Merge remote-tracking branch 'origin/master' into task/486-deploy-the-workstation-transcriber

Owner's call. E4B is 4.2GB against 6.7GB plus a 0.86GB draft, so with CW2
resident the card holds 5.8GB of 16GB instead of 9.2GB.

Measured against a same-session 12B control on the 96-case fixture: 83.3% full
against 84.4%, 89.6% intent-only against 91.7%, destination 19/33 against
23/33, p50 294ms against 344ms. Destination is the column that moved. E4B names
nothing where the 12B names recall or calendar, which walks the whole chain
rather than answering wrong.

MTP is gone with the 12B and cannot come back. It is a separate gguf of
architecture gemma4-assistant with nextn_predict_layers=4, and the only one on
disk is trained against the 12B's hidden states. Neither target gguf carries
nextn tensors, so neither self-speculates.

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

CLAUDE.md

@@ -47,6 +47,31 @@ free — `worldGap` in `cmd/mavend/worldmodel.go`, which the owner hears instead
 answer. A box with no `workstation` block behaves exactly as it did before the seam: naming
 a gap requires a gap. The offload table in `docs/offload.md` says which caller is which.
 
+**Speech-to-text moved on 2026-08-09** (V-486). `sttSeam` in `cmd/mavend/voicewire.go`
+builds an `stt.Pair` beside `modelSeam`, preferring CrisperWhisper 2.0 turbo on workpc
+with mavsttd as the floor. It takes only the silent half of the rule. A worse
+transcript is still a turn, so `stt.Pair` has no `TranscribeRemote`. The fallback is
+never spoken. CW2 turbo scores **10.4% WER in Russian against 27.5%** for the `ggml-small.bin`
+mavsttd loads, over 200 Golos clips
+(`docs/evals/2026-08-09-crisperwhisper2-russian-wer.md`). It runs in Intended mode, not
+Verbatim, though that corpus cannot separate the two.
+**whisper.cpp cannot load CW2 at all.** It reads its language count off the vocabulary
+size, and CW2's 51897 tokens shift seven special token ids. So it is not a second
+endpoint on mavgpud. It is its own transformers service on port 8081
+(`deploy/cw2/serve.py`), which Maven reaches directly. `stt.HTTPTranscriber`
+posts raw PCM to it with a bearer token, because audio is the most sensitive thing that
+crosses this seam. The switch is `workstation.stt` in
+`deploy/mavend.json`, and deleting the block sends every utterance to mavsttd.
+**mavgpud runs that service as a second child.** That is not an optimisation. CW2 is a
+ROCm process on the same card, so it registers on the KFD like any contender. Under its own
+systemd unit it made mavgpud evict llama-server every few seconds. That took the
+gemma-4-12b arm down for eight minutes on 2026-08-09 before anyone noticed. The card needs
+one owner. Any GPU service added beside this daemon has the same defect, so add it to
+`cmd/mavgpud` and not to systemd. CW2 is on the yield clock and not the idle one. At 1.6GB
+it denies the card to nobody, and unloading it would only send the next voice turn to the
+homesrv floor.
+Text-to-speech has not moved and piper on homesrv is still the only synthesizer.
+
 ## Build & test
 
 CGO daemons (`mavend`, `mavsttd`, `mavttsd`, `mavenclient`) need the vendored toolchain
@@ -230,11 +255,21 @@ re-run it, start a **second** llama-server on a fixed host port — the resident
 `--port 0` inside the container and no host process can reach it.
 
 **The numbers above are the homesrv floor, not the ceiling.** With the workstation up, routing
-completes through `llm.Pair` against gemma-4-12b and scores **84.4% full / 93.5% intent-only at
-p50 329ms** — better than the resident model and about 2.5× faster (`docs/evals/2026-08-02-workstation-gemma4-12b.md`,
-Vikunja #485). The workstation is never assumed up, so both sets of numbers are live. Judge a
+completes through `llm.Pair` against the model mavgpud holds, which is better than the resident
+model and about 2.5× faster. gemma-4-12b scored **84.4% full / 93.5% intent-only at p50 329ms**
+(`docs/evals/2026-08-02-workstation-gemma4-12b.md`, Vikunja #485). The workstation is never
+assumed up, so both sets of numbers are live. Judge a
 routing change against the classifier and the resident model, since those are what always answer.
 
+**The workstation runs gemma-4-E4B since 2026-08-09** (owner's call), and it is a
+step down measured the same day (`docs/evals/2026-08-09-e4b-vs-12b-routing.md`).
+Against a same-session 12B control it scores **83.3% full / 89.6% intent-only,
+destination 19/33 against 23/33, at p50 294ms against 344ms**. So it costs four
+destination cases and buys 50ms. Read destination as the finding: it names nothing
+where the 12B names `recall` or `calendar`, which is safe but walks the whole chain.
+It also has no MTP and cannot be given any here. The only `gemma4-assistant`
+draft on disk is trained against the 12B's hidden states.
+
 **The intended third engine is not a generative model** (owner's call, 05-08-2026, V-546,
 `docs/plans/18-routing-heads-on-e5-small.md`). Routing has a bounded output space, so it is
 classification, and the 118M multilingual-e5-small is already resident. Three heads on one

cmd/mavend/sttseam_test.go

@@ -0,0 +1,43 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/kami/maven/internal/config"
+	"github.com/kami/maven/internal/stt"
+)
+
+// A box with no workstation.stt block transcribes exactly as it did before the
+// seam existed: the floor is handed back untouched, and nothing probes.
+func TestSttSeamWithNoBlockIsTheFloor(t *testing.T) {
+	floor := stt.NewStub()
+	got, pair := sttSeam(&config.Config{}, floor)
+	if pair != nil {
+		t.Fatal("no block must build no pair")
+	}
+	if got != stt.Transcriber(floor) {
+		t.Fatal("no block must hand back the floor itself")
+	}
+}
+
+func TestSttSeamPrefersTheWorkstation(t *testing.T) {
+	cfg := &config.Config{Workstation: &config.WorkstationConfig{
+		URL: "http://127.0.0.1:1",
+		Stt: &config.WorkstationSttConfig{
+			URL:    "http://127.0.0.1:2/transcribe",
+			Health: "http://127.0.0.1:2/health",
+		},
+	}}
+	got, pair := sttSeam(cfg, stt.NewStub())
+	if pair == nil {
+		t.Fatal("a configured block must build a pair")
+	}
+	defer pair.Stop()
+	if got != stt.Transcriber(pair) {
+		t.Fatal("the pair is what callers must transcribe through")
+	}
+	// Nothing answers on port 2, so the seam is the floor until it does.
+	if pair.Available() {
+		t.Fatal("an unreachable workstation must not be available")
+	}
+}

cmd/mavend/voicewire.go

@@ -55,7 +55,11 @@ type voiceWiring struct {
 	// unless a `workstation` block names an address. Held here only so the
 	// prober is stopped on shutdown; callers were handed it at build time.
 	pair *llm.Pair
-	mcp  *mcpWiring
+	// sttPair — CrisperWhisper 2.0 on the workstation with mavsttd as the
+	// floor, nil unless the `workstation.stt` block names an address. Held for
+	// the same reason as pair: to stop its prober on shutdown.
+	sttPair *stt.Pair
+	mcp     *mcpWiring
 	// home — the Home Assistant client, nil unless the `smarthome` block is
 	// enabled (Vikunja #256). Its devices land in the same allowlist as every
 	// other act, so nothing else here has to know about it.
@@ -89,6 +93,9 @@ func (w *voiceWiring) close() {
 	if w.pair != nil {
 		w.pair.Stop()
 	}
+	if w.sttPair != nil {
+		w.sttPair.Stop()
+	}
 	w.mcp.close()
 }
 
@@ -117,6 +124,7 @@ func wireVoice(cfg *config.Config, coreAPI ipc.CoreAPI, phr phraser.Phraser, mem
 	} else {
 		transcriber = stt.NewStub()
 	}
+	transcriber, w.sttPair = sttSeam(cfg, transcriber)
 	w.transcriber = transcriber
 
