Handle missing FastAPI dependencies gracefully

[Copyxyzai]

Summary

• guard the FastAPI and Pydantic imports so running the module without optional web dependencies prints clear installation guidance instead of a stack trace
• provide an ASGI placeholder and CLI exit checks that direct users to install FastAPI/uvicorn before launching the server
• document the optional FastAPI, uvicorn, and Pydantic requirements in the README web interface section

Testing

• python -m compileall app/web/server.py

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https://chatgpt.com/codex/tasks/task_e_68dc4c8a38088324b4608255df8522b9

[Copilot]

Pull Request Overview

This PR adds robust dependency handling for the FastAPI web server, enabling graceful degradation when optional web dependencies are missing. The changes ensure users receive clear installation guidance instead of cryptic stack traces when trying to run the web interface without the required packages.

• Adds import guards and fallback implementations for FastAPI and Pydantic dependencies
• Creates an ASGI placeholder that provides clear error messages when FastAPI is unavailable
• Documents the optional web dependencies and server launch instructions in the README

Reviewed Changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated 3 comments.

File	Description
app/web/static/index.html	Complete new web interface implementation with chat functionality
app/web/server.py	FastAPI server with dependency guards and graceful error handling
app/logger.py	Enhanced logger with optional loguru dependency handling
README.md	Added web interface documentation with dependency installation instructions

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[Copilot]

The ASGI placeholder function should properly handle the ASGI protocol by sending an HTTP response instead of raising an exception. The current implementation will cause the ASGI server to crash rather than gracefully informing the user.

Suggested change

	raise RuntimeError(
	"FastAPI is not installed. Install dependencies with 'pip install fastapi "
	"uvicorn' or via requirements.txt before running the web server."
	)
	if scope["type"] == "http":
	content = (
	b"FastAPI is not installed. Install dependencies with 'pip install fastapi uvicorn' "
	b"or via requirements.txt before running the web server."
	)
	await send(
	{
	"type": "http.response.start",
	"status": 503,
	"headers": [
	[b"content-type", b"text/plain; charset=utf-8"],
	[b"content-length", str(len(content)).encode("ascii")],
	],
	}
	)
	await send(
	{
	"type": "http.response.body",
	"body": content,
	}
	)
	else:
	# For non-HTTP scopes, just close the connection if possible
	pass

[Copilot]

The uvicorn import should be wrapped in a try-except block to handle cases where uvicorn is not installed, providing a clear error message similar to the FastAPI handling.

Suggested change

	import uvicorn
	try:
	import uvicorn
	except ModuleNotFoundError as exc:
	raise SystemExit(
	"Uvicorn is required to run the OpenManus web server. Install it with "
	"'pip install uvicorn' or via 'pip install -r requirements.txt'."
	) from exc

[Copilot]

[nitpick] The function signature uses modern Python union syntax (str | None) but should be consistent with the typing imports. Consider using Optional[str] from typing module for broader compatibility.