fix(pkg-py): Handle statically rendered dependencies correctly (#134)

* Introduce failing test (by statically rendering a UI object with dependencies)

* fix(pkg-py): lazily process UI dependencies of a ChatMessage()

* Get test passing

* Update changelog

* Fix import lint

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]
+
+### Bug fixes
+
+* Fixed an issue (introduced in v0.2.0) where statically rendered messages with HTML dependencies weren't being handled properly. (#134)
+
 ## [0.2.3] - 2025-09-10
 
 ### Bug fixes

pkg-py/src/shinychat/_chat.py

@@ -20,15 +20,7 @@
 )
 from weakref import WeakValueDictionary
 
-from htmltools import (
-    HTML,
-    HTMLDependency,
-    Tag,
-    TagAttrValue,
-    TagChild,
-    TagList,
-    css,
-)
+from htmltools import HTML, Tag, TagAttrValue, TagChild, TagList, css
 from shiny import reactive
 from shiny._deprecated import warn_deprecated
 from shiny.bookmark import BookmarkState, RestoreState
@@ -1001,9 +993,12 @@ async def _send_append_message(
         if icon is not None:
             msg["icon"] = str(icon)
 
+        # Register deps with the session and get the dictionary format
+        # for client-side rendering
         deps = message.html_deps
         if deps:
-            msg["html_deps"] = deps
+            processed = self._session._process_ui(TagList(*deps))
+            msg["html_deps"] = processed["deps"]
 
         # print(msg)
 
@@ -1766,7 +1761,7 @@ def chat_ui(
         message_tags.append(
             Tag(
                 "shiny-chat-message",
-                *[HTMLDependency(**d) for d in msg.html_deps],
+                *msg.html_deps,
                 content=msg.content,
                 icon=icon_attr,
                 data_role=msg.role,

pkg-py/src/shinychat/_chat_types.py

@@ -3,8 +3,7 @@
 from dataclasses import dataclass
 from typing import Literal, TypedDict
 
-from htmltools import HTML, Tag, TagChild, Tagifiable, TagList
-from shiny.session import get_current_session
+from htmltools import HTML, HTMLDependency, TagChild, TagList
 
 from ._typing_extensions import NotRequired
 
@@ -26,28 +25,18 @@ def __init__(
     ):
         self.role: Role = role
 
-        is_html = isinstance(content, (Tag, TagList, HTML, Tagifiable))
-
         # content _can_ be a TagChild, but it's most likely just a string (of
         # markdown), so only process it if it's not a string.
         deps = []
         if not isinstance(content, str):
-            session = get_current_session()
-            if session and not session.is_stub_session():
-                res = session._process_ui(content)
-                deps = res["deps"]
-            else:
-                res = TagList(content).render()
-                deps = [d.as_dict() for d in res["dependencies"]]
-            content = res["html"]
-
-        if is_html:
+            ui = TagList(content).render()
+            content, deps = ui["html"], ui["dependencies"]
             # Code blocks with `{=html}` infostrings are rendered as-is by a
             # custom rendering method in markdown-stream.ts
             content = f"\n\n````````{{=html}}\n{content}\n````````\n\n"
 
         self.content = content
-        self.html_deps = deps
+        self.html_deps: list[HTMLDependency] = deps
 
 
 # A message once transformed have been applied
@@ -58,7 +47,7 @@ class TransformedMessage:
     role: Role
     transform_key: Literal["content_client", "content_server"]
     pre_transform_key: Literal["content_client", "content_server"]
-    html_deps: list[dict[str, str]] | None = None
+    html_deps: list[HTMLDependency] | None = None
 
     @classmethod
     def from_chat_message(cls, message: ChatMessage) -> "TransformedMessage":

pkg-py/tests/playwright/chat/shiny_output/app.py

@@ -3,6 +3,7 @@
 import plotly.express as px  # pyright: ignore[reportMissingTypeStubs]
 from shiny import reactive, render
 from shiny.express import ui
+from shinychat.express import Chat
 from shinywidgets import render_plotly, render_widget
 
 ui.page_opts(
@@ -18,12 +19,9 @@ def map():
         return ipyl.Map(center=(52, 10), zoom=8)
 
 
-chat = ui.Chat(
-    id="chat",
-    messages=[map_ui],
-)
+chat = Chat(id="chat")
 
-chat.ui()
+chat.ui(messages=[map_ui])
 
 with ui.hold() as df_1:
 
@@ -48,7 +46,7 @@ def df2():
 
 @reactive.effect
 async def _():
-    await chat.append_message_stream(df_2)
+    await chat.append_message(df_2)
 
 
 with ui.hold() as plot_ui: