feat(ui): add streaming support to canvas artifacts

Signed-off-by: Petr Kadlec <petr@puradesign.cz>

Author: kapetr

…-sdk-py/examples/artifacts_test_agent.py …-sdk-py/examples/canvas_ui_test_agent.pyapps/agentstack-sdk-py/examples/artifacts_test_agent.py renamed to apps/agentstack-sdk-py/examples/canvas_ui_test_agent.py apps/agentstack-sdk-py/examples/artifacts_test_agent.py renamed to apps/agentstack-sdk-py/examples/canvas_ui_test_agent.py

@@ -1,6 +1,7 @@
 # Copyright 2025 © BeeAI a Series of LF Projects, LLC
 # SPDX-License-Identifier: Apache-2.0
 
+import asyncio
 import os
 import random
 import re
@@ -29,6 +30,28 @@
 ]
 
 
+def generate_recipe_response(recipe_title: str, description: str, closing_message: str) -> str:
+    """Generate a recipe response with the given title, description, and closing message."""
+    return f"""\
+{description}
+
+```recipe
+# {recipe_title}
+
+## Ingredients
+- bread (1 slice)
+- butter (1 slice)
+
+## Instructions
+1. Cut a slice of bread.
+2. Cut a slice of butter.
+3. Spread the slice of butter on the slice of bread.
+```
+
+{closing_message}
+"""
+
+
 @server.agent(
     name="Canvas example agent",
 )
@@ -49,81 +72,85 @@ async def artifacts_agent(
     print(f"Canvas Edit Request: {canvas_edit_request}")
 
     if canvas_edit_request:
-        recipe_title = "Canvas Recipe EDITED"
-
         original_recipe = (
             canvas_edit_request.artifact.parts[0].root.text
             if isinstance(canvas_edit_request.artifact.parts[0].root, TextPart)
             else ""
         )
         edited_part = original_recipe[canvas_edit_request.start_index : canvas_edit_request.end_index]
-        description = f"You requested to edit this part:\n\n*{edited_part}*\n\n"
-
-        response = f"""\
-{description}
-
-```recipe
-# Canvas Recipe EDITED
-
-## Ingredients
-- bread (1 slice)
-- butter (1 slice)
-
-## Instructions
-1. Cut a slice of bread.
-2. Cut a slice of butter.
-3. Spread the slice of butter on the slice of bread.
-```
-
-Enjoy your edited meal!
-"""
+        description = f"You requested to edit this part:\n\n{edited_part}\n\n"
+        recipe_title = "Canvas Recipe EDITED"
+        closing_message = "Enjoy your edited meal!"
     else:
         recipe_title = random.choice(RECIPE_TITLES)
         description = "Here's your recipe:"
+        closing_message = "Enjoy your meal!"
 
-        response = f"""\
-{description}
-
-```recipe
-# {recipe_title}
-
-## Ingredients
-- bread (1 slice)
-- butter (1 slice)
-
-## Instructions
-1. Cut a slice of bread.
-2. Cut a slice of butter.
-3. Spread the slice of butter on the slice of bread.
-```
-
-Enjoy your meal!
-"""
+    response = generate_recipe_response(recipe_title, description, closing_message)
 
     match = re.compile(r"```recipe\n(.*?)\n```", re.DOTALL).search(response)
-    print(
-        f"Match: {match}\npre_text: {response[: match.start() if match else 'N/A']}\npost_text: {response[match.end() if match else 'N/A' :]}"
-    )
 
     if not match:
         yield response
         return
 
+    await asyncio.sleep(1)
+
     if pre_text := response[: match.start()].strip():
         message = AgentMessage(text=pre_text)
         yield message
         await context.store(message)
 
+    await asyncio.sleep(1)
+
     recipe_content = match.group(1).strip()
     first_line = recipe_content.split("\n", 1)[0]
+
+    # Extract the title and remove it from content if it's a heading
+    if first_line.startswith("#"):
+        artifact_name = first_line.lstrip("# ").strip()
+        # Remove the first line from recipe_content if there's more content
+        recipe_content = recipe_content.split("\n", 1)[1].strip() if "\n" in recipe_content else recipe_content
+    else:
+        artifact_name = "Recipe"
+
+    # Split recipe content into x chunks for streaming
+    num_chunks = 8
+    content_length = len(recipe_content)
+    chunk_size = content_length // num_chunks
+    chunks = []
+
+    for i in range(num_chunks):
+        start = i * chunk_size
+        # Last chunk gets any remaining characters
+        end = content_length if i == num_chunks - 1 else (i + 1) * chunk_size
+        chunks.append(recipe_content[start:end])
+
     artifact = AgentArtifact(
-        # artifact_id='recipe-artifact-1',
-        name=first_line.lstrip("# ").strip() if first_line.startswith("#") else "Recipe",
+        name=artifact_name,
         parts=[TextPart(text=recipe_content)],
     )
-    yield artifact
     await context.store(artifact)
 
+    # Send first chunk with artifact_id to establish the artifact
+    first_artifact = AgentArtifact(
+        artifact_id=artifact.artifact_id,
+        name=artifact_name,
+        parts=[TextPart(text=chunks[0])],
+    )
+    yield first_artifact
+
+    # Send remaining chunks using the same artifact_id
+    for chunk in chunks[1:]:
+        chunk_artifact = AgentArtifact(
+            artifact_id=artifact.artifact_id,
+            name=artifact_name,
+            parts=[TextPart(text=chunk)],
+        )
+        yield chunk_artifact
+        await context.store(chunk_artifact)
+        await asyncio.sleep(0.3)
+
     if post_text := response[match.end() :].strip():
         message = AgentMessage(text=post_text)
         yield message