earendil-works/pi · error · JsonlDecodeError

schema

schema

Error message

is not a JSON object

What it means

Thrown by the JSONL codec's parseObject when a line parses as valid JSON but is not a plain object (e.g. an array, number, string, or null on its own line). It is a schema-shape guard: JSONL session entries must be objects, so any other top-level JSON value means the file was not written by the session writer.

Solutions

1. Ensure every JSONL line decodes to an object; remove or correct lines that hold arrays or scalars.

When it happens

Trigger: Thrown at packages/agent/src/harness/session/jsonl/codec.ts:40 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/694e9dfc86ac4a4a. Report an issue: GitHub.

Appendix: source

Thrown at packages/agent/src/harness/session/jsonl/codec.ts:40

	"queue_enqueued",
	"queue_cancelled",
	"write_deferred",
	"usage",
]);
const OPERATION_KINDS = new Set(["run", "compaction", "navigation"]);

function isObject(value: unknown): value is Record<string, unknown> {
	return typeof value === "object" && value !== null && !Array.isArray(value);
}

function parseObject(line: string): Record<string, unknown> {
	let value: unknown;
	try {
		value = JSON.parse(line);
	} catch (error) {
		throw new JsonlDecodeError("syntax", "is not valid JSON", error instanceof Error ? error : undefined);
	}
	if (!isObject(value)) throw new JsonlDecodeError("schema", "is not a JSON object");
	return value;
}

function requireString(value: unknown, field: string): string {
	if (typeof value !== "string") throw new JsonlDecodeError("schema", `has invalid ${field}`);
	return value;
}

function requireSequence(value: unknown): number {
	if (!Number.isSafeInteger(value) || (value as number) <= 0) {
		throw new JsonlDecodeError("schema", "has invalid seq");
	}
	return value as number;
}

function requireTimestamp(value: unknown): number {
	if (!Number.isSafeInteger(value) || (value as number) < 0) {
		throw new JsonlDecodeError("schema", "has invalid timestamp");

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