feat: durable runtime support

src/google/adk/a2a/converters/event_converter.py

@@ -24,6 +24,9 @@
 from typing import Optional
 import uuid
 
+from google.adk.platform import time as platform_time
+from google.adk.platform import uuid as platform_uuid
+
 from a2a.server.events import Event as A2AEvent
 from a2a.types import DataPart
 from a2a.types import Message
@@ -254,7 +257,7 @@ def convert_a2a_task_to_event(
         invocation_id=(
             invocation_context.invocation_id
             if invocation_context
-            else str(uuid.uuid4())
+            else platform_uuid.new_uuid()
         ),
         author=author or "a2a agent",
         branch=invocation_context.branch if invocation_context else None,
@@ -299,7 +302,7 @@ def convert_a2a_message_to_event(
         invocation_id=(
             invocation_context.invocation_id
             if invocation_context
-            else str(uuid.uuid4())
+            else platform_uuid.new_uuid()
         ),
         author=author or "a2a agent",
         branch=invocation_context.branch if invocation_context else None,
@@ -349,7 +352,7 @@ def convert_a2a_message_to_event(
         invocation_id=(
             invocation_context.invocation_id
             if invocation_context
-            else str(uuid.uuid4())
+            else platform_uuid.new_uuid()
         ),
         author=author or "a2a agent",
         branch=invocation_context.branch if invocation_context else None,
@@ -408,7 +411,7 @@ def convert_event_to_a2a_message(
 
     if output_parts:
       return Message(
-          message_id=str(uuid.uuid4()), role=role, parts=output_parts
+          message_id=platform_uuid.new_uuid(), role=role, parts=output_parts
       )
 
   except Exception as e:
@@ -449,7 +452,7 @@ def _create_error_status_event(
       status=TaskStatus(
           state=TaskState.failed,
           message=Message(
-              message_id=str(uuid.uuid4()),
+              message_id=platform_uuid.new_uuid(),
               role=Role.agent,
               parts=[TextPart(text=error_message)],
               metadata={
@@ -458,7 +461,7 @@ def _create_error_status_event(
               if event.error_code
               else {},
           ),
-          timestamp=datetime.now(timezone.utc).isoformat(),
+          timestamp=datetime.fromtimestamp(platform_time.get_time(), tz=timezone.utc).isoformat(),
       ),
       final=False,
   )
@@ -486,7 +489,7 @@ def _create_status_update_event(
   status = TaskStatus(
       state=TaskState.working,
       message=message,
-      timestamp=datetime.now(timezone.utc).isoformat(),
+      timestamp=datetime.fromtimestamp(platform_time.get_time(), tz=timezone.utc).isoformat(),
   )
 
   if any(

src/google/adk/a2a/executor/a2a_agent_executor.py

@@ -23,6 +23,9 @@
 from typing import Optional
 import uuid
 
+from google.adk.platform import time as platform_time
+from google.adk.platform import uuid as platform_uuid
+
 from a2a.server.agent_execution import AgentExecutor
 from a2a.server.agent_execution.context import RequestContext
 from a2a.server.events.event_queue import EventQueue
@@ -143,7 +146,7 @@ async def execute(
               status=TaskStatus(
                   state=TaskState.submitted,
                   message=context.message,
-                  timestamp=datetime.now(timezone.utc).isoformat(),
+                  timestamp=datetime.fromtimestamp(platform_time.get_time(), tz=timezone.utc).isoformat(),
               ),
               context_id=context.context_id,
               final=False,
@@ -162,9 +165,9 @@ async def execute(
                 task_id=context.task_id,
                 status=TaskStatus(
                     state=TaskState.failed,
-                    timestamp=datetime.now(timezone.utc).isoformat(),
+                    timestamp=datetime.fromtimestamp(platform_time.get_time(), tz=timezone.utc).isoformat(),
                     message=Message(
-                        message_id=str(uuid.uuid4()),
+                        message_id=platform_uuid.new_uuid(),
                         role=Role.agent,
                         parts=[TextPart(text=str(e))],
                     ),
@@ -208,7 +211,7 @@ async def _handle_request(
             task_id=context.task_id,
             status=TaskStatus(
                 state=TaskState.working,
-                timestamp=datetime.now(timezone.utc).isoformat(),
+                timestamp=datetime.fromtimestamp(platform_time.get_time(), tz=timezone.utc).isoformat(),
             ),
             context_id=context.context_id,
             final=False,
@@ -247,7 +250,7 @@ async def _handle_request(
               last_chunk=True,
               context_id=context.context_id,
               artifact=Artifact(
-                  artifact_id=str(uuid.uuid4()),
+                  artifact_id=platform_uuid.new_uuid(),
                   parts=task_result_aggregator.task_status_message.parts,
               ),
           )
@@ -258,7 +261,7 @@ async def _handle_request(
               task_id=context.task_id,
               status=TaskStatus(
                   state=TaskState.completed,
-                  timestamp=datetime.now(timezone.utc).isoformat(),
+                  timestamp=datetime.fromtimestamp(platform_time.get_time(), tz=timezone.utc).isoformat(),
               ),
               context_id=context.context_id,
               final=True,
@@ -270,7 +273,7 @@ async def _handle_request(
               task_id=context.task_id,
               status=TaskStatus(
                   state=task_result_aggregator.task_state,
-                  timestamp=datetime.now(timezone.utc).isoformat(),
+                  timestamp=datetime.fromtimestamp(platform_time.get_time(), tz=timezone.utc).isoformat(),
                   message=task_result_aggregator.task_status_message,
               ),
               context_id=context.context_id,

