infochanged

Agents, Workers - Run the Pi Durable harness on Cloudflare with the Agents SDK

Announced: 2026-10-02
Tags: Agents, Workers
Severity: info, set by reef/rss-rule-v1
Source: https://developers.cloudflare.com/changelog/post/2026-10-02-pi-harness/

The <a href="https://developers.cloudflare.com/agents/">Agents SDK</a> now provides first-class support for building agents using the Pi harness. You can build long-running agents using the combination of <a href="https://earendil.com/posts/pi-1-0/" target="_blank" rel="noopener">Pi 1.0 ↗︎</a>, <a href="https://earendil.com/posts/pi-durable/" target="_blank" rel="noopener">Pi Durable ↗︎</a>, and the new <code>PiHarness</code> class that the Cloudflare Agents SDK provides, ensuring your agent's work is durably persisted, even if interrupted mid-turn. Built with <a href="https://earendil.com/" target="_blank" rel="noopener">Earendil ↗︎</a>, this integration is our first step toward first-class support for third-party agent harnesses on Cloudflare. <button type="button" data-nb-button class="group inline-flex w-max shrink-0 items-center justify-center rounded-full font-medium whitespace-nowrap no-underline shadow-xs transition-colors select-none focus-visible:outline-2 focus-visible:outline-ring focus-visible:outline-offset-2 disabled:cursor-not-allowed disabled:opacity-50 bg-card text-foreground ring ring-border hover:bg-accent hover:ring-border-strong h-10 gap-2 px-4 text-sm copy-prompt-btn group/copy cursor-copy" data-prompt="Read https://developers.cloudflare.com/agents/harnesses/pi/ and the example at https://github.com/cloudflare/agents/tree/main/examples/next/harnesses/pi, then use them to build and deploy my first Pi Durable agent on Cloudflare with the Agents SDK. Give me the deployed URL." data-tooltip="Build and deploy a Pi Durable agent"><img src="https://developers.cloudflare.com/icons/agents/claude/light.svg" alt="" class="block h-5 w-5 dark:hidden" loading="lazy" decoding="async"><img src="https://developers.cloudflare.com/icons/agents/claude/dark.svg" alt="" class="hidden h-5 w-5 dark:block" loading="lazy" decoding="async"><img src="https://developers.cloudflare.com/icons/agents/codex/light.svg" alt="" class="block h-5 w-5 dark:hidden" loading="lazy" decoding="async"><img src="https://developers.cloudflare.com/icons/agents/codex/dark.svg" alt="" class="hidden h-5 w-5 dark:block" loading="lazy" decoding="async"><img src="https://developers.cloudflare.com/icons/agents/cursor/light.svg" alt="" class="block h-5 w-5 dark:hidden" loading="lazy" decoding="async"><img src="https://developers.cloudflare.com/icons/agents/cursor/dark.svg" alt="" class="hidden h-5 w-5 dark:block" loading="lazy" decoding="async"><img src="https://developers.cloudflare.com/icons/agents/opencode/light.svg" alt="" class="block h-5 w-5 dark:hidden" loading="lazy" decoding="async"><img src="https://developers.cloudflare.com/icons/agents/opencode/dark.svg" alt="" class="hidden h-5 w-5 dark:block" loading="lazy" decoding="async">Copy promptPrompt copied!</button><script type="module" src="https://developers.cloudflare.com/home/runner/work/cloudflare-docs/cloudflare-docs/src/components/CopyPromptButton.astro?astro&type=script&index=0&lang.ts"></script> <a href="https://deploy.workers.cloudflare.com/?url=https://github.com/cloudflare/agents/tree/main/examples/next/harnesses/pi" target="_blank" rel="noopener"><img src="https://deploy.workers.cloudflare.com/button" alt="Deploy to Cloudflare"></a> <aside role="note" aria-label="Beta" class="aside-card flex items-start gap-3 rounded-lg px-4 py-3 my-4" style="--_c: var(--nb-warning); --_t: