What does this PR do?

Description

This PR resolves an issue where custom OpenAI-compatible base URLs (e.g., https://api.x.ai) were dropping the required /v1 path segment during chat_completions API calls, leading to 404 upstream errors.

Fixes #4600

Root Cause

The AIAgent initialization explicitly passed the user-provided base_url directly into client_kwargs. The underlying openai python client strictly appends the endpoint (like chat/completions) directly to the base URL. If the user didn't manually include /v1 at the end of their OPENAI_BASE_URL, the resulting upstream path became /chat/completions instead of /v1/chat/completions, which breaks standard OpenAI-compatible providers (xAI, vLLM, Ollama, etc.).

Changes

• Intercepts the base_url right before the openai client is constructed.
• Strips any trailing slashes and checks if the URL ends with /v1.
• Automatically appends /v1/ if it's missing.
• Scoped strictly to api_mode == "chat_completions".
• Safely excluded custom-routed providers like copilot-acp and openrouter to prevent side effects.

Related Issue

Fixes #

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ New feature (non-breaking change that adds functionality)
• 🔒 Security fix
• 📝 Documentation update
• ✅ Tests (adding or improving test coverage)
• ♻️ Refactor (no behavior change)
• 🎯 New skill (bundled or hub)

Changes Made

How to Test

Checklist

Code

• I've read the Contributing Guide
• My commit messages follow Conventional Commits (fix(scope):, feat(scope):, etc.)
• I searched for existing PRs to make sure this isn't a duplicate
• My PR contains only changes related to this fix/feature (no unrelated commits)
• I've run pytest tests/ -q and all tests pass
• I've added tests for my changes (required for bug fixes, strongly encouraged for features)
• I've tested on my platform:

Documentation & Housekeeping

• I've updated relevant documentation (README, docs/, docstrings) — or N/A
• I've updated cli-config.yaml.example if I added/changed config keys — or N/A
• I've updated CONTRIBUTING.md or AGENTS.md if I changed architecture or workflows — or N/A
• I've considered cross-platform impact (Windows, macOS) per the compatibility guide — or N/A
• I've updated tool descriptions/schemas if I changed tool behavior — or N/A

For New Skills

• This skill is broadly useful to most users (if bundled) — see Contributing Guide
• SKILL.md follows the standard format (frontmatter, trigger conditions, steps, pitfalls)
• No external dependencies that aren't already available (prefer stdlib, curl, existing Hermes tools)
• I've tested the skill end-to-end: hermes --toolsets skills -q "Use the X skill to do Y"

Screenshots / Logs