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/28-reviewer.ts

@@ -0,0 +1,111 @@
+// A reviewer agent next to the main one: a cheaper model, a review role and loop, read-only tools, and its own
+// checkout of the project.
+// Run from packages/durable:
+//   node --conditions=source --experimental-strip-types test/examples/28-reviewer.ts
+import { mkdtemp, rm, writeFile } from "node:fs/promises";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { BACKGROUND_CONTEXT } from "@earendil-works/chord/context";
+import type { AssistantMessage } from "@earendil-works/pi-ai";
+import { createModels } from "@earendil-works/pi-ai/models";
+import { fauxAssistantMessage, fauxProvider, fauxToolCall } from "@earendil-works/pi-ai/providers/faux";
+import { NodeExecutionEnv } from "../../src/env/node.ts";
+import {
+	AssistantEntry,
+	createRegistry,
+	defineExtension,
+	GenerationTask,
+	Harness,
+	hook,
+	MemoryStorage,
+	section,
+} from "../../src/index.ts";
+import { CodingTools, createReadTool } from "../../src/tools/index.ts";
+
+const context = BACKGROUND_CONTEXT;
+const textOf = (message: AssistantMessage) =>
+	message.content.flatMap((part) => (part.type === "text" ? [part.text] : [])).join("");
+
+// ─── Product code: the reviewer extension ───────────────────────────────────
+
+const DONE = "No further findings.";
+// A role and a review loop: every answer that still has findings gets a second pass.
+const Reviewer = defineExtension({
+	name: "reviewer",
+	sections: [section("role", () => `You review diffs. Report problems as a list. Never edit files.`)],
+	hooks: [
+		hook(GenerationTask, {
+			onYield: (answer) =>
+				textOf(answer).includes(DONE)
+					? undefined
+					: { continue: `Look again for anything you missed. Say "${DONE}" when there is nothing left.` },
+		}),
+	],
+});
+
+// ─── Host setup ─────────────────────────────────────────────────────────────
+
+// The reviewer works in its own checkout, in practice a `git worktree add`.
+const worktree = await mkdtemp(join(tmpdir(), "pi-durable-review-"));
+await writeFile(join(worktree, "user.ts"), "export const name = (user) => user.name;\n");
+
+const faux = fauxProvider({ models: [{ id: "big" }, { id: "small" }] });
+const models = createModels();
+models.setProvider(faux.provider);
+faux.setResponses([
+	fauxAssistantMessage(fauxToolCall("read", { path: "user.ts" }), { stopReason: "toolUse" }),
+	fauxAssistantMessage("1. `name` does not handle a missing user."),
+	fauxAssistantMessage(`2. \`user\` has no type. ${DONE}`),
+]);
+
+const registry = createRegistry();
+registry.install(CodingTools);
+registry.install(Reviewer);
+const harness = await Harness.open(
+	new MemoryStorage(),
+	// The main agent selects only CodingTools; the reviewer opts in.
+	{
+		models,
+		registry,
+		settings: { extensions: [CodingTools] },
+		env: ({ cwd = process.cwd() }) => new NodeExecutionEnv({ cwd }),
+	},
+	context,
+);
+await harness.root(context, { agent: { model: { provider: "faux", modelId: "big" } } });
+
+// Everything the reviewer is, stored on its conversation: the model, exactly these extensions in this order, only
+// the read tool, and its directory. A restart keeps all of it.
+const reviewer = await harness.createConversation(
+	{
+		ownership: { kind: "ownerless" },
+		agent: {
+			model: { provider: "faux", modelId: "small" },
+			extensions: [CodingTools, Reviewer],
+			tools: [createReadTool()],
+			cwd: worktree,
+		},
+	},
+	context,
+);
+const agent = await reviewer.agent(context);
+console.log(
+	"reviewer:",
+	agent.model?.modelId,
+	agent.extensions.map((extension) => extension.name),
+	agent.tools.map((tool) => tool.name),
+	agent.cwd === worktree,
+);
+
+await (await reviewer.submit({ type: "input", content: "Review user.ts." }, context)).wait(context);
+const page = await reviewer.entries({}, 20, undefined, context);
+for (const entry of [...page.items].reverse()) {
+	const message = entry.model?.[0];
+	if (message?.role === "user") console.log(">", message.content);
+	if (AssistantEntry.is(entry) && textOf(message as AssistantMessage) !== "") {
+		console.log("reviewer:", textOf(message as AssistantMessage));
+	}
+}
+
+await harness.close(context);
+await rm(worktree, { recursive: true, force: true });