[kimi] Add bark message producer for Matrix bark messages (#671) (#732)

src/infrastructure/presence.py

@@ -8,6 +8,62 @@ and WebSocket gateway.
 import time
 from datetime import UTC, datetime
 
+# Valid bark styles for Matrix protocol
+BARK_STYLES = {"speech", "thought", "whisper", "shout"}
+
+
+def produce_bark(agent_id: str, text: str, reply_to: str = None, style: str = "speech") -> dict:
+    """Format a chat response as a Matrix bark message.
+
+    Barks appear as floating text above agents in the Matrix 3D world with
+    typing animation. This function formats the text for the Matrix protocol.
+
+    Parameters
+    ----------
+    agent_id:
+        Unique identifier for the agent (e.g. ``"timmy"``).
+    text:
+        The chat response text to display as a bark.
+    reply_to:
+        Optional message ID or reference this bark is replying to.
+    style:
+        Visual style of the bark. One of: "speech" (default), "thought",
+        "whisper", "shout". Invalid styles fall back to "speech".
+
+    Returns
+    -------
+    dict
+        Bark message with keys ``type``, ``agent_id``, ``data`` (containing
+        ``text``, ``reply_to``, ``style``), and ``ts``.
+
+    Examples
+    --------
+    >>> produce_bark("timmy", "Hello world!")
+    {
+        "type": "bark",
+        "agent_id": "timmy",
+        "data": {"text": "Hello world!", "reply_to": None, "style": "speech"},
+        "ts": 1742529600,
+    }
+    """
+    # Validate and normalize style
+    if style not in BARK_STYLES:
+        style = "speech"
+
+    # Truncate text to 280 characters (bark, not essay)
+    truncated_text = text[:280] if text else ""
+
+    return {
+        "type": "bark",
+        "agent_id": agent_id,
+        "data": {
+            "text": truncated_text,
+            "reply_to": reply_to,
+            "style": style,
+        },
+        "ts": int(time.time()),
+    }
+
 
 def serialize_presence(presence: dict) -> dict:
     """Transform an ADR-023 presence dict into the world-state API shape.

tests/unit/test_presence.py

@@ -4,7 +4,7 @@ from unittest.mock import patch
 
 import pytest
 
-from infrastructure.presence import produce_agent_state, serialize_presence
+from infrastructure.presence import produce_agent_state, produce_bark, serialize_presence
 
 
 class TestSerializePresence:
@@ -163,3 +163,109 @@ class TestProduceAgentState:
         """When display_name is missing, it's derived from agent_id.title()."""
         data = produce_agent_state("spark", {})["data"]
         assert data["display_name"] == "Spark"
+
+
+class TestProduceBark:
+    """Tests for produce_bark() — Matrix bark message producer."""
+
+    @patch("infrastructure.presence.time")
+    def test_full_message_structure(self, mock_time):
+        """Returns dict with type, agent_id, data, and ts keys."""
+        mock_time.time.return_value = 1742529600
+        result = produce_bark("timmy", "Hello world!")
+
+        assert result["type"] == "bark"
+        assert result["agent_id"] == "timmy"
+        assert result["ts"] == 1742529600
+        assert isinstance(result["data"], dict)
+
+    def test_data_fields(self):
+        """data dict contains text, reply_to, and style."""
+        result = produce_bark("timmy", "Hello world!", reply_to="msg-123", style="shout")
+        data = result["data"]
+
+        assert data["text"] == "Hello world!"
+        assert data["reply_to"] == "msg-123"
+        assert data["style"] == "shout"
+
+    def test_default_style_is_speech(self):
+        """When style is not provided, defaults to 'speech'."""
+        result = produce_bark("timmy", "Hello!")
+        assert result["data"]["style"] == "speech"
+
+    def test_default_reply_to_is_none(self):
+        """When reply_to is not provided, defaults to None."""
+        result = produce_bark("timmy", "Hello!")
+        assert result["data"]["reply_to"] is None
+
+    def test_text_truncated_to_280_chars(self):
+        """Text longer than 280 chars is truncated."""
+        long_text = "A" * 500
+        result = produce_bark("timmy", long_text)
+        assert len(result["data"]["text"]) == 280
+        assert result["data"]["text"] == "A" * 280
+
+    def test_text_exactly_280_chars_not_truncated(self):
+        """Text exactly 280 chars is not truncated."""
+        text = "B" * 280
+        result = produce_bark("timmy", text)
+        assert result["data"]["text"] == text
+
+    def test_text_shorter_than_280_not_padded(self):
+        """Text shorter than 280 chars is not padded."""
+        result = produce_bark("timmy", "Short")
+        assert result["data"]["text"] == "Short"
+
+    @pytest.mark.parametrize(
+        ("style", "expected_style"),
+        [
+            ("speech", "speech"),
+            ("thought", "thought"),
+            ("whisper", "whisper"),
+            ("shout", "shout"),
+        ],
+    )
+    def test_valid_styles_preserved(self, style, expected_style):
+        """Valid style values are preserved."""
+        result = produce_bark("timmy", "Hello!", style=style)
+        assert result["data"]["style"] == expected_style
+
+    @pytest.mark.parametrize(
+        "invalid_style",
+        ["yell", "scream", "", "SPEECH", "Speech", None, 123],
+    )
+    def test_invalid_style_defaults_to_speech(self, invalid_style):
+        """Invalid style values fall back to 'speech'."""
+        result = produce_bark("timmy", "Hello!", style=invalid_style)
+        assert result["data"]["style"] == "speech"
+
+    def test_empty_text_handled(self):
+        """Empty text is handled gracefully."""
+        result = produce_bark("timmy", "")
+        assert result["data"]["text"] == ""
+
+    def test_ts_is_unix_timestamp(self):
+        """ts should be an integer Unix timestamp."""
+        result = produce_bark("timmy", "Hello!")
+        assert isinstance(result["ts"], int)
+        assert result["ts"] > 0
+
+    def test_agent_id_passed_through(self):
+        """agent_id appears in the top-level message."""
+        result = produce_bark("spark", "Hello!")
+        assert result["agent_id"] == "spark"
+
+    def test_with_all_parameters(self):
+        """Full parameter set produces expected output."""
+        result = produce_bark(
+            agent_id="timmy",
+            text="Running test suite...",
+            reply_to="parent-msg-456",
+            style="thought",
+        )
+
+        assert result["type"] == "bark"
+        assert result["agent_id"] == "timmy"
+        assert result["data"]["text"] == "Running test suite..."
+        assert result["data"]["reply_to"] == "parent-msg-456"
+        assert result["data"]["style"] == "thought"