Eric Hare c0eebb1a51 fix: restore route discovery under FastAPI 0.137 lazy include_router (#13710)
The recent uv update bumped FastAPI 0.136.3 -> 0.137.1 (Starlette 1.2.1 ->
1.3.1), which changed `include_router` to lazy inclusion: an included sub-router
is now stored as an internal `_IncludedRouter` wrapper instead of eagerly
flattening its `APIRoute` objects onto the parent. Anything that introspects
`app.router.routes` no longer sees nested routes.

Production impact: `_get_route_keys` (plugin conflict-protection) iterates
`app.router.routes` to build the reserved set before loading plugins. With the
core routers now behind `_IncludedRouter` wrappers, the reserved set was empty,
so a plugin could silently shadow core Langflow routes. Fix by descending
through the wrapper via its public `original_router` / `include_context`
(accumulating the include-time prefix), so discovery works on both eager
(<=0.136) and lazy (>=0.137) inclusion.

The same assumption broke route-introspection tests, now made version-agnostic:
- test_deployments_routes.py: read routes from the router via a flattener
- test_extensions_route_guard.py: `collect_paths` descends through the wrapper

These failures surfaced on release-1.10.1 and are unrelated to any PR content.
2026-06-16 17:21:39 -07:00
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2025-03-20 00:05:55 +00:00
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Langflow is a powerful platform for building and deploying AI-powered agents and workflows. It provides developers with both a visual authoring experience and built-in API and MCP servers that turn every workflow into a tool that can be integrated into applications built on any framework or stack. Langflow comes with batteries included and supports all major LLMs, vector databases and a growing library of AI tools.

Highlight features

  • Visual builder interface to quickly get started and iterate.
  • Source code access lets you customize any component using Python.
  • Interactive playground to immediately test and refine your flows with step-by-step control.
  • Multi-agent orchestration with conversation management and retrieval.
  • Deploy as an API or export as JSON for Python apps.
  • Deploy as an MCP server and turn your flows into tools for MCP clients.
  • Observability with LangSmith, LangFuse and other integrations.
  • Enterprise-ready security and scalability.

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Requires Python 3.103.14 and uv (recommended package manager).

Install

From a fresh directory, run:

uv pip install langflow -U

The latest Langflow package is installed. For more information, see Install and run the Langflow OSS Python package.

Run

To start Langflow, run:

uv run langflow run

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Run from source

If you've cloned this repository and want to contribute, run this command from the repository root:

make run_cli

For more information, see DEVELOPMENT.md.

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Start a Langflow container with default settings:

docker run -p 7860:7860 langflowai/langflow:latest

Langflow is available at http://localhost:7860/. For configuration options, see the Docker deployment guide.

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