Implement planned topic: 0019-activity-info-defaults

references/python/advanced-features.md

@@ -134,7 +134,7 @@ client = await Client.connect(
 
 - The only field is `resolution_interval_millis: int = 30000`  — how often to re-resolve DNS, in milliseconds.
 - `DnsLoadBalancingConfig.default`  is a pre-built instance with the default 30-second interval.
-- `dns_load_balancing_config` defaults to 30 seconds if you don't pass anything explicitly. 
+- `dns_load_balancing_config` defaults to 30 seconds if you don't pass anything explicitly.
 - Pass `dns_load_balancing_config=None` to disable DNS load balancing entirely.
 
 ### Mutual exclusion with HTTP CONNECT proxy

references/python/integrations/google-adk.md

@@ -9,7 +9,6 @@ The integration is built on the Python SDK [Plugin system](https://docs.temporal
 > [!NOTE]
 > This feature is in Public Preview. It is perfectly acceptable to use this feature on behalf of a user, but you should inform them that you are making use of a feature in Public Preview.
 
-
 For general Temporal AI/LLM patterns (retries, rate limits, multi-agent orchestration) see `references/core/ai-patterns.md` and `references/python/ai-patterns.md`.
 
 ## Prerequisites

references/python/integrations/langgraph.md

@@ -214,4 +214,4 @@ For LangSmith tracing of LangGraph nodes and Temporal Activities together, use t
 
 - `references/python/ai-patterns.md` — Python AI/LLM patterns (Pydantic data converter, LLM Activity design, retry/error classification).
 - `references/core/ai-patterns.md` — language-agnostic AI/LLM patterns.
-- `references/python/integrations/langsmith.md` - Companion LangSmith plugin. 
+- `references/python/integrations/langsmith.md` - Companion LangSmith plugin.

references/python/integrations/langsmith.md

@@ -100,7 +100,6 @@ The plugin makes `@traceable` replay-safe in the Workflow sandbox. You do not ne
 - The plugin injects metadata using `workflow.now()` for timestamps and `workflow.random()` for UUIDs instead of `datetime.now()` and `uuid4()`.
 - LangSmith HTTP calls run on a background thread pool that does not interfere with deterministic Workflow execution.
 
-
 ## Context propagation
 
 Trace context flows automatically across Client → Workflow → Activity → Child Workflow → Nexus via Temporal headers. Do not pass context manually.

references/python/integrations/openai-agents-sdk.md

@@ -164,7 +164,6 @@ Note that the initial run context comes from the `context=...` argument you pass
 
 In addition, since a `@function_tool` runs in the workflow, they can also call Temporal activities or other durable primitives themselves.
 
-
 **Don't put I/O, system clock, or sources of randomness inside a `@function_tool` body.** Make it an `@activity.defn` and wrap with `activity_as_tool` instead.
 
 ### Picking between the two

references/python/testing.md

@@ -154,6 +154,45 @@ async def test_activity():
     assert result == "expected"
 ```
 
+### Customize Activity Info
+
+`ActivityEnvironment()` populates `env.info` with a default `temporalio.activity.Info` on construction, so activity code that calls `activity.info()` works out of the box. When your test needs specific values (e.g. asserting on `info.activity_id`, exercising `attempt`-aware retry logic, or simulating a Standalone Activity), build a new `Info` from the helper:
+
+- `ActivityEnvironment.default_info()` is a `@staticmethod` taking no arguments. It returns a fresh `temporalio.activity.Info` populated with sentinel test values: `activity_id="test"`, `task_queue="test"`, `workflow_id="test"`, `workflow_run_id="test-run"`, `workflow_type="test"`, `namespace="default"`, `workflow_namespace="default"`, `attempt=1`, `start_to_close_timeout=timedelta(seconds=1)`, `schedule_to_close_timeout=timedelta(seconds=1)`, `activity_run_id=None`, `retry_policy=None`, `heartbeat_timeout=None`.
+- Customize by passing the result through `dataclasses.replace`, then assigning to `env.info` **before** calling `env.run`:
+
+```python
+import dataclasses
+from temporalio.testing import ActivityEnvironment
+
+env = ActivityEnvironment()
+env.info = dataclasses.replace(
+    ActivityEnvironment.default_info(),
+    activity_id="order-1234",
+    attempt=3,
+)
+await env.run(my_activity, "arg")
+```
+
+For Standalone Activities ([see `references/python/standalone-activities.md`](standalone-activities.md)), the `activity_run_id` field on `Info` is `None` for Workflow-orchestrated Activities; set it to a string and clear the `workflow_*` fields (each is `Optional[str]`) to test Standalone-flavoured code paths:
+
+```python
+env.info = dataclasses.replace(
+    ActivityEnvironment.default_info(),
+    activity_run_id="standalone-run-id",
+    workflow_id=None,
+    workflow_run_id=None,
+    workflow_type=None,
+    workflow_namespace=None,
+)
+```
+
+Common mistakes:
+
+- Calling `default_info()` as a module-level function (e.g. `activity.default_info()`); it lives on `temporalio.testing.ActivityEnvironment` as a static method.
+- Passing fields directly to `default_info(...)`; it accepts no arguments. Use `dataclasses.replace` on the returned `Info`.
+- Mutating `env.info` after `env.run` has started — the activity has already captured the context.
+
 ## Best Practices
 
 1. Use the `WorkflowEnvironment.start_local` environment for most testing

references/python/workflow-streams.md

@@ -11,7 +11,6 @@ Use it for modest fan-out progress streaming: AI-agent runs, order pipelines, mu
 
 Only available in the Python SDK today; cross-language is on the roadmap.
 
-
 ## When to use / not to use
 
 - Use it for: updating a UI as an AI agent works; surfacing status from a payment or order pipeline; reporting intermediate results from a data job.

references/ruby/gotchas.md

@@ -59,7 +59,6 @@ require_relative 'activities/my_activity'
 
 Transient network errors should be retried. Authentication errors should not be. See `references/ruby/error-handling.md` to understand how to classify errors with `non_retryable: true` and `non_retryable_error_types`.
 
-
 ## Heartbeating
 
 ### Forgetting to Heartbeat Long Activities