# LangChain 1.3.15

- Product: LangChain (https://whatsnew.fyi/product/langchain)
- Vendor: LangChain
- Date: 2026-08-11
- Version: 1.3.15
- Original notes: https://github.com/langchain-ai/langchain/releases/tag/langchain%3D%3D1.3.15
- Permalink: https://whatsnew.fyi/product/langchain/releases/1.3.15

What's New is an index, not a publisher: every entry below links to the vendor's own release notes, which are the authoritative source. Entries are labelled where they are hand-curated sample data, pre-releases, or drawn from a secondary source such as a developer blog.

Reuse: the summaries, labels and curation here are © What's New. Quote freely with attribution and a link back; wholesale republication of the corpus is not permitted — terms: https://whatsnew.fyi/terms. The vendors' own release notes remain their publishers'.

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- **added** — Expose `trace_policy` on `AgentMiddleware`
- **fixed** — Preserve history on `SummarizationMiddleware` summary failure
- **fixed** — Handle import error in `LLMToolEmulator` by `model`
- **added** — Add `state_schema` param to `wrap_tool_call`
- **fixed** — Re-export `PIIMatch` from `middleware` package
- **fixed** — Restrict narrowed `ToolStrategy` in bound tools
- **added** — Filter internal middleware model calls from `messages` projection
- **fixed** — Handle malformed structured-output responses
- **fixed** — Prevent orphaned `tool_calls` in `ToolCallLimitMiddleware` end behavior
- **fixed** — Add aliases for bedrock mantle chat models
- **added** — Add LangSmith provider to `init_chat_model`
- **fixed** — Clear stale `structured_response` between checkpointed turns
- **fixed** — Stop HITL approval gates from silently failing open
- **fixed** — Propagate model middleware control flow
- **added** — Add `reasoning_effort` as a standard chat model parameter

Changes since langchain==1.3.14

release(langchain): 1.3.15 (#39595)
feat(langchain): expose `trace_policy` on `AgentMiddleware` (#38910)
chore(langchain): fix type errors in tests (#39589)
chore: bump h2 from 4.3.0 to 4.4.1 in /libs/langchain_v1 (#39324)
fix(langchain): preserve history on `SummarizationMiddleware` summary failure (#39268)
fix(langchain): handle import error in `LLMToolEmulator` by `model` (#39290)
refactor(langchain): update doc strings (#39305)
feat(langchain): add `state_schema` param to `wrap_tool_call` (#39292)
fix(langchain): re-export `PIIMatch` from `middleware` package (#39291)
fix(langchain): restrict narrowed `ToolStrategy` in bound tools (#39259)
feat(langchain): filter internal middleware model calls from `messages` projection (#39252)
chore: bump aiohttp from 3.14.1 to 3.14.3 in /libs/langchain_v1 (#39242)
chore: bump cryptography from 48.0.1 to 50.0.0 in /libs/langchain_v1 (#39240)
test(langchain): regression test for shell tool + checkpointer msgpack error (#39267)
fix(langchain): handle malformed structured-output responses (#39245)
fix(langchain): prevent orphaned `tool_calls` in `ToolCallLimitMiddleware` end behavior (#39258)
fix(langchain): add aliases for bedrock mantle chat models (#39260)
feat(langchain): add LangSmith provider to `init_chat_model` (#39224)
fix(langchain): clear stale `structured_response` between checkpointed turns (#39248)
fix(langchain): stop HITL approval gates from silently failing open (#39247)
chore: bump the minor-and-patch group across 3 directories with 7 updates (#39187)
fix(langchain): propagate model middleware control flow (#39199)
fix(langchain): update Anthropic config test (#39172)
chore: bump pyasn1 from 0.6.3 to 0.6.4 in /libs/langchain_v1 (#39026)
chore: bump pillow from 12.2.0 to 12.3.0 in /libs/langchain_v1 (#38994)
feat(core): add `reasoning_effort` as a standard chat model parameter (#38887)
docs(langchain): clarify `ToolRetryMiddleware` exception handling (#38884)