paperclip/packages/plugins/sandbox-providers/modal

@paperclipai/plugin-modal

First-party Modal sandbox provider plugin for Paperclip.

Like the other sandbox-provider packages in this repo, it lives inside the Paperclip monorepo but is intentionally excluded from the root pnpm workspace and shaped to publish and install like a standalone npm package. That lets operators install it from the Plugins page by package name without introducing root lockfile churn for Modal's SDK dependencies.

Install

From a Paperclip instance, install:

@paperclipai/plugin-modal

The host plugin installer runs npm install into the managed plugin directory, so the modal SDK dependency is pulled in during installation.

Runtime support note

Paperclip and this plugin require Node 24 or later. The plugin logs a startup warning when it detects an older host runtime.

Configuration

Configure Modal from Instance Settings -> Environments, not from the plugin's plugin page.

Field	Required	Description
appName	yes	Modal App name. The plugin calls modal.apps.fromName(appName, { createIfMissing: true }), so the App is created on first acquire if it does not already exist.
image	yes	Container image passed to modal.images.fromRegistry(), e.g. python:3.13 or node:24.
tokenId / tokenSecret	yes	Modal auth tokens. Both must be provided together. Paperclip stores pasted values as company secrets. The plugin worker runs in a child process that does not inherit host env vars, so MODAL_TOKEN_ID / MODAL_TOKEN_SECRET set on the Paperclip server are not read by the plugin — provide the tokens in this form.
environment	no	Optional Modal environment name. Falls back to the SDK profile default.
workdir	no	Remote working directory inside the sandbox. Defaults to /workspace/paperclip.
sandboxTimeoutMs	no	Maximum sandbox lifetime in milliseconds. Must be a positive multiple of 1000 between 1000 and 86_400_000 (24 hours). Defaults to 3_600_000 (1 hour).
idleTimeoutMs	no	Optional idle timeout in milliseconds. Modal terminates the sandbox if no exec is active for this duration. Must be a positive multiple of 1000.
execTimeoutMs	no	Default per-exec timeout in milliseconds when the caller does not pass one. Must be a positive multiple of 1000. Defaults to 300_000 (5 minutes).
blockNetwork	no	Block all egress network access.
cidrAllowlist	no	List of CIDRs the sandbox may reach. Cannot be combined with blockNetwork.
reuseLease	no	When true, the sandbox is detached (not terminated) on release and reattached by id later. Defaults to false.

Reuse semantics

Modal does not expose a separate pause/resume primitive for sandboxes — there is no equivalent to e2b's pause(). The plugin implements reuseLease as follows:

• reuseLease: false (default): On release the sandbox is terminate()d. Subsequent runs create a new sandbox.
• reuseLease: true: On release the plugin calls sandbox.detach(). The sandbox keeps running on Modal until its configured sandboxTimeoutMs or idleTimeoutMs elapses. The next acquire/resume reconnects via modal.sandboxes.fromId(providerLeaseId). If the sandbox has expired, fromId raises NotFoundError and the plugin reports the lease as expired so Paperclip reacquires.

Because there is no real pause, reuseLease: true keeps billing running until the sandbox or idle timeout cuts it off. Tune idleTimeoutMs to a value that matches your reuse window.

Local development

cd packages/plugins/sandbox-providers/modal
pnpm install --ignore-workspace --no-lockfile
pnpm build
pnpm test
pnpm typecheck

These commands assume the repo root has already been installed once so the local @paperclipai/plugin-sdk workspace package is available to the compiler during development.

Operator verification

1. Provision Modal credentials in your Modal account (modal token new) or use a service account.
2. Install the plugin from the Paperclip Plugins page.
3. In Instance Settings -> Environments, add a new Modal sandbox environment with at least appName, image, tokenId, and tokenSecret.
4. Run the environment Probe action. A success result confirms auth, app creation, image pull, and exec round-trip.
5. Run at least one Paperclip task with a remote-managed adapter (for example claude_local) bound to that environment. The adapter should provision the sandbox, run commands in it, and clean it up.

Full end-to-end manual QA is tracked separately in PAPA-354.

Package layout

• src/manifest.ts declares the sandbox-provider driver metadata
• src/plugin.ts implements the environment lifecycle hooks
• src/worker.ts boots the plugin under the host worker runtime
• paperclipPlugin.manifest and paperclipPlugin.worker point the host at the built plugin entrypoints in dist/