var(--nb-warning-muted);" data-astro-cid-znle5jil><svg width="1em" height="1em" viewBox="0 0 256 256" class="h-[1em] w-[1em]" data-astro-cid-znle5jil="true" data-icon="ph:warning"><path fill="currentColor" d="M236.8 188.09L149.35 36.22a24.76 24.76 0 0 0-42.7 0L19.2 188.09a23.51 23.51 0 0 0 0 23.72A24.35 24.35 0 0 0 40.55 224h174.9a24.35 24.35 0 0 0 21.33-12.19a23.51 23.51 0 0 0 .02-23.72m-13.87 15.71a8.5 8.5 0 0 1-7.48 4.2H40.55a8.5 8.5 0 0 1-7.48-4.2a7.59 7.59 0 0 1 0-7.72l87.45-151.87a8.75 8.75 0 0 1 15 0l87.45 151.87a7.59 7.59 0 0 1-.04 7.72M120 144v-40a8 8 0 0 1 16 0v40a8 8 0 0 1-16 0m20 36a12 12 0 1 1-12-12a12 12 0 0 1 12 12"/></svg><div class="flex min-w-0 flex-1 flex-col gap-0.5" data-astro-cid-znle5jil>Beta<div class="aside-card-body text-sm leading-normal" data-astro-cid-znle5jil><code>PiHarness</code> is in beta. <a href="https://earendil.com/posts/pi-durable/" target="_blank" rel="noopener">Pi Durable ↗︎</a> is a new, experimental package, and the <code>PiHarness</code> API will likely change as Pi Durable matures.</div></div></aside> <code>PiHarness</code> is a new "Lifecycle capability" provided by the Cloudflare Agents SDK. Pi Durable provides the agent harness and the Lifecycle is responsible for keeping the agent running in the Durable Object. The Lifecycle is a core concept in the Agents SDK ensuring that long-running work can run in a Durable Object, surviving restarts, crashes, and network issues. We will share more on Lifecycle capabilities in the near future. <div tabindex="-1" class="heading-wrapper level-h4"><h4 id="install">Install</h4><a class="anchor-link" href="#install"><svg width="16" height="16" viewBox="0 0 24 24"><path fill="currentcolor" d="m12.11 15.39-3.88 3.88a2.52 2.52 0 0 1-3.5 0 2.47 2.47 0 0 1 0-3.5l3.88-3.88a1 1 0 0 0-1.42-1.42l-3.88 3.89a4.48 4.48 0 0 0 6.33 6.33l3.89-3.88a1 1 0 1 0-1.42-1.42Zm8.58-12.08a4.49 4.49 0 0 0-6.33 0l-3.89 3.88a1 1 0 0 0 1.42 1.42l3.88-3.88a2.52 2.52 0 0 1 3.5 0 2.47 2.47 0 0 1 0 3.5l-3.88 3.88a1 1 0 1 0 1.42 1.42l3.88-3.89a4.49 4.49 0 0 0 0-6.33ZM8.83 15.17a1 1 0 0 0 1.1.22 1 1 0 0 0 .32-.22l4.92-4.92a1 1 0 0 0-1.42-1.42l-4.92 4.92a1 1 0 0 0 0 1.42Z"></path></svg></a></div> <script> if (!customElements.get("nb-pm-restore")) { customElements.define( "nb-pm-restore", class extends HTMLElement { connectedCallback() { const card = this.closest("[data-nb-pm]"); if (!card) return; let saved; try { saved = sessionStorage.getItem("ui-pm-tab"); } catch { return; } if (!saved) return; const tabs = card.querySelectorAll("[data-nb-pm-tab]"); let idx = -1; tabs.forEach(function (t, i) { if (t.textContent.trim() === saved) idx = i; }); if (idx < 1) return; tabs.forEach(function (t, i) { t.setAttribute("aria-selected", String(i === idx)); }); card.querySelectorAll("[data-nb-pm-panel]").forEach(function (p, i) { p.hidden = i !== idx; }); } }, ); } </script><div data-nb-pm class="w-full"><div class="flex w-full flex-col overflow-hidden rounded-lg text-sm ring ring-border bg-card"><div class="flex items-center gap-2 px-3 py-2 text-[0.8125rem] font-medium leading-5 text-muted-foreground bg-[var(--nb-surface-sunken)]" role="tablist" aria-label="Package manager"><button role="tab" type="button" aria-selected="true" aria-controls="pm-panel-pm-3c6fc231-npm" id="pm-tab-pm-3c6fc231-npm" data-nb-pm-tab class="text-muted-foreground hover:bg-accent hover:text-foreground aria-selected:bg-selected aria-selected:text-foreground focus-visible:outline-ring m-0 cursor-pointer rounded-md border-0 bg-transparent px-2 py-0.5 text-xs leading-5 font-medium transition-colors focus-visible:outline-2 focus-visible:outline-offset-2">npm</button><button