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Mason DaughertyandGitHub
385033fd9c
Preserve LangChain package-version trace metadata when graph-bound config and invoke-time config both contribute `lc_versions`. The earlier broad nested metadata merge has been narrowed to the LangChain-owned `lc_versions` namespace, so arbitrary user metadata keeps the existing last-writer-wins behavior. ## Changes - Add a shared metadata merge path used by `merge_configs()` and `ensure_config()` so top-level metadata keys are preserved across bound and runtime configs. - Special-case only `metadata["lc_versions"]` for one-level package-version accumulation; duplicate package entries remain last-writer-wins and non-mapping values still replace. - Keep generic nested metadata maps, including user-owned `metadata["versions"]`, as replacement-only to avoid changing arbitrary metadata semantics. - Raise the `langchain-core` lower bound to `>=1.4.7` so LangGraph’s `lc_versions` handling aligns with the lc-core package-version instrumentation. - Cover both config merge helpers with tests for `lc_versions` accumulation, non-recursive replacement within the package map, generic nested metadata replacement, and defensive copying of mapping values. ## Test note The stream event assertions for `test_imp_exception` now avoid depending on leaked internal task-path metadata. With older `langchain-core`, callback metadata could be mutated by later task runs, so every task event in this test appeared to have the final task path index. That made even the `task_with_exception` start event report `metadata["langgraph_node"] == "my_task"`, which is inconsistent with the event name. `langchain-core>=1.4.6` preserves per-event metadata more accurately: the first `my_task`, `task_with_exception`, and second `my_task` report distinct task path indexes. The test now asserts the stable behavior instead: event sequence, tags, required metadata, root stream payloads, exception handling, and final outputs, without requiring the old leaked task index.