How to Configure Ponytail Mode to "full": Environment, Config File, and Session Methods

Set the PONYTAIL_DEFAULT_MODE environment variable to full, create a config.json file with "defaultMode": "full" in your platform-specific config directory, or rely on the built-in default—Ponytail resolves the active mode using a strict hierarchy that checks environment variables first, user configuration files second, and falls back to the internal constant last.

Ponytail is an open-source code optimization tool that trims over-engineered patterns using intensity-based rulesets. When you configure Ponytail mode to full, you activate the most aggressive trimming level available in the standard runtime modes. The resolution logic lives in hooks/ponytail-config.js, where the system validates and prioritizes configuration sources at startup.

Understanding the Mode Resolution Hierarchy

Ponytail determines the active mode at runtime using a three-tier priority system implemented in the getDefaultMode() function (lines 76–99 in hooks/ponytail-config.js). The resolver checks sources in this exact order:

1. Environment variable PONYTAIL_DEFAULT_MODE
2. User configuration file at the platform-specific config path (e.g., ~/.config/ponytail/config.json or $XDG_CONFIG_HOME/ponytail/config.json)
3. Built-in constant DEFAULT_MODE, defined on line 16 as 'full'

The resolver only accepts values listed in the RUNTIME_MODES array (lines 18–19): off, lite, full, and ultra. Invalid values in environment variables or config files are ignored, causing the system to fall back to the next source in the hierarchy.

Setting Ponytail Mode to "full" Permanently

Method 1: Environment Variable (Highest Priority)

Setting the environment variable forces full mode across all sessions regardless of config file contents. This method is ideal for CI/CD pipelines and containerized environments.

export PONYTAIL_DEFAULT_MODE=full

To verify the resolver detects this setting, run:

node -e "console.log(require('./hooks/ponytail-config').getDefaultMode())"

This outputs full if the variable is set correctly. The resolver checks process.env.PONYTAIL_DEFAULT_MODE first (line 78) and validates it against RUNTIME_MODES before accepting it.

Method 2: Configuration File (Persistent)

For a permanent, user-specific default, write the mode to Ponytail's configuration file. The writeDefaultMode() helper (lines 36–51 in hooks/ponytail-config.js) handles file creation, or you can manually create the JSON file:

mkdir -p ~/.config/ponytail
cat > ~/.config/ponytail/config.json <<'EOF'
{
  "defaultMode": "full"
}
EOF

The configuration key must be defaultMode (not mode or intensity). When getDefaultMode() executes, it reads this file (lines 86–94) and uses the value only if it matches a valid runtime level. If the file is missing or contains invalid JSON, the resolver seamlessly falls back to the built-in DEFAULT_MODE.

Changing Mode During a Session

To temporarily override the default configuration for a single conversation without modifying environment variables or config files, use the slash command:

/ponytail full

This command is handled by the mode-tracker hook (hooks/ponytail-mode-tracker.js), which updates the session's persisted mode and injects the corresponding ruleset into every subsequent LLM turn. To query the current mode without changing it, send:

/ponytail

The response displays "Ponytail mode: full" when the full intensity is active.

Verifying the Active Configuration

After configuration, confirm the mode is correctly resolved using one of these methods:

• Session check: Send /ponytail in the chat and verify the response states "full"
• Programmatic check: Run getDefaultMode() from the Node.js REPL as shown in the environment variable section above
• Status line: If PONYTAIL_HIDE_STATUS is not set, the status line indicator shows the active mode

If you see a different mode than expected, check for conflicting environment variables:

echo $PONYTAIL_DEFAULT_MODE

Or remove lingering config files to force the built-in default:

rm -f ~/.config/ponytail/config.json
unset PONYTAIL_DEFAULT_MODE

Summary

• Ponytail mode to full is resolved via a strict hierarchy: environment variable → config file → built-in default
• Environment variable PONYTAIL_DEFAULT_MODE=full takes highest priority and overrides all other settings
• Config file location is platform-specific (typically ~/.config/ponytail/config.json) and uses the key defaultMode
• Built-in fallback is defined in hooks/ponytail-config.js line 16 as const DEFAULT_MODE = 'full', meaning full is the default if no overrides exist
• Session commands (/ponytail full) override defaults for the current conversation only
• Review mode (review) cannot be set as a default; it is session-only and filtered out by the resolver (line 80)

Frequently Asked Questions

What is the difference between "full" and "ultra" mode in Ponytail?

Both are valid runtime levels defined in RUNTIME_MODES, but full represents the standard maximum intensity while ultra applies even more aggressive trimming rules. The full mode is the built-in default constant (DEFAULT_MODE), making it the recommended baseline for aggressive optimization. ultra may remove patterns that full preserves, so use it only when you want the most extreme reduction in code complexity.

Why does my Ponytail mode reset to "lite" when I restart?

This indicates a configuration source is setting lite explicitly. Check your shell profile for export PONYTAIL_DEFAULT_MODE=lite or inspect the config file at ~/.config/ponytail/config.json. The resolver prioritizes environment variables over the built-in default of full, so any lingering PONYTAIL_DEFAULT_MODE definition will override your intended setting. Clear the variable with unset PONYTAIL_DEFAULT_MODE and delete the config file to restore the default full behavior.

Can I set the "review" mode as my default?

No, the review mode is session-only and cannot be configured as a permanent default. The resolver in getDefaultMode() explicitly filters out review during validation (see the comment at line 80). This mode is designed for temporary, one-time code reviews rather than ongoing optimization, so it must be activated per-session using /ponytail review.

How do I completely deactivate Ponytail?

Set the mode to off using any configuration method: export PONYTAIL_DEFAULT_MODE=off, set "defaultMode": "off" in config.json, or send /ponytail off during a session. The off value is a valid entry in RUNTIME_MODES that disables all trimming rules. Alternatively, standalone deactivation commands like stop ponytail or normal mode trigger the isDeactivationCommand function (lines 40–43) to disable Ponytail for that specific message context.

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