role="tab" type="button" aria-selected="false" aria-controls="pm-panel-pm-3c6fc231-yarn" id="pm-tab-pm-3c6fc231-yarn" data-nb-pm-tab class="text-muted-foreground hover:bg-accent hover:text-foreground aria-selected:bg-selected aria-selected:text-foreground focus-visible:outline-ring m-0 cursor-pointer rounded-md border-0 bg-transparent px-2 py-0.5 text-xs leading-5 font-medium transition-colors focus-visible:outline-2 focus-visible:outline-offset-2">yarn</button><button role="tab" type="button" aria-selected="false" aria-controls="pm-panel-pm-3c6fc231-pnpm" id="pm-tab-pm-3c6fc231-pnpm" data-nb-pm-tab class="text-muted-foreground hover:bg-accent hover:text-foreground aria-selected:bg-selected aria-selected:text-foreground focus-visible:outline-ring m-0 cursor-pointer rounded-md border-0 bg-transparent px-2 py-0.5 text-xs leading-5 font-medium transition-colors focus-visible:outline-2 focus-visible:outline-offset-2">pnpm</button><button role="tab" type="button" aria-selected="false" aria-controls="pm-panel-pm-3c6fc231-bun" id="pm-tab-pm-3c6fc231-bun" data-nb-pm-tab class="text-muted-foreground hover:bg-accent hover:text-foreground aria-selected:bg-selected aria-selected:text-foreground focus-visible:outline-ring m-0 cursor-pointer rounded-md border-0 bg-transparent px-2 py-0.5 text-xs leading-5 font-medium transition-colors focus-visible:outline-2 focus-visible:outline-offset-2">bun</button></div><div role="tabpanel" id="pm-panel-pm-3c6fc231-npm" aria-labelledby="pm-tab-pm-3c6fc231-npm" data-nb-pm-panel class="bg-card ring-border relative overflow-hidden rounded-lg text-inherit ring"><div class="flex items-stretch"><pre class="text-foreground my-0 min-w-0 grow overflow-x-auto border-0 bg-transparent px-4 py-3 font-mono text-sm leading-relaxed whitespace-pre"><code data-nb-pm-code>npm i agents@latest @earendil-works/pi-durable @earendil-works/pi-ai</code></pre><button type="button" data-nb-pm-copy data-nb-command="npm i agents@latest @earendil-works/pi-durable @earendil-works/pi-ai" aria-label="Copy to clipboard" class="border-border text-muted-foreground hover:text-foreground focus-visible:outline-ring m-0 flex shrink-0 cursor-pointer items-center justify-center border-0 border-l border-solid bg-transparent px-3 transition-colors focus-visible:outline-2 focus-visible:-outline-offset-2"><svg width="1em" height="1em" viewBox="0 0 256 256" class="h-[18px] w-[18px]" data-icon="ph:copy"><path fill="currentColor" d="M216 32H88a8 8 0 0 0-8 8v40H40a8 8 0 0 0-8 8v128a8 8 0 0 0 8 8h128a8 8 0 0 0 8-8v-40h40a8 8 0 0 0 8-8V40a8 8 0 0 0-8-8m-56 176H48V96h112Zm48-48h-32V88a8 8 0 0 0-8-8H96V48h112Z"/></svg><svg width="1em" height="1em" viewBox="0 0 256 256" class="hidden h-[18px] w-[18px]" data-icon="ph:check"><path fill="currentColor" d="m229.66 77.66l-128 128a8 8 0 0 1-11.32 0l-56-56a8 8 0 0 1 11.32-11.32L96 188.69L218.34 66.34a8 8 0 0 1 11.32 11.32"/></svg></button></div></div><div role="tabpanel" id="pm-panel-pm-3c6fc231-yarn" aria-labelledby="pm-tab-pm-3c6fc231-yarn" hidden data-nb-pm-panel class="bg-card ring-border relative overflow-hidden rounded-lg text-inherit ring"><div class="flex items-stretch"><pre class="text-foreground my-0 min-w-0 grow overflow-x-auto border-0 bg-transparent px-4 py-3 font-mono text-sm leading-relaxed whitespace-pre"><code data-nb-pm-code>yarn add agents@latest @earendil-works/pi-durable @earendil-works/pi-ai</code></pre><button type="button" data-nb-pm-copy data-nb-command="yarn add agents@latest @earendil-works/pi-durable @earendil-works/pi-ai" aria-label="Copy to clipboard" class="border-border text-muted-foreground hover:text-foreground focus-visible:outline-ring