 	// ----- tts (Stub in-process OR Remote) -----
@@ -390,6 +398,44 @@ func modelSeam(cfg *config.Config, resident *llm.Client) (router.Completer, *llm
 	return pair, pair
 }
 
+// sttSeam builds the transcription seam the voice path and the meeting
+// recorder share. It is modelSeam for audio and follows the same rule.
+//
+// With no `workstation.stt` block it hands back the floor untouched, which is
+// today's deploy exactly. With one, it is an stt.Pair preferring CrisperWhisper
+// 2.0 on workpc, which scores 10.4% WER in Russian against the floor's 27.5%
+// (docs/evals/2026-08-09-crisperwhisper2-russian-wer.md).
+//
+// Only the silent half of the degradation rule applies here. A worse transcript
+// is still a turn, so there is nothing to name a gap about and the fallback is
+// never spoken. That is why stt.Pair has no TranscribeRemote.
+func sttSeam(cfg *config.Config, floor stt.Transcriber) (stt.Transcriber, *stt.Pair) {
+	if cfg.Workstation == nil || cfg.Workstation.Stt == nil {
+		return floor, nil
+	}
+	s := cfg.Workstation.Stt
+	lang := ""
+	if cfg.Voice != nil {
+		lang = cfg.Voice.Lang
+		if cfg.Voice.Stt != nil && cfg.Voice.Stt.Lang != "" {
+			lang = cfg.Voice.Stt.Lang
+		}
+	}
+	pair := stt.NewPair(
+		stt.NewHTTPTranscriber(s.URL, s.Token, lang, time.Duration(s.Timeout)),
+		floor,
+		s.Health,
+		time.Duration(s.Probe),
+	)
+	pair.Start(context.Background())
+	if s.Token == "" {
+		log.Print("voice: the workstation transcriber has no token, so anything on the LAN can post audio to it")
+	}
+	log.Printf("voice: workstation transcriber at %s, probed every %s, mavsttd as the floor",
+		s.URL, time.Duration(s.Probe))
+	return pair, pair
+}
+
 func pickLLMRouter(enabled bool, c router.Completer) *router.LLMRouter {
 	if !enabled {
 		return nil

cmd/mavgpud/gpu.go

@@ -34,22 +34,31 @@ type probe struct {
 	drmDev  string
 }
 
-// foreign lists every ROCm process that is not ours. selfPID is the supervisor's
-// llama-server child, or 0 when it is not running.
+// foreign lists every ROCm process that is not ours. self holds the pids of the
+// supervisor's own children, and a child that is not running contributes 0.
+//
+// There is more than one child since 09-08-2026. CW2 registers on the KFD like
+// any ROCm job, so a supervisor that excluded only llama-server would read its
+// own transcriber as a contender, yield the card to it, and never keep a model
+// loaded again.
 //
 // An unreadable kfd tree returns no processes and no error. That is deliberate
 // and it is the safe direction only because startVRAM also has to agree before
 // anything launches: a supervisor that cannot see the KFD never sees free VRAM
 // either, because the CPT run holding the card shows up in the drm totals.
-func (p probe) foreign(selfPID int) []gpuProc {
+func (p probe) foreign(self ...int) []gpuProc {
 	entries, err := os.ReadDir(p.kfdRoot)
 	if err != nil {
 		return nil
 	}
+	mine := make(map[int]bool, len(self))
+	for _, pid := range self {
+		mine[pid] = true
+	}
 	var out []gpuProc
 	for _, e := range entries {
 		pid, err := strconv.Atoi(e.Name())
-		if err != nil || pid == selfPID {
+		if err != nil || mine[pid] {
 			continue
 		}
 		out = append(out, gpuProc{

cmd/mavgpud/gpu_test.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"context"
 	"net/http"
 	"net/http/httptest"
 	"net/url"
@@ -8,6 +9,7 @@ import (
 	"path/filepath"
 	"strconv"
 	"testing"
+	"time"
 )
 
 // fakeKFD builds the sysfs shape the workstation actually has: one directory
@@ -47,6 +49,24 @@ func TestForeignExcludesOurChild(t *testing.T) {
 	}
 }
 
+// The transcriber is a ROCm process on the same card, so it registers on the
+// KFD exactly like a contender does. Reading it as one is what happened on
+// 2026-08-09 while CW2 ran under its own systemd unit: mavgpud yielded, waited
+// five polls, loaded the model, yielded again, and never held it for a whole
+// minute. Excluding every child is the fix and this is the test of it.
+func TestForeignExcludesEveryChild(t *testing.T) {
+	p := probe{kfdRoot: fakeKFD(t, map[int]int64{478104: 12791693312, 999: 4096, 1001: 1717986918})}
+
+	ours := p.foreign(999, 1001)
+	if len(ours) != 1 || ours[0].PID != 478104 {
+		t.Fatalf("only the CPT run is a contender, got %+v", ours)
+	}
+	// A child that is not running reports pid 0, which must exclude nothing.
+	if got := p.foreign(999, 0); len(got) != 2 {
+		t.Errorf("a stopped child excludes nobody: got %d contenders, want 2", len(got))
+	}
+}
+
 // An empty KFD tree is the state that permits a start, so it must read as empty
 // rather than as an error the caller has to interpret.
 func TestForeignEmptyAndMissing(t *testing.T) {
@@ -81,7 +101,7 @@ func TestFreeVRAM(t *testing.T) {
 // rather than hanging or proxying into a closed port. Maven reads this endpoint
 // on a timer forever, including while the workstation is busy.
 func TestHealthAndProxyRefuseWhenNotReady(t *testing.T) {
-	s := &supervisor{run: newRunner("/bin/true", nil, "")}
+	s := &supervisor{run: newRunner("fake", "/bin/true", nil, "")}
 	h := s.handler(mustURL(t, "http://127.0.0.1:1"))
 
 	for _, path := range []string{"/health", "/v1/chat/completions"} {
@@ -101,3 +121,28 @@ func mustURL(t *testing.T, s string) *url.URL {
 	}
 	return u
 }
+
+// Yielding is all or nothing. A CPT run wants the whole card, so handing back
+// the language model while the transcriber keeps 1.6GB mapped would leave the
+// other job failing its allocation, which is the outcome yielding exists to
+// prevent.
+func TestYieldStopsEveryChild(t *testing.T) {
+	idle := "while : ; do sleep 1 ; done"
+	s := &supervisor{
+		cfg:   config{EvictAfter: 1, StopGrace: duration(2 * time.Second)},
+		probe: probe{kfdRoot: fakeKFD(t, map[int]int64{478104: 12791693312})},
+		run:   newRunner("llama-server", fakeServer(t, idle), nil, ""),
+		stt:   newRunner("cw2", fakeServer(t, idle), nil, ""),
+	}
+	for _, r := range s.children() {
+		if err := r.start(); err != nil {
+			t.Fatal(err)
+		}
+	}
+	s.tick(context.Background())
+	for _, r := range s.children() {
+		if r.running() {
+			t.Errorf("%s outlived the yield", r.name)
+		}
+	}
+}

cmd/mavgpud/main.go

@@ -10,6 +10,11 @@
 // the card. Not on demand, because a 7-14B takes tens of seconds to load and a
 // world question would be answered by a gap every time the card had been quiet.
 // Not always on, because that holds 16GB against the owner's own jobs.
+//
+// It supervises a second child since 09-08-2026, the CW2 transcriber, and for
+// one reason only: it is a ROCm process on the same card. Any GPU service the
+// owner leaves running beside this daemon reads as a contender and evicts the
+// model, so the card needs one owner rather than two neighbours.
 package main
 
 import (
@@ -36,6 +41,10 @@ type config struct {
 	// owner's business and not this daemon's schema.
 	LlamaArgs []string `json:"llama_args"`
 
+	// Stt is optional. Without it mavgpud supervises llama-server alone, which
+	// is everything it did before 09-08-2026.
+	Stt *sttConfig `json:"stt,omitempty"`
+
 	KFDRoot   string `json:"kfd_root"`
 	DRMDevice string `json:"drm_device"`
 
@@ -51,6 +60,22 @@ type config struct {
 	StartAfter int `json:"start_after_polls"`
 }
 
