chore: import upstream snapshot with attribution

python/samples/04-hosting/durabletask/11_subworkflow/README.md

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+# Composed Workflow (Sub-Workflow) on a Standalone Durable Task Worker
+
+This sample demonstrates **workflow composition** on a standalone Durable Task
+worker: an inner agent-framework `Workflow` is embedded as a node inside an outer
+`Workflow` using `WorkflowExecutor`. On the durable host, the inner workflow runs
+as its own durable **child orchestration**.
+
+## Key Concepts Demonstrated
+
+- Embedding one `Workflow` inside another with
+  `WorkflowExecutor(inner_workflow, id=...)`.
+- A single `DurableAIAgentWorker.configure_workflow(outer_workflow)` call walks the
+  composition and auto-registers a durable orchestration for **each** workflow:
+  - `dafx-review_pipeline` — the outer workflow.
+  - `dafx-sentiment_analysis` — the inner workflow, run as a durable **child
+    orchestration** when the outer workflow reaches the `WorkflowExecutor` node.
+- Per-workflow scoping: each workflow's agent executors become durable entities and
+  its non-agent executors become durable activities, named per workflow so the same
+  executor id in two workflows never collides.
+- Output forwarding: the inner workflow yields a string and, because
+  `allow_direct_output` is left at its default (`False`), that output is forwarded to
+  the outer workflow as a message delivered to the `reporter` executor.
+
+## Composition Layout
+
+```text
+review_pipeline (outer)
+  intake (executor)
+    -> sentiment_sub = WorkflowExecutor(sentiment_analysis)
+         sentiment_agent (agent) -> sentiment_formatter (executor)
+    -> reporter (executor)
+```
+
+## Environment Setup
+
+See the [README.md](../README.md) in the parent directory for environment setup.
+
+This sample uses Azure AI Foundry credentials:
+
+- `FOUNDRY_PROJECT_ENDPOINT`
+- `FOUNDRY_MODEL`
+
+It also needs a Durable Task Scheduler. For local development, start the
+emulator (defaults to `http://localhost:8080`):
+
+```bash
+docker run -d -p 8080:8080 -p 8082:8082 mcr.microsoft.com/dts/dts-emulator:latest
+```
+
+## Running the Sample
+
+Start the worker in one terminal:
+
+```bash
+cd samples/04-hosting/durabletask/11_subworkflow
+python worker.py
+```
+
+In a second terminal, run the client:
+
+```bash
+python client.py
+```
+
+The client targets only the outer workflow (`review_pipeline`); the sub-workflow
+runs automatically as a child orchestration. Each review flows:
+
+`intake` → `sentiment_sub` (child orchestration: `sentiment_agent` →
+`sentiment_formatter`) → `reporter` → `"Review analysis complete -> sentiment: ..."`.