Let mavwaked hear the nudges it was already being sent (V-671)

It wired no PushHandler, and SendRequest discards a push frame when there
is none. That was not a missing feature but a silent one. mavend routes a
nudge to the voice session that spoke most recently, so once mavwaked had
spoken once it WAS that session. PushToMostRecent succeeded, the
dispatcher counted the nudge delivered and stopped rerouting to the away
channels, and mavwaked threw the audio away. He heard nothing, anywhere.

It now connects at startup rather than at the first utterance, because
the dispatcher has to tell "he is not at the machine" from "he is, and
she has nothing to say". The receiver redials on its own clock, since
mavend restarts on every deploy.

A nudge is queued, not played where it arrives. The capture loop picks it
up on the next frame, so the half-duplex gate and barge-in cover it the
way they cover a reply. It resets the VAD first: playback is about to
suppress every frame, and a half-heard sentence would otherwise splice
onto whatever he says next. A nudge arriving while one still waits
replaces it, which is the contract internal/voice states for PushHandler.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013ptwopxyo3Z2kwFckHkLvN

cmd/mavwaked/session.go

@@ -7,6 +7,7 @@ package main
 import (
 	"context"
 	"log"
+	"sync"
 	"time"
 
 	"github.com/kami/maven/internal/audio"
@@ -62,11 +63,19 @@ type session struct {
 	// whenever playback ends.
 	loudFrames int
 
+	// pending holds a nudge the push receiver handed over, waiting for the
+	// capture loop to speak it. It is the one field written from another
+	// goroutine, hence the mutex; everything else in this struct belongs to
+	// the capture loop alone.
+	nudgeMu sync.Mutex
+	pending *audio.Audio
+
 	// counters, read by tests and logged on the way out.
 	suppressed int // frames dropped because she was speaking
 	dropped    int // frames dropped as round-trip backlog
 	bargeIns   int // times playback was cut because he spoke over her
 	sent       int // utterances shipped to the daemon
+	nudges     int // proactive pushes spoken through the speaker
 
 	// loudSum and loudSeen accumulate the energy of suppressed frames, so
 	// the operator can read what the room actually measures and set
@@ -150,6 +159,10 @@ func (s *session) feed(ctx context.Context, frame []byte) error {
 		s.vad.Reset()
 	}
 
+	if s.startPendingNudge() {
+		return nil
+	}
+
 	utt, state := s.vad.Feed(PCMToI16(frame))
 	if state == StateSpeech || utt.Bytes == nil {
 		return nil
@@ -157,6 +170,54 @@ func (s *session) feed(ctx context.Context, frame []byte) error {
 	return s.dispatch(ctx, utt)
 }
 
+// Nudge hands proactive audio to the session, to be spoken as soon as the
+// capture loop finds a quiet moment. Safe to call from the push receiver
+// goroutine; nothing else here is.
+//
+// A nudge arriving while one is already waiting REPLACES it. That is the
+// contract internal/voice states for PushHandler: the next nudge replaces the
+// stale one in his attention rather than dogpiling on it.
+func (s *session) Nudge(a audio.Audio) {
+	if len(a.Bytes) == 0 {
+		return
+	}
+	s.nudgeMu.Lock()
+	if s.pending != nil {
+		log.Printf("mavwaked: nudge replaced one still waiting to be spoken")
+	}
+	s.pending = &a
+	s.nudgeMu.Unlock()
+}
+
+// takeNudge removes and returns the waiting nudge, or nil.
+func (s *session) takeNudge() *audio.Audio {
+	s.nudgeMu.Lock()
+	defer s.nudgeMu.Unlock()
+	a := s.pending
+	s.pending = nil
+	return a
+}
+
+// startPendingNudge speaks a waiting nudge and reports whether it started
+// one. It runs on the capture loop, past the half-duplex gate, so a nudge
+// never cuts across a reply and never plays into a backlog drain.
+//
+// The VAD is reset first. Playback is about to suppress every frame until it
+// ends, and a half-heard sentence left in the VAD would splice onto whatever
+// he says afterwards. Barge-in needs no special case: it reads the player,
+// and the player does not care which audio it is playing.
+func (s *session) startPendingNudge() bool {
+	a := s.takeNudge()
+	if a == nil {
+		return false
+	}
+	s.vad.Reset()
+	s.nudges++
+	log.Printf("mavwaked: speaking nudge (%.2fs audio)", a.Duration())
+	s.player.Play(*a)
+	return true
+}
+
 // keepRecent stores a copy of one barge-in trigger frame, keeping at most
 // barge.Frames of them.
 func (s *session) keepRecent(frame []byte) {