+// sttConfig is the CW2 transcriber, which mavgpud runs for one reason: it is a
+// ROCm process on this card. Left to its own systemd unit it registers on the
+// KFD, the supervisor reads it as a contender, and llama-server is evicted
+// within two polls and restarted five polls later, forever. That thrash was
+// observed on 2026-08-09 and it is what folded the service in here.
+//
+// Maven talks to it directly, not through this daemon. There is no proxy and no
+// idle timer: at 1.6GB it denies the card to nobody, and unloading it would only
+// send the next voice turn to the homesrv floor for no gain.
+type sttConfig struct {
+	// Addr is where the service binds, and it is read only to probe /health.
+	Addr string   `json:"addr"`
+	Bin  string   `json:"bin"`
+	Args []string `json:"args"`
+}
+
 func defaults() config {
 	return config{
 		Listen:      ":8080",
@@ -99,12 +124,18 @@ func main() {
 	}
 
 	base := "http://" + cfg.LlamaAddr
-	run := newRunner(cfg.LlamaBin, cfg.LlamaArgs, base+"/health")
+	run := newRunner("llama-server", cfg.LlamaBin, cfg.LlamaArgs, base+"/health")
 	sup := &supervisor{
 		cfg:   cfg,
 		probe: probe{kfdRoot: cfg.KFDRoot, drmDev: cfg.DRMDevice},
 		run:   run,
 	}
+	if s := cfg.Stt; s != nil {
+		if s.Bin == "" || s.Addr == "" {
+			log.Fatal("mavgpud: stt needs both bin and addr")
+		}
+		sup.stt = newRunner("cw2", s.Bin, s.Args, "http://"+s.Addr+"/health")
+	}
 	sup.touch()
 
 	ctx, cancel := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
@@ -129,13 +160,17 @@ func main() {
 	shut, done := context.WithTimeout(context.Background(), 5*time.Second)
 	defer done()
 	_ = srv.Shutdown(shut)
-	run.stop(time.Duration(cfg.StopGrace))
+	for _, r := range sup.children() {
+		r.stop(time.Duration(cfg.StopGrace))
+	}
 }
 
 type supervisor struct {
 	cfg   config
 	probe probe
 	run   *runner
+	// stt is the CW2 transcriber, or nil when the config names none.
+	stt *runner
 
 	lastReq atomic.Int64 // unix nanos of the last request Maven sent
 
@@ -198,7 +233,11 @@ func (s *supervisor) loop(ctx context.Context) {
 // allocates, so we see a contender during its startup rather than after it has
 // already failed to get the memory it wanted.
 func (s *supervisor) tick(ctx context.Context) {
-	others := s.probe.foreign(s.run.pid())
+	var pids []int
+	for _, r := range s.children() {
+		pids = append(pids, r.pid())
+	}
+	others := s.probe.foreign(pids...)
 	if len(others) > 0 {
 		s.foreignStreak++
 		s.clearStreak = 0
@@ -207,31 +246,65 @@ func (s *supervisor) tick(ctx context.Context) {
 		s.clearStreak++
 	}
 
-	if s.run.running() {
-		s.run.refreshReady(ctx)
-		switch {
-		case s.foreignStreak >= s.cfg.EvictAfter:
-			log.Printf("mavgpud: yielding the card to %s", describe(others))
-			s.run.stop(time.Duration(s.cfg.StopGrace))
-		case s.idle() > time.Duration(s.cfg.IdleTimeout):
-			log.Printf("mavgpud: idle for %s, unloading", s.idle().Round(time.Second))
-			s.run.stop(time.Duration(s.cfg.StopGrace))
+	// Yielding is all or nothing. A CPT run wants the whole card, and handing
+	// back 8GB while holding 1.6GB is the shape of a failed allocation.
+	if s.foreignStreak >= s.cfg.EvictAfter && s.anyRunning() {
+		log.Printf("mavgpud: yielding the card to %s", describe(others))
+		for _, r := range s.children() {
+			r.stop(time.Duration(s.cfg.StopGrace))
 		}
 		return
 	}
 
-	if s.clearStreak < s.cfg.StartAfter {
+	clear := s.clearStreak >= s.cfg.StartAfter
+
+	if s.run.running() {
+		s.run.refreshReady(ctx)
+		if s.idle() > time.Duration(s.cfg.IdleTimeout) {
+			log.Printf("mavgpud: idle for %s, unloading", s.idle().Round(time.Second))
+			s.run.stop(time.Duration(s.cfg.StopGrace))
+		}
+	} else if clear && s.probe.freeVRAM() >= s.cfg.MinFreeVRAM {
+		s.touch() // the idle clock starts at load, not at the last request before it
+		if err := s.run.start(); err != nil {
+			log.Printf("mavgpud: start llama-server: %v", err)
+		}
+	}
+
+	if s.stt == nil {
 		return
 	}
-	if free := s.probe.freeVRAM(); free < s.cfg.MinFreeVRAM {
+	if s.stt.running() {
+		s.stt.refreshReady(ctx)
 		return
 	}
-	s.touch() // the idle clock starts at load, not at the last request before it
-	if err := s.run.start(); err != nil {
-		log.Printf("mavgpud: start llama-server: %v", err)
+	// No VRAM precondition here, unlike llama-server. That check exists because
+	// a 12B refuses to load when the card is short, and 1.6GB fits wherever the
+	// KFD is clear. Reading free VRAM would also block the transcriber for good
+	// once the language model was resident, since it holds more than the floor.
+	if clear {
+		if err := s.stt.start(); err != nil {
+			log.Printf("mavgpud: start cw2: %v", err)
+		}
 	}
 }
 
+func (s *supervisor) children() []*runner {
+	if s.stt == nil {
+		return []*runner{s.run}
+	}
+	return []*runner{s.run, s.stt}
+}
+
+func (s *supervisor) anyRunning() bool {
+	for _, r := range s.children() {
+		if r.running() {
+			return true
+		}
+	}
+	return false
+}
+
 // describe names the contenders in the log. This log is the instrument for the
 // open question in #488: whether polling the KFD misses a job that wants the
 // card without registering there.

cmd/mavgpud/runner.go

@@ -10,14 +10,18 @@ import (
 	"time"
 )
 
-// runner owns one llama-server process. Owning it is the point of the daemon:
-// the workstation cannot keep a 7-14B resident, because that holds 16GB against
+// runner owns one GPU process. Owning it is the point of the daemon: the
+// workstation cannot keep a 7-14B resident, because that holds 16GB against
 // the owner's CPT runs, Correx and the manga-recap pipeline. So the thing that
 // stays up is this, which costs no VRAM, and the model comes and goes under it.
+//
+// There are two of them since 09-08-2026: llama-server and the CW2 transcriber.
+// name is what the log calls this one.
 type runner struct {
+	name string
 	bin  string
 	args []string
-	// ready is llama-server's own /health, which answers "is a model loaded".
+	// ready is the child's own /health, which answers "is a model loaded".
 	// Loading a 7-14B takes tens of seconds, so started is not ready.
 	readyURL string
 
@@ -32,9 +36,9 @@ type runner struct {
 	http     *http.Client
 }
 
-func newRunner(bin string, args []string, readyURL string) *runner {
+func newRunner(name, bin string, args []string, readyURL string) *runner {
 	return &runner{
-		bin: bin, args: args, readyURL: readyURL,
+		name: name, bin: bin, args: args, readyURL: readyURL,
 		http: &http.Client{Timeout: 2 * time.Second},
 	}
 }
@@ -60,7 +64,7 @@ func (r *runner) isReady() bool {
 	return r.ready
 }
 
-// start launches llama-server. It returns as soon as the process exists, not
+// start launches the child. It returns as soon as the process exists, not
 // when the model is loaded.
 func (r *runner) start() error {
 	r.mu.Lock()
@@ -76,7 +80,7 @@ func (r *runner) start() error {
 		return err
 	}
 	r.cmd, r.ready, r.yielding = cmd, false, false
-	log.Printf("mavgpud: started llama-server pid=%d", cmd.Process.Pid)
+	log.Printf("mavgpud: started %s pid=%d", r.name, cmd.Process.Pid)
 	go func() {
 		err := cmd.Wait()
 		r.mu.Lock()
@@ -84,15 +88,15 @@ func (r *runner) start() error {
 		r.cmd, r.ready, r.yielding = nil, false, false
 		r.mu.Unlock()
 		if yielded {
-			log.Printf("mavgpud: llama-server stopped, card yielded (%v)", err)
+			log.Printf("mavgpud: %s stopped, card yielded (%v)", r.name, err)
 			return
 		}
-		log.Printf("mavgpud: llama-server exited: %v", err)
+		log.Printf("mavgpud: %s exited: %v", r.name, err)
 	}()
 	return nil
 }
 
