chore: import upstream snapshot with attribution

contributing/samples/hitl/request_input_tool/README.md

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+# Request Input Tool Sample
+
+## Overview
+
+This sample demonstrates how an LLM agent can proactively request clarification or confirmation from the user using the built-in `request_input` tool without losing its context/flow.
+
+It showcases a highly realistic support assistant that dynamically constructs a JSON schema to only ask for missing details when creating IT support tickets.
+
+## Sample Inputs
+
+- `I want to file a technical ticket for a database crash.`
+
+  The agent will analyze the prompt, identify that the `title` and `category` are already provided, and dynamically call `request_input` with a schema requesting only `description` and `priority`.
+
+- `File a priority HIGH technical ticket titled database crash explained as the MySQL server throwing OOM errors.`
+
+  The agent has all required details and will call `create_support_ticket` immediately without needing clarification.
+
+## Graph
+
+```mermaid
+graph TD
+    User[User Prompt] --> Agent[Support Assistant Agent]
+    Agent -->|Needs Clarification| RequestInput[request_input tool]
+    RequestInput -->|User Response| Agent
+    Agent -->|All Details Gathered| CreateTicket[create_support_ticket tool]
+```
+
+## How To
+
+This sample uses **Pattern B: Standalone Agents** with the `request_input` tool:
+
+1. **Import `request_input`**:
+
+   ```python
+   from google.adk.tools import request_input
+   ```
+
+1. **Add it to the LLM Agent's tools list**:
+
+   ```python
+   root_agent = Agent(
+       name="support_assistant_agent",
+       tools=[create_support_ticket, request_input],
+       ...
+   )
+   ```
+
+When the LLM decides it needs clarification, it calls `request_input` with a question and a dynamic `response_schema`. The ADK framework automatically intercepts this, yields a long-running interrupt to the client, and injects the user's reply back as a `FunctionResponse` into the LLM's chat history.

contributing/samples/hitl/request_input_tool/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.
+
+from google.adk import Agent
+from google.adk.tools import request_input
+from google.genai import types
+from pydantic import BaseModel
+from pydantic import Field
+
+
+class SupportTicket(BaseModel):
+  """Details of the IT support ticket to be created."""
+
+  title: str = Field(description="A brief summary of the issue.")
+  description: str = Field(description="Detailed explanation of the problem.")
+  priority: str = Field(
+      default="MEDIUM",
+      description="Ticket priority: LOW, MEDIUM, HIGH, or CRITICAL.",
+  )
+  category: str = Field(
+      description=(
+          "Issue category, e.g., billing, technical, account, or database."
+      )
+  )
+
+
+def create_support_ticket(ticket: SupportTicket) -> dict[str, str]:
+  """Create a support ticket in the IT ticketing system."""
+  return {
+      "status": "success",
+      "message": (
+          f"Successfully created ticket '{ticket.title}'"
+          f" [Category: {ticket.category}, Priority: {ticket.priority}]."
+      ),
+      "ticket_id": "INC-98471",
+  }
+
+
+root_agent = Agent(
+    name="support_assistant_agent",
+    instruction="""
+      You are a helpful IT support assistant responsible for creating support tickets.
+      When the user requests to create or file a ticket:
+      1. Identify which ticket details (title, description, priority, category) are already provided in the conversation.
+      2. If any mandatory details are missing, call the `request_input` tool.
+      3. When calling `request_input`, you must construct a dynamic JSON `response_schema` (type: "object") that ONLY requests the missing details, and specify a helpful message explaining what is needed.
+      4. Once all details are gathered, call `create_support_ticket` with the complete SupportTicket details.
+    """,
+    tools=[create_support_ticket, request_input],
+    generate_content_config=types.GenerateContentConfig(temperature=0.1),
+)

contributing/samples/hitl/request_input_tool/tests/create_support_ticket.json

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+{
+  "events": [
+    {
+      "author": "user",
+      "content": {
+        "parts": [
+          {
+            "text": "I want to file a technical ticket for a database crash."
+          }
+        ],
+        "role": "user"
+      },
+      "id": "e-1",
+      "invocationId": "i-1",
+      "nodeInfo": {
+        "path": ""
+      }
+    },
+    {
+      "author": "support_assistant_agent",
+      "content": {
+        "parts": [
+          {
+            "functionCall": {
+              "args": {
+                "message": "I can help with that. Please provide the description and priority of the database crash:",
+                "response_schema": {
+                  "properties": {
+                    "description": {
+                      "description": "Detailed explanation of the database crash problem.",
+                      "title": "Description",
+                      "type": "string"
+                    },
+                    "priority": {
+                      "description": "Ticket priority: LOW, MEDIUM, HIGH, or CRITICAL.",
+                      "title": "Priority",
+                      "type": "string"
+                    }
+                  },
+                  "required": [
+                    "description",
+                    "priority"
+                  ],
+                  "title": "TicketClarification",
+                  "type": "object"
+                }
+              },
+              "id": "fc-1",
+              "name": "adk_request_input"
+            }
+          }
+        ],
+        "role": "model"
+      },
+      "finishReason": "STOP",
+      "id": "e-2",
+      "invocationId": "i-1",
+      "longRunningToolIds": [
+        "fc-1"
+      ],
+      "nodeInfo": {
+        "path": "support_assistant_agent@1"
+      }
+    },
+    {
+      "author": "user",
+      "content": {
+        "parts": [
+          {
+            "functionResponse": {
+              "id": "fc-1",
+              "name": "adk_request_input",
+              "response": {
+                "description": "The MySQL server is throwing OOM errors and restarting repeatedly.",
+                "priority": "HIGH"
+              }
+            }
+          }
+        ],
+        "role": "user"
+      },
+      "id": "e-3",
+      "invocationId": "i-1",
+      "nodeInfo": {
+        "path": ""
+      }
+    },
+    {
+      "author": "support_assistant_agent",
+      "content": {
+        "parts": [
+          {
+            "functionCall": {
+              "args": {
+                "ticket": {
+                  "category": "database",
+                  "description": "The MySQL server is throwing OOM errors and restarting repeatedly.",
+                  "priority": "HIGH",
+                  "title": "Database crash"
+                }
+              },
+              "id": "fc-2",
+              "name": "create_support_ticket"
+            }
+          }
+        ],
+        "role": "model"
+      },
+      "finishReason": "STOP",
+      "id": "e-4",
+      "invocationId": "i-1",
+      "longRunningToolIds": [],
+      "nodeInfo": {
+        "path": "support_assistant_agent@1"
+      }
+    },
+    {
+      "author": "support_assistant_agent",
+      "content": {
+        "parts": [
+          {
+            "functionResponse": {
+              "id": "fc-2",
+              "name": "create_support_ticket",
+              "response": {
+                "message": "Successfully created ticket 'Database crash' [Category: database, Priority: HIGH].",
+                "status": "success",
+                "ticket_id": "INC-98471"
+              }
+            }
+          }
+        ],
+        "role": "user"
+      },
+      "id": "e-5",
+      "invocationId": "i-1",
+      "nodeInfo": {
+        "path": "support_assistant_agent@1"
+      }
+    },
+    {
+      "author": "support_assistant_agent",
+      "content": {
+        "parts": [
+          {
+            "text": "Successfully created ticket 'Database crash' [Category: database, Priority: HIGH] with ticket ID INC-98471."
+          }
+        ],
+        "role": "model"
+      },
+      "finishReason": "STOP",
+      "id": "e-6",
+      "invocationId": "i-1",
+      "nodeInfo": {
+        "path": "support_assistant_agent@1"
+      }
+    }
+  ]
+}