earendil-works/pi · error

grammar constrained sampling requires an object parameter sc

Error message

grammar constrained sampling requires an object parameter schema

What it means

Error "grammar constrained sampling requires an object parameter schema" thrown in earendil-works/pi.

Source

Thrown at packages/ai/src/api/constrained-sampling.ts:192

	let delta = "";
	if (!buffer.started) {
		delta += `{${JSON.stringify(inputProperty)}:"`;
		buffer.started = true;
	}
	delta += JSON.stringify(inputDelta).slice(1, -1);
	buffer.input = nextInput;

	if (close) {
		delta += '"}';
		buffer.closed = true;
	}
	return delta;
}

function inferGrammarInputProperty(tool: Tool): string {
	const schema = tool.parameters as JsonSchemaObject;
	if (schema.type !== "object") {
		throw new Error("grammar constrained sampling requires an object parameter schema");
	}
	if (!Array.isArray(schema.required) || schema.required.length !== 1 || typeof schema.required[0] !== "string") {
		throw new Error("grammar constrained sampling requires exactly one required string property");
	}

	const inputProperty = schema.required[0];
	if (!schema.properties?.[inputProperty]) {
		throw new Error(`grammar constrained sampling requires a properties entry for ${inputProperty}`);
	}
	if (schema.properties[inputProperty]?.type !== "string") {
		throw new Error(`grammar constrained sampling property ${inputProperty} must have type string`);
	}
	return inputProperty;
}

export function resolveJsonSchemaStrictSampling(tool: Tool, supportsStrictMode: boolean): boolean | undefined {
	const config = tool.constrainedSampling;
	if (!config || config.type !== "json_schema") return undefined;

View on GitHub (pinned to 4af9d21d3b)

Solutions

1. Give the grammar tool an object parameter schema.

When it happens

Trigger: Thrown at packages/ai/src/api/constrained-sampling.ts:192 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of earendil-works/pi@4af9d21d3b (2026-08-24). Data as JSON: /api/errors/a6a0290882367f6d. Report an issue: GitHub.