-// stop ends llama-server and waits for the VRAM to come back. SIGTERM first so
+// stop ends the child and waits for the VRAM to come back. SIGTERM first so
 // it unmaps cleanly, SIGKILL after the grace window. Returning before the
 // process is gone would let the supervisor report a free card while 14GB is
 // still mapped, which is the one lie that would make yielding useless.
@@ -117,11 +121,11 @@ func (r *runner) stop(grace time.Duration) {
 		}
 		time.Sleep(100 * time.Millisecond)
 	}
-	log.Printf("mavgpud: llama-server did not exit in %s, killing", grace)
+	log.Printf("mavgpud: %s did not exit in %s, killing", r.name, grace)
 	_ = syscall.Kill(pgid, syscall.SIGKILL)
 }
 
-// refreshReady asks llama-server whether the model is loaded. Called once per
+// refreshReady asks the child whether the model is loaded. Called once per
 // supervisor tick, never per request.
 func (r *runner) refreshReady(ctx context.Context) {
 	if !r.running() {
@@ -141,6 +145,6 @@ func (r *runner) refreshReady(ctx context.Context) {
 	r.ready = ok
 	r.mu.Unlock()
 	if ok && !was {
-		log.Printf("mavgpud: model ready")
+		log.Printf("mavgpud: %s ready", r.name)
 	}
 }

cmd/mavgpud/runner_test.go

@@ -25,7 +25,7 @@ func fakeServer(t *testing.T, body string) string {
 // status of a routine yield is identical to that of a real crash. Reading the
 // mavgpud log, the two were indistinguishable (Vikunja #491).
 func TestStopMarksTheExitAsAYield(t *testing.T) {
-	r := newRunner(fakeServer(t, "while : ; do sleep 1 ; done"), nil, "")
+	r := newRunner("fake", fakeServer(t, "while : ; do sleep 1 ; done"), nil, "")
 	if err := r.start(); err != nil {
 		t.Fatalf("start: %v", err)
 	}
@@ -49,7 +49,7 @@ func TestStopMarksTheExitAsAYield(t *testing.T) {
 // Stopping when nothing is running must not arm the flag for the next child.
 // The next exit after that would be a real crash logged as a yield.
 func TestStopWithNoChildDoesNotArmTheFlag(t *testing.T) {
-	r := newRunner("/nonexistent", nil, "")
+	r := newRunner("fake", "/nonexistent", nil, "")
 	r.stop(10 * time.Millisecond)
 	r.mu.Lock()
 	defer r.mu.Unlock()

deploy/cw2/serve.py

@@ -0,0 +1,156 @@
+"""CrisperWhisper 2.0 turbo as an HTTP service, for Maven's stt.Pair.
+
+Two endpoints and no framework.
+
+  GET  /health      200 once the model is loaded, 503 while it is loading.
+  POST /transcribe  raw 16kHz mono PCM in, {"text","confidence"} out.
+
+The body is the PCM itself rather than JSON. A minute of 16kHz mono is under
+2MB raw and about 2.6MB base64, and the format is fixed at the Maven seam, so
+headers carry it more cheaply than an envelope.
+
+Why this exists at all: whisper.cpp cannot load CW2. It derives its language
+count from the vocabulary size, and CW2's 51897 tokens shift seven special
+token ids. So mavsttd stays whisper.cpp on homesrv and this runs beside the
+model on workpc, where it scores 10.4% WER in Russian against the floor's 27.5%
+(docs/evals/2026-08-09-crisperwhisper2-russian-wer.md in the Maven repo).
+
+Intended mode, not verbatim. The owner asked for what he meant to say, not
+every stutter on the way there.
+"""
+
+import hmac
+import json
+import logging
+import os
+import sys
+import threading
+import time
+from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
+
+import numpy as np
+
+HOST = os.environ.get("CW2_HOST", "0.0.0.0")
+PORT = int(os.environ.get("CW2_PORT", "8081"))
+SIZE = os.environ.get("CW2_SIZE", "turbo")
+MODE = os.environ.get("CW2_MODE", "intended")
+TOKEN = os.environ.get("CW2_TOKEN", "")
+# 25MB is about thirteen minutes of 16kHz mono. Longer than any utterance and
+# short enough that a wrong caller cannot exhaust memory.
+MAX_BODY = int(os.environ.get("CW2_MAX_BODY", str(25 * 1024 * 1024)))
+
+logging.basicConfig(
+    level=logging.INFO, format="%(asctime)s cw2: %(message)s", stream=sys.stderr
+)
+log = logging.getLogger("cw2")
+
+_model = None
+# The card holds one model and transcribes one utterance at a time. The lock is
+# what makes a second caller wait rather than corrupt the first.
+_lock = threading.Lock()
+
+
+def load_model():
+    global _model
+    from crisperwhisper import CrisperWhisperModel
+
+    t0 = time.perf_counter()
+    # backend is forced. With ctranslate2 importable, "auto" picks ct2, which is
+    # CUDA-only and this card is AMD.
+    m = CrisperWhisperModel(
+        SIZE, backend="transformers", compute_type="float16", device="cuda"
+    )
+    _model = m
+    log.info("loaded %s in %.1fs, mode=%s", SIZE, time.perf_counter() - t0, MODE)
+
+
+def authorised(headers):
+    if not TOKEN:
+        return True
+    got = headers.get("Authorization", "")
+    return hmac.compare_digest(got, "Bearer " + TOKEN)
+
+
+class Handler(BaseHTTPRequestHandler):
+    protocol_version = "HTTP/1.1"
+
+    def log_message(self, fmt, *args):
+        log.info(fmt, *args)
+
+    def _send(self, code, payload):
+        body = json.dumps(payload, ensure_ascii=False).encode("utf-8")
+        self.send_response(code)
+        self.send_header("Content-Type", "application/json; charset=utf-8")
+        self.send_header("Content-Length", str(len(body)))
+        self.end_headers()
+        self.wfile.write(body)
+
+    def do_GET(self):
+        if self.path.rstrip("/") != "/health":
+            self._send(404, {"error": "not found"})
+            return
+        if _model is None:
+            self._send(503, {"status": "loading"})
+            return
+        self._send(200, {"status": "ok", "model": SIZE, "mode": MODE})
+
+    def do_POST(self):
+        if self.path.rstrip("/") != "/transcribe":
+            self._send(404, {"error": "not found"})
+            return
+        if not authorised(self.headers):
+            self._send(401, {"error": "unauthorised"})
+            return
+        if _model is None:
+            self._send(503, {"error": "loading"})
+            return
+
+        length = int(self.headers.get("Content-Length", "0"))
+        if length <= 0 or length > MAX_BODY:
+            self._send(413, {"error": "bad body length"})
+            return
+        raw = self.rfile.read(length)
+
+        rate = int(self.headers.get("X-Sample-Rate", "16000"))
+        channels = int(self.headers.get("X-Channels", "1"))
+        bits = int(self.headers.get("X-Sample-Bits", "16"))
+        lang = self.headers.get("X-Language", "ru") or "ru"
+        if channels != 1 or bits != 16:
+            self._send(400, {"error": "want 16-bit mono pcm"})
+            return
+
+        # int16 little-endian to the float32 the encoder wants.
+        wav = np.frombuffer(raw, dtype="<i2").astype(np.float32) / 32768.0
+        if wav.size == 0:
+            self._send(200, {"text": "", "confidence": 0.0})
+            return
+
+        t0 = time.perf_counter()
+        try:
+            with _lock:
+                res = _model.transcribe(wav, sr=rate, language=lang, mode=MODE)
+        except Exception as exc:  # noqa: BLE001 - the caller falls back to mavsttd
+            log.exception("transcribe failed")
+            self._send(500, {"error": str(exc)})
+            return
+        elapsed = time.perf_counter() - t0
+        text = (res.text or "").strip()
+        log.info("%.2fs audio in %.2fs: %r", wav.size / rate, elapsed, text[:60])
+        # The model reports no calibrated score. 1.0 would be a claim, and the
+        # Maven side reads confidence only to log it.
+        self._send(200, {"text": text, "confidence": 0.0})
+
+
+def main():
+    if not TOKEN:
+        log.warning("no CW2_TOKEN set: anything on the LAN can post audio here")
+    # Bind before loading, so a restart answers 503 rather than refusing the
+    # connection. Both make Maven fall back, but only one of them says why.
+    srv = ThreadingHTTPServer((HOST, PORT), Handler)
+    threading.Thread(target=load_model, daemon=True).start()
+    log.info("listening on %s:%d", HOST, PORT)
+    srv.serve_forever()
+
+
+if __name__ == "__main__":
+    main()

