %q", got)
+	}
+	// Audio is the most sensitive thing crossing this seam.
+	if got := gotHeader.Get("Authorization"); got != "Bearer s3cret" {
+		t.Fatalf("Authorization = %q", got)
+	}
+}
+
+func TestHTTPTranscriberOmitsEmptyToken(t *testing.T) {
+	t.Parallel()
+	var auth string
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		auth = r.Header.Get("Authorization")
+		_, _ = io.WriteString(w, `{"text":"x"}`)
+	}))
+	defer srv.Close()
+	a := audio.Audio{Format: audio.PCM16kMono, Bytes: []byte("x")}
+	if _, _, err := NewHTTPTranscriber(srv.URL, "", "ru", time.Second).Transcribe(context.Background(), a); err != nil {
+		t.Fatalf("Transcribe: %v", err)
+	}
+	if auth != "" {
+		t.Fatalf("Authorization should be absent, got %q", auth)
+	}
+}
+
+func TestHTTPTranscriberRefusesWrongFormat(t *testing.T) {
+	t.Parallel()
+	a := audio.Audio{Format: audio.Format{SampleRate: 44100, Channels: 2, SampleBits: 16, Encoding: "pcm_s16le"}}
+	_, _, err := NewHTTPTranscriber("http://example.invalid", "", "ru", time.Second).Transcribe(context.Background(), a)
+	if !errors.Is(err, ErrFormat) {
+		t.Fatalf("want ErrFormat, got %v", err)
+	}
+}
+
+func TestHTTPTranscriberErrorsOnBadStatus(t *testing.T) {
+	t.Parallel()
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		w.WriteHeader(http.StatusUnauthorized)
+	}))
+	defer srv.Close()
+	a := audio.Audio{Format: audio.PCM16kMono, Bytes: []byte("x")}
+	_, _, err := NewHTTPTranscriber(srv.URL, "", "ru", time.Second).Transcribe(context.Background(), a)
+	if err == nil {
+		t.Fatal("a 401 must be an error, so the Pair falls back")
+	}
+}