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Move historical LangSmith runs into Arize AX so your team can investigate past traffic in the same place you monitor new traces. Importing history is different from pointing your app at AX for the first time. Instrumentation alone only captures new traffic. The migration skill copies existing LangSmith runs into an AX project with OpenInference attributes your AX UI expects.

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What you can migrate

The skill maps LangSmith’s final run outputs to a plain-text output.value (not a raw tool/message timeline), copies session_id / thread_id to session.id, and preserves the run tree with parent links.

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Migrate existing LangSmith data

1

Install the migration skill

See Install skills if you need the full Arize Skills setup.
2

Ask your coding agent to start

Use the Arize LangSmith migration skill. I want to import historical LangSmith traces into AX.
Tell the agent your LangSmith project name and the AX space and destination project you want. Prefer a new AX project name so imported history stays separate from live traffic until you review it.
3

Provide connection details privately

Give the agent credentials through a local env file path you control, or let it generate a secure command you run in a separate terminal. Do not paste API keys into agent chat.The agent can resolve human-readable AX space names; you do not need to hunt for opaque IDs.
4

Review the plan and import

The agent confirms the source LangSmith project, destination AX project, and what it will import. Approve before it writes to AX.It exports runs through the LangSmith API and ingests them into AX over OTLP. A small project often finishes in a few minutes; larger histories take longer while AX indexes spans.
5

Verify in Arize AX

In the destination project, open a few traces and check:
  1. Output — the turn or root span shows the same final text you see in LangSmith Output (not a JSON message/parts dump)
  2. Tree — child spans nest under parents
  3. Sessions — turns that shared a LangSmith session_id / thread_id group under the same AX session
If something looks wrong, ask the agent to adjust the mapping and re-import into a fresh project rather than mixing retries.
6

Migrate prompts (optional)

Ask the agent to import LangSmith Prompt Hub prompts into the AX Prompt Hub. You can choose latest only or full version history.The agent lists prompts (list_prompts / commits API), maps chat messages into AX message roles, creates each prompt with ax prompts create or the Python prompts client, then adds older commits with create_version and applies labels such as production when LangSmith tags exist.Confirm variable style ({var} vs {{var}}) if a template is ambiguous — AX supports F_STRING and MUSTACHE.

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What good imported traces look like

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After you migrate

Historical import does not change where your running app sends new spans. When you are ready for new traffic in AX, follow Set up tracing and Configure your tracer.
Keep LangSmith available until you have verified the import, because the skill reads from the LangSmith API. See the arize-migrate-langsmith skill source for current behavior and limits.