Issue

When using llama-swap for example:

The POST path no longer includes additional basepath routes:

.aider.conf.yml:

openai-api-base: http://192.168.5.144:8012/v1

This base has a '/v1' which should be sent to the endpoint, however it is now getting stripped.

Expected llama-swap output Log (for aider-chat==0.82.2) shows correct '/v1' in POST path

INFO] Request 192.168.5.142 "POST /v1/chat/completions HTTP/1.1" 200 60298 "OpenAI/Python 1.73.0" 56.987908917s

Observed llama-swap output Log (for aider-chat > 0.82.2) shows request no longer honours the openai-api-base correctly: ('/v1' no longer getting sent)

[INFO] Request 192.168.5.142 "POST /chat/completions HTTP/1.1" 404 -1 "OpenAI/Python 1.75.0" 16.917µs

This causes aider to recieve a 404 error on the API request for any input:

diff> hello

litellm.NotFoundError: NotFoundError: OpenAIException - 404 page not found

Version and model info

Aider v0.83.1
Model: openai/Qwen3-32B with diff edit format
Git repo: .git with 0 files
Repo-map: disabled
Added ../../../../.aider.conventions.md to the chat (read-only).