Fixing Cursor Composer Agent Not Using the Current venv

Fixing Cursor Composer Agent Not Using the Current venv

If you’ve run into this frustrating bug in Cursor — where the Composer Agent ignores your active Python virtual environment — you’re not alone.

You open a terminal in Cursor, activate your venv, and everything looks good. But when Cursor’s AI tries to run a command, it spawns a fresh terminal that doesn’t respect your venv. Suddenly, packages are missing and commands break.

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Why this happens

• Cursor uses its own integrated terminal profiles.

• If it defaults to a different shell (like zsh when you use fish), your venv/bin/activate script may not run correctly.

• The AI agent executes commands in that “wrong” shell, so your venv context is lost.

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The Fix: Set Your Default Shell in Cursor

You can force Cursor to always use the correct shell by editing your User Settings (JSON).

Open Command Palette → Preferences: Open User Settings (JSON) and add:

Linux / macOS

For fish

"terminal.integrated.defaultProfile.linux": "fish",
"terminal.integrated.profiles": {
  "fish": { "path": "/usr/bin/fish" }
}

For zsh

"terminal.integrated.defaultProfile.linux": "zsh",
"terminal.integrated.profiles": {
  "zsh": { "path": "/usr/bin/zsh" }
}

For bash

"terminal.integrated.defaultProfile.linux": "bash",
"terminal.integrated.profiles": {
  "bash": { "path": "/usr/bin/bash" }
}

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Windows

If you’re on Windows, Cursor defaults to PowerShell or Command Prompt. You can override that:

For PowerShell

"terminal.integrated.defaultProfile.windows": "PowerShell",
"terminal.integrated.profiles": {
  "PowerShell": {
    "path": "C:\\\\Windows\\\\System32\\\\WindowsPowerShell\\\\v1.0\\\\powershell.exe"
  }
}

For Command Prompt

"terminal.integrated.defaultProfile.windows": "Command Prompt",
"terminal.integrated.profiles": {
  "Command Prompt": {
    "path": "C:\\\\Windows\\\\System32\\\\cmd.exe"
  }
}

For WSL

"terminal.integrated.defaultProfile.windows": "Ubuntu-20.04",
"terminal.integrated.profiles": {
  "Ubuntu-20.04": {
    "path": "wsl.exe",
    "args": ["-d", "Ubuntu-20.04"]
  }
}

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Why this works

• Cursor terminals and Composer agent now start in the same shell you actually use.

• When you activate a venv, the activation script matches your shell type.

• Composer’s commands inherit the correct $VIRTUAL_ENV (Linux/macOS) or %VIRTUAL_ENV% (Windows) and $PATH.

• No more “missing module” errors just because the AI ignored your environment.

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Bonus Tip

If you often switch projects, consider:

• direnv for auto-activation of venvs, or

• Adding a small snippet in your shell config to auto-activate when you cd into a project.

This ensures that whenever Cursor (or you) enter a directory with a venv, it activates automatically.

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✅ After this change, Cursor’s Composer Agent will finally respect your Python venvs — and your AI workflow won’t break in the middle of coding.