deploy/mavend.json

@@ -78,10 +78,30 @@
     "Addressed by LAN address, not container name: mavgpud runs on another",
     "machine and there is no shared docker network to name it on."
   ],
+  "//workstation.stt": [
+    "CrisperWhisper 2.0 turbo on the same machine, a second service on port",
+    "8081 and not a second endpoint on mavgpud. whisper.cpp cannot load CW2 at",
+    "all: it derives its language count from the vocabulary size, and CW2's",
+    "51897 tokens shift seven special token ids. So it runs under transformers",
+    "there and mavsttd stays whisper.cpp here.",
+    "Worth the second service: CW2 turbo scores 10.4% WER in Russian against",
+    "27.5% for the ggml-small.bin mavsttd loads, measured on 200 Golos clips",
+    "in docs/evals/2026-08-09-crisperwhisper2-russian-wer.md.",
+    "Deleting this block sends every utterance to mavsttd, which is what the",
+    "box did before it existed. A worse transcript is still a turn, so the",
+    "fallback is silent and Kami is never told which machine heard him.",
+    "The token is what stops anything on the LAN posting audio to that port."
+  ],
   "workstation": {
     "url": "http://192.168.1.105:8080",
     "probe": "15s",
-    "timeout": "90s"
+    "timeout": "90s",
+    "stt": {
+      "url": "http://192.168.1.105:8081/transcribe",
+      "token": "${MAVEN_STT_TOKEN}",
+      "probe": "15s",
+      "timeout": "10s"
+    }
   },
 
   "//search": [

deploy/mavgpud.json

@@ -2,9 +2,14 @@
   "listen": ":8080",
   "llama_addr": "127.0.0.1:10000",
   "llama_bin": "llama-server",
+  "//llama_args": [
+    "E4B carries no MTP tensors, so the speculative flags are gone with the 12B.",
+    "MTP on this box is a separate gguf of architecture gemma4-assistant with",
+    "nextn_predict_layers=4, and mtp-gemma-4-12B-it-BF16 is the only one there is.",
+    "Its head is trained against the 12B's hidden states, so it cannot drive E4B."
+  ],
   "llama_args": [
-    "-m", "/mnt/D/AI/gemma4/gemma-4-12B-it-qat-UD-Q4_K_XL.gguf",
-    "-md", "/mnt/D/AI/gemma4/mtp-gemma-4-12B-it-BF16.gguf",
+    "-m", "/mnt/D/AI/gemma4/gemma-4-E4B-it-qat-UD-Q4_K_XL.gguf",
     "-ngl", "99",
     "-fa", "on",
     "-np", "1",
@@ -15,11 +20,22 @@
     "--batch-size", "2048",
     "--ubatch-size", "512",
     "--jinja",
-    "--chat-template-kwargs", "{\"enable_thinking\":false}",
-    "--spec-type", "draft-mtp",
-    "--spec-draft-n-max", "2"
+    "--chat-template-kwargs", "{\"enable_thinking\":false}"
   ],
 
+  "//stt": [
+    "CrisperWhisper 2.0 turbo, which Maven reaches directly on port 8081.",
+    "mavgpud runs it because it is a ROCm process on this card: under its own",
+    "systemd unit it registered on the KFD and the supervisor evicted",
+    "llama-server every few seconds. CW2_TOKEN comes from the unit's",
+    "EnvironmentFile and is never a flag value."
+  ],
+  "stt": {
+    "addr": "127.0.0.1:8081",
+    "bin": "/home/kami/Programs/cw2-eval/.venv/bin/python",
+    "args": ["/home/kami/Programs/cw2-service/serve.py"]
+  },
+
   "kfd_root": "/sys/class/kfd/kfd/proc",
   "drm_device": "/sys/class/drm/card1/device",
 

deploy/mavgpud.service

@@ -1,5 +1,5 @@
 [Unit]
-# Runs on the workstation (bugmachine), not on homesrv. Install as a systemd
+# Runs on the workstation (workpc), not on homesrv. Install as a systemd
 # user unit and turn on lingering, so the card is supervised after a reboot
 # with nobody logged in:
 #
@@ -8,10 +8,15 @@
 #   scp deploy/mavgpud.service workpc:~/.config/systemd/user/mavgpud.service
 #   ssh workpc 'systemctl --user daemon-reload && systemctl --user enable --now mavgpud'
 #   sudo loginctl enable-linger kami
-Description=Maven GPU supervisor (holds llama-server while the card is free)
+Description=Maven GPU supervisor (holds llama-server and CW2 while the card is free)
 After=network.target
 
 [Service]
+# CW2_TOKEN for the transcriber child, which inherits this environment. The
+# token is read from a file and never appears as a flag value, the rule
+# mavpoll and mavmaild follow. Missing file, no transcriber auth, so keep the
+# dash off: a mavgpud that cannot read it must fail loudly.
+EnvironmentFile=%h/Programs/cw2-service/cw2.env
 ExecStart=%h/.local/bin/mavgpud -config %h/.config/mavgpud.json
 Restart=always
 RestartSec=5