src/google/adk/agents/invocation_context.py

@@ -16,7 +16,8 @@
 
 from typing import Any
 from typing import Optional
-import uuid
+
+from google.adk.platform import uuid as platform_uuid
 
 from google.genai import types
 from pydantic import BaseModel
@@ -409,4 +410,4 @@ def _find_matching_function_call(
 
 
 def new_invocation_context_id() -> str:
-  return "e-" + str(uuid.uuid4())
+  return "e-" + platform_uuid.new_uuid()

src/google/adk/agents/remote_a2a_agent.py

@@ -26,6 +26,8 @@
 from urllib.parse import urlparse
 import uuid
 
+from google.adk.platform import uuid as platform_uuid
+
 from a2a.client import Client as A2AClient
 from a2a.client import ClientEvent as A2AClientEvent
 from a2a.client.card_resolver import A2ACardResolver
@@ -549,7 +551,7 @@ async def _run_async_impl(
         return
 
       a2a_request = A2AMessage(
-          message_id=str(uuid.uuid4()),
+          message_id=platform_uuid.new_uuid(),
           parts=message_parts,
           role="user",
           context_id=context_id,

src/google/adk/artifacts/base_artifact_service.py

@@ -19,6 +19,8 @@
 from typing import Any
 from typing import Optional
 
+from google.adk.platform import time as platform_time
+
 from google.genai import types
 from pydantic import alias_generators
 from pydantic import BaseModel
@@ -47,7 +49,7 @@ class ArtifactVersion(BaseModel):
       description="Optional user-supplied metadata stored with the artifact.",
   )
   create_time: float = Field(
-      default_factory=lambda: datetime.now().timestamp(),
+      default_factory=lambda: platform_time.get_time(),
       description=(
           "Unix timestamp (seconds) when the version record was created."
       ),

src/google/adk/events/event.py

@@ -14,10 +14,10 @@
 
 from __future__ import annotations
 
-from datetime import datetime
 from typing import Optional
-import uuid
 
+from google.adk.platform import time as platform_time
+from google.adk.platform import uuid as platform_uuid
 from google.genai import types
 from pydantic import alias_generators
 from pydantic import ConfigDict
@@ -70,7 +70,7 @@ class Event(LlmResponse):
   # Do not assign the ID. It will be assigned by the session.
   id: str = ''
   """The unique identifier of the event."""
-  timestamp: float = Field(default_factory=lambda: datetime.now().timestamp())
+  timestamp: float = Field(default_factory=lambda: platform_time.get_time())
   """The timestamp of the event."""
 
   def model_post_init(self, __context):
@@ -125,4 +125,4 @@ def has_trailing_code_execution_result(
 
   @staticmethod
   def new_id():
-    return str(uuid.uuid4())
+    return platform_uuid.new_uuid()

src/google/adk/flows/llm_flows/_code_execution.py

@@ -20,6 +20,8 @@
 import copy
 import dataclasses
 import datetime
+
+from google.adk.platform import time as platform_time
 import logging
 import os
 import re
@@ -288,7 +290,7 @@ async def _run_post_processor(
         if part.inline_data.display_name:
           file_name = part.inline_data.display_name
         else:
-          now = datetime.datetime.now().astimezone()
+          now = datetime.datetime.fromtimestamp(platform_time.get_time()).astimezone()
           timestamp = now.strftime('%Y%m%d_%H%M%S')
           file_extension = part.inline_data.mime_type.split('/')[-1]
           file_name = f'{timestamp}.{file_extension}'

