chore: import upstream snapshot with attribution

2026-07-13 13:25:13 +08:00
commit ec2b666284
2231 changed files with 491535 additions and 0 deletions
@@ -0,0 +1,46 @@
+# ADK Workflow Loop Sample
+
+## Overview
+
+This sample demonstrates how to create a feedback loop between different nodes in **ADK Workflows**.
+
+It takes a user-provided topic and uses the `generate_headline` agent to write a headline. The `evaluate_headline` agent then grades the headline as either "tech-related" or "unrelated", providing feedback if it's unrelated. The `route_headline` function checks this grade. If the headline is "unrelated", the workflow loops back to the `generate_headline` agent, passing the feedback so it can try again. This process repeats until a "tech-related" headline is generated.
+
+In ADK Workflows, loops allow for iterative refinement and evaluation by conditionally routing execution back to an earlier node in the sequence.
+
+## Sample Inputs
+
+- `flower`
+
+- `quantum mechanics`
+
+- `renewable energy`
+
+## Graph
+
+```mermaid
+graph TD
+    START --> process_input
+    process_input --> generate_headline
+    generate_headline --> evaluate_headline
+    evaluate_headline --> route_headline
+    route_headline -->|unrelated| generate_headline
+    route_headline -->|tech-related| END[Loop ends]
+```
+
+## How To
+
+1. Define a node (like `route_headline`) that yields an `Event` with a specific route based on a condition:
+
+   ```python
+   def route_headline(node_input: Feedback):
+     return Event(route=node_input.grade)
+   ```
+
+1. In the `Workflow` edges definition, create a conditional edge that connects the routing node back to a previous node in the workflow, using a routing map dict:
+
+   ```python
+   (route_headline, {"unrelated": generate_headline})
+   ```
+
+   This creates the cycle. If the route yielded by `route_headline` is "unrelated", execution jumps back to `generate_headline`.