mavttsd: a pronunciation dictionary, so she says the names right (V-458)

piper reads a Russian sentence with a Russian voice, and a Latin service id
inside it comes out spelled, mangled or read as if it were a Russian word:
"Vikunja", "SearXNG", "homesrv". The lever available is the text, so the
dictionary maps a name to how it should be spelled for the voice to say it,
and mavttsd applies it at the last edge before piper — every caller's text
passes through that one point, and nothing upstream has to know how a name
sounds.

Data, not code. deploy/tts-lexicon.json ships 29 names; adding one needs a
restart of mavttsd and no rebuild of the daemon that produced the text. Off
unless -lexicon is set, like every other optional capability, and a path that
is set and unreadable stops startup — saying names wrong in silence is the
failure it exists to remove.

Two details worth keeping: the alternation is sorted longest-first, or "Home
Assistant" reads as "Хоум Assistant"; and the boundaries are written out
rather than left to \b, which is ASCII-only and never fires next to a
Cyrillic letter.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

cmd/mavttsd/piper_handler.go

@@ -9,6 +9,7 @@ import (
 	"os/exec"
 
 	"github.com/kami/maven/internal/audio"
+	"github.com/kami/maven/internal/tts"
 	"github.com/kami/maven/internal/worker"
 )
 
@@ -18,15 +19,20 @@ type piperHandler struct {
 	configPath    string
 	espeakData    string
 	tashkeelModel string
+	// lexicon rewrites service ids and Latin names into the spelling the
+	// Russian voice reads correctly (Vikunja #458). Nil-safe: an unconfigured
+	// dictionary rewrites nothing.
+	lexicon *tts.Lexicon
 }
 
-func newPiperHandler(piperPath, modelPath, espeakData, tashkeelModel string) *piperHandler {
+func newPiperHandler(piperPath, modelPath, espeakData, tashkeelModel string, lexicon *tts.Lexicon) *piperHandler {
 	return &piperHandler{
 		piperPath:     piperPath,
 		modelPath:     modelPath,
 		configPath:    modelPath + ".json",
 		espeakData:    espeakData,
 		tashkeelModel: tashkeelModel,
+		lexicon:       lexicon,
 	}
 }
 
@@ -66,7 +72,14 @@ func (h *piperHandler) Synthesize(ctx context.Context, req worker.SynthesizeReq)
 		return worker.SynthesizeResp{}, fmt.Errorf("piper: start: %w", err)
 	}
 
-	if _, err := io.WriteString(stdin, req.Text); err != nil {
+	// The dictionary is applied here, at the last edge before the voice: every
+	// caller's text passes through this one point, and nothing upstream has to
+	// know how a name is spelled out loud.
+	text := req.Text
+	if h.lexicon != nil {
+		text = h.lexicon.Apply(text)
+	}
+	if _, err := io.WriteString(stdin, text); err != nil {
 		stdin.Close()
 		stdout.Close()
 		_ = cmd.Wait()