docs/evals/2026-08-09-crisperwhisper2-russian-wer.md

@@ -0,0 +1,110 @@
+# CrisperWhisper 2.0 in Russian, measured
+
+Date: 2026-08-09. Vikunja V-665.
+Corpus: `bond005/sberdevices_golos_10h_crowd`, test split, first 200 clips.
+Harness: `~/Programs/cw2-eval` on workpc, not in this repo.
+Runner: `./.venv/bin/python run_asr.py <arm>...` then `score.py`.
+
+The model card benchmarks disfluency F1 in German and English. It never names
+Russian and publishes no per-language WER. So the measurement came before the
+wiring.
+
+## The corpus
+
+200 clips, 13.7 minutes, 1001 reference words. Median clip 3.91s, range 1.04s
+to 13.5s. Golos crowd is short crowd-sourced Russian spoken close to the
+microphone, which is the nearest public thing to someone talking to Maven. The
+alternatives are read speech, which flatters every model equally.
+
+Two rows carry a null transcription and are skipped.
+
+Scoring normalizes both sides: lowercase, `ё` to `е`, punctuation stripped, and
+digits expanded to Russian words through num2words. Without that last step a
+model is penalized for writing `60000` where the reference says
+`шестьдесят тысяч`. Thousands separators are joined before expansion, or
+`60 000` expands to `шестьдесят ноль`.
+
+## Headline
+
+| arm | WER | CER | exact | empty | RTF |
+|---|---|---|---|---|---|
+| cw2-turbo-intended | **10.4%** | 3.4% | 65.5% | 0 | 0.065 |
+| cw2-turbo-verbatim | 10.8% | **3.1%** | **66.5%** | 0 | 0.065 |
+| whisper-turbo | 11.8% | 4.1% | 64.0% | 0 | 0.031 |
+| cw2-large-intended | 12.3% | 3.8% | 63.5% | 0 | 0.107 |
+| whisper-small | 27.5% | 9.8% | 35.0% | 0 | 0.026 |
+
+`whisper-small` is the floor, because `ggml-small.bin` is what mavsttd loads on
+homesrv today. CW2 turbo beats it by 17 points of WER and takes exact matches
+from 35.0% to 65.5%.
+
+Two results are worth naming beyond the winner. CW2 turbo beats its own base
+model, whisper-large-v3-turbo, by 1.4 points. And it beats CW2 large by 1.9
+points, which inverts what the card implies by calling turbo a degraded draft.
+No arm returned an empty transcript.
+
+## Intended and verbatim are closer than the mode names suggest
+
+The two modes disagree on 70 of the 200 clips before normalization and on 29
+after it. So the raw difference is mostly casing and punctuation, which
+normalization removes and which Maven does not read either.
+
+Verbatim scores worse on WER and better on CER and exact matches. The reason is
+script, not disfluency:
+
+```text
+ref: футбольный матч челси брайтон
+int: Футбольный матч Chelsea-Брайтон.
+ver: Футбольный матч Челси Брайтон.
+```
+
+Intended writes foreign entity names in Latin script and verbatim
+transliterates them. Golos references are Cyrillic throughout, so verbatim
+collects the exact matches. That is a property of this corpus rather than a
+quality difference.
+
+**This corpus cannot settle the mode choice.** Golos crowd is clean short
+commands with almost no disfluency. The two modes have nothing to disagree
+about here. They separate on spontaneous speech with fillers, restarts and
+repairs, which is what the owner speaks. Intended stays the choice for the
+reason it was always the choice. Maven wants what was meant, not every stumble
+on the way there.
+
+The Latin-script habit is the one finding here that touches routing. The
+routing heads were trained on Cyrillic utterances, so an entity name arriving
+in Latin script is out of distribution for them. Nothing measures that yet.
+
+## The runtime is workpc, because whisper.cpp cannot load CW2
+
+`num_languages()` in `deps/whisper.cpp/src/whisper.cpp` derives the language
+count from the vocabulary size:
+
+```cpp
+return n_vocab - 51765 - (is_multilingual() ? 1 : 0);
+```
+
+CW2 carries 31 extra tokens, so `n_vocab` is 51897 and this yields 131
+languages. The derived `dt` offset becomes 33 and shifts seven special token
+ids, including `token_beg` and `token_transcribe`. The architecture is
+otherwise byte-identical to whisper-large-v3-turbo, and the new tokens sit
+above every whisper special id.
+
+So loading CW2 in whisper.cpp is a patch to a vendored dependency, not a port.
+It was not taken, because STT is moving to workpc anyway under V-486. CW2 turbo
+becomes the preferred remote and `ggml-small.bin` on homesrv stays the floor,
+which is the shape `modelSeam` already uses for routing and replies. The 27.5%
+floor is what a turn falls back to when the workstation is down, and this table
+is what that costs.
+
+## License
+
+Standard CW2 weights carry `nyra-health-non-commercial-research`. The Pro
+variants are commercial-license only. Maven is personal and self-hosted, so the
+standard weights are usable and the Pro ones are not free to take.
+
+## What is not measured
+
+Disfluent spontaneous speech, which is the whole reason to prefer Intended.
+Long-form audio beyond 13.5s. Far-field or noisy microphones. English, which
+Maven also speaks. The ONNX turbo export, which was never run, since the
+transformers path already meets the latency budget at RTF 0.065.

docs/evals/2026-08-09-e4b-vs-12b-routing.md

@@ -0,0 +1,51 @@
+# gemma-4-E4B against gemma-4-12B on the routing fixture
+
+*Measured 2026-08-09 on workpc. The owner asked for the swap. This is what it costs.*
+
+Both arms ran the same 96-case fixture through `TestLLMRouterBaseline`, minutes
+apart, against the same llama-server build and the same mavgpud. The 12B arm is a
+control run and not the 2026-08-02 number. That one predates five fixture cases,
+the destination labels and a llama.cpp upgrade.
+
+| | full | intent-only | destination | p50 | p95 |
+|---|---|---|---|---|---|
+| gemma-4-12B-it-qat-UD-Q4_K_XL, MTP draft | 81/96 (84.4%) | 91.7% | 23/33 (69.7%) | 344ms | 471ms |
+| gemma-4-E4B-it-qat-UD-Q4_K_XL | 80/96 (83.3%) | 89.6% | 19/33 (57.6%) | 294ms | 562ms |
+
+E4B costs one case of full accuracy, two of intent and **four of destination**,
+and buys 50ms at p50. Read the destination column as the finding. One case is
+three points on 33. So 23 against 19 is outside the noise a single case makes,
+and the other two columns are not.
+
+Both arms produce three false clarifies and one missed clarify, and neither
+errored on any case.
+
+## What E4B loses
+
+Four of the five destination regressions are the same shape: it names nothing
+where the 12B names `recall` or `calendar`. `ru-query-015` ("сколько я прошёл
+шагов") goes further and names `self`. Naming nothing is the safe direction,
+because `SourceUnknown` walks the whole chain, so these turns are still answered.
+They cost latency and they are what a fourth head is meant to fix (V-546).
+
+Two Russian intent cases regress, both with the interrogative off the front.
+`ru-chat-003` ("расскажи анекдот про программистов") goes to `query`.
+`ru-fact-003` ("поужинал") goes to `chat`.
+
+## MTP
+
+E4B has none, and there is no way to give it any on this box. MTP on workpc is
+a separate gguf of architecture `gemma4-assistant` carrying
+`nextn_predict_layers=4`, and `mtp-gemma-4-12B-it-BF16.gguf` is the only one on
+disk. Its head is trained against the 12B's hidden states, so it cannot drive an
+E4B target. Scanning both target ggufs finds no `nextn` tensors in either, so
+neither model self-speculates.
+
+So the 12B arm above ran with speculative decoding and E4B ran without, and E4B
+was still faster.
+
+## Cost on the card
+
+E4B is 4.2GB against 6.7GB plus a 0.86GB draft. With CW2 resident at 1.6GB that
+is 5.8GB of 16GB against 9.2GB. Nothing in Maven needs the difference, so this is
+headroom for the owner's own jobs rather than a capability.

docs/offload.md

@@ -1,6 +1,6 @@
 # Offloading model work to the workstation
 
-*Last verified: 2026-08-05 @ b789676. Living doc: correct it in place, do not append.*
+*Last verified: 2026-08-09 @ 50c6637. Living doc: correct it in place, do not append.*
 
 Owner's call, 2026-08-02. Vikunja #483 is the umbrella. Tasks #484 to #487 are the
 work, and this file holds the shape and the rules all four must obey.
@@ -105,6 +105,17 @@ how we find out whether the blind spot is real.
 untouched. The model, the context size, the layer count and the MTP flags are the
 owner's business and not this daemon's schema.
 
+**Every GPU service on that box belongs under this supervisor**, added to
+`cmd/mavgpud` rather than to systemd beside it. The rule was learned on
+2026-08-09. The CW2 transcriber ran as its own user unit and registered on the
+KFD like any ROCm job. So the supervisor read its own transcriber as a
+contender. It yielded the card every few seconds and the gemma-4-12b arm was
+down for eight minutes before anyone looked. So the supervisor takes a `stt`
+block and starts CW2 itself. Yielding is all or nothing, because a job that
+wants the card wants all of it. Idle unloading is not. It applies to
+llama-server, which holds 8GB. CW2 holds 1.6GB, and unloading it would cost the
+next voice turn its quality for nothing.
+
 ## What stays on homesrv, permanently
 
 The **embedder** (multilingual-e5-small, ONNX, CPU). It backs the classifier, which
@@ -149,6 +160,29 @@ flips. It is wired anyway: `PhraseReminder` is on the same transport and is on.
 Then the embedder above, **whisper.cpp** in `mavsttd`, and **piper** in `mavttsd`.
 `mavwaked` uses no model at all: an energy-threshold VAD over 30ms frames.
 
