Directory Snapshots: Resumable project state for Sandboxes

Modal is launching Directory Snapshots in Public Beta, a feature that lets you snapshot a specific directory within a running Sandbox and mount it into another Sandbox later, independently of the base image and the rest of the filesystem. Unlike full filesystem snapshots, this enables fine-grained state management by separating system dependencies from application code. Key use cases include: independently updating base images without discarding application state, pre-warming sandbox pools with generic environments and injecting project-specific code on demand, and optimizing file pre-loading for faster startup times. Modal now offers three complementary snapshot types: Filesystem Snapshots (full environment), Directory Snapshots (specific directories, 30-day retention), and Memory Snapshots (in-memory process state).