---

I created this script to help others get benefit from the free tier offered by Github

I appreciate all the support I got for making this, but would now suggest people look at TheLolos' excellent fork at https://github.com/TheLoloS/Copilot-CLI-Unlocker which significantly expands the capabilities

Copilot Model Patcher

A tool to add custom models to GitHub Copilot CLI's allowed models list.

Requirements

• Bash shell (macOS, Linux, WSL)
• Perl (pre-installed on macOS/Linux)
• GitHub Copilot CLI installed

Platform Support:

• ✅ macOS
• ✅ Linux
• ✅ Windows (via WSL/Git Bash)

Quick Start

cd ~/copilot-patch
chmod +x patch-models.sh
./patch-models.sh --dry-run    # Preview changes
./patch-models.sh              # Apply patch

After patching, update your config at ~/.copilot/config.json:

{
  "model": "gpt-5-mini"
}

Problem Statement

The GitHub Copilot CLI has a hardcoded array of allowed models in its minified index.js file. If you configure a model in ~/.copilot/config.json that isn't in this list, the CLI silently falls back to another model.

Example: Setting "model": "gpt-5-mini" in your config won't work if "gpt-5-mini" isn't in the allowed list.

Solution Overview

This patcher:

1. Locates the models array variable in the minified code
2. Adds your desired models to the array
3. Creates timestamped backups before making changes
4. Validates the patch was successful

Usage

Basic Usage

./patch-models.sh                  # Add gpt-5-mini (default)
./patch-models.sh --dry-run        # Preview without making changes

The script will automatically:

1. Detect your Copilot installation location
2. Add the specified models to the allowed list
3. Create a timestamped backup
4. Remind you to update ~/.copilot/config.json

Add Specific Models

./patch-models.sh --models gpt-5-mini,o1
./patch-models.sh --models claude-opus-4

Patch Custom Location

./patch-models.sh --file /path/to/custom/index.js

Installation Location Detection

The script automatically searches these locations (in order):

1. $HOME/node_modules/@github/copilot/index.js
2. Global npm modules (from npm root -g)
3. /usr/local/lib/node_modules/@github/copilot/index.js
4. /opt/homebrew/lib/node_modules/@github/copilot/index.js (Homebrew on Apple Silicon)

You can override with --file if your installation is elsewhere.

When to Run

You need to re-run this patcher:

• After updating the @github/copilot npm package
• When the CLI is reinstalled
• If you encounter "model not available" errors

How It Works

1. The Minified Structure

The Copilot CLI's index.js is a ~13.5 MB minified file. Inside, there's a variable (currently Yv) that contains the allowed models:

Yv=["claude-sonnet-4.5","claude-sonnet-4","claude-haiku-4.5","gpt-5"]

Note: The variable name changes between versions (Ef, Yv, etc.) but the patcher auto-detects it.

2. Detection Strategy

The patcher finds this array by searching for a recognizable pattern:

• Looks for variable assignments containing known model names (like "claude-sonnet")
• Extracts the variable name dynamically (works even if Yv changes to Zv, Aa, etc.)
• Parses the current models from the array

3. Patching Process

# Original
Yv=["claude-sonnet-4.5","claude-sonnet-4","claude-haiku-4.5","gpt-5"]

# Patched
Yv=["claude-sonnet-4.5","claude-sonnet-4","claude-haiku-4.5","gpt-5","gpt-5-mini"]

The patcher:

1. Creates a backup: index.js.bak.YYYYMMDD-HHMMSS
2. Uses Perl with environment variables to safely handle special characters
3. Performs the replacement in-place
4. Verifies the new array exists in the file
5. Restores backup if verification fails
6. Reminds you to update ~/.copilot/config.json

Adapting for Future Updates

If GitHub updates the Copilot CLI and this patcher stops working, here's how to adapt it:

Step 1: Locate the New Models Array

# Search for known model patterns
grep -o 'gpt-5.*gpt-4.*claude' ~/node_modules/@github/copilot/index.js

# Or search for array-like structures
grep -o '\["gpt-[^]]*\]' ~/node_modules/@github/copilot/index.js
grep -o '\["claude-[^]]*\]' ~/node_modules/@github/copilot/index.js

Step 2: Find the Variable Name

Once you find the array, look for what variable it's assigned to:

# Extract variable name and full assignment
grep -o '[A-Za-z_$][A-Za-z0-9_$]*=\["claude-sonnet-[^]]*\]' ~/node_modules/@github/copilot/index.js

Example output:

Yv=["claude-sonnet-4.5","claude-sonnet-4","claude-haiku-4.5","gpt-5"]

The variable name is Yv (the part before =).

