release(core): 1.3.0a1

[Eugene Yurtsev (eyurtsev)]

1.3.0a1 release

[codspeed-hq]

Merging this PR will degrade performance by 73.85%

❌ 13 regressed benchmarks
⏩ 29 skipped benchmarks¹

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	WallTime	test_import_time[PydanticOutputParser]	486.3 ms	1,397.2 ms	-65.19%
❌	WallTime	test_async_callbacks_in_sync	14.8 ms	56.7 ms	-73.85%
❌	WallTime	test_import_time[Document]	159.5 ms	485.2 ms	-67.14%
❌	WallTime	test_import_time[BaseChatModel]	463.5 ms	1,378.6 ms	-66.38%
❌	WallTime	test_import_time[RunnableLambda]	428.6 ms	1,275 ms	-66.38%
❌	WallTime	test_import_time[InMemoryRateLimiter]	156.8 ms	445.9 ms	-64.84%
❌	WallTime	test_import_time[HumanMessage]	226.9 ms	675 ms	-66.39%
❌	WallTime	test_import_time[InMemoryVectorStore]	556.7 ms	1,510 ms	-63.14%
❌	WallTime	test_import_time[ChatPromptTemplate]	542.1 ms	1,619.3 ms	-66.52%
❌	WallTime	test_import_time[CallbackManager]	264.3 ms	813 ms	-67.5%
❌	WallTime	test_import_time[tool]	492.6 ms	1,412.3 ms	-65.12%
❌	WallTime	test_import_time[LangChainTracer]	407.9 ms	1,174.7 ms	-65.28%
❌	WallTime	test_import_time[Runnable]	408.3 ms	1,274.8 ms	-67.97%

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_{Comparing eugene/core_version (fdd4ffa) with master (2c9296c)}

Footnotes

1. 29 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[Eugene Yurtsev (eyurtsev)]

Something off w/ codspeed set up still -- i see no regression in local measurements. Going to unblock since it's an alpha release and we'll need to revisit prior to actual release

[Copilot]

Pull request overview

Bumps the langchain-core package version to the 1.3.0a1 alpha release across the core library’s packaging and runtime version sources.

Changes:

• Update pyproject.toml project version to 1.3.0a1
• Update runtime VERSION constant to 1.3.0a1
• Update uv.lock entry for the editable langchain-core package to 1.3.0a1

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated no comments.

File	Description
libs/core/uv.lock	Updates the locked editable langchain-core package version to 1.3.0a1.
libs/core/pyproject.toml	Updates the package metadata version to 1.3.0a1.
libs/core/langchain_core/version.py	Updates the library’s runtime version constant to 1.3.0a1.

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