chore: import upstream snapshot with attribution

contributing/samples/core/input_output_schema/README.md

@@ -0,0 +1,54 @@
+# Input and Output Schema
+
+## Overview
+
+This sample demonstrates how to configure structured `input_schema` and `output_schema` on an ADK agent. When configured with these schemas and `mode='single_turn'`, the agent can be seamlessly used as a structured tool by a parent agent.
+
+## Sample Inputs
+
+- `What is the weather in San Jose?`
+
+  *The parent agent calls `weather_agent` with `{"city": "San Jose"}`. The sub-agent returns `{"temperature": "26 C", "conditions": "Sunny"}`. The parent agent then formulates a friendly response.*
+
+- `Can you check the weather for Cupertino?`
+
+  *The parent agent calls `weather_agent` with `{"city": "Cupertino"}`. The sub-agent returns `{"temperature": "16 C", "conditions": "Foggy"}`.*
+
+## Graph
+
+```mermaid
+graph TD
+    User[User Input] --> RootAgent[root_agent]
+    RootAgent -- Tool Call: CityQuery --> WeatherAgent[weather_agent]
+    WeatherAgent -- Structured Output: WeatherInfo --> RootAgent
+    RootAgent --> Response[User Response]
+```
+
+## How To
+
+### Configuring Input and Output Schemas
+
+To define structured input and output contracts for an agent, pass Pydantic models to the `input_schema` and `output_schema` parameters of the `Agent` constructor:
+
+```python
+class CityQuery(BaseModel):
+  city: str = Field(description="The name of the city")
+
+class WeatherInfo(BaseModel):
+  temperature: str = Field(description="The temperature in Celsius")
+  conditions: str = Field(description="The weather condition")
+
+weather_agent = Agent(
+    name="weather_agent",
+    mode="single_turn",
+    input_schema=CityQuery,
+    output_schema=WeatherInfo,
+    instruction="Provide weather information for the requested city.",
+)
+```
+
+### Using the Agent as a Tool
+
+When `weather_agent` is included in the `sub_agents` list of `root_agent`, the ADK framework automatically wraps it in an `AgentTool`. The parent agent sees a tool that accepts `CityQuery` parameters and returns `WeatherInfo`.
+
+When the tool is invoked, the framework executes `weather_agent` in an isolated context, validates its input against `input_schema`, and validates its generated response against `output_schema`.

contributing/samples/core/input_output_schema/agent.py

@@ -0,0 +1,53 @@
+# 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 __future__ import annotations
+
+from google.adk import Agent
+from pydantic import BaseModel
+from pydantic import Field
+
+
+class CityQuery(BaseModel):
+  city: str = Field(
+      description='The name of the city to query weather for, e.g. San Jose'
+  )
+
+
+class WeatherInfo(BaseModel):
+  temperature: str = Field(description='The temperature in Celsius')
+  conditions: str = Field(description='The weather condition, e.g. Sunny')
+
+
+weather_agent = Agent(
+    name='weather_agent',
+    mode='single_turn',
+    input_schema=CityQuery,
+    output_schema=WeatherInfo,
+    instruction="""\
+Provide weather information for the requested city.
+
+For San Jose, return temperature: 26 C, conditions: Sunny.
+For Cupertino, return temperature: 16 C, conditions: Foggy.
+For any other city, return temperature: unknown, conditions: unknown.
+""",
+)
+
+root_agent = Agent(
+    name='root_agent',
+    instruction="""\
+You are a helpful weather concierge assistant. Use the weather_agent tool to get weather information for the user's city, and then answer the user in a friendly manner.
+""",
+    sub_agents=[weather_agent],
+)

contributing/samples/core/input_output_schema/tests/weather_cupertino.json

@@ -0,0 +1,106 @@
+{
+  "events": [
+    {
+      "author": "user",
+      "content": {
+        "parts": [
+          {
+            "text": "What is the weather in Cupertino?"
+          }
+        ],
+        "role": "user"
+      },
+      "id": "e-1",
+      "invocationId": "i-1",
+      "nodeInfo": {
+        "path": ""
+      }
+    },
+    {
+      "author": "root_agent",
+      "content": {
+        "parts": [
+          {
+            "functionCall": {
+              "args": {
+                "city": "Cupertino"
+              },
+              "id": "fc-1",
+              "name": "weather_agent"
+            }
+          }
+        ],
+        "role": "model"
+      },
+      "finishReason": "STOP",
+      "id": "e-2",
+      "invocationId": "i-1",
+      "longRunningToolIds": [],
+      "nodeInfo": {
+        "path": "root_agent@1"
+      }
+    },
+    {
+      "author": "weather_agent",
+      "branch": "weather_agent@fc-1",
+      "content": {
+        "parts": [
+          {
+            "text": "{\"temperature\": \"16 C\", \"conditions\": \"Foggy\"}"
+          }
+        ],
+        "role": "model"
+      },
+      "finishReason": "STOP",
+      "id": "e-3",
+      "invocationId": "i-1",
+      "nodeInfo": {
+        "messageAsOutput": true,
+        "outputFor": [
+          "root_agent@1/weather_agent@1"
+        ],
+        "path": "root_agent@1/weather_agent@1"
+      }
+    },
+    {
+      "author": "root_agent",
+      "content": {
+        "parts": [
+          {
+            "functionResponse": {
+              "id": "fc-1",
+              "name": "weather_agent",
+              "response": {
+                "conditions": "Foggy",
+                "temperature": "16 C"
+              }
+            }
+          }
+        ],
+        "role": "user"
+      },
+      "id": "e-4",
+      "invocationId": "i-1",
+      "nodeInfo": {
+        "path": "root_agent@1"
+      }
+    },
+    {
+      "author": "root_agent",
+      "content": {
+        "parts": [
+          {
+            "text": "The weather in Cupertino is Foggy with a temperature of 16 C.\n"
+          }
+        ],
+        "role": "model"
+      },
+      "finishReason": "STOP",
+      "id": "e-5",
+      "invocationId": "i-1",
+      "nodeInfo": {
+        "path": "root_agent@1"
+      }
+    }
+  ]
+}