+Speech-to-text is wired as of 09-08-2026, and it takes only the silent half of the
+rule. A worse transcript is still a turn, so there is nothing to name a gap about
+and `stt.Pair` has no `TranscribeRemote`. `sttSeam` in `cmd/mavend/voicewire.go`
+builds it, beside `modelSeam` and at the same place in `wireVoice`, so the voice
+path and the meeting recorder still share one transcriber.
+
+The remote is not a second endpoint on mavgpud. whisper.cpp cannot load
+CrisperWhisper 2.0 at all. It reads its language count off the vocabulary
+size, and CW2's 51897 tokens shift seven special token ids. So CW2 runs under
+transformers as its own service on port 8081, and `stt.HTTPTranscriber` is the
+second transport for the same seam. It posts raw PCM with the format in headers.
+It carries a bearer token, because audio is the most sensitive thing that
+crosses here.
+
+It is a second endpoint on nothing, but it is a second **child** of mavgpud, and
+that part is not optional. See the supervisor section above for why: a ROCm
+service the supervisor does not own is a contender it yields to.
+
+The margin is the reason: CW2 turbo scores 10.4% WER in Russian against 27.5% for
+the `ggml-small.bin` mavsttd loads, over 200 Golos clips
+(`docs/evals/2026-08-09-crisperwhisper2-russian-wer.md`). Text-to-speech has not
+moved and piper on homesrv is still the only synthesizer.
+
 Speech-to-text stays two stages when it moves. One call carrying both a clip and the router
 prompt was measured on 05-08-2026. It scores 54.2% intent-only against 84.7% for whisper on
 homesrv, on the same 72 cases. The model transcribes clips it then routes wrong, so a long
@@ -173,8 +207,9 @@ cleaner transcripts, not accuracy. See `docs/evals/2026-08-05-audio-in-routing.m
    which fixes what the 1.7B gets wrong: world knowledge, and the persona the CPT
    targets. The degradation path is already written and measured, since the
    classifier scores 68.8% full accuracy at p50 16.6µs on its own.
-3. **Speech-to-text and text-to-speech** (#486). They gain a real margin, but on
-   quality alone, and both already work.
+3. **Speech-to-text and text-to-speech** (#486). Speech-to-text is wired, see
+   above. Text-to-speech is not, and piper is good enough that nothing argues
+   for moving it yet.
 4. **The wake word** (#487). Independent of all of the above.
 
 ## Assumptions

internal/config/workstation.go

@@ -1,6 +1,7 @@
 package config
 
 import (
+	"net/url"
 	"strings"
 	"time"
 )
@@ -35,12 +36,54 @@ type WorkstationConfig struct {
 	// 0 ⇒ DefaultWorkstationTimeout. A big model on a LAN host is slower than
 	// the resident one, and a request that overruns falls back to the floor.
 	Timeout Duration `json:"timeout,omitempty"`
+
+	// Stt — CrisperWhisper 2.0 on the same machine, a separate service on its
+	// own port. Absent ⇒ every utterance goes to mavsttd, which is today.
+	Stt *WorkstationSttConfig `json:"stt,omitempty"`
+}
+
+// WorkstationSttConfig — speech-to-text on the workstation.
+//
+// It is a second service and not a second endpoint on mavgpud: whisper.cpp
+// cannot load CrisperWhisper 2.0 at all, because it derives its language count
+// from the vocabulary size and CW2's 51897 tokens shift seven special token
+// ids. So CW2 runs under transformers, and this block addresses it.
+//
+// Worth the trouble: CW2 turbo scores 10.4% WER in Russian against 27.5% for
+// the ggml-small.bin homesrv loads
+// (docs/evals/2026-08-09-crisperwhisper2-russian-wer.md).
+type WorkstationSttConfig struct {
+	// URL — the transcribe endpoint, e.g.
+	// "http://192.168.1.105:8081/transcribe". Empty ⇒ the block is normalised
+	// to nil and mavsttd takes every turn.
+	URL string `json:"url,omitempty"`
+
+	// Health — the admission endpoint. Empty ⇒ the URL's origin + "/health".
+	// It answers 503 while the card is held, and that is the signal.
+	Health string `json:"health,omitempty"`
+
+	// Token — the bearer token the service checks. Audio is the most sensitive
+	// thing that crosses this seam, so a LAN deployment should set one. Write
+	// it as ${MAVEN_STT_TOKEN} and keep the value in deploy/telegram.env, the
+	// way every other secret in this file is written.
+	Token string `json:"token,omitempty"`
+
+	// Probe — how often admission is re-checked. 0 ⇒ DefaultWorkstationProbe.
+	Probe Duration `json:"probe,omitempty"`
+
+	// Timeout — the per-request budget for one utterance. 0 ⇒
+	// DefaultWorkstationSttTimeout. A request that overruns falls back to
+	// mavsttd, which costs a worse transcript and not the turn.
+	Timeout Duration `json:"timeout,omitempty"`
 }
 
 // Workstation defaults, applied in normaliseWorkstation.
 const (
 	DefaultWorkstationProbe   = 15 * time.Second
 	DefaultWorkstationTimeout = 90 * time.Second
+	// One utterance, not one completion. A voice turn waits on this, so the
+	// budget is a few seconds and not a minute and a half.
+	DefaultWorkstationSttTimeout = 10 * time.Second
 )
 
 // normaliseWorkstation applies the block's defaults. No address, no preferred
@@ -63,4 +106,36 @@ func (c *Config) normaliseWorkstation() {
 	if w.Timeout <= 0 {
 		w.Timeout = Duration(DefaultWorkstationTimeout)
 	}
+	normaliseWorkstationStt(w)
+}
+
+// normaliseWorkstationStt applies the speech-to-text block's defaults. No
+// address, no remote: mavsttd then takes every utterance, which is today.
+func normaliseWorkstationStt(w *WorkstationConfig) {
+	if w.Stt != nil && strings.TrimSpace(w.Stt.URL) == "" {
+		w.Stt = nil
+	}
+	if w.Stt == nil {
+		return
+	}
+	s := w.Stt
+	if strings.TrimSpace(s.Health) == "" {
+		s.Health = healthOrigin(s.URL)
+	}
+	if s.Probe <= 0 {
+		s.Probe = Duration(DefaultWorkstationProbe)
+	}
+	if s.Timeout <= 0 {
+		s.Timeout = Duration(DefaultWorkstationSttTimeout)
+	}
+}
+
+// healthOrigin derives the admission endpoint from the transcribe endpoint.
+// The URL names a path, so appending to it would ask for /transcribe/health.
+func healthOrigin(raw string) string {
+	u, err := url.Parse(raw)
+	if err != nil || u.Host == "" {
+		return strings.TrimRight(raw, "/") + "/health"
+	}
+	return u.Scheme + "://" + u.Host + "/health"
 }

