fix: message_content() and message_content_chunk() now accept ChatMessage() as input (#132)

* fix: message_content() and message_content_chunk() now accept ChatMessage() as input

* Update changelog

Author: cpsievert

pkg-py/CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [UNRELEASED]
+
+### Improvements
+
+* `message_content()` and `message_content_chunk()` can now take `ChatMessage()` as input. (#)
+
 ## [0.2.1] - 2025-09-10
 
 ### New features

pkg-py/src/shinychat/_chat_normalize.py

@@ -44,6 +44,8 @@ def message_content(message):
     """
     if isinstance(message, (str, HTML)) or message is None:
         return ChatMessage(content=message)
+    if isinstance(message, ChatMessage):
+        return message
     if isinstance(message, dict):
         if "content" not in message:
             raise ValueError("Message dictionary must have a 'content' key")
@@ -90,6 +92,8 @@ def message_content_chunk(chunk):
     """
     if isinstance(chunk, (str, HTML)) or chunk is None:
         return ChatMessage(content=chunk)
+    if isinstance(chunk, ChatMessage):
+        return chunk
     if isinstance(chunk, dict):
         if "content" not in chunk:
             raise ValueError("Chunk dictionary must have a 'content' key")

pkg-py/tests/pytest/test_chat.py

@@ -181,15 +181,55 @@ def generate_content(token_count: int) -> str:
 
 
 def test_string_normalization():
-    m = message_content_chunk("Hello world!")
+    m = message_content("Hello world!")
     assert m.content == "Hello world!"
     assert m.role == "assistant"
+    mc = message_content_chunk("Hello world!")
+    assert mc.content == "Hello world!"
+    assert mc.role == "assistant"
 
 
 def test_dict_normalization():
-    m = message_content_chunk({"content": "Hello world!", "role": "assistant"})
+    m = message_content({"content": "Hello world!", "role": "assistant"})
     assert m.content == "Hello world!"
     assert m.role == "assistant"
+    mc = message_content_chunk({"content": "Hello world!"})
+    assert mc.content == "Hello world!"
+    assert mc.role == "assistant"
+
+
+def test_chat_message_normalization():
+    m = message_content(ChatMessage(content="Hello world!", role="assistant"))
+    assert m.content == "Hello world!"
+    assert m.role == "assistant"
+    mc = message_content_chunk(ChatMessage(content="Hello world!"))
+    assert mc.content == "Hello world!"
+    assert mc.role == "assistant"
+
+
+def test_tagifiable_normalization():
+    from shiny.ui import HTML, div
+
+    # Interpreted as markdown (without escaping)
+    m = message_content("Hello <span>world</span>!")
+    assert m.content == "Hello <span>world</span>!"
+    assert m.role == "assistant"
+
+    # Interpreted as HTML (without escaping)
+    m = message_content(HTML("Hello <span>world</span>!"))
+    assert (
+        m.content
+        == "\n\n````````{=html}\nHello <span>world</span>!\n````````\n\n"
+    )
+    assert m.role == "assistant"
+
+    # Interpreted as HTML (if top-level object is tag-like, inner string contents get escaped)
+    m = message_content(div("Hello <span>world</span>!"))
+    assert (
+        m.content
+        == "\n\n````````{=html}\n<div>Hello &lt;span&gt;world&lt;/span&gt;!</div>\n````````\n\n"
+    )
+    assert m.role == "assistant"
 
 
 def test_langchain_normalization():