fix(tts): unify voice resolution — dashboard settings affect tts tool (#1175)

The dashboard /tts page writes to system_configs[tts.<provider>.voice],
but the LLM-invoked tts tool was only checking args > agent OtherConfig
> builtin_tool_tenant_configs[tts].default_voice_id. Two different
storage locations → the user's chosen voice was ignored, Edge defaulted
to en-US-AriaNeural even when "HoaiMy" (vi-VN-HoaiMyNeural) was set
correctly in the dashboard.

Add system_configs as a 4th-level fallback so the dashboard becomes
the single source of truth.

- TtsTool gains SetSystemConfigStore(s) setter
- resolveVoiceAndModel takes providerName + looks up
  tts.<provider>.voice/model when no higher-precedence source set
- effectiveProvider resolved BEFORE voice/model so the right key is hit
- Wired at gateway boot in cmd/gateway.go (after pgStores ready)
- 4 unit tests covering: fallback, arg precedence, no-store, empty provider

Verified against production trace 019e6036-44bb-703b-85fa-dee34f7ab2c0
where the tts tool was called with provider=edge, no voice arg, and
defaulted to English instead of the configured Vietnamese voice.

cmd/gateway.go

@@ -278,6 +278,10 @@ func runGateway() {
 		browserMgr.SetCookieProvider(newStoreBrowserCookieProvider(pgStores.BrowserCookies))
 	}
 
+	if ttsTool != nil && pgStores.SystemConfigs != nil {
+		ttsTool.SetSystemConfigStore(pgStores.SystemConfigs)
+	}
+
 	// Recover from crashes: flip ghost 'summoning' rows to 'summon_failed'.
 	// Summon goroutines don't survive process restart; stale DB rows would trap the UI.
 	if pgStores.Agents != nil {

internal/tools/tts.go

@@ -27,13 +27,20 @@ import (
 // Implements Tool + ContextualTool interfaces.
 // Per-call channel is read from ctx for thread-safety.
 type TtsTool struct {
-	mu        sync.RWMutex
-	manager   *tts.Manager
-	vaultIntc *VaultInterceptor
+	mu            sync.RWMutex
+	manager       *tts.Manager
+	vaultIntc     *VaultInterceptor
+	systemConfigs store.SystemConfigStore
 }
 
 func (t *TtsTool) SetVaultInterceptor(v *VaultInterceptor) { t.vaultIntc = v }
 
+func (t *TtsTool) SetSystemConfigStore(s store.SystemConfigStore) {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	t.systemConfigs = s
+}
+
 // NewTtsTool creates a TTS tool backed by the given manager.
 func NewTtsTool(mgr *tts.Manager) *TtsTool {
 	return &TtsTool{manager: mgr}
@@ -98,7 +105,7 @@ type agentAudioConfig struct {
 // resolveVoiceAndModel computes the effective voice + model IDs for the
 // request using the documented precedence order:
 //
-//	args > agent (store.AgentAudioFromCtx OtherConfig) > tenant (BuiltinToolSettings) > empty.
+//	args > agent (store.AgentAudioFromCtx OtherConfig) > tenant (BuiltinToolSettings) > system_configs > empty.
 //
 // Empty return values signal "use provider default" downstream — they are not
 // errors. Missing agent snapshot emits slog.Warn so operators can spot
@@ -108,7 +115,7 @@ type agentAudioConfig struct {
 // tts_voice_id override (not from tool args or tenant defaults). Callers use
 // this flag to emit a warning when the voice is later found incompatible with
 // the selected provider.
-func (t *TtsTool) resolveVoiceAndModel(ctx context.Context, argVoice, argModel string) (voice, model string, voiceFromAgent bool) {
+func (t *TtsTool) resolveVoiceAndModel(ctx context.Context, providerName, argVoice, argModel string) (voice, model string, voiceFromAgent bool) {
 	voice, model = argVoice, argModel
 
