Changelog

Agents SDK v0.33.0 upgrades PiHarness to Pi 1.5 ↗︎. The release reduces storage transactions while streaming, improves throughput across many sessions, and reduces memory use when streaming large tool calls.

• Far fewer storage writes while streaming. Pi stores streamed answers and tool output in batches, within a second of each update, instead of on every update. Over SQLite, this cuts storage transactions by about 27x for long answers and 5.7x for turns with parallel tools, and CPU by about a quarter.
• Higher throughput across many sessions. Pi's scheduler no longer rechecks every conversation on each commit. In a SQLite benchmark with 2,048 sessions, one Pi harness went from 88 to 459 agent runs per second.
• Less memory on large answers. Streaming a 500 KB tool call used to take about 20 seconds of CPU and a 100 MB heap. Pi now appends new text instead of copying it on every update.

Streaming updates remain visible immediately, but are persisted in batches. With the default settings, a crash can lose up to about one second of streamed progress. Refer to Recovery to configure this interval.

• A view of each session. session.watch() replaces session.events(). It returns the newest transcript entries and the session's live state, such as the answer being streamed, running tools, and why the last run ended without an answer.
• Continue without adding a message. The new session.continue() API starts a new run using the existing transcript, for example after a model error or when a run reaches its turn limit.
• Turn limit. defaults.maxTurns caps the tool rounds a run can take in new sessions.
• Tasks that keep crashing end. Pi now ends a task cut off by its restart limit instead of parking it. retry() and the parked status are removed.
• Browser in Pi's code mode. Scripts in Pi's code mode can call browserTool and pass its screenshots to image(). browserTool also stops when the harness aborts its call.

For an existing session and submission operationId, check the result before offering a continuation. For example, after resolving a model error:

const result = await session.wait(operationId);

if (result.status === "unanswered" && result.reason === "model_error") {
	const receipt = await session.continue({
		operationId: `${operationId}:continue`,
	});
	const continued = await session.wait(receipt.operationId);
	console.log(continued.status, continued.text);
}

const result = await session.wait(operationId);

if (result.status === "unanswered" && result.reason === "model_error") {
	const receipt = await session.continue({
		operationId: `${operationId}:continue`,
	});
	const continued = await session.wait(receipt.operationId);
	console.log(continued.status, continued.text);
}

This starts a new run without appending a user message. The session must be idle. If the transcript already ends in an answer, the operation returns unanswered with reason nothing_to_answer. Refer to Work with sessions.

Once a conversation runs on Pi 1.5, Pi 1.4 cannot read it. After upgrading, roll forward to fix deployment issues rather than rolling back to Pi 1.4.

Update callers of session.events() to use session.watch(), and remove uses of retry() and the parked status. Refer to the Pi Durable 1.5.0 changelog ↗︎ for the full list of breaking changes.

The Agents SDK v0.33.0 changelog ↗︎ has step-by-step upgrade instructions. Point your coding agent at them and upgrade today:

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