diff --git a/extensions/voice-call/src/config.test.ts b/extensions/voice-call/src/config.test.ts
index fad18e67faa..1b12e9e84c5 100644
--- a/extensions/voice-call/src/config.test.ts
+++ b/extensions/voice-call/src/config.test.ts
@@ -189,4 +189,30 @@ describe("normalizeVoiceCallConfig", () => {
     expect(normalized.tunnel.provider).toBe("none");
     expect(normalized.webhookSecurity.allowedHosts).toEqual([]);
   });
+
+  it("accepts partial nested TTS overrides and preserves nested objects", () => {
+    const normalized = normalizeVoiceCallConfig({
+      tts: {
+        provider: "elevenlabs",
+        elevenlabs: {
+          apiKey: {
+            source: "env",
+            provider: "elevenlabs",
+            id: "ELEVENLABS_API_KEY",
+          },
+          voiceSettings: {
+            speed: 1.1,
+          },
+        },
+      },
+    });
+
+    expect(normalized.tts?.provider).toBe("elevenlabs");
+    expect(normalized.tts?.elevenlabs?.apiKey).toEqual({
+      source: "env",
+      provider: "elevenlabs",
+      id: "ELEVENLABS_API_KEY",
+    });
+    expect(normalized.tts?.elevenlabs?.voiceSettings).toEqual({ speed: 1.1 });
+  });
 });
diff --git a/extensions/voice-call/src/config.ts b/extensions/voice-call/src/config.ts
index 405eda179d9..9721cf380e2 100644
--- a/extensions/voice-call/src/config.ts
+++ b/extensions/voice-call/src/config.ts
@@ -368,6 +368,55 @@ function cloneDefaultVoiceCallConfig(): VoiceCallConfig {
   return structuredClone(DEFAULT_VOICE_CALL_CONFIG);
 }
 
+function normalizeVoiceCallTtsConfig(
+  defaults: VoiceCallTtsConfig,
+  overrides: DeepPartial<NonNullable<VoiceCallTtsConfig>> | undefined,
+): VoiceCallTtsConfig {
+  if (!defaults && !overrides) {
+    return undefined;
+  }
+
+  return TtsConfigSchema.parse({
+    ...(defaults ?? {}),
+    ...(overrides ?? {}),
+    modelOverrides:
+      defaults?.modelOverrides || overrides?.modelOverrides
+        ? {
+            ...(defaults?.modelOverrides ?? {}),
+            ...(overrides?.modelOverrides ?? {}),
+          }
+        : undefined,
+    elevenlabs:
+      defaults?.elevenlabs || overrides?.elevenlabs
+        ? {
+            ...(defaults?.elevenlabs ?? {}),
+            ...(overrides?.elevenlabs ?? {}),
+            voiceSettings:
+              defaults?.elevenlabs?.voiceSettings || overrides?.elevenlabs?.voiceSettings
+                ? {
+                    ...(defaults?.elevenlabs?.voiceSettings ?? {}),
+                    ...(overrides?.elevenlabs?.voiceSettings ?? {}),
+                  }
+                : undefined,
+          }
+        : undefined,
+    openai:
+      defaults?.openai || overrides?.openai
+        ? {
+            ...(defaults?.openai ?? {}),
+            ...(overrides?.openai ?? {}),
+          }
+        : undefined,
+    edge:
+      defaults?.edge || overrides?.edge
+        ? {
+            ...(defaults?.edge ?? {}),
+            ...(overrides?.edge ?? {}),
+          }
+        : undefined,
+  });
+}
+
 export function normalizeVoiceCallConfig(config: VoiceCallConfigInput): VoiceCallConfig {
   const defaults = cloneDefaultVoiceCallConfig();
   return {
@@ -387,7 +436,7 @@ export function normalizeVoiceCallConfig(config: VoiceCallConfigInput): VoiceCal
     },
     streaming: { ...defaults.streaming, ...config.streaming },
     stt: { ...defaults.stt, ...config.stt },
-    tts: config.tts ?? defaults.tts,
+    tts: normalizeVoiceCallTtsConfig(defaults.tts, config.tts),
   };
 }
 
diff --git a/src/daemon/service.ts b/src/daemon/service.ts
index b0de0baa49b..9685ed1ece5 100644
--- a/src/daemon/service.ts
+++ b/src/daemon/service.ts
@@ -64,7 +64,9 @@ export type GatewayService = {
   readRuntime: (env: GatewayServiceEnv) => Promise<GatewayServiceRuntime>;
 };
 
-const GATEWAY_SERVICE_REGISTRY = {
+type SupportedGatewayServicePlatform = "darwin" | "linux" | "win32";
+
+const GATEWAY_SERVICE_REGISTRY: Record<SupportedGatewayServicePlatform, GatewayService> = {
   darwin: {
     label: "LaunchAgent",
     loadedText: "loaded",
@@ -101,12 +103,17 @@ const GATEWAY_SERVICE_REGISTRY = {
     readCommand: readScheduledTaskCommand,
     readRuntime: readScheduledTaskRuntime,
   },
-} satisfies Partial<Record<NodeJS.Platform, GatewayService>>;
+};
+
+function isSupportedGatewayServicePlatform(
+  platform: NodeJS.Platform,
+): platform is SupportedGatewayServicePlatform {
+  return Object.hasOwn(GATEWAY_SERVICE_REGISTRY, platform);
+}
 
 export function resolveGatewayService(): GatewayService {
-  const service = GATEWAY_SERVICE_REGISTRY[process.platform];
-  if (service) {
-    return service;
+  if (isSupportedGatewayServicePlatform(process.platform)) {
+    return GATEWAY_SERVICE_REGISTRY[process.platform];
   }
   throw new Error(`Gateway service install not supported on ${process.platform}`);
 }