Claude Code

1. Overview

Claude Code is Anthropic’s official terminal AI coding client. Through GravitexAI (Anthropic-compatible API) you get:

Multi-vendor access

Use the full Claude family, Kimi K2, GPT and more behind one endpoint

Dual-thread model

Heavy tasks on the main thread, lightweight ones on the haiku thread

No subscription

Pay per token — no Claude Pro required

Stable globally

Distributed nodes with automatic failover

2. Install Node.js (skip if installed)

Make sure Node.js is ≥ 18.0.

Windows
macOS
Ubuntu / Debian

Download: https://nodejs.org/dist/v22.18.0/node-v22.18.0-x64.msi

sudo xcode-select --install
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
brew install node
node --version

curl -fsSL https://deb.nodesource.com/setup_lts.x | sudo bash -
sudo apt-get install -y nodejs
node --version

Uninstall other proxy clients (optional)

If you previously installed another forked @anthropic-ai/claude-code, clean it up first:

# Check installation locations
npm ls @anthropic-ai/claude-code
npm ls -g @anthropic-ai/claude-code

# Uninstall
npm uninstall @anthropic-ai/claude-code
npm uninstall -g @anthropic-ai/claude-code

3. Install Claude Code

Global install

npm install -g @anthropic-ai/claude-code

Verify install

claude --version

4. Get your GravitexAI key

Go to the GravitexAI console.

Create a key

Open API Keys → create a new token.

Note the info

base_url = "https://api.gravitex.ai"
api_key  = "sk-zbTYx*******************************fceTvn5"

Claude Code’s ANTHROPIC_BASE_URL does not need a /v1 suffix — use https://api.gravitex.ai directly.

5. Configure Environment Variables

5.1 Basic example (single model)

Mac / Linux
Windows CMD
Windows PowerShell

export ANTHROPIC_BASE_URL="https://api.gravitex.ai"
export ANTHROPIC_AUTH_TOKEN="sk-zbTYx*******************************fceTvn5"
export ANTHROPIC_MODEL="kimi-k2-250905"
cd your-project-folder
claude

set ANTHROPIC_BASE_URL=https://api.gravitex.ai
set ANTHROPIC_AUTH_TOKEN=sk-zbTYx*******************************fceTvn5
set ANTHROPIC_MODEL=kimi-k2-250905
cd your-project-folder
claude

$env:ANTHROPIC_BASE_URL="https://api.gravitex.ai"
$env:ANTHROPIC_AUTH_TOKEN="sk-zbTYx*******************************fceTvn5"
$env:ANTHROPIC_MODEL="kimi-k2-250905"
cd your-project-folder
claude

5.2 Dual-thread architecture

By default Claude Code uses a dual-thread model architecture that saves cost:

Thread	Env var	Purpose
Main	`ANTHROPIC_MODEL`	Primary codegen, conversation, complex tasks
Haiku	`ANTHROPIC_DEFAULT_HAIKU_MODEL`	File watching, linter checks, completion, background jobs

Typical pairing: main thread on claude-opus-4-7 or claude-sonnet-4-6 for heavy lifting, haiku thread on claude-haiku-4-5-20251001 for background work — high quality at much lower token cost.

5.3 Recommended config (dual model)

Mac / Linux
Windows CMD
Windows PowerShell

export ANTHROPIC_BASE_URL="https://api.gravitex.ai"
export ANTHROPIC_AUTH_TOKEN="sk-zbTYx*******************************fceTvn5"
export ANTHROPIC_MODEL="claude-sonnet-4-6"
export ANTHROPIC_DEFAULT_HAIKU_MODEL="claude-haiku-4-5-20251001"
cd your-project-folder
claude

set ANTHROPIC_BASE_URL=https://api.gravitex.ai
set ANTHROPIC_AUTH_TOKEN=sk-zbTYx*******************************fceTvn5
set ANTHROPIC_MODEL=claude-sonnet-4-6
set ANTHROPIC_DEFAULT_HAIKU_MODEL=claude-haiku-4-5-20251001
cd your-project-folder
claude

$env:ANTHROPIC_BASE_URL="https://api.gravitex.ai"
$env:ANTHROPIC_AUTH_TOKEN="sk-zbTYx*******************************fceTvn5"
$env:ANTHROPIC_MODEL="claude-sonnet-4-6"
$env:ANTHROPIC_DEFAULT_HAIKU_MODEL="claude-haiku-4-5-20251001"
cd your-project-folder
claude

