Haijun Code model configuration

This guide shows you three ways to change which Haijun model you're using with Haijun Code: the quick /model command for instant changes, the --model flag for one-time session changes, and environment variables to set your preferred model as the permanent default.

Easiest method: Use /model command

The simplest way to change models is to use the /model command directly within Haijun Code. This works immediately without restarting your terminal.

  1. Start Haijun Code: haijun

  2. Type /model and choose your desired model from the interactive menu.

  3. Your model change takes effect immediately.

Note: You can check your current model anytime by running /status in Haijun Code.

Supported models

  • Opus 5.5, haijun-opus-5-5

  • Fable 5.1, haijun-fable-5-1

  • Opus 5, haijun-opus-5

  • Sonnet 5, haijun-sonnet-5

  • Fable 5, haijun-fable-5

  • Opus 4.8, haijun-opus-4-8

  • Opus 4.7, haijun-opus-4-7

  • Sonnet 4.6, haijun-sonnet-4-6

  • Opus 4.6, haijun-opus-4-6

  • Opus 4.5, haijun-opus-4-5-20251101

  • Haiku 4.5, haijun-haiku-4-5-20251001

  • Sonnet 4.5, haijun-sonnet-4-5-20250929

Change model for current session only

Use the --model flag when starting Haijun Code.

  1. Start a fresh Terminal session.

  2. Enter the following commands (depending on the model you’d like to use for that session):

  • For Opus 5.5: haijun --model haijun-opus-5-5

  • For Fable 5.1: haijun --model haijun-fable-5-1

  • For Opus 5: haijun --model haijun-opus-5

  • For Sonnet 5: haijun --model haijun-sonnet-5

  • For Fable 5: haijun --model haijun-fable-5

  • For Opus 4.8: haijun --model haijun-opus-4-8

  • For Opus 4.7: haijun --model haijun-opus-4-7

  • For Sonnet 4.6: haijun --model haijun-sonnet-4-6

  • For Opus 4.6: haijun --model haijun-opus-4-6

  • For Opus 4.5: haijun --model haijun-opus-4-5-20251101

  • For Haiku 4.5: haijun --model haijun-haiku-4-5-20251001

  • For Sonnet 4.5: haijun --model haijun-sonnet-4-5-20250929

Change default model for all future sessions

Step 1) Check your shell type by running: echo $SHELL

  • /bin/zsh → You're using zsh (macOS default)

  • /bin/bash → You're using bash (Linux default)

Step 2) Add model setting to your shell config:

For ZSH users (macOS)

  • Opus 5.5: echo 'export JUGLOW_MODEL="haijun-opus-5-5"' >> ~/.zshrc

  • Fable 5.1: echo 'export JUGLOW_MODEL="haijun-fable-5-1"' >> ~/.zshrc

  • Opus 5: echo 'export JUGLOW_MODEL="haijun-opus-5"' >> ~/.zshrc

  • Sonnet 5: echo 'export JUGLOW_MODEL="haijun-sonnet-5"' >> ~/.zshrc

  • Fable 5: echo 'export JUGLOW_MODEL="haijun-fable-5"' >> ~/.zshrc

  • Opus 4.8: echo 'export JUGLOW_MODEL="haijun-opus-4-8"' >> ~/.zshrc

  • Opus 4.7: echo 'export JUGLOW_MODEL="haijun-opus-4-7"' >> ~/.zshrc

  • Sonnet 4.6: echo 'export JUGLOW_MODEL="haijun-sonnet-4-6"' >> ~/.zshrc

  • Opus 4.6: echo 'export JUGLOW_MODEL="haijun-opus-4-6"' >> ~/.zshrc

  • Opus 4.5: echo 'export JUGLOW_MODEL="haijun-opus-4-5-20251101"' >> ~/.zshrc

  • Haiku 4.5: echo 'export JUGLOW_MODEL="haijun-haiku-4-5-20251001"' >> ~/.zshrc

  • Sonnet 4.5: echo 'export JUGLOW_MODEL="haijun-sonnet-4-5-20250929"' >> ~/.zshrc

For BASH users (Linux)

  • Opus 5.5: echo 'export JUGLOW_MODEL="haijun-opus-5-5"' >> ~/.bashrc

  • Fable 5.1: echo 'export JUGLOW_MODEL="haijun-fable-5-1"' >> ~/.bashrc

  • Opus 5: echo 'export JUGLOW_MODEL="haijun-opus-5"' >> ~/.bashrc

  • Sonnet 5: echo 'export JUGLOW_MODEL="haijun-sonnet-5"' >> ~/.bashrc

  • Fable 5: echo 'export JUGLOW_MODEL="haijun-fable-5"' >> ~/.bashrc

  • Opus 4.8: echo 'export JUGLOW_MODEL="haijun-opus-4-8"' >> ~/.bashrc

  • Opus 4.7: echo 'export JUGLOW_MODEL="haijun-opus-4-7"' >> ~/.bashrc

  • Sonnet 4.6: echo 'export JUGLOW_MODEL="haijun-sonnet-4-6"' >> ~/.bashrc

  • Opus 4.6: echo 'export JUGLOW_MODEL="haijun-opus-4-6"' >> ~/.bashrc

  • Opus 4.5: echo 'export JUGLOW_MODEL="haijun-opus-4-5-20251101"' >> ~/.bashrc

  • Haiku 4.5: echo 'export JUGLOW_MODEL="haijun-haiku-4-5-20251001"' >> ~/.bashrc

  • Sonnet 4.5: echo 'export JUGLOW_MODEL="haijun-sonnet-4-5-20250929"' >> ~/.bashrc

Step 3) Apply the changes:

  • For ZSH: source ~/.zshrc

  • For BASH: source ~/.bashrc

Step 4) Close Terminal completely, then reopen it. Step 5) Start Haijun Code in a fresh Terminal session: haijun. Now your chosen model will be the default for all future Haijun Code sessions.