Step 3: Update the Search Pattern

If the patcher can't auto-detect the array, you can update the script's search pattern:

Edit patch-models.sh around line 85:

# Old pattern (searches for claude-sonnet models)
ARRAY_PATTERN=$(grep -o '[A-Za-z_$][A-Za-z0-9_$]*=\["claude-sonnet-[^]]*\]' "$TARGET_FILE" | head -n 1 || true)

# If models change, update the search term:
# For GPT-focused arrays:
ARRAY_PATTERN=$(grep -o '[A-Za-z_$][A-Za-z0-9_$]*=\["gpt-[^]]*\]' "$TARGET_FILE" | head -n 1 || true)

# For any model array with known model name:
ARRAY_PATTERN=$(grep -o '[A-Za-z_$][A-Za-z0-9_$]*=\["known-model-name[^]]*\]' "$TARGET_FILE" | head -n 1 || true)

Step 4: Verify Your Changes

Always test with --dry-run first:

./patch-models.sh --dry-run

Look for:

• ✓ Variable name detected correctly
• ✓ Current models list makes sense
• ✓ New array includes your additions

Technical Details

File Locations (Auto-detected)

$HOME/node_modules/@github/copilot/index.js           # Local install
$(npm root -g)/@github/copilot/index.js               # Global npm
/usr/local/lib/node_modules/@github/copilot/index.js  # Standard global
/opt/homebrew/lib/node_modules/@github/copilot/index.js # Homebrew (Apple Silicon)

Config File Location

$HOME/.copilot/config.json

Backup Pattern

index.js.bak.YYYYMMDD-HHMMSS

Example: index.js.bak.20251109-101507

Key Variables (as of Nov 2025)

• Models Array Variable: Yv (auto-detected, was Ef in earlier versions)
• Default Models: claude-sonnet-4.5, claude-sonnet-4, claude-haiku-4.5, gpt-5
• File Size: ~13.5 MB (minified)

Why Perl Instead of Sed?

# sed has issues with special characters in minified code
sed 's/old/new/' file.js  # ❌ Can break on [], (), etc.

# perl with environment variables and \Q...\E is safe
export SEARCH="old" REPLACE="new"
perl -pe 's/\Q$ENV{SEARCH}\E/$ENV{REPLACE}/' file.js  # ✅ Safe for minified code

Troubleshooting

Error: "Could not find models array"

The file structure changed. Follow "Adapting for Future Updates" above.

Error: "Replacement failed"

1. Check if the file is already patched:

   grep "gpt-5-mini" ~/node_modules/@github/copilot/index.js

2. Try restoring from a backup:

   ls -lt ~/node_modules/@github/copilot/index.js.bak.*
   cp ~/node_modules/@github/copilot/index.js.bak.YYYYMMDD-HHMMSS \
      ~/node_modules/@github/copilot/index.js

Model Still Not Working

1. Verify the patch was applied:

   grep -o '[A-Za-z_$][A-Za-z0-9_$]*=\[.*gpt-5-mini.*\]' ~/node_modules/@github/copilot/index.js

2. Check your config file:

   cat ~/.copilot/config.json | grep model

   Should show:

   "model": "gpt-5-mini"

3. Ensure exact spelling:

   • ✅ gpt-5-mini
   • ❌ gpt5-mini (missing hyphen)
   • ❌ GPT-5-mini (wrong case)

Files in This Directory

copilot-patch/
├── patch-models.sh          # Main patcher script
├── README.md               # This file
└── CHANGELOG.md            # Version history (if tracking updates)

Contributing / Maintenance

When updating this patcher for future Copilot versions:

1. Document the changes in CHANGELOG.md
2. Note the Copilot version number
3. Update the "Key Variables" section above
4. Test thoroughly with --dry-run

Example Session

$ cd ~/copilot-patch

$ ./patch-models.sh --dry-run
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
  Copilot Model Patcher
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Requirements:
  • Bash shell (macOS, Linux, WSL)
  • Perl (pre-installed on macOS/Linux)
  • GitHub Copilot CLI installed

Platform Support:
  ✅ macOS    ✅ Linux    ✅ Windows (WSL/Git Bash)

✓ Target file: /Users/username/node_modules/@github/copilot/index.js

Step 1: Locating models array...
✓ Found variable: Yv
✓ Current array: ["claude-sonnet-4.5","claude-sonnet-4","claude-haiku-4.5","gpt-5"]

Step 2: Parsing current models...
✓ Current models:
    - claude-sonnet-4.5
    - claude-sonnet-4
    - claude-haiku-4.5
    - gpt-5

Step 3: Building new models array...
+  Adding model: gpt-5-mini
✓ New array: ["claude-sonnet-4.5","claude-sonnet-4","claude-haiku-4.5","gpt-5","gpt-5-mini"]

━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
  DRY RUN MODE - No changes will be made
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Would replace:
  FROM: Yv=["claude-sonnet-4.5","claude-sonnet-4","claude-haiku-4.5","gpt-5"]
  TO:   Yv=["claude-sonnet-4.5","claude-sonnet-4","claude-haiku-4.5","gpt-5","gpt-5-mini"]

To apply changes, run without --dry-run flag

$ ./patch-models.sh
[... applies patch ...]
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
  ✅ Successfully patched!
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

📋 Backup saved to: index.js.bak.20251109-143022

Models now available:
  - claude-sonnet-4.5
  - claude-sonnet-4
  - claude-haiku-4.5
  - gpt-5
  - gpt-5-mini (newly added)

━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
  ⚠️  Next Step: Update Your Config
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Edit your Copilot config: ~/.copilot/config.json

Change the "model" field to use a free model, for example:
  "model": "gpt-5-mini"

Available free models you just added:
  - gpt-5-mini

License

This is a utility script for personal use. The GitHub Copilot CLI itself is proprietary software from GitHub.

Support

For issues with:

• This patcher: Check the troubleshooting section above
• Copilot CLI itself: Contact GitHub Support
• Model availability: Check with your GitHub organization's settings