How to Customize the Behavior of PrimeAgent: A Complete Configuration Guide

PrimeAgent offers multiple configuration layers—including environment variables, CLI flags, custom prompts, themes, tool definitions, and provider settings—that allow you to tailor its runtime behavior without modifying core source code.

PrimeAgent is an open-source coding agent from PrimeIntellect-ai/prime-agent designed with extensibility at its core. You can customize the behavior of PrimeAgent through a layered configuration system that spans environment variables, JSON configuration files, and TypeScript modules. This guide examines the specific files and APIs that control each customization point, from low-level runtime settings to high-level UI theming.

Environment and Global Configuration

The foundation of PrimeAgent customization starts with packages/coding-agent/src/config.js, which handles environment variable loading and global settings. The system recognizes $AGENT_DIR as the base directory for all agent data and configuration files. You can define API keys, default models, and daemon socket paths through standard .env files or shell environment variables.

Create a .env file in your repository root or $AGENT_DIR to configure providers:

# .env

OPENAI_API_KEY=sk-XXXXXXXXXXXXXXXXXXXX
ANTHROPIC_API_KEY=sk-ant-XXXXXXXXXXXXXXXX

PrimeAgent automatically detects these keys via the environment API key handler and makes the providers selectable with the /login command.

CLI Flags and Session Commands

Runtime behavior is controlled through commands documented in packages/coding-agent/docs/usage.md. The CLI supports session management flags like --resume <id> to restore saved states, while interactive commands such as /autonomous, /goal, /refine, and /heartbeat adjust agent behavior during execution.

These flags integrate with the configuration loader to override defaults on a per-session basis. For example, you can limit autonomous operation depth or refine the current goal without restarting the daemon process.

Customizing System Prompts and Memory

The agent's personality and instructions can be reshaped via custom prompt configurations. As demonstrated in packages/coding-agent/test/system-prompt.test.ts, you can supply a JSON configuration with customPrompt, appendSystemPrompt, or a custom_memory object to prepend or append content to the base system prompt.

Create a custom prompt configuration file:

// $AGENT_DIR/custom-prompt.json
{
  "customPrompt": "You are a specialist in data-visualization. Always produce Plotly charts.",
  "appendSystemPrompt": "\n# Remember: keep responses concise."

}

Launch the session with prime-agent --prompt-config $AGENT_DIR/custom-prompt.json or set PRIME_PROMPT_CONFIG in your .env file to apply the configuration automatically.

Theming and UI Appearance

Visual customization is handled through JSON theme files stored in $AGENT_DIR/themes/<name>.json. The expected schema is documented in packages/coding-agent/test/theme-export.test.ts, supporting properties like background, foreground, and accent colors.

Create a custom theme file:

// $AGENT_DIR/themes/solarized-dark.json
{
  "name": "solarized-dark",
  "background": "#002b36",
  "foreground": "#839496",
  "accent": "#b58900"
}

Activate your theme by launching with prime-agent --theme solarized-dark. The TUI reloads theme configurations on the fly, allowing you to iterate on color schemes without restarting the agent.

Tool Definitions and Custom Renderers

PrimeAgent allows you to define custom tools by implementing the ToolDefinition interface. The test file packages/coding-agent/test/tool-execution-component.test.ts shows how to create tools with custom renderCall and renderResult methods that control how tool interactions appear in the TUI.

Define a custom tool with specialized rendering:

// my-tools/custom_tool.ts
import { ToolDefinition, Text } from "prime-agent";

export const customTool: ToolDefinition = {
  name: "custom_tool",
  description: "Shows a custom call/result pair",
  renderCall: (ctx) => new Text(`⚙️ Call: ${ctx.input}`, 0, 0),
  renderResult: (ctx) => new Text(`✅ Result: ${ctx.output}`, 0, 0),
};

Register these tools through the --tools CLI argument or by importing them into your session's tool list. This approach allows you to create visual indicators or formatted output specific to your workflow.

TUI Components and Key Bindings

Keyboard shortcuts and editor behavior are configurable through packages/tui/src/keys.ts or custom keybinding modules. For advanced UI customization, packages/tui/src/editor-component.ts defines the interface for plugging in alternative editor components, enabling integration with vim, emacs, or custom text widgets.

Override default keybindings with a custom module:

// $AGENT_DIR/keybindings.ts
export const MY_KEYBINDINGS = {
  "Ctrl-O": "openFile",
  "Ctrl-S": "saveFile",
};

Run with prime-agent --keybindings $AGENT_DIR/keybindings.ts to apply your custom shortcuts. Custom components must implement the editor interface to handle input and rendering within the terminal UI.

Adding Custom LLM Providers

To integrate new LLM backends, modify packages/ai/src/types.ts to define provider-specific options and register the implementation in packages/ai/src/providers/register-builtins.ts. The packages/ai/README.md documentation outlines the registration steps and option struct requirements.

This architecture allows PrimeAgent to support proprietary or self-hosted models alongside built-in providers. The configuration object bubbles through the daemon, worker, and IPython kernel as shown in packages/coding-agent/docs/architecture.md, ensuring every component respects the same provider settings.

Summary

• Use packages/coding-agent/src/config.js and .env files for global environment and API key configuration
• Control session behavior via CLI flags like --resume and interactive commands documented in packages/coding-agent/docs/usage.md
• Override system prompts using JSON configs with customPrompt and appendSystemPrompt fields as tested in packages/coding-agent/test/system-prompt.test.ts
• Deploy custom themes by placing JSON files in $AGENT_DIR/themes/ and activating with --theme
• Extend functionality through custom ToolDefinition implementations with specialized renderers
• Customize the TUI through packages/tui/src/keys.ts or by implementing the editor interface from packages/tui/src/editor-component.ts
• Add new LLM providers by extending types in packages/ai/src/types.ts and registering in packages/ai/src/providers/register-builtins.ts

Frequently Asked Questions

How do I change the default LLM model in PrimeAgent?

Set the model preference through environment variables in your .env file or use the /login command to switch between configured providers. The configuration loader in packages/coding-agent/src/config.js processes these settings at startup, making models from OpenAI, Anthropic, or custom providers available for selection.

Can I customize the appearance of tool execution in the terminal?

Yes, by defining a custom ToolDefinition with renderCall and renderResult methods as shown in packages/coding-agent/test/tool-execution-component.test.ts. These methods return Text components that control how tool calls and results display in the TUI, allowing you to create visual indicators or formatted output specific to your workflow.

Where should I place custom theme files for PrimeAgent?

Place JSON theme files in $AGENT_DIR/themes/<name>.json, following the schema demonstrated in packages/coding-agent/test/theme-export.test.ts. Activate your theme by launching with prime-agent --theme <name> or reload themes dynamically during a session.

Is it possible to add custom keyboard shortcuts to the PrimeAgent TUI?

Yes, you can override default keybindings by supplying a custom TypeScript module that exports key mappings, or by modifying packages/tui/src/keys.ts directly. For complex editor behavior, implement the editor interface defined in packages/tui/src/editor-component.ts to handle custom input methods and rendering logic.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
    }
  }
}