feat(pkg-py): Add new message_content() and message_content_chunk()

pkg-py/CHANGELOG.md

@@ -7,10 +7,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [UNRELEASED]
 
-* The chat input no longer submits incomplete text when the user has activated IME completions (e.g. while typing in Japanese or Chinese). (#85)
+### New features
+
+* Added new `get_message_content()` and `get_message_chunk_content()` generic (`singledispatch`) functions. These functions aren't intended to be called directly by users, but instead, provide an opportunity to teach `Chat.append_message()`/`Chat.append_message_stream()` to extract message contents from different types of objects. (#96)
 
+### Bug fixes
+
+* The chat input no longer submits incomplete text when the user has activated IME completions (e.g. while typing in Japanese or Chinese). (#85)
 
 ## [0.1.0] - 2025-08-07
 
 This first release of the `shinychat` package simply copies the `Chat` and `MarkdownStream` components exactly as they are in version 1.4.0 of `shiny`. Future versions of `shiny` will import these components from `shinychat`. By maintaining these components via a separate library, we can ship features more quickly and independently of `shiny`.
-

pkg-py/src/shinychat/__init__.py

@@ -1,4 +1,15 @@
+from . import playwright, types
 from ._chat import Chat, chat_ui
+from ._chat_normalize import get_message_chunk_content, get_message_content
 from ._markdown_stream import MarkdownStream, output_markdown_stream
 
-__all__ = ["Chat", "chat_ui", "MarkdownStream", "output_markdown_stream"]
+__all__ = [
+    "Chat",
+    "chat_ui",
+    "MarkdownStream",
+    "output_markdown_stream",
+    "get_message_content",
+    "get_message_chunk_content",
+    "types",
+    "playwright",
+]

pkg-py/src/shinychat/_chat.py

@@ -52,7 +52,7 @@
     is_chatlas_chat_client,
     set_chatlas_state,
 )
-from ._chat_normalize import normalize_message, normalize_message_chunk
+from ._chat_normalize import get_message_chunk_content, get_message_content
 from ._chat_provider_types import (
     AnthropicMessage,
     GoogleMessage,
@@ -636,7 +636,7 @@ async def append_message(
             self._pending_messages.append((message, False, "append", None))
             return
 
-        msg = normalize_message(message)
+        msg = get_message_content(message)
         msg = await self._transform_message(msg)
         if msg is None:
             return
@@ -753,7 +753,7 @@ async def _append_message_chunk(
         self._current_stream_id = stream_id
 
         # Normalize various message types into a ChatMessage()
-        msg = normalize_message_chunk(message)
+        msg = get_message_chunk_content(message)
 
         if operation == "replace":
             self._current_stream_message = (