src/google/adk/flows/llm_flows/audio_cache_manager.py

@@ -16,6 +16,8 @@
 
 import logging
 import time
+
+from google.adk.platform import time as platform_time
 from typing import TYPE_CHECKING
 
 from google.genai import types
@@ -70,7 +72,7 @@ def cache_audio(
       raise ValueError("cache_type must be either 'input' or 'output'")
 
     audio_entry = RealtimeCacheEntry(
-        role=role, data=audio_blob, timestamp=time.time()
+        role=role, data=audio_blob, timestamp=platform_time.get_time()
     )
     cache.append(audio_entry)
 

src/google/adk/flows/llm_flows/base_llm_flow.py

@@ -17,6 +17,8 @@
 from abc import ABC
 import asyncio
 import datetime
+
+from google.adk.platform import time as platform_time
 import inspect
 import logging
 from typing import AsyncGenerator
@@ -839,7 +841,7 @@ async def _run_one_step_async(
           async for event in agen:
             # Update the mutable event id to avoid conflict
             model_response_event.id = Event.new_id()
-            model_response_event.timestamp = datetime.datetime.now().timestamp()
+            model_response_event.timestamp = platform_time.get_time()
             yield event
 
   async def _preprocess_async(

src/google/adk/flows/llm_flows/functions.py

@@ -29,8 +29,8 @@
 from typing import Dict
 from typing import Optional
 from typing import TYPE_CHECKING
-import uuid
 
+from google.adk.platform import uuid as platform_uuid
 from google.genai import types
 
 from ...agents.active_streaming_tool import ActiveStreamingTool
@@ -175,7 +175,7 @@ def run_async_tool_in_new_loop():
 
 
 def generate_client_function_call_id() -> str:
-  return f'{AF_FUNCTION_CALL_ID_PREFIX}{uuid.uuid4()}'
+  return f'{AF_FUNCTION_CALL_ID_PREFIX}{platform_uuid.new_uuid()}'
 
 
 def populate_client_function_call_id(model_response_event: Event) -> None:

src/google/adk/flows/llm_flows/transcription_manager.py

@@ -16,6 +16,8 @@
 
 import logging
 import time
+
+from google.adk.platform import time as platform_time
 from typing import TYPE_CHECKING
 
 from google.genai import types
@@ -89,7 +91,7 @@ async def _create_and_save_transcription_event(
           author=author,
           input_transcription=transcription if is_input else None,
           output_transcription=transcription if not is_input else None,
-          timestamp=time.time(),
+          timestamp=platform_time.get_time(),
       )
 
       # Save transcription event to session

src/google/adk/platform/time.py

@@ -0,0 +1,44 @@
+# 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.
+
+"""Platform module for abstracting system time generation."""
+
+from contextvars import ContextVar
+import time
+from typing import Callable
+
+_default_time_provider: Callable[[], float] = time.time
+_time_provider_context_var: ContextVar[Callable[[], float]] = (
+    ContextVar("time_provider", default=_default_time_provider)
+)
+
+
+def set_time_provider(provider: Callable[[], float]) -> None:
+  """Sets the provider for the current time.
+
+  Args:
+    provider: A callable that returns the current time in seconds since the
+      epoch.
+  """
+  _time_provider_context_var.set(provider)
+
+
+def reset_time_provider() -> None:
+  """Resets the time provider to its default implementation."""
+  _time_provider_context_var.set(_default_time_provider)
+
+
+def get_time() -> float:
+  """Returns the current time in seconds since the epoch."""
+  return _time_provider_context_var.get()()

src/google/adk/platform/uuid.py

@@ -0,0 +1,43 @@
+# 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.
+
+"""Platform module for abstracting unique ID generation."""
+
+from contextvars import ContextVar
+import uuid
+from typing import Callable
+
+_default_id_provider: Callable[[], str] = lambda: str(uuid.uuid4())
+_id_provider_context_var: ContextVar[Callable[[], str]] = (
+    ContextVar("id_provider", default=_default_id_provider)
+)
+
+
+def set_id_provider(provider: Callable[[], str]) -> None:
+  """Sets the provider for generating unique IDs.
+
+  Args:
+    provider: A callable that returns a unique ID string.
+  """
+  _id_provider_context_var.set(provider)
+
+
+def reset_id_provider() -> None:
+  """Resets the ID provider to its default implementation."""
+  _id_provider_context_var.set(_default_id_provider)
+
+
+def new_uuid() -> str:
+  """Returns a new unique ID."""
+  return _id_provider_context_var.get()()