chore(vendor): import pi 1.3.0

Imported as a linear vendor commit so forge rebases do not replay the upstream root tree.

git-subtree-dir: third_party/pi

git-subtree-split: 71023aec1546d6d677a65669c5665c0927ce0dd0

third_party/pi/packages/durable/test/examples/01-documents.ts

@@ -0,0 +1,45 @@
+// Store document state next to transcript entries.
+// Run from packages/durable:
+//   node --conditions=source --experimental-strip-types test/examples/01-documents.ts
+import { BACKGROUND_CONTEXT } from "@earendil-works/chord/context";
+import { createSession, defineDoc, MemoryStorage } from "../../src/index.ts";
+
+const context = BACKGROUND_CONTEXT;
+const session = createSession(new MemoryStorage());
+
+// A document is a JSON object attached to something; here, one per conversation.
+// "rewindable" keeps old values readable, so you can ask what the document
+// looked like when a particular entry was written.
+// `fork` says what a forked copy of the conversation starts with (see 02-forks.ts).
+const Notes = defineDoc<{ text: string }>({
+	kind: "example.notes",
+	version: 1,
+	scope: "conversation",
+	history: "rewindable",
+	fork: "asOf", // a fork starts with the value these notes had at the fork entry
+	initial: () => ({ text: "" }),
+});
+
+const chat = await session.commit((tx) => tx.createConversation({ ownership: { kind: "ownerless" } }), context);
+
+// tx.doc() returns an editable copy of the document (created on first use).
+// Plain assignments to it are saved when the commit finishes.
+const firstEntry = await session.commit(async (tx) => {
+	const entry = await tx.appendEntry(chat.id, { kind: "note", data: "hello" });
+	(await tx.doc(Notes, chat.id)).text = "after hello";
+	return entry;
+}, context);
+
+const secondEntry = await session.commit(async (tx) => {
+	const entry = await tx.appendEntry(chat.id, { kind: "note", data: "goodbye" });
+	(await tx.doc(Notes, chat.id)).text = "after goodbye";
+	return entry;
+}, context);
+
+// snapshot() reads the latest value. snapshotAsOf() reads the value that was
+// saved in the same commit as the given entry.
+console.log("latest notes:", await session.snapshot(Notes, chat.id, context));
+console.log("notes at first entry:", await session.snapshotAsOf(Notes, chat.id, firstEntry.id, context));
+console.log("notes at second entry:", await session.snapshotAsOf(Notes, chat.id, secondEntry.id, context));
+
+await session.close(context);