Build(deps): Bump langchain from 1.3.18 to 1.4.0 in /backend

[dependabot]

Bumps langchain from 1.3.18 to 1.4.0.

Release notes

Sourced from langchain's releases.

langchain-perplexity==1.4.0

Changes since langchain-perplexity==1.3.2

release(perplexity): 1.4.0 (#37993) feat(perplexity): bind_tools and Responses-API tool round-trip (#37934) hotfix(openai): min core dep (#37990)

langchain-openai==1.4.0

Changes since langchain-openai==1.3.5

release(openai): 1.4.0 (#38983) chore: bump pillow from 12.2.0 to 12.3.0 in /libs/partners/openai (#38999) feat(core): add reasoning_effort as a standard chat model parameter (#38887) chore(model-profiles): refresh model profile data (#38797)

langchain==1.4.0

Changes since langchain==1.3.18

docs(langchain): runnable langchain.mcp examples (#39976) feat(langchain): langchain.mcp namespace, MCPAdapter (#39939) perf(anthropic,langchain): omit middleware trace inputs (#40098) fix(langchain): include model destination in agent tool routing (#38355) chore(langchain): bump vcrpy test dependency minimum to >=8.2.0 (#39942)

langchain==1.4.0a4

Initial release

release(langchain): 1.4.0a4 test(langchain): cover mixed-era ClientGroup and group elicitation Update libs/langchain_v1/langchain/mcp/adapter.py fix(langchain): drive MCP elicitation via member session for fastmcp 4.0.1 fix(sdk): use latest fastmcp and rm reentrant impl cr cr refactor(langchain): inline MCP client arming into __init__ refactor(langchain): stamp an arm marker instead of introspecting the handler closure fix(langchain): gate MCP interrupt routing on the negotiated protocol era refactor(langchain): drop MCP elicitation flag, derive interrupt routing from the client fix(sdk): add _ReentrantClientGroup fix(langchain): narrow MCPAdapter.client union in mcp tests for mypy chore(langchain): format mcp/adapter.py release(langchain): 1.4.0a3 feat(langchain): group MCP tool metadata under an mcp namespace refactor(langchain): stop exporting MCPAdapterTarget from langchain.mcp refactor(langchain): rename convert_mcp_tool_to_langchain_tool to as_langchain_tool refactor(langchain): rename MCPAdapter.get_tools to list_tools feat(langchain): expose cache_mode on MCPAdapter.get_tools chore(langchain): require fastmcp 4.0.0 feat(langchain): accept a ClientGroup as an MCPAdapter target feat(langchain): mark the langchain.mcp namespace as beta

... (truncated)

Commits

• 79cab2d release(anthropic): 1.7.1 (#40181)
• 1e6a4f0 chore(model-profiles): refresh model profile data (#40171)
• 8330dfe docs(langchain): runnable langchain.mcp examples (#39976)
• 280442b feat(langchain): langchain.mcp namespace, MCPAdapter (#39939)
• f5ee2b6 chore(chroma): bump Pygments security constraint (#40162)
• 234255c chore(model-profiles): refresh model profile data (#40009)
• 79e0e4a chore(deps): bump mistune from 3.3.0 to 3.3.3 in /libs/langchain (#40149)
• e90201b chore(deps): bump mistune from 3.3.0 to 3.3.3 in /libs/core (#40150)
• 4240248 chore(deps): bump mistune from 3.3.0 to 3.3.3 in /libs/text-splitters (#40148)
• 530290a chore(deps): bump uv to 0.12.8 (#40092)
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