m-0 flex shrink-0 cursor-pointer items-center justify-center border-0 border-l border-solid bg-transparent px-3 transition-colors focus-visible:outline-2 focus-visible:-outline-offset-2"><svg width="1em" height="1em" viewBox="0 0 256 256" class="h-[18px] w-[18px]" data-icon="ph:copy"><path fill="currentColor" d="M216 32H88a8 8 0 0 0-8 8v40H40a8 8 0 0 0-8 8v128a8 8 0 0 0 8 8h128a8 8 0 0 0 8-8v-40h40a8 8 0 0 0 8-8V40a8 8 0 0 0-8-8m-56 176H48V96h112Zm48-48h-32V88a8 8 0 0 0-8-8H96V48h112Z"/></svg><svg width="1em" height="1em" viewBox="0 0 256 256" class="hidden h-[18px] w-[18px]" data-icon="ph:check"><path fill="currentColor" d="m229.66 77.66l-128 128a8 8 0 0 1-11.32 0l-56-56a8 8 0 0 1 11.32-11.32L96 188.69L218.34 66.34a8 8 0 0 1 11.32 11.32"/></svg></button></div></div><div role="tabpanel" id="pm-panel-pm-3c6fc231-pnpm" aria-labelledby="pm-tab-pm-3c6fc231-pnpm" hidden data-nb-pm-panel class="bg-card ring-border relative overflow-hidden rounded-lg text-inherit ring"><div class="flex items-stretch"><pre class="text-foreground my-0 min-w-0 grow overflow-x-auto border-0 bg-transparent px-4 py-3 font-mono text-sm leading-relaxed whitespace-pre"><code data-nb-pm-code>pnpm add agents@latest @earendil-works/pi-durable @earendil-works/pi-ai</code></pre><button type="button" data-nb-pm-copy data-nb-command="pnpm add agents@latest @earendil-works/pi-durable @earendil-works/pi-ai" aria-label="Copy to clipboard" class="border-border text-muted-foreground hover:text-foreground focus-visible:outline-ring m-0 flex shrink-0 cursor-pointer items-center justify-center border-0 border-l border-solid bg-transparent px-3 transition-colors focus-visible:outline-2 focus-visible:-outline-offset-2"><svg width="1em" height="1em" viewBox="0 0 256 256" class="h-[18px] w-[18px]" data-icon="ph:copy"><path fill="currentColor" d="M216 32H88a8 8 0 0 0-8 8v40H40a8 8 0 0 0-8 8v128a8 8 0 0 0 8 8h128a8 8 0 0 0 8-8v-40h40a8 8 0 0 0 8-8V40a8 8 0 0 0-8-8m-56 176H48V96h112Zm48-48h-32V88a8 8 0 0 0-8-8H96V48h112Z"/></svg><svg width="1em" height="1em" viewBox="0 0 256 256" class="hidden h-[18px] w-[18px]" data-icon="ph:check"><path fill="currentColor" d="m229.66 77.66l-128 128a8 8 0 0 1-11.32 0l-56-56a8 8 0 0 1 11.32-11.32L96 188.69L218.34 66.34a8 8 0 0 1 11.32 11.32"/></svg></button></div></div><div role="tabpanel" id="pm-panel-pm-3c6fc231-bun" aria-labelledby="pm-tab-pm-3c6fc231-bun" hidden data-nb-pm-panel class="bg-card ring-border relative overflow-hidden rounded-lg text-inherit ring"><div class="flex items-stretch"><pre class="text-foreground my-0 min-w-0 grow overflow-x-auto border-0 bg-transparent px-4 py-3 font-mono text-sm leading-relaxed whitespace-pre"><code data-nb-pm-code>bun add agents@latest @earendil-works/pi-durable @earendil-works/pi-ai</code></pre><button type="button" data-nb-pm-copy data-nb-command="bun add agents@latest @earendil-works/pi-durable @earendil-works/pi-ai" aria-label="Copy to clipboard" class="border-border text-muted-foreground hover:text-foreground focus-visible:outline-ring m-0 flex shrink-0 cursor-pointer items-center justify-center border-0 border-l border-solid bg-transparent px-3 transition-colors focus-visible:outline-2 focus-visible:-outline-offset-2"><svg width="1em" height="1em" viewBox="0 0 256 256" class="h-[18px] w-[18px]" data-icon="ph:copy"><path fill="currentColor" d="M216 32H88a8 8 0 0 0-8 8v40H40a8 8 0 0 0-8 8v128a8 8 0 0 0 8 8h128a8 8 0 0 0 8-8v-40h40a8 8 0 0 0 8-8V40a8 8 0 0 0-8-8m-56 176H48V96h112Zm48-48h-32V88a8 8 0 0 0-8-8H96V48h112Z"/></svg><svg width="1em" height="1em" viewBox="0 0 256 256" class="hidden h-[18px] w-[18px]" data-icon="ph:check"><path