langgraph-agent-builder

Distribution name: langgraph-agent-builder. CLI command: lab. Python import package: langgraph_agent_builder.

Design-time low-code flow builder for the agentplane platform. Compose flows on a canvas, validate them with the shared agentplane-core rules, and publish them to the agentplane runtime — which serves each flow as an A2A agent or MCP tool behind the gateway. The builder itself hosts nothing: no endpoints, no execution. When the builder process stops, every published flow keeps working.

cd backend && uv sync
uv run lab serve        # design-time API + bundled frontend

• FlowDefinition is the format. Drafts, exports and imports are canonical FlowDefinition YAML/JSON (deterministic order, canvas positions confined to the layout block). Files are git-safe: resources by name, never secrets.
• Types come from the platform. FlowDefinition, node config models, ValidationIssue and validate_structure() are imported from agentplane-core/agentplane-sdk, pinned exactly from PyPI — the builder defines zero contract types of its own.
• Validate merges instant local checks with the runtime's authoritative answer (POST /definitions/validate), each issue marked local/runtime.
• Publish = update the runtime draft + deploy (returns the endpoint URL; registration happens platform-side). Playground = ephemeral deploy; the chat panel talks A2A to /a2a/_draft/{name} through the gateway.

Configuration (env prefix BUILDER_)

Development

uv run pytest && uv run ruff format . && uv run ruff check --fix . && uv run mypy

The platform contract is the exact PyPI pin in pyproject.toml plus ../schemas/flow-definition.schema.json; upgrading it is a deliberate PR (bump the pin, refresh the schema) gated by the round-trip and contract tests.