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")
+	}
+}

internal/stt/pair.go

@@ -0,0 +1,157 @@
+package stt
+
+import (
+	"context"
+	"errors"
+	"log"
+	"net/http"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/kami/maven/internal/audio"
+)
+
+// Pair — a preferred transcriber on the workstation, with mavsttd as the floor.
+//
+// Same arrangement as llm.Pair and for the same reason. The microphone is at
+// workpc, the card there has 16GB, and CrisperWhisper 2.0 turbo scores 10.4%
+// WER in Russian against 27.5% for the ggml-small.bin homesrv loads
+// (docs/evals/2026-08-09-crisperwhisper2-russian-wer.md). The workstation is
+// never assumed up: it sleeps, and the card is often held by a training run.
+//
+// Speech-to-text has only the silent half of the degradation rule. A worse
+// transcript is still a turn, and there is nothing to name a gap about, so
+// Transcribe always falls back. That is the whole difference from llm.Pair,
+// which also carries CompleteRemote for callers that must refuse instead.
+type Pair struct {
+	remote Transcriber
+	floor  Transcriber
+
+	// up — the cached admission answer, written only by the prober and read by
+	// every turn. A voice turn must never wait on a machine that may be asleep.
+	up atomic.Bool
+
+	health   string
+	interval time.Duration
+	http     *http.Client
+	stop     chan struct{}
+	stopOnce sync.Once
+}
+
+const (
+	probeTimeout         = 2 * time.Second
+	defaultProbeInterval = 15 * time.Second
+)
+
+// ErrNoFloor — a Pair was built with no local transcriber to fall back to. A
+// configuration mistake: the floor is what makes the remote optional.
+var ErrNoFloor = errors.New("stt: no floor transcriber")
+
+// NewPair builds the two-transcriber arrangement. remote may be nil, which is
+// the unconfigured deploy: every turn goes to the floor and nothing probes.
+func NewPair(remote, floor Transcriber, health string, interval time.Duration) *Pair {
+	if interval <= 0 {
+		// The config normalises this, so a zero here is a caller that built the
+		// Pair directly. Panicking in a ticker is the wrong way to say so.
+		interval = defaultProbeInterval
+	}
+	return &Pair{
+		remote:   remote,
+		floor:    floor,
+		health:   health,
+		interval: interval,
+		http:     &http.Client{Timeout: probeTimeout},
+		stop:     make(chan struct{}),
+	}
+}
+
+// Start begins probing. The first probe runs before the first tick, so a
+// workstation that is already up serves the first utterance rather than the
+// second. Safe with a nil remote.
+func (p *Pair) Start(ctx context.Context) {
+	if p.remote == nil || p.health == "" {
+		return
+	}
+	go func() {
+		p.probe(ctx)
+		t := time.NewTicker(p.interval)
+		defer t.Stop()
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case <-p.stop:
+				return
+			case <-t.C:
+				p.probe(ctx)
+			}
+		}
+	}()
+}
+
+// Stop ends the prober. Idempotent and safe from two goroutines.
+func (p *Pair) Stop() {
+	p.stopOnce.Do(func() { close(p.stop) })
+}
+
+// Available reports whether the workstation will transcribe right now.
+func (p *Pair) Available() bool {
+	return p.remote != nil && p.up.Load()
+}
+
+func (p *Pair) probe(ctx context.Context) {
+	ctx, cancel := context.WithTimeout(ctx, probeTimeout)
+	defer cancel()
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, p.health, nil)
+	if err != nil {
+		p.set(false)
+		return
+	}
+	resp, err := p.http.Do(req)
+	if err != nil {
+		p.set(false)
+		return
+	}
+	defer resp.Body.Close()
+	p.set(resp.StatusCode == http.StatusOK)
+}
+
+// set records the admission answer and logs only transitions. A machine that
+// sleeps nightly would otherwise write one line per interval forever.
+func (p *Pair) set(up bool) {
+	if p.up.Swap(up) == up {
+		return
+	}
+	if up {
+		log.Printf("stt: workstation transcriber available at %s", p.health)
+	} else {
+		log.Print("stt: workstation transcriber unavailable, falling back to mavsttd")
+	}
+}
+
+// Transcribe sends the audio to the workstation when it will take work, and to
+// mavsttd otherwise. A remote that fails mid-request falls back too, because
+// the admission answer is a cache and can be one interval out of date.
+//
+// Killing the remote mid-session must not drop the turn. That is the whole
+// point of the floor, and it is what TestPairFallsBackWhenRemoteFails pins.
+func (p *Pair) Transcribe(ctx context.Context, a audio.Audio) (string, float64, error) {
+	if p.floor == nil {
+		return "", 0, ErrNoFloor
+	}
+	if p.Available() {
+		text, conf, err := p.remote.Transcribe(ctx, a)
+		if err == nil {
+			log.Print("stt: transcribed on the workstation")
+			return text, conf, nil
+		}
+		// The cached answer was wrong. Correct it now rather than sending the
+		// next utterance into the same hole, then fall back.
+		p.set(false)
+		log.Printf("stt: workstation failed mid-request, falling back: %v", err)
+	}
+	return p.floor.Transcribe(ctx, a)
+}
+
+var _ Transcriber = (*Pair)(nil)

internal/stt/pair_test.go

@@ -0,0 +1,143 @@
+package stt
+
+import (
+	"context"
+	"errors"
+	"net/http"
+	"net/http/httptest"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/kami/maven/internal/audio"
+)
+
+// scripted — a Transcriber that answers with a fixed text, or fails.
+type scripted struct {
+	text  string
+	err   error
+	calls atomic.Int32
+}
+
+func (s *scripted) Transcribe(_ context.Context, _ audio.Audio) (string, float64, error) {
+	s.calls.Add(1)
+	if s.err != nil {
+		return "", 0, s.err
+	}
+	return s.text, 0.9, nil
+}
+
+func sample() audio.Audio {
+	return audio.Audio{Format: audio.PCM16kMono, Bytes: make([]byte, 3200)}
+}
+
+// up builds a Pair whose admission answer is already true, without probing.
+func up(remote, floor Transcriber) *Pair {
+	p := NewPair(remote, floor, "", time.Minute)
+	p.up.Store(true)
+	return p
+}
+
+func TestPairPrefersTheWorkstation(t *testing.T) {
+	t.Parallel()
+	remote := &scripted{text: "с рабочей станции"}
+	floor := &scripted{text: "с homesrv"}
+	text, _, err := up(remote, floor).Transcribe(context.Background(), sample())
+	if err != nil {
+		t.Fatalf("Transcribe: %v", err)
+	}
+	if text != "с рабочей станции" {
+		t.Fatalf("want the remote transcript, got %q", text)
+	}
+	if floor.calls.Load() != 0 {
+		t.Fatalf("floor was called %d times, want 0", floor.calls.Load())
+	}
+}
+
+// The turn is what matters. A remote that dies mid-session must cost a worse
+// transcript and nothing else. This is the V-486 bar.
+func TestPairFallsBackWhenRemoteFails(t *testing.T) {
+	t.Parallel()
+	remote := &scripted{err: errors.New("connection refused")}
+	floor := &scripted{text: "с homesrv"}
+	p := up(remote, floor)
+
+	text, conf, err := p.Transcribe(context.Background(), sample())
+	if err != nil {
+		t.Fatalf("a failed remote must not fail the turn: %v", err)
+	}
+	if text != "с homesrv" {
+		t.Fatalf("want the floor transcript, got %q", text)
+	}
+	if conf != 0.9 {
+		t.Fatalf("want the floor confidence, got %v", conf)
+	}
+	if p.Available() {
+		t.Fatal("a failed request must correct the cached admission answer")
+	}
+
+	// The next utterance goes straight to the floor rather than into the
+	// same hole.
+	if _, _, err := p.Transcribe(context.Background(), sample()); err != nil {
+		t.Fatalf("second turn: %v", err)
+	}
+	if remote.calls.Load() != 1 {
+		t.Fatalf("remote called %d times, want 1", remote.calls.Load())
+	}
+}
+
+func TestPairWithNoRemoteIsTheFloor(t *testing.T) {
+	t.Parallel()
+	floor := &scripted{text: "с homesrv"}
+	p := NewPair(nil, floor, "", time.Minute)
+	p.Start(context.Background()) // no health url, so this is a no-op
+	if p.Available() {
+		t.Fatal("an unconfigured remote is never available")
+	}
+	text, _, err := p.Transcribe(context.Background(), sample())
+	if err != nil {
+		t.Fatalf("Transcribe: %v", err)
+	}
+	if text != "с homesrv" {
+		t.Fatalf("want the floor transcript, got %q", text)
+	}
+}
+
+func TestPairWithNoFloorRefuses(t *testing.T) {
+	t.Parallel()
+	_, _, err := NewPair(nil, nil, "", time.Minute).Transcribe(context.Background(), sample())
+	if !errors.Is(err, ErrNoFloor) {
+		t.Fatalf("want ErrNoFloor, got %v", err)
+	}
+}
+
+func TestPairProbeReadsHealth(t *testing.T) {
+	t.Parallel()
+	var ok atomic.Bool
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		if !ok.Load() {
+			w.WriteHeader(http.StatusServiceUnavailable)
+			return
+		}
+		w.WriteHeader(http.StatusOK)
+	}))
+	defer srv.Close()
+
+	p := NewPair(&scripted{text: "remote"}, &scripted{text: "floor"}, srv.URL, time.Minute)
+	p.probe(context.Background())
+	if p.Available() {
+		t.Fatal("a 503 means the card is busy, so the workstation is not available")
+	}
+	ok.Store(true)
+	p.probe(context.Background())
+	if !p.Available() {
+		t.Fatal("a 200 means the workstation will take work")
+	}
+}
+
+func TestPairStopIsIdempotent(t *testing.T) {
+	t.Parallel()
+	p := NewPair(nil, &scripted{}, "", time.Minute)
+	p.Stop()
+	p.Stop()
+}