Sandbox limits

Scripts run in an isolated SES sandbox in a dedicated utility process:

• Timeout: each enabled script in a list gets its own limit (default 5000 ms). Configure Script timeout (ms) in Settings → General; set to 0 to disable. A send with multiple scripts can use up to the sum of each script's limit. Each await hc.fetch(...), await hc.sleep(...), await hc.send(...), await hc.sendJSON(...), await hc.fs.*, or await hc.livePage(...) (including page load waits) call counts toward the same script timeout.
• Network: scripts cannot open arbitrary network connections. Outbound HTTP is available only through await hc.fetch(...) when Allow script network requests is enabled in Settings → General.
• Filesystem: scripts cannot open arbitrary paths. File I/O is available only through await hc.fs.* when Allow script file read / Allow script file write are enabled. Paths are confined to the script file root (git repo directory for git-backed collections, otherwise the configured root or home directory). There is no Node fs module or browser DOM.
• Live page: scripts cannot open embedded browser tabs unless Allow script live page access is enabled. Use await hc.livePage(...) when that setting is on — see hc.livePage and Live pages.
• Language: modern JavaScript (scripts are transpiled with esbuild and evaluated as async functions). Top-level await is supported. Relative snippet imports (import … from './snippet-name.js') are supported; bare npm package imports and require are not supported yet.
• Globals: only hc, console, and standard JavaScript globals are available

If a script throws or times out, the error is recorded and the send continues with the last known request state. Syntax errors and runtime exceptions surface in the send console.