Code Mode
Models write scripts that run tools inside a QuickJS WebAssembly sandbox
The Code Mode template (TypeScript only) uses CodeModeTransform to let a model run a multi-step pipeline in a single call. Instead of calling tools one at a time, the model sends a JavaScript script; NitroStack runs it in an isolated QuickJS WebAssembly sandbox where the script calls tools locally and returns only the final result.
The three meta-tools
search
Find tools by keywords or a task description.
get_schema
Get full parameter schemas for a list of tools.
execute
Run a script in the sandbox, with callTool(name, args) available.
Create the project
Scaffold the template and start it:
npx @nitrostack/cli init code-orchestrator --template typescript-code-mode
cd code-orchestrator
npm run devThe project has four controllers (data, finance, inventory, support), widgets, and a sample script in src/scripts/sample-batch.js.
How it works
The root module configures the sandbox:
transforms: [
new CodeModeTransform({
workerPoolSize: 4,
memoryLimitMb: 128,
timeoutMs: 15000,
searchToolDescription: DEFAULT_CODE_MODE_SEARCH_DESCRIPTION,
alwaysVisible: [
'finance_get_financial_summary',
'finance_audit_ledger',
'inventory_check_stock',
'inventory_report',
'support_get_system_status',
'data_aggregate_sum',
],
}),
],A script chains tool calls and returns one object. This is the core of the sample script:
const filterRes = await callTool('data_filter_records', { values: rawValues, min: 50 });
const sumRes = await callTool('data_aggregate_sum', { values: filterRes.filtered });
const formatRes = await callTool('data_transform_format', { prefix: 'METRIC', values: filterRes.filtered });
return { totalSum: sumRes.sum, average: sumRes.avg, records: formatRes.formatted };Sandbox limits
The guest script has no access to Node.js globals such as process, require, or fs. Each run is also bounded:
| Option | Default | What happens at the limit |
|---|---|---|
memoryLimitMb | 100 (this template: 128) | The worker stops and returns an out-of-memory error. |
timeoutMs | 30000 (this template: 15000) | The worker is terminated, for example on an infinite loop. |
maxToolCalls | 50 | Further tool calls are refused. |
allowDestructive | false | When false, calling a tool marked destructiveHint: true throws an error. |