Python: Workflow visualization. (#372)

* Workflow visualization.

* fix typing

* address comments

* update all samples

* Update fan in edge group visual

* fix quality check

* Update python/samples/getting_started/workflow/step_06_map_reduce.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* address comment

* Catch up with changes in workflow; add to_mermaid method

* Update examples

* fix test

* add installation guide to error messages

* Remove visualization for samples except for one.

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Evan Mattson <35585003+moonbox3@users.noreply.github.com>

python/samples/getting_started/workflow/README.md

@@ -0,0 +1,11 @@
+# Workflow Getting Started Samples
+
+## Installation
+
+You can install the workflow package with visualization dependency:
+
+```bash
+pip install agent-framework-workflow[viz]
+```
+
+To export visualization images you also need to [install GraphViz](https://graphviz.org/download/).

python/samples/getting_started/workflow/step_01_simple_workflow_sequential.py

@@ -2,7 +2,13 @@
 
 import asyncio
 
-from agent_framework.workflow import Executor, WorkflowBuilder, WorkflowCompletedEvent, WorkflowContext, handler
+from agent_framework.workflow import (
+    Executor,
+    WorkflowBuilder,
+    WorkflowCompletedEvent,
+    WorkflowContext,
+    handler,
+)
 
 """
 The following sample demonstrates a basic workflow with two executors

python/samples/getting_started/workflow/step_01a_simple_workflow_sequential_non_stream.py

@@ -2,7 +2,13 @@
 
 import asyncio
 
-from agent_framework.workflow import Executor, WorkflowBuilder, WorkflowCompletedEvent, WorkflowContext, handler
+from agent_framework.workflow import (
+    Executor,
+    WorkflowBuilder,
+    WorkflowCompletedEvent,
+    WorkflowContext,
+    handler,
+)
 
 """
 The following sample demonstrates a basic workflow with two executors

python/samples/getting_started/workflow/step_06_map_reduce_and_visualization.py

@@ -12,6 +12,7 @@ from agent_framework.workflow import (
     WorkflowBuilder,
     WorkflowCompletedEvent,
     WorkflowContext,
+    WorkflowViz,
     handler,
 )
 
@@ -23,6 +24,8 @@ to a final count per word.
 
 Intermediate results are stored in a temporary directory, and the
 final results are written to a file in the same directory.
+
+This sample also shows how you can visualize a workflow using `WorkflowViz`.
 """
 
 # Define the temporary directory for storing intermediate results
@@ -286,6 +289,24 @@ async def main():
         .build()
     )
 
+    # Step 2.5: Visualize the workflow (optional)
+    print("🎨 Generating workflow visualization...")
+    viz = WorkflowViz(workflow)
+    # Print out the mermaid string.
+    print("🧜 Mermaid string: \n=======")
+    print(viz.to_mermaid())
+    print("=======")
+    # Print out the DiGraph string.
+    print("📊 DiGraph string: \n=======")
+    print(viz.to_digraph())
+    print("=======")
+    try:
+        # Export the DiGraph visualization as SVG.
+        svg_file = viz.export(format="svg")
+        print(f"🖼️  SVG file saved to: {svg_file}")
+    except ImportError:
+        print("💡 Tip: Install 'viz' extra to export workflow visualization: pip install agent-framework-workflow[viz]")
+
     # Step 3: Open the text file and read its content.
     async with aiofiles.open(os.path.join(DIR, "resources", "long_text.txt"), "r") as f:
         raw_text = await f.read()