LangGraph plugin samples

[DABH]

Summary

Add seven samples demonstrating the Temporal LangGraph plugin, which runs LangGraph workflows as durable Temporal workflows. Each graph node or @task executes as a Temporal activity with automatic retries, timeouts, and crash recovery.

Samples are provided for both the Graph API (declarative StateGraph with nodes and edges) and the Functional API (imperative @task / @entrypoint decorators).

Sample	Graph API	Functional API	Description
Human-in-the-loop	✅	✅	Chatbot that uses interrupt() to pause for human approval, Temporal signals to receive feedback, and queries to expose the pending draft.
Continue-as-new	✅	✅	Multi-stage data pipeline that uses continue-as-new with task result caching so previously-completed stages are not re-executed.
ReAct Agent	✅	✅	Tool-calling agent loop. Graph API uses add_conditional_edges; Functional API uses a while loop.
Control Flow	—	✅	Parallel task execution, for loops, and if/else branching — patterns that are natural in the Functional API.

Key Features Demonstrated

• Durable execution — Every graph node / @task runs as a Temporal activity with configurable timeouts and retry policies.
• Human-in-the-loop — LangGraph's interrupt() pauses the graph; Temporal signals deliver human input; queries expose pending state to UIs.
• Continue-as-new with caching — get_cache() captures completed task results; passing the cache to the next execution avoids re-running them.
• Conditional routing — Graph API's add_conditional_edges and Functional API's native if/else/while for agent loops.
• Parallel execution — Functional API launches multiple tasks concurrently by creating futures before awaiting them.

Related PRs

• SDK: AI-36: Add LangGraph plugin sdk-python#1448
• Supersedes: LangGraph Samples #272

Test plan

• Samples are not runnable until the SDK PR lands; verify after merge of AI-36: Add LangGraph plugin sdk-python#1448
• Run each sample with uv run langgraph_plugin/<api>/<sample>/run_worker.py + run_workflow.py

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[Copilot]

Pull request overview

Adds a new langgraph_plugin/ sample suite to demonstrate running LangGraph workflows as durable Temporal workflows via the Temporal LangGraph plugin, covering both LangGraph Graph API and Functional API patterns.

Changes:

• Introduces 7 new LangGraph+Temporal sample workflows (human-in-the-loop, continue-as-new w/ caching, ReAct agent, control-flow).
• Adds a new langgraph dependency group and includes langgraph_plugin in the build packages list.
• Updates repository documentation to link to the new sample suite and provides a dedicated README for running the samples.

Reviewed changes

Copilot reviewed 24 out of 34 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
pyproject.toml	Adds langgraph dependency group, includes langgraph_plugin in wheel packages, adjusts lint/test tasks, and adds mypy override.
README.md	Links the new langgraph_plugin samples from the repo root README.
langgraph_plugin/README.md	Adds usage documentation and a sample matrix for the new suite.
langgraph_plugin/init.py	Declares the new top-level sample package.
langgraph_plugin/graph_api/init.py	Declares Graph API samples namespace.
langgraph_plugin/graph_api/react_agent/init.py	Declares Graph API ReAct agent package.
langgraph_plugin/graph_api/react_agent/workflow.py	Implements Graph API ReAct agent workflow and graph definition.
langgraph_plugin/graph_api/react_agent/run_worker.py	Worker wiring for Graph API ReAct agent sample.
langgraph_plugin/graph_api/react_agent/run_workflow.py	Starter script for Graph API ReAct agent sample.
langgraph_plugin/graph_api/human_in_the_loop/init.py	Declares Graph API human-in-the-loop package.
langgraph_plugin/graph_api/human_in_the_loop/workflow.py	Implements Graph API interrupt + Temporal signal/query human approval flow.
langgraph_plugin/graph_api/human_in_the_loop/run_worker.py	Worker wiring for Graph API human-in-the-loop sample.
langgraph_plugin/graph_api/human_in_the_loop/run_workflow.py	Starter script for Graph API human-in-the-loop sample.
langgraph_plugin/graph_api/continue_as_new/init.py	Declares Graph API continue-as-new package.
langgraph_plugin/graph_api/continue_as_new/workflow.py	Implements Graph API pipeline w/ continue-as-new + cache handoff.
langgraph_plugin/graph_api/continue_as_new/run_worker.py	Worker wiring for Graph API continue-as-new sample.
langgraph_plugin/graph_api/continue_as_new/run_workflow.py	Starter script for Graph API continue-as-new sample.
langgraph_plugin/functional_api/init.py	Declares Functional API samples namespace.
langgraph_plugin/functional_api/react_agent/init.py	Declares Functional API ReAct agent package.
langgraph_plugin/functional_api/react_agent/workflow.py	Implements Functional API ReAct agent via @task + @entrypoint.
langgraph_plugin/functional_api/react_agent/run_worker.py	Worker wiring for Functional API ReAct agent sample.
langgraph_plugin/functional_api/react_agent/run_workflow.py	Starter script for Functional API ReAct agent sample.
langgraph_plugin/functional_api/human_in_the_loop/init.py	Declares Functional API human-in-the-loop package.
langgraph_plugin/functional_api/human_in_the_loop/workflow.py	Implements Functional API interrupt + signal/query human approval flow.
langgraph_plugin/functional_api/human_in_the_loop/run_worker.py	Worker wiring for Functional API human-in-the-loop sample.
langgraph_plugin/functional_api/human_in_the_loop/run_workflow.py	Starter script for Functional API human-in-the-loop sample.
langgraph_plugin/functional_api/control_flow/init.py	Declares Functional API control-flow package.
langgraph_plugin/functional_api/control_flow/workflow.py	Implements Functional API sample demonstrating parallelism + branching.
langgraph_plugin/functional_api/control_flow/run_worker.py	Worker wiring for Functional API control-flow sample.
langgraph_plugin/functional_api/control_flow/run_workflow.py	Starter script for Functional API control-flow sample.
langgraph_plugin/functional_api/continue_as_new/init.py	Declares Functional API continue-as-new package.
langgraph_plugin/functional_api/continue_as_new/workflow.py	Implements Functional API pipeline w/ continue-as-new + cache handoff.
langgraph_plugin/functional_api/continue_as_new/run_worker.py	Worker wiring for Functional API continue-as-new sample.
langgraph_plugin/functional_api/continue_as_new/run_workflow.py	Starter script for Functional API continue-as-new sample.

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