Merge the voice daemon sweep: four named values, one dead import block (#239)

Read all of mavsttd, mavttsd, mavwaked and mavenclient. What changed is small
and behaviour-preserving: whisperThreads and noSpeechFloor named in
whisper_handler.go, piperSampleRate and targetSampleRate named in
piper_handler.go where 22050 and 16000 were repeated four times across the
resampler, and mavenclient/main.go lost four imports kept alive by var _ lines
for helpers that never arrived.

Three things the sweep checked and found already right, which is why they are
worth recording. mavwaked's header says it has no wake-word model, which is
true and matches V-487 rather than being a drifted comment. whisperHandler.Close
does not race an in-flight Transcribe, because worker.Server.Close closes the
listener and then waits on the group before main's deferred Close runs. No
subprocess, pipe or CGO context leaks on an error path.

defaultSocket is genuinely duplicated between mavsttd and mavttsd and stays
that way: folding it means exporting an unexported config helper, which is a
larger change than this sweep's scope.

The agent refuted the brief's prediction of swallowed errors and leaked
handles. This file set had magic values and dead code instead.

(V-581)

cmd/mavenclient/main.go

@@ -31,15 +31,11 @@ import (
 	"errors"
 	"flag"
 	"fmt"
-	"io"
 	"log"
-	"net"
 	"os"
 	"os/signal"
 	"path/filepath"
-	"strconv"
 	"syscall"
-	"time"
 
 	"github.com/kami/maven/internal/audio"
 	"github.com/kami/maven/internal/voice"
@@ -155,9 +151,3 @@ func writeWAV(path string, a audio.Audio) error {
 // jsonUnmarshal — kept local rather than pulling encoding/json into main.go
 // top-level space.
 func jsonUnmarshal(b []byte, v any) error { return json.Unmarshal(b, v) }
-
-// keep strconv + io + net + time alive for future duration/size helpers.
-var _ = strconv.Atoi
-var _ io.Reader = (io.Reader)(nil)
-var _ = net.IPv4
-var _ = time.Second

cmd/mavsttd/whisper_handler.go

@@ -22,6 +22,18 @@ import (
 // to it before sending, so it's also the rate the silence gate assumes.
 const whisperSampleRate = 16000
 
+// whisperThreads — greedy decode is single-pass and this is a laptop CPU
+// (homesrv), not a server box; 4 was picked to leave headroom for the rest
+// of the daemons sharing the machine, not measured against a latency target.
+const whisperThreads = 4
+
+// noSpeechFloor — whisper's own no_speech_prob past this point means the
+// segment it transcribed is not speech (the model still emits token
+// probabilities for silence/noise, so a high avgLogProb-derived confidence
+// can coexist with a segment that should be zero). Read as "at least 90%
+// sure this was not speech."
+const noSpeechFloor = 0.9
+
 type whisperHandler struct {
 	ctx    *C.struct_whisper_context
 	minMs  int     // clips shorter than this are dropped (hallucination bait)
@@ -101,7 +113,7 @@ func (h *whisperHandler) Transcribe(ctx context.Context, req worker.TranscribeRe
 	params.print_realtime = false
 	params.print_timestamps = false
 	params.print_special = false
-	params.n_threads = C.int(4)
+	params.n_threads = C.int(whisperThreads)
 	params.single_segment = true
 
 	lang := C.CString(req.Lang)
@@ -162,7 +174,7 @@ func (h *whisperHandler) Transcribe(ctx context.Context, req worker.TranscribeRe
 	}
 
 	noSpeechProb := float64(C.whisper_full_get_segment_no_speech_prob(h.ctx, 0))
-	if noSpeechProb > 0.9 {
+	if noSpeechProb > noSpeechFloor {
 		confidence = 0
 	}
 

cmd/mavttsd/piper_handler.go

@@ -116,18 +116,27 @@ func (h *piperHandler) Synthesize(ctx context.Context, req worker.SynthesizeReq)
 	}, nil
 }
 
-// resample22050To16000 converts raw 16-bit PCM from 22050 Hz to 16000 Hz
-// using linear interpolation.
+// piperSampleRate is the rate piper's onnx voices render at (ru_RU-irina and
+// the other models this daemon has been pointed at). targetSampleRate is the
+// canonical maven wire rate (audio.PCM16kMono) that every downstream
+// consumer — playback, the voice wire, whisper on the way back in — expects.
+const (
+	piperSampleRate  = 22050
+	targetSampleRate = 16000
+)
+
+// resample22050To16000 converts raw 16-bit PCM from piperSampleRate to
+// targetSampleRate using linear interpolation.
 func resample22050To16000(input []byte) []byte {
 	if len(input) < 2 {
 		return nil
 	}
 
 	nSamples := len(input) / 2
-	outSamples := int(float64(nSamples) * 16000.0 / 22050.0)
+	outSamples := int(float64(nSamples) * float64(targetSampleRate) / float64(piperSampleRate))
 	output := make([]byte, outSamples*2)
 
-	ratio := 22050.0 / 16000.0
+	ratio := float64(piperSampleRate) / float64(targetSampleRate)
 
 	for i := 0; i < outSamples; i++ {
 		srcPos := float64(i) * ratio