One Aggregator Key Across All Claude Code Windows in a Monorepo: Keeping Parallel Sessions From Colliding

Why a Single Key Across Windows Matters in a Monorepo

In a monorepo, developers often run multiple Claude Code sessions simultaneously—one per package, service, or feature branch. On Windows, each session might try to read the same environment variables or config files. Without a strategy, parallel sessions can overwrite each other's API keys, causing authentication errors or unintended cross-session interference.

Using a single aggregator API key simplifies management: you have one credential to top up, monitor, and rotate. The aggregator supports multiple models (Claude, GPT, DeepSeek, Qwen, GLM, Kimi) through one API, so you avoid juggling separate keys per provider. Pricing is transparent: you pay the official model price × 1.3, and key contributors receive credits at official price × 1.1 (or × 1.2 for premium models) in USDC.

Setting Up the Aggregator Key on Windows

Store the Key Securely

Avoid hardcoding the key in scripts or committing it to the repo. On Windows, use one of these methods:

• User environment variable (persists across sessions): set AGGREGATORAPIKEY via System Properties → Environment Variables, or with setx AGGREGATORAPIKEY "your-key" in Command Prompt.
• Project-specific .env file (git-ignored): place the key in a .env file at the monorepo root or per-package, and load it with a library like dotenv.
• Windows Credential Manager: for GUI-based management, though less script-friendly.

Configure Claude Code to Use the Key

Claude Code typically reads API keys from environment variables. Ensure each Windows session inherits the AGGREGATORAPIKEY. If you use a launcher script, explicitly pass the variable to avoid missing values in new shells.

Preventing Session Collisions

Parallel sessions can collide if they share mutable state. Follow these practices:

Use Isolated Working Directories

Each Claude Code session should operate in its own project folder or worktree. On Windows, you can create separate directories per feature:

git worktree add ../feature-a
cd ../feature-a

This prevents file locks and accidental overwrites of configuration files.

Avoid Shared Temporary Files

Claude Code may cache session data or logs. Configure each session to use a unique temp directory via environment variables like TMP or TEMP. For example, in PowerShell:

$env:TMP = "C:\temp\claude-session-a"
$env:TEMP = $env:TMP

Scope Environment Variables per Session

If you need different keys for different projects, set variables at the session level (e.g., in a terminal window) rather than globally. Use a .env file per worktree and load it only in that session.

Managing API Key Rotation and Top-Ups

With a single aggregator key, you can top up once and use it across all sessions. The aggregator accepts USDC on Base without KYC, so you can replenish credits quickly. Monitor usage per key in the aggregator dashboard to avoid unexpected depletion during parallel work.

Best Practices for Monorepo Teams

• Document key setup in your monorepo's README so all developers follow the same pattern.
• Use a shared key for CI/CD but restrict its permissions if the aggregator supports scoped keys.
• Rotate keys periodically and update environment variables across Windows machines.
• Leverage contributor credits: if team members contribute to the aggregator's key pool, they receive USDC credits at official price × 1.1 (or × 1.2 for premium models), offsetting costs.

Troubleshooting Common Issues

• Authentication errors: verify the AGGREGATORAPIKEY is set in the current shell. Use echo $env:AGGREGATORAPIKEY in PowerShell.
• Session interference: ensure each Claude Code instance runs in a separate worktree and has its own temp directory.
• Rate limits: the aggregator may enforce per-key limits. If you hit them, consider using separate keys for heavy parallel workloads—though this adds management overhead.

By following these steps, you can run multiple Claude Code sessions on Windows without key conflicts, all while using a single aggregator key that simplifies billing and model access.