contributing/samples/core/input_output_schema/tests/weather_sanjose.json

@@ -0,0 +1,106 @@
+{
+  "events": [
+    {
+      "author": "user",
+      "content": {
+        "parts": [
+          {
+            "text": "What is the weather in San Jose?"
+          }
+        ],
+        "role": "user"
+      },
+      "id": "e-1",
+      "invocationId": "i-1",
+      "nodeInfo": {
+        "path": ""
+      }
+    },
+    {
+      "author": "root_agent",
+      "content": {
+        "parts": [
+          {
+            "functionCall": {
+              "args": {
+                "city": "San Jose"
+              },
+              "id": "fc-1",
+              "name": "weather_agent"
+            }
+          }
+        ],
+        "role": "model"
+      },
+      "finishReason": "STOP",
+      "id": "e-2",
+      "invocationId": "i-1",
+      "longRunningToolIds": [],
+      "nodeInfo": {
+        "path": "root_agent@1"
+      }
+    },
+    {
+      "author": "weather_agent",
+      "branch": "weather_agent@fc-1",
+      "content": {
+        "parts": [
+          {
+            "text": "{\"temperature\": \"26 C\", \"conditions\": \"Sunny\"}"
+          }
+        ],
+        "role": "model"
+      },
+      "finishReason": "STOP",
+      "id": "e-3",
+      "invocationId": "i-1",
+      "nodeInfo": {
+        "messageAsOutput": true,
+        "outputFor": [
+          "root_agent@1/weather_agent@1"
+        ],
+        "path": "root_agent@1/weather_agent@1"
+      }
+    },
+    {
+      "author": "root_agent",
+      "content": {
+        "parts": [
+          {
+            "functionResponse": {
+              "id": "fc-1",
+              "name": "weather_agent",
+              "response": {
+                "conditions": "Sunny",
+                "temperature": "26 C"
+              }
+            }
+          }
+        ],
+        "role": "user"
+      },
+      "id": "e-4",
+      "invocationId": "i-1",
+      "nodeInfo": {
+        "path": "root_agent@1"
+      }
+    },
+    {
+      "author": "root_agent",
+      "content": {
+        "parts": [
+          {
+            "text": "The weather in San Jose is sunny with a temperature of 26 degrees Celsius. Enjoy your day!"
+          }
+        ],
+        "role": "model"
+      },
+      "finishReason": "STOP",
+      "id": "e-5",
+      "invocationId": "i-1",
+      "nodeInfo": {
+        "path": "root_agent@1"
+      }
+    }
+  ]
+}

contributing/samples/core/input_output_schema/tests/weather_tokyo.json

@@ -0,0 +1,106 @@
+{
+  "events": [
+    {
+      "author": "user",
+      "content": {
+        "parts": [
+          {
+            "text": "What is the weather in Tokyo?"
+          }
+        ],
+        "role": "user"
+      },
+      "id": "e-1",
+      "invocationId": "i-1",
+      "nodeInfo": {
+        "path": ""
+      }
+    },
+    {
+      "author": "root_agent",
+      "content": {
+        "parts": [
+          {
+            "functionCall": {
+              "args": {
+                "city": "Tokyo"
+              },
+              "id": "fc-1",
+              "name": "weather_agent"
+            }
+          }
+        ],
+        "role": "model"
+      },
+      "finishReason": "STOP",
+      "id": "e-2",
+      "invocationId": "i-1",
+      "longRunningToolIds": [],
+      "nodeInfo": {
+        "path": "root_agent@1"
+      }
+    },
+    {
+      "author": "weather_agent",
+      "branch": "weather_agent@fc-1",
+      "content": {
+        "parts": [
+          {
+            "text": "{\"temperature\": \"unknown\", \"conditions\": \"unknown\"}"
+          }
+        ],
+        "role": "model"
+      },
+      "finishReason": "STOP",
+      "id": "e-3",
+      "invocationId": "i-1",
+      "nodeInfo": {
+        "messageAsOutput": true,
+        "outputFor": [
+          "root_agent@1/weather_agent@1"
+        ],
+        "path": "root_agent@1/weather_agent@1"
+      }
+    },
+    {
+      "author": "root_agent",
+      "content": {
+        "parts": [
+          {
+            "functionResponse": {
+              "id": "fc-1",
+              "name": "weather_agent",
+              "response": {
+                "conditions": "unknown",
+                "temperature": "unknown"
+              }
+            }
+          }
+        ],
+        "role": "user"
+      },
+      "id": "e-4",
+      "invocationId": "i-1",
+      "nodeInfo": {
+        "path": "root_agent@1"
+      }
+    },
+    {
+      "author": "root_agent",
+      "content": {
+        "parts": [
+          {
+            "text": "I'm sorry, I don't have the current weather information for Tokyo."
+          }
+        ],
+        "role": "model"
+      },
+      "finishReason": "STOP",
+      "id": "e-5",
+      "invocationId": "i-1",
+      "nodeInfo": {
+        "path": "root_agent@1"
+      }
+    }
+  ]
+}