Rationale behind the minimal sandbox image?

[ryan-minato]

I noticed that the sandbox image in gemini-cli is extremely minimal. It lacks not only modern dev tools like pnpm and uv, but even a basic Python interpreter.

I expected a more "batteries-included" environment, like devcontainers/universal, for seamless development and task execution. Could you share the design rationale behind choosing such a restricted feature set? Is this driven by security isolation, cold-start performance, or a specific architectural goal?

[tuapuikia]

You can build your own image with all the software you needs.

[ryan-minato]

You can build your own image with all the software you needs.

I am aware that it is possible to use a custom image by creating a .gemini/sandbox.Dockerfile and setting BUILD_SANDBOX=1. However, this currently seems to only work when running the tool from source.

When using the version installed via npm, it triggers the error: “Cannot build sandbox using installed gemini binary”

gemini-cli/packages/cli/src/utils/sandbox.ts

Lines 259 to 264 in 9e7f52b

	if (process.env['BUILD_SANDBOX']) {
	if (!gcPath.includes('gemini-cli/packages/')) {
	throw new FatalSandboxError(
	'Cannot build sandbox using installed gemini binary; ' +
	'run `npm link ./packages/cli` under gemini-cli repo to switch to linked binary.',
	);

To be honest, I don't understand the reasoning behind this restriction. Before diving into the source code, I had assumed that the gemini-cli-sandbox alias was injected via the build context.

Regardless of the implementation details, the fact that the npm version cannot utilize custom images makes this feature inaccessible to the majority of users. It would be much better if this limitation were removed, or at the very least, if the default image were made more comprehensive to cover more use cases.

[tuapuikia]

I build my own custom sandbox image with all the SDKs and tools I need. The container is like my mini VM that has its own tools and is destroyed after use. The Dockerfile method is not feasible in my honest opinion.