langchain

LangChain Quickstart (Official Middleware)

This guide shows the shipped LangChain lane:

1. Build a real create_agent(..., middleware=[GaitLangChainMiddleware(...)]) agent.
2. Enforce only in wrap_tool_call.
3. Surface additive correlation metadata with an optional callback handler.
4. Capture one Gait runpack for the whole agent run with run_session(...).

Run

From repo root:

go build -o ./gait ./cmd/gait
(cd sdk/python && uv sync --extra langchain --extra dev)
(cd sdk/python && uv run --python 3.11 --extra langchain python ../../examples/integrations/langchain/quickstart.py --scenario allow)
(cd sdk/python && uv run --python 3.11 --extra langchain python ../../examples/integrations/langchain/quickstart.py --scenario block)
(cd sdk/python && uv run --python 3.11 --extra langchain python ../../examples/integrations/langchain/quickstart.py --scenario require_approval)

Expected allow output:

framework=langchain
scenario=allow
verdict=allow
executed=true
trace_path=/.../gait-out/integrations/langchain/trace_allow.json
executor_output=/.../gait-out/integrations/langchain/executor_allow.json
runpack_path=/.../gait-out/integrations/langchain/runpacks/runpack_run_langchain_allow.zip

Expected block output:

framework=langchain
scenario=block
verdict=block
executed=false
trace_path=/.../gait-out/integrations/langchain/trace_block.json

Expected approval output:

framework=langchain
scenario=require_approval
verdict=require_approval
executed=false
trace_path=/.../gait-out/integrations/langchain/trace_require_approval.json

Deterministic artifacts:

• gait-out/integrations/langchain/trace_allow.json
• gait-out/integrations/langchain/trace_block.json
• gait-out/integrations/langchain/trace_require_approval.json
• gait-out/integrations/langchain/runpacks/runpack_run_langchain_allow.zip
• gait-out/integrations/langchain/runpacks/runpack_run_langchain_block.zip
• gait-out/integrations/langchain/runpacks/runpack_run_langchain_require_approval.zip

Language contract:

• official wording: middleware with optional callback correlation
• callbacks do not make allow or block decisions
• only allow executes the tool