fix: convert markdown to HTML in approval messages

Matrix needs formatted_body as HTML, not raw markdown. Added _md_to_html
for bold/italic/code conversion.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

pipelines/engine.py

@@ -217,12 +217,28 @@ class PipelineEngine:
                 error=str(exc),
             )
 
+    @staticmethod
+    def _md_to_html(text: str) -> str:
+        """Convert basic markdown to HTML for Matrix formatted_body."""
+        import re as _re
+        html = text
+        # Bold: **text** -> <strong>text</strong>
+        html = _re.sub(r'\*\*(.+?)\*\*', r'<strong>\1</strong>', html)
+        # Italic: *text* -> <em>text</em>
+        html = _re.sub(r'(?<!\*)\*(?!\*)(.+?)(?<!\*)\*(?!\*)', r'<em>\1</em>', html)
+        # Code: `text` -> <code>text</code>
+        html = _re.sub(r'`(.+?)`', r'<code>\1</code>', html)
+        # Newlines
+        html = html.replace("\n", "<br>")
+        return html
+
     async def _execute_approval_step(
         self, step: dict, target_room: str, execution_id: str, timeout_s: int
     ) -> str:
         """Post approval message and wait for reaction."""
         message = step.get("message", "Approve this action?")
-        formatted_msg = f"**Approval Required**\n\n{message}\n\nReact with \U0001f44d to approve or \U0001f44e to decline."
+        body = f"**Approval Required**\n\n{message}\n\nReact with \U0001f44d to approve or \U0001f44e to decline."
+        html = self._md_to_html(body)
 
         # Send message and get event ID
         resp = await self.matrix_client.room_send(
@@ -230,9 +246,9 @@ class PipelineEngine:
             message_type="m.room.message",
             content={
                 "msgtype": "m.text",
-                "body": formatted_msg,
+                "body": body,
                 "format": "org.matrix.custom.html",
-                "formatted_body": formatted_msg.replace("\n", "<br>"),
+                "formatted_body": html,
             },
         )
         event_id = resp.event_id if hasattr(resp, "event_id") else None