 	// Pull agent-level config from the dispatcher-injected snapshot.
@@ -153,6 +160,22 @@ func (t *TtsTool) resolveVoiceAndModel(ctx context.Context, argVoice, argModel s
 			model = tenantCfg.DefaultModel
 		}
 	}
+
+	t.mu.RLock()
+	systemConfigs := t.systemConfigs
+	t.mu.RUnlock()
+	if (voice == "" || model == "") && systemConfigs != nil && providerName != "" {
+		if voice == "" {
+			if v, err := systemConfigs.Get(ctx, "tts."+providerName+".voice"); err == nil && v != "" {
+				voice = v
+			}
+		}
+		if model == "" {
+			if m, err := systemConfigs.Get(ctx, "tts."+providerName+".model"); err == nil && m != "" {
+				model = m
+			}
+		}
+	}
 	return voice, model, voiceFromAgent
 }
 
@@ -252,9 +275,6 @@ func (t *TtsTool) Execute(ctx context.Context, args map[string]any) *Result {
 	argModel, _ := args["model"].(string)
 	providerName, _ := args["provider"].(string)
 
-	// Resolve voice/model via args > agent (ctx snapshot) > tenant > default.
-	voice, model, voiceFromAgent := t.resolveVoiceAndModel(ctx, argVoice, argModel)
-
 	// Read generic agent TTS params once; adapt PER-ATTEMPT below (Finding #1 CRITICAL).
 	// Storing generic keys here so each fallback provider gets its own adapted copy.
 	genericAgentParams := t.resolveAgentGenericTTSParams(ctx)
@@ -264,6 +284,12 @@ func (t *TtsTool) Execute(ctx context.Context, args map[string]any) *Result {
 	mgr := t.manager
 	t.mu.RUnlock()
 
+	effectiveProvider := providerName
+	if effectiveProvider == "" {
+		effectiveProvider = t.resolvePrimary(ctx, mgr)
+	}
+	voice, model, voiceFromAgent := t.resolveVoiceAndModel(ctx, effectiveProvider, argVoice, argModel)
+
 	// Determine format based on channel (read from ctx — thread-safe)
 	channel := ToolChannelFromCtx(ctx)
 	opts := tts.Options{Voice: voice, Model: model}

internal/tools/tts_agent_ctx_test.go

@@ -35,7 +35,7 @@ func ctxWithAgentAudio(t *testing.T, voiceID, modelID string) context.Context {
 func TestResolveVoiceAndModel_ArgsWinOverAgent(t *testing.T) {
 	tool := NewTtsTool(makeTTSManager("elevenlabs"))
 	ctx := ctxWithAgentAudio(t, "AGENT_V", "AGENT_M")
-	v, m, _ := tool.resolveVoiceAndModel(ctx, "ARG_V", "ARG_M")
+	v, m, _ := tool.resolveVoiceAndModel(ctx, "edge", "ARG_V", "ARG_M")
 	if v != "ARG_V" {
 		t.Errorf("voice: got %q, want ARG_V (args must win)", v)
 	}
@@ -50,7 +50,7 @@ func TestResolveVoiceAndModel_AgentWinsOverTenantWhenArgsEmpty(t *testing.T) {
 	ctx = WithBuiltinToolSettings(ctx, BuiltinToolSettings{
 		"tts": rawJSON(t, map[string]string{"default_voice_id": "TENANT_V", "default_model": "TENANT_M"}),
 	})
-	v, m, _ := tool.resolveVoiceAndModel(ctx, "", "")
+	v, m, _ := tool.resolveVoiceAndModel(ctx, "edge", "", "")
 	if v != "AGENT_V" {
 		t.Errorf("voice: got %q, want AGENT_V (agent > tenant)", v)
 	}
@@ -65,7 +65,7 @@ func TestResolveVoiceAndModel_TenantFallbackWhenAgentSilent(t *testing.T) {
 	ctx := WithBuiltinToolSettings(context.Background(), BuiltinToolSettings{
 		"tts": rawJSON(t, map[string]string{"default_voice_id": "TENANT_V", "default_model": "TENANT_M"}),
 	})
-	v, m, _ := tool.resolveVoiceAndModel(ctx, "", "")
+	v, m, _ := tool.resolveVoiceAndModel(ctx, "edge", "", "")
 	if v != "TENANT_V" {
 		t.Errorf("voice: got %q, want TENANT_V", v)
 	}
@@ -76,7 +76,7 @@ func TestResolveVoiceAndModel_TenantFallbackWhenAgentSilent(t *testing.T) {
 
