feat: add LangChain Runner protocol implementation (AIC-2388)#1338
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jsonbailey wants to merge 1 commit intojb/aic-2388/js-openai-runnerfrom
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feat: add LangChain Runner protocol implementation (AIC-2388)#1338jsonbailey wants to merge 1 commit intojb/aic-2388/js-openai-runnerfrom
jsonbailey wants to merge 1 commit intojb/aic-2388/js-openai-runnerfrom
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Adds LangChainModelRunner, LangChainAgentRunner, and LangChainRunnerFactory that implement the Runner protocol introduced in JS PR 6. The runners return RunnerResult instead of the legacy ChatResponse / StructuredResponse. LangChainAgentRunner uses LangChain's native bindTools to run a tool-calling loop, populating LDAIMetrics.toolCalls with the names of tools the model invoked. Tool implementations are supplied via a ToolRegistry passed to LangChainRunnerFactory.createAgent. mapProvider is renamed to mapProviderName on both the helper module and the LangChainProvider class; the old mapProvider name is kept as a deprecated alias. The deprecated LangChainProvider class is preserved so AIProviderFactory continues to work during the migration. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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Summary
Adds Runner-protocol classes for the LangChain provider, mirroring the OpenAI runner work in JS PR 7. New classes:
LangChainModelRunner—Runnerfor chat completions;run(messages, outputType?)returnsRunnerResult { content, metrics, raw, parsed? }. Structured output is parsed viawithStructuredOutputand exposed onparsed.LangChainAgentRunner—Runnerfor a single agent. Runs a tool-calling loop using LangChain's nativebindToolsandToolMessage. Tool definitions come fromconfig.model.parameters.tools; tool callables come from a caller-suppliedToolRegistry. PopulatesLDAIMetrics.toolCallswith the names of tools the model invoked.LangChainRunnerFactory— exposescreateModel(config)andcreateAgent(config, tools?).convertMessagesToLangChain,mapProviderName,getAIMetricsFromResponse,getAIUsageFromResponse— helper functions.mapProvideris renamed tomapProviderNameon both the helper module and theLangChainProviderclass; the old name is preserved as a@deprecatedalias so existing callers continue to work.The legacy
LangChainProviderclass is preserved soAIProviderFactory(also@deprecated) keeps working until the managed layer fully migrates toRunner.run().Stacked on
jb/aic-2388/js-openai-runner(JS PR 7).Test plan
yarn workspace @launchdarkly/server-sdk-ai-langchain test— 37 tests pass (existing 16 + 21 new)yarn workspace @launchdarkly/server-sdk-ai-langchain lint— cleanyarn workspace @launchdarkly/server-sdk-ai-langchain run build— clean🤖 Generated with Claude Code