chore: import upstream snapshot with attribution

contributing/samples/workflows/sequence/README.md

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+# ADK Workflow Sequence Sample
+
+## Overview
+
+This sample demonstrates how to create a simple sequential workflow with **ADK Workflows**.
+
+It connects two LLM agents in a chain. The first agent (`generate_fruit_agent`) is instructed to return the name of a random fruit. The output of this agent becomes the input for the second agent (`generate_benefit_agent`), which then tells a health benefit about that specific fruit.
+
+In a sequence, the execution flows unconditionally from one node to the next in the order they are defined.
+
+## Sample Inputs
+
+This sample does not require any input to run.
+
+## Graph
+
+```mermaid
+graph TD
+    START --> generate_fruit_agent
+    generate_fruit_agent --> generate_benefit_agent
+```
+
+## How To
+
+1. Define the agents or functions that will make up the steps in your sequence.
+
+   ```python
+   generate_fruit_agent = Agent(...)
+   generate_benefit_agent = Agent(...)
+   ```
+
+1. Pass a tuple of three or more elements to `edges` to define an unconditional sequence starting from the first element and passing through each subsequent node in order.
+
+   ```python
+   Workflow(
+       name="root_agent",
+       edges=[("START", generate_fruit_agent, generate_benefit_agent)],
+   )
+   ```

contributing/samples/workflows/sequence/__init__.py

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+# Copyright 2026 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from . import agent

contributing/samples/workflows/sequence/agent.py

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+# Copyright 2026 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Sample workflow for simple sequential workflow with LLM agents."""
+
+from google.adk import Agent
+from google.adk import Workflow
+
+generate_fruit_agent = Agent(
+    name="generate_fruit_agent",
+    instruction="""Return the name of a random fruit.
+      Return only the name, nothing else.""",
+)
+
+generate_benefit_agent = Agent(
+    name="generate_benefit_agent",
+    instruction="""Tell me a health benefit about the specified fruit.""",
+)
+
+
+root_agent = Workflow(
+    name="root_agent",
+    edges=[("START", generate_fruit_agent, generate_benefit_agent)],
+)

contributing/samples/workflows/sequence/tests/go.json

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+{
+  "appName": "sequence",
+  "events": [
+    {
+      "author": "user",
+      "content": {
+        "parts": [
+          {
+            "text": "go"
+          }
+        ],
+        "role": "user"
+      },
+      "id": "e-1",
+      "invocationId": "i-1",
+      "nodeInfo": {
+        "path": ""
+      }
+    },
+    {
+      "author": "generate_fruit_agent",
+      "content": {
+        "parts": [
+          {
+            "text": "Apple"
+          }
+        ],
+        "role": "model"
+      },
+      "finishReason": "STOP",
+      "id": "e-2",
+      "invocationId": "i-1",
+      "nodeInfo": {
+        "messageAsOutput": true,
+        "outputFor": [
+          "root_agent@1/generate_fruit_agent@1"
+        ],
+        "path": "root_agent@1/generate_fruit_agent@1"
+      }
+    },
+    {
+      "author": "generate_benefit_agent",
+      "content": {
+        "parts": [
+          {
+            "text": "Apples are a good source of **dietary fiber**, particularly soluble fiber like pectin. This can help with digestion, promote a feeling of fullness (aiding in weight management), and may contribute to lowering cholesterol levels."
+          }
+        ],
+        "role": "model"
+      },
+      "finishReason": "STOP",
+      "id": "e-3",
+      "invocationId": "i-1",
+      "nodeInfo": {
+        "messageAsOutput": true,
+        "outputFor": [
+          "root_agent@1/generate_benefit_agent@1",
+          "root_agent@1"
+        ],
+        "path": "root_agent@1/generate_benefit_agent@1"
+      }
+    }
+  ],
+  "id": "0e5ab646-61d6-49cd-b058-24fde0afebae",
+  "state": {
+    "__session_metadata__": {
+      "displayName": "go"
+    }
+  },
+  "userId": "user"
+}