 func TestResolveVoiceAndModel_EmptyAllMeansDefault(t *testing.T) {
 	tool := NewTtsTool(makeTTSManager("elevenlabs"))
-	v, m, _ := tool.resolveVoiceAndModel(context.Background(), "", "")
+	v, m, _ := tool.resolveVoiceAndModel(context.Background(), "edge", "", "")
 	if v != "" {
 		t.Errorf("voice: got %q, want empty (no sources → provider default)", v)
 	}
@@ -92,7 +92,7 @@ func TestResolveVoiceAndModel_PartialAgentConfig(t *testing.T) {
 	ctx = WithBuiltinToolSettings(ctx, BuiltinToolSettings{
 		"tts": rawJSON(t, map[string]string{"default_model": "TENANT_M"}),
 	})
-	v, m, _ := tool.resolveVoiceAndModel(ctx, "", "")
+	v, m, _ := tool.resolveVoiceAndModel(ctx, "edge", "", "")
 	if v != "AGENT_V" {
 		t.Errorf("voice: got %q, want AGENT_V", v)
 	}

internal/tools/tts_systemconfigs_fallback_test.go

@@ -0,0 +1,76 @@
+package tools
+
+import (
+	"context"
+	"testing"
+)
+
+type fakeSystemConfigStore struct {
+	data map[string]string
+}
+
+func (f *fakeSystemConfigStore) Get(_ context.Context, key string) (string, error) {
+	return f.data[key], nil
+}
+func (f *fakeSystemConfigStore) Set(_ context.Context, key, value string) error {
+	if f.data == nil {
+		f.data = map[string]string{}
+	}
+	f.data[key] = value
+	return nil
+}
+func (f *fakeSystemConfigStore) Delete(_ context.Context, key string) error {
+	delete(f.data, key)
+	return nil
+}
+func (f *fakeSystemConfigStore) List(_ context.Context) (map[string]string, error) {
+	return f.data, nil
+}
+
+func TestResolveVoiceAndModel_SystemConfigsFallback(t *testing.T) {
+	tool := NewTtsTool(nil)
+	sc := &fakeSystemConfigStore{data: map[string]string{
+		"tts.edge.voice": "vi-VN-HoaiMyNeural",
+		"tts.edge.model": "edge-tts-1",
+	}}
+	tool.SetSystemConfigStore(sc)
+
+	v, m, _ := tool.resolveVoiceAndModel(context.Background(), "edge", "", "")
+	if v != "vi-VN-HoaiMyNeural" {
+		t.Errorf("voice fallback failed: got %q, want vi-VN-HoaiMyNeural", v)
+	}
+	if m != "edge-tts-1" {
+		t.Errorf("model fallback failed: got %q, want edge-tts-1", m)
+	}
+}
+
+func TestResolveVoiceAndModel_ArgWinsOverSystemConfigs(t *testing.T) {
+	tool := NewTtsTool(nil)
+	tool.SetSystemConfigStore(&fakeSystemConfigStore{data: map[string]string{
+		"tts.edge.voice": "vi-VN-HoaiMyNeural",
+	}})
+
+	v, _, _ := tool.resolveVoiceAndModel(context.Background(), "edge", "en-US-AriaNeural", "")
+	if v != "en-US-AriaNeural" {
+		t.Errorf("arg voice must win over system_configs: got %q", v)
+	}
+}
+
+func TestResolveVoiceAndModel_NoStoreNoFallback(t *testing.T) {
+	tool := NewTtsTool(nil)
+	v, m, _ := tool.resolveVoiceAndModel(context.Background(), "edge", "", "")
+	if v != "" || m != "" {
+		t.Errorf("expected empty fallback when no system_configs wired, got voice=%q model=%q", v, m)
+	}
+}
+
+func TestResolveVoiceAndModel_EmptyProviderSkipsFallback(t *testing.T) {
+	tool := NewTtsTool(nil)
+	tool.SetSystemConfigStore(&fakeSystemConfigStore{data: map[string]string{
+		"tts..voice": "should-not-match",
+	}})
+	v, m, _ := tool.resolveVoiceAndModel(context.Background(), "", "", "")
+	if v != "" || m != "" {
+		t.Errorf("empty provider must skip lookup, got voice=%q model=%q", v, m)
+	}
+}