feat:allow api_base (base_url) in .env

[saccharin98]

• ## Summary

Adds lightweight API base URL support for OpenAI-compatible providers through LiteLLM.

Changes

• Pass OPENAI_BASE_URL / OPENAI_API_BASE / CHATGPT_API_BASE to LiteLLM as api_base
• Add --base-url / --api-base CLI options in run_pageindex.py
• Document OpenAI-compatible/Ollama usage in README
• Add mock tests for sync and async LiteLLM API base forwarding

Test Plan

• python3 -m pytest tests/test_litellm_api_base.py
• python3 -m pytest tests/test_config.py tests/test_litellm_api_base.py
• python3 run_pageindex.py --help
• git diff --check

Closes #229

[rejojer]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.

🤖 Generated with Claude Code

_{- If this code review was useful, please react with 👍. Otherwise, react with 👎.}

[saccharin98]

Code review

Found 1 issue:

1. Unconditional api_base applied to all LiteLLM providers — _litellm_api_base_kwargs() passes the api_base parameter to every litellm.completion() / litellm.acompletion() call regardless of the model or provider. When OPENAI_BASE_URL is set (e.g. for Ollama or a local endpoint), non-OpenAI models like anthropic/claude-sonnet or gemini/... will also be routed to that endpoint, causing failures. Before this PR, no api_base was passed, so multi-provider usage worked correctly. The fix should conditionally apply api_base only for OpenAI-compatible models/providers.

PageIndex/pageindex/index/utils.py

Lines 13 to 21 in 11b8cd7

	def _litellm_api_base_kwargs():
	api_base = (
	os.getenv("OPENAI_BASE_URL")
	or os.getenv("OPENAI_API_BASE")
	or os.getenv("CHATGPT_API_BASE")
	)
	return {"api_base": api_base} if api_base else {}

PageIndex/pageindex/utils.py

Lines 26 to 34 in 11b8cd7

	def _litellm_api_base_kwargs():
	api_base = (
	os.getenv("OPENAI_BASE_URL")
	or os.getenv("OPENAI_API_BASE")
	or os.getenv("CHATGPT_API_BASE")
	)
	return {"api_base": api_base} if api_base else {}

🤖 Generated with Claude Code

_{- If this code review was useful, please react with 👍. Otherwise, react with 👎.}