feat: integrate Pi backend and Pi Web

pi/packages/ai/test/scratch.ts

@@ -0,0 +1,57 @@
+// Scratch script showing real-world use of the new Models API.
+// Run from packages/ai: node test/scratch.ts
+// Requires ANTHROPIC_API_KEY.
+
+import { createModels } from "../src/models.ts";
+import { anthropicProvider } from "../src/providers/anthropic.ts";
+import type { Context } from "../src/types.ts";
+
+// ---------------------------------------------------------------------------
+// 1. Build a Models runtime and register a built-in provider factory.
+//    (Apps wanting everything use `builtinModels()` from providers/all.)
+// ---------------------------------------------------------------------------
+
+const models = createModels();
+models.setProvider(anthropicProvider());
+
+// ---------------------------------------------------------------------------
+// 2. Look up a model and check auth.
+// ---------------------------------------------------------------------------
+
+const model = models.getModel("anthropic", "claude-haiku-4-5");
+if (!model) throw new Error("model not found");
+
+const auth = await models.getAuth(model.provider);
+console.log(`model: ${model.provider}/${model.id}`);
+console.log(`auth:  ${auth ? `configured via ${auth.source}` : "not configured"}\n`);
+if (!auth) process.exit(1);
+
+const context: Context = {
+	systemPrompt: "You are terse.",
+	messages: [{ role: "user", content: "Say exactly: ok", timestamp: Date.now() }],
+};
+
+// ---------------------------------------------------------------------------
+// 3. Simple completion (request-level auth resolution happens inside).
+// ---------------------------------------------------------------------------
+
+const message = await models.completeSimple(model, context);
+console.log(`completeSimple -> [${message.stopReason}]`, message.content);
+
+// ---------------------------------------------------------------------------
+// 4. Streaming with deltas.
+// ---------------------------------------------------------------------------
+
+context.messages.push(message, {
+	role: "user",
+	content: "Now count from 1 to 5, one number per line.",
+	timestamp: Date.now(),
+});
+
+process.stdout.write("streamSimple   -> ");
+const stream = models.streamSimple(model, context);
+for await (const event of stream) {
+	if (event.type === "text_delta") process.stdout.write(event.delta.replaceAll("\n", " "));
+}
+const final = await stream.result();
+console.log(`[${final.stopReason}] cost: $${final.usage.cost.total.toFixed(6)}`);