5.4 Single model (optional)

If you only want one model, there are two options: Option A — set both env vars to the same model

export ANTHROPIC_BASE_URL="https://api.gravitex.ai"
export ANTHROPIC_AUTH_TOKEN="sk-zbTYx*******************************fceTvn5"
export ANTHROPIC_MODEL="kimi-k2-250905"
export ANTHROPIC_DEFAULT_HAIKU_MODEL="kimi-k2-250905"
cd your-project-folder
claude

Option B — switch in-session Keep the dual-model config, start Claude Code, then in the interactive UI:

/model haiku

The main thread switches to the model from ANTHROPIC_DEFAULT_HAIKU_MODEL.

6. Recommended Combinations (via GravitexAI)

Scenario	Main (`ANTHROPIC_MODEL`)	Haiku (`ANTHROPIC_DEFAULT_HAIKU_MODEL`)
Production (top)	`claude-opus-4-7`	`claude-haiku-4-5-20251001`
Daily dev (recommended)	`claude-sonnet-4-6`	`claude-haiku-4-5-20251001`
Cost-optimized	`kimi-k2-250905`	`claude-haiku-4-5-20251001`
Long context	`claude-sonnet-4-5-20250929` (200K)	`claude-haiku-4-5-20251001`
Quick smoke-test	`claude-haiku-4-5-20251001`	`claude-haiku-4-5-20251001`

See full IDs in the GravitexAI model catalog.

7. FAQ

401 / invalid API key

Check ANTHROPIC_AUTH_TOKEN for stray whitespace or newlines.
Confirm the key is active in the GravitexAI console.
Ensure your balance is positive.

404 / wrong endpoint

For Claude Code, do not append /v1 to ANTHROPIC_BASE_URL. Use https://api.gravitex.ai (Anthropic protocol differs from OpenAI).

How to switch models inside Claude Code?

In the interactive UI:

/model              # show current model
/model haiku        # switch to ANTHROPIC_DEFAULT_HAIKU_MODEL
/model sonnet       # alias supported in some versions

Or exit, change env vars, and re-launch.

`model not found` error

Use the full ID from the GravitexAI model list, e.g.:

✅ claude-sonnet-4-5-20250929
❌ claude-sonnet-4-5

The version suffix is required.

How to reduce token cost?

Prefer the dual-model setup with Haiku as the background thread.
Use --max-turns and similar flags to cap conversation length.
Maintain project memory under .claude/ to avoid repeating context.
Use /clear to drop stale context.

Team-wide config?

Put env vars into a project .env, your shell profile, or direnv. Each engineer only swaps in their own ANTHROPIC_AUTH_TOKEN.

8. References

Claude Code official docs: https://docs.anthropic.com/en/docs/claude-code
GravitexAI console: https://maas.gravitex.ai
Model catalog: https://maas.gravitex.ai/#/models
API keys: https://maas.gravitex.ai/#/keys

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1. Overview

Multi-vendor access

Dual-thread model

No subscription

Stable globally

2. Install Node.js (skip if installed)

Uninstall other proxy clients (optional)

3. Install Claude Code

4. Get your GravitexAI key

5. Configure Environment Variables

5.1 Basic example (single model)

5.2 Dual-thread architecture

5.3 Recommended config (dual model)

5.4 Single model (optional)

6. Recommended Combinations (via GravitexAI)

7. FAQ

8. References

​1. Overview

Multi-vendor access

Dual-thread model

No subscription

Stable globally

​2. Install Node.js (skip if installed)

​Uninstall other proxy clients (optional)

​3. Install Claude Code

​4. Get your GravitexAI key

​5. Configure Environment Variables

​5.1 Basic example (single model)

​5.2 Dual-thread architecture

​5.3 Recommended config (dual model)

​5.4 Single model (optional)

​6. Recommended Combinations (via GravitexAI)

​7. FAQ

​8. References

1. Overview

2. Install Node.js (skip if installed)

Uninstall other proxy clients (optional)

3. Install Claude Code

4. Get your GravitexAI key

5. Configure Environment Variables

5.1 Basic example (single model)

5.2 Dual-thread architecture

5.3 Recommended config (dual model)

5.4 Single model (optional)

6. Recommended Combinations (via GravitexAI)

7. FAQ

8. References