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Closes #34442 [Docs](https://github.com/langchain-ai/docs/pull/4377) --- Add parity with LangChain.js trigger semantics for Python `SummarizationMiddleware`. `trigger` can now express AND conditions within a single dict-style `TriggerClause` while preserving the existing tuple and list-of-tuples behavior. A simple user story: a support agent is helping debug an issue over a long conversation. One tool call may return a large log snippet, briefly pushing the token count over a limit, but the conversation is still only a few messages long and the recent context is valuable. Separately, the user may send many short follow-up messages that increase message count without using much context. With `trigger={"tokens": 4000, "messages": 10}`, both thresholds must be met at the same time: at least 4,000 tokens and at least 10 messages. This means 5,000 tokens across only 3 messages does not summarize, and 20 short messages totaling only 1,000 tokens does not summarize either. Summarization waits until the conversation is large enough by both measures, making it less likely to discard useful recent context too early. ## Changes - Add `TriggerClause` support so `trigger={"tokens": 4000, "messages": 10}` only summarizes when all configured thresholds are met - Export `TriggerClause` from `langchain.agents.middleware` so users can import and annotate dict-style trigger clauses from the public middleware entrypoint - Normalize tuple and mapping trigger inputs through `_normalize_trigger`, preserving existing `ContextSize` tuple semantics as single-condition clauses - Defensively copy mutable trigger list and dict inputs during initialization so caller-side mutations do not change the middleware's stored public configuration after construction - Keep list inputs as OR semantics across clauses, including mixed lists like `[{"tokens": 4000, "messages": 10}, ("messages", 50)]` - Update `_should_summarize` to evaluate AND within each clause and OR across clauses for `tokens`, `messages`, and `fraction` - Update the docs and API link map so `TriggerClause` resolves in the Python middleware docs - Preserve tuple-trigger compatibility while allowing message-based `keep` configurations to summarize at least one message when a trigger fires near the cutoff boundary AI assistance was used to help draft and refine this contribution. --------- Co-authored-by: Mason Daugherty <mason@langchain.dev> Co-authored-by: Mason Daugherty <github@mdrxy.com>
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LangChain is a framework for building agents and LLM-powered applications. It helps you chain together interoperable components and third-party integrations to simplify AI application development — all while future-proofing decisions as the underlying technology evolves.
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pip install langchain
# or
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