feat: add TTS hint to system prompt

src/agents/system-prompt.ts

@@ -103,6 +103,13 @@ function buildMessagingSection(params: {
   ];
 }
 
+function buildVoiceSection(params: { isMinimal: boolean; ttsHint?: string }) {
+  if (params.isMinimal) return [];
+  const hint = params.ttsHint?.trim();
+  if (!hint) return [];
+  return ["## Voice (TTS)", hint, ""];
+}
+
 function buildDocsSection(params: { docsPath?: string; isMinimal: boolean; readToolName: string }) {
   const docsPath = params.docsPath?.trim();
   if (!docsPath || params.isMinimal) return [];
@@ -137,6 +144,7 @@ export function buildAgentSystemPrompt(params: {
   heartbeatPrompt?: string;
   docsPath?: string;
   workspaceNotes?: string[];
+  ttsHint?: string;
   /** Controls which hardcoded sections to include. Defaults to "full". */
   promptMode?: PromptMode;
   runtimeInfo?: {
@@ -464,6 +472,7 @@ export function buildAgentSystemPrompt(params: {
       runtimeChannel,
       messageToolHints: params.messageToolHints,
     }),
+    ...buildVoiceSection({ isMinimal, ttsHint: params.ttsHint }),
   ];
 
   if (extraSystemPrompt) {