sweep: name voice-daemon magic numbers, drop dead keep-alive vars (V-581)

mavsttd/whisper_handler.go: name the no_speech_prob confidence-zeroing
floor (0.9) and the whisper thread count (4), both previously bare
literals with no reason attached.

mavttsd/piper_handler.go: name piper's render rate (22050) and the
canonical wire rate (16000) used by the resampler, instead of repeating
the two numbers inline four times.

mavenclient/main.go: remove the strconv/io/net/time imports and their
`var _ = ...` keep-alive lines — dead weight with no caller, not future
scaffolding.

Behaviour-preserving; no test changed. go test -race ./internal/...
./cmd/... is green.

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