fill="currentColor" d="m229.66 77.66l-128 128a8 8 0 0 1-11.32 0l-56-56a8 8 0 0 1 11.32-11.32L96 188.69L218.34 66.34a8 8 0 0 1 11.32 11.32"/></svg></button></div></div><nb-pm-restore style="display:contents"></nb-pm-restore></div></div><script type="module" src="https://developers.cloudflare.com/home/runner/work/cloudflare-docs/cloudflare-docs/src/components/ui/package-managers/PackageManagerTabs.astro?astro&type=script&index=0&lang.ts"></script> Both Pi packages are optional peer dependencies of <code>agents</code>, so you only install them if you use the harness. <div tabindex="-1" class="heading-wrapper level-h4"><h4 id="use-it-in-an-agent">Use it in an Agent</h4><a class="anchor-link" href="#use-it-in-an-agent"><svg width="16" height="16" viewBox="0 0 24 24"><path fill="currentcolor" d="m12.11 15.39-3.88 3.88a2.52 2.52 0 0 1-3.5 0 2.47 2.47 0 0 1 0-3.5l3.88-3.88a1 1 0 0 0-1.42-1.42l-3.88 3.89a4.48 4.48 0 0 0 6.33 6.33l3.89-3.88a1 1 0 1 0-1.42-1.42Zm8.58-12.08a4.49 4.49 0 0 0-6.33 0l-3.89 3.88a1 1 0 0 0 1.42 1.42l3.88-3.88a2.52 2.52 0 0 1 3.5 0 2.47 2.47 0 0 1 0 3.5l-3.88 3.88a1 1 0 1 0 1.42 1.42l3.88-3.89a4.49 4.49 0 0 0 0-6.33ZM8.83 15.17a1 1 0 0 0 1.1.22 1 1 0 0 0 .32-.22l4.92-4.92a1 1 0 0 0-1.42-1.42l-4.92 4.92a1 1 0 0 0 0 1.42Z"></path></svg></a></div> Creating a Pi agent requires configuring the Pi <code>Harness</code> with a model, skills, and tools, then registering the <code>PiHarness</code> with the <code>Agent</code> class. <div><div data-nb-tabs data-nb-sync-key="workersExamples" class><div class="relative flex border-b border-border" role="tablist" data-nb-tabs-list></div><div class="mt-3"><div role="tabpanel" data-nb-tabs-content data-nb-tab-label="JavaScript" class><figure class="nb-code-figure" data-nb-lang="js"><pre class="astro-code astro-code-themes github-light github-dark nb-shiki-c6xiwz" tabindex="0" data-language="js" data-nb-lang="js"><code>import { Agent } from "agents"; import { createModels } from "@earendil-works/pi-ai/models"; import { createRegistry, Harness } from "@earendil-works/pi-durable"; import { PiHarness } from "agents/harness/pi"; import { createAI } from "agents/models/pi-ai"; export class Assistant extends Agent { ai = createAI({ binding: this.env.AI }); registry = createRegistry(); harness = new PiHarness({ harness: ({ storage, context }) => { const models = createModels(); models.setProvider(this.ai.provider); return Harness.open( storage, { models, registry: this.registry }, context, ); }, defaults: { model: this.ai("@cf/moonshotai/kimi-k2.7-code") }, }); constructor(ctx, env) { super(ctx, env); this.lifecycle.use(this.harness); } async ask(prompt) { const { text } = await this.harness.prompt(prompt); return text; } }</code></pre></figure></div><div role="tabpanel" data-nb-tabs-content data-nb-tab-label="TypeScript" class><figure class="nb-code-figure" data-nb-lang="ts"><pre class="astro-code astro-code-themes github-light github-dark nb-shiki-c6xiwz" tabindex="0" data-language="ts" data-nb-lang="ts"><code>import { Agent } from "agents"; import { createModels } from "@earendil-works/pi-ai/models"; import { createRegistry, Harness } from "@earendil-works/pi-durable"; import { PiHarness } from "agents/harness/pi"; import { createAI } from "agents/models/pi-ai"; export class Assistant extends Agent<Env> { ai = createAI({ binding: this.env.AI }); registry = createRegistry(); harness = new PiHarness({ harness: ({ storage, context }) => { const models = createModels(); models.setProvider(this.ai.provider); return Harness.open( storage, { models, registry: this.registry }, context, ); }, defaults: { model: this.ai("@cf/moonshotai/kimi-k2.7-code") }, }); constructor(ctx: DurableObjectState, env: Env) { super(ctx, env); this.lifecycle.use(this.harness); } async ask(prompt: string) { const { text } = await this.harness.prompt(prompt); return text; } }</code></pre></figure></div></div></div><script type="module" src="https://developers.cloudflare.com/home/runner/work/cloudflare-docs/cloudflare-docs/src/components/ui/tabs/Tabs.astro?astro&type=script&index=0&lang.ts"></script></div> The <code>agents/models/pi-ai</code> entry point supports AI Gateway and Workers AI models, so you can get started with Cloudflare models right away or use your existing Pi AI provider. <div tabindex="-1" class="heading-wrapper level-h4"><h4 id="add-tools-with-extensions">Add tools with extensions</h4><a class="anchor-link" href="#add-tools-with-extensions"><svg width="16" height="16" viewBox="0 0 24 24"><path fill="currentcolor" d="m12.11 15.39-3.88 3.88a2.52 2.52 0 0 1-3.5 0 2.47 2.47 0 0 1 0-3.5l3.88-3.88a1 1 0 0 0-1.42-1.42l-3.88 3.89a4.48 4.48 0 0 0 6.33 6.33l3.89-3.88a1 1 0 1 0-1.42-1.42Zm8.58-12.08a4.49 4.49 0 0 0-6.33 0l-3.89 3.88a1 1 0 0 0 1.42 1.42l3.88-3.88a2.52 2.52 0 0 1 3.5 0 2.47 2.47 0 0 1 0 3.5l-3.88 3.88a1 1 0 1 0 1.42 1.42l3.88-3.89a4.49 4.49 0 0 0 0-6.33ZM8.83 15.17a1 1 0 0 0 1.1.22 1 1 0 0 0 .32-.22l4.92-4.92a1 1 0 0 0-1.42-1.42l-4.92 4.92a1 1 0 0 0 0 1.42Z"></path></svg></a></div> Both tools and system prompt sections are provided to the Pi <code>Harness</code> via extensions. <div><div data-nb-tabs data-nb-sync-key="workersExamples" class><div class="relative flex border-b border-border" role="tablist" data-nb-tabs-list></div><div class="mt-3"><div role="tabpanel" data-nb-tabs-content data-nb-tab-label="JavaScript" class><figure class="nb-code-figure" data-nb-lang="js"><pre class="astro-code astro-code-themes github-light github-dark nb-shiki-c6xiwz" tabindex="0" data-language="js" data-nb-lang="js"><code>import { Type } from "@earendil-works/pi-ai"; import { skills } from "agents/harness/pi"; const WordCount = Type.Object({ text: Type.String() }); const wordCount = { name: "word_count", description: "Count the words in a text.", parameters: WordCount, replay: "safe", async execute({ text }) { const words = text.split(/\s+/).filter(Boolean).length; return { content: [{ type: "text", text: String(words) }] }; }, }; // In the harness factory, before Harness.open(): registry.install({ name: "editor", sections: [ { key: "preamble", render: () => "You are an editor.", tag: false }, ], tools: [wordCount], }); registry.install(await skills(sources));</code></pre></figure></div><div role="tabpanel" data-nb-tabs-content data-nb-tab-label="TypeScript" class><figure class="nb-code-figure" data-nb-lang="ts"><pre class="astro-code astro-code-themes github-light github-dark nb-shiki-c6xiwz" tabindex="0" data-language="ts" data-nb-lang="ts"><code>import { Type } from "@earendil-works/pi-ai"; import type { ToolRegistration } from "@earendil-works/pi-durable"; import { skills } from "agents/harness/pi"; const WordCount = Type.Object({ text: Type.String() }); const wordCount: ToolRegistration<typeof WordCount> = { name: "word_count", description: "Count the words in a text.", parameters: WordCount, replay: "safe", async execute({ text }) { const words = text.split(/\s+/).filter(Boolean).length; return { content: [{ type: "text", text: String(words) }] }; }, }; // In the harness factory, before Harness.open(): registry.install({ name: "editor", sections: [ { key: "preamble", render: () => "You are an editor.", tag: false }, ], tools: [wordCount], }); registry.install(await skills(sources));</code></pre></figure></div></