Local LLM Coding Assistant with OpenCode

This guide covers setting up OpenCode as a local LLM coding assistant — no cloud API required.

note

This guide assumes Ollama is already installed and a model is available. See Install and Configure Ollama for setup instructions.

Environment

• Machine: Lenovo Legion (Ubuntu 24.04)
• GPU: NVIDIA RTX 5090 (24 GB VRAM)
• Model: Qwen 3.6 27B
• Use case: Local C++/CUDA/ROS 2 development assistance

Step 1. Install OpenCode

OpenCode is distributed as a self-contained binary — no Python virtual environment required. Use the official install script:

curl -fsSL https://opencode.ai/install | bash

Verify the installation:

opencode --version

note

The install script places the binary under ~/.opencode/bin/. If opencode is not found after installation, add it to your PATH:

echo 'export PATH="$HOME/.opencode/bin:$PATH"' >> ~/.bashrc
source ~/.bashrc

Step 2. Configure the Ollama Provider

OpenCode connects to Ollama through its OpenAI-compatible API endpoint. Create the config directory and file:

mkdir -p ~/.config/opencode

Create ~/.config/opencode/opencode.json:

{
  "$schema": "https://opencode.ai/config.json",
  "provider": {
    "ollama": {
      "npm": "@ai-sdk/openai-compatible",
      "name": "Ollama (Local)",
      "options": {
        "baseURL": "http://localhost:11434/v1"
      },
      "models": {
        "qwen3.6:27b": {},
        "qwen3.6-8k:latest": {},
        "qwen3-coder-next:latest": {}
      }
    }
  }
}

note

OpenCode uses /v1 (the OpenAI-compatible endpoint), not Ollama's native /api endpoint. Omitting /v1 will cause connection failures. Verify the endpoint is reachable before launching OpenCode:

curl http://localhost:11434/v1/models

This should return a JSON list of available models.

Add a Placeholder Auth Entry

OpenCode requires an auth entry for every configured provider even when no API key is needed. Create ~/.local/share/opencode/auth.json:

mkdir -p ~/.local/share/opencode
cat > ~/.local/share/opencode/auth.json << 'EOF'
{
  "ollama": {
    "type": "api",
    "key": "ollama"
  }
}
EOF

Step 3. Launch OpenCode

Navigate to your project directory and launch OpenCode:

cd ~/your_project
opencode

OpenCode opens a full TUI in your terminal. On first launch it may download a small provider package (@ai-sdk/openai-compatible) — this is a one-time step.

To select the model, type /models inside the TUI and choose from the Ollama (Local) provider entries.

Step 4. Basic TUI Commands

Command	Description
/models	Switch the active model
/init	Analyse the project and generate an AGENTS.md context file
/undo	Revert the last AI-made file change (requires a Git repo)
/redo	Reapply a reverted change
/share	Generate a shareable link for the current session
/exit	Quit OpenCode

Adding files to context: use @filename inline in your prompt to reference a file or folder, e.g.:

@src/perception/fcn_segmentation/src/fcn_segmentation.cpp explain this file

Mode toggle: press Tab to switch between Plan mode (read-only, proposes changes without applying them) and Build mode (applies changes directly). OpenCode starts in Plan mode by default.

Shell passthrough: prefix a line with ! to run a shell command directly, e.g. !make -j4.

Session info panel: the right-hand panel shows token context usage, LSP status, and current working directory. Toggle it with Ctrl+X then I.

Tips

• Do not let OpenCode push directly to GitHub. Recommended workflow: OpenCode edits → review changes yourself → manually run git commit and git push.

• Use /undo to revert the last AI-made change if needed (requires the project to be a Git repo).

• Clipboard / text selection: OpenCode automatically copies selected text to the clipboard, which can conflict with your terminal emulator. To restore normal terminal copy behavior:

  echo 'export OPENCODE_EXPERIMENTAL_DISABLE_COPY_ON_SELECT=true' >> ~/.bashrc
  source ~/.bashrc

  Alternatively, hold Shift while selecting to use the terminal's native selection without any config change.