feat(tts): add Gemini audio tag rewrite

tests/tools/test_tts_gemini.py

@@ -2,6 +2,7 @@
 
 import base64
 import struct
+from types import SimpleNamespace
 from unittest.mock import MagicMock, patch
 
 import pytest
@@ -312,6 +313,112 @@ class TestGenerateGeminiTts:
         assert prompt_text == "Hi"
         assert "persona prompt file unavailable" in caplog.text
 
+    def test_audio_tags_disabled_does_not_call_rewriter(
+        self, tmp_path, monkeypatch, mock_gemini_response
+    ):
+        from tools.tts_tool import _generate_gemini_tts
+
+        config = {
+            "gemini": {
+                "model": "gemini-3.1-flash-tts-preview",
+                "audio_tags": False,
+            }
+        }
+        monkeypatch.setenv("GEMINI_API_KEY", "test-key")
+
+        with patch("agent.auxiliary_client.call_llm") as mock_call_llm, \
+             patch("requests.post", return_value=mock_gemini_response) as mock_post:
+            _generate_gemini_tts("Hi there.", str(tmp_path / "test.wav"), config)
+
+        mock_call_llm.assert_not_called()
+        prompt_text = mock_post.call_args[1]["json"]["contents"][0]["parts"][0]["text"]
+        assert prompt_text == "Hi there."
+
+    def test_audio_tags_enabled_rewrites_hidden_tts_script(
+        self, tmp_path, monkeypatch, mock_gemini_response
+    ):
+        from tools.tts_tool import _generate_gemini_tts
+
+        persona_file = tmp_path / "voice-persona.md"
+        persona_file.write_text(
+            "### DIRECTOR'S NOTES\nStyle: Warm and amused.",
+            encoding="utf-8",
+        )
+        response = SimpleNamespace(
+            choices=[
+                SimpleNamespace(
+                    message=SimpleNamespace(content="[warmly] Hi there. [soft laugh]")
+                )
+            ]
+        )
+        config = {
+            "gemini": {
+                "model": "gemini-3.1-flash-tts-preview",
+                "audio_tags": True,
+                "persona_prompt_file": str(persona_file),
+            }
+        }
+        monkeypatch.setenv("GEMINI_API_KEY", "test-key")
+
+        with patch("agent.auxiliary_client.call_llm", return_value=response) as mock_call_llm, \
+             patch("requests.post", return_value=mock_gemini_response) as mock_post:
+            _generate_gemini_tts("Hi there.", str(tmp_path / "test.wav"), config)
+
+        mock_call_llm.assert_called_once()
+        call_kwargs = mock_call_llm.call_args.kwargs
+        assert call_kwargs["task"] == "tts_audio_tags"
+        assert "Audio tags are inline square-bracket modifiers" in call_kwargs["messages"][0]["content"]
+        assert "Style: Warm and amused." in call_kwargs["messages"][1]["content"]
+        assert "Hi there." in call_kwargs["messages"][1]["content"]
+
+        prompt_text = mock_post.call_args[1]["json"]["contents"][0]["parts"][0]["text"]
+        assert "Synthesize speech from the TRANSCRIPT only" in prompt_text
+        assert "### DIRECTOR'S NOTES\nStyle: Warm and amused." in prompt_text
+        assert "#### TRANSCRIPT\n[warmly] Hi there. [soft laugh]" in prompt_text
+
+    def test_audio_tags_enabled_skips_non_tag_capable_model(
+        self, tmp_path, monkeypatch, mock_gemini_response, caplog
+    ):
+        from tools.tts_tool import _generate_gemini_tts
+
+        config = {
+            "gemini": {
+                "model": "gemini-2.5-flash-preview-tts",
+                "audio_tags": True,
+            }
+        }
+        monkeypatch.setenv("GEMINI_API_KEY", "test-key")
+
+        with patch("agent.auxiliary_client.call_llm") as mock_call_llm, \
+             patch("requests.post", return_value=mock_gemini_response) as mock_post:
+            _generate_gemini_tts("Hi there.", str(tmp_path / "test.wav"), config)
+
+        mock_call_llm.assert_not_called()
+        prompt_text = mock_post.call_args[1]["json"]["contents"][0]["parts"][0]["text"]
+        assert prompt_text == "Hi there."
+        assert "not known to support Gemini audio tags" in caplog.text
+
+    def test_audio_tag_rewrite_failure_falls_back_to_original_text(
+        self, tmp_path, monkeypatch, mock_gemini_response, caplog
+    ):
+        from tools.tts_tool import _generate_gemini_tts
+
+        config = {
+            "gemini": {
+                "model": "gemini-3.1-flash-tts-preview",
+                "audio_tags": True,
+            }
+        }
+        monkeypatch.setenv("GEMINI_API_KEY", "test-key")
+
+        with patch("agent.auxiliary_client.call_llm", side_effect=RuntimeError("boom")), \
+             patch("requests.post", return_value=mock_gemini_response) as mock_post:
+            _generate_gemini_tts("Hi there.", str(tmp_path / "test.wav"), config)
+
+        prompt_text = mock_post.call_args[1]["json"]["contents"][0]["parts"][0]["text"]
+        assert prompt_text == "Hi there."
+        assert "audio tag rewrite failed" in caplog.text
+
 
 class TestGeminiInCheckRequirements:
     def test_gemini_api_key_satisfies_requirements(self, monkeypatch):