feat(langchain): emit source-url/source-document parts from citations#15757
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LangChain citation annotations on text content blocks (e.g. from web search or RAG) were previously dropped instead of being surfaced to the UI. They are now mapped to spec-compliant AI SDK source-url / source-document UI message stream parts across the model, streamEvents, and LangGraph (messages + values) paths. Citation metadata that the source parts cannot represent natively (citedText, startIndex, endIndex, source) is preserved under providerMetadata.langchain so the projection is lossless. Sources are deduped by sourceId; url-less citations are keyed by content rather than position to avoid collisions when the messages and values events surface differing citation subsets. Co-authored-by: Cursor <cursoragent@cursor.com>
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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@dflynn15 please sign the commits, see https://docs.github.com/en/authentication/managing-commit-signature-verification/signing-commits (otherwise we cannot merge) |
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Thanks for the flag, all fixed up, apologies for that @lgrammel! |
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Summary
The
@ai-sdk/langchainadapter previously dropped LangChain citation annotations entirely. Models that return citations through LangChain (web search, RAG, etc.) produced no source information in auseChatUI, even though the same models surfacesource-urlparts when used through native AI SDK providers.This change maps LangChain citation annotations to spec-compliant
source-url/source-documentUI message stream parts.{ type: 'citation', url?, title?, source?, citedText?, startIndex?, endIndex? }entries in theannotationsarray of a text content block. The adapter's text extractors only read.text, so these were silently discarded.urlbecomesource-urlparts (keyed by url); url-less citations with atitle/sourcebecomesource-documentparts. Url-less citations with no human-readable label are skipped rather than emitted as a placeholder.processModelChunk),streamEvents(on_chat_model_stream), and LangGraph (messages+values).citedText,startIndex,endIndex,source) is preserved underproviderMetadata.langchain, so the projection is lossless.sourceId. Url-less citations are keyed by content (not position) so that differing citation subsets/orderings between themessagesandvaluesevents don't cause id collisions.Test plan
extractCitationsFromContentBlocks(array content, serializedkwargsmessages, empty annotations, plain-string content).emitSourceChunks:source-url,source-document,providerMetadataround-trip + omission, dedupe across calls, url-less id collision regression, and skipping label-less citations.streamEvents, and LangGraph (messages + values dedupe) paths.pnpm --filter @ai-sdk/langchain test(node + edge) — 208 passing.tsc --noEmitclean for the package.Notes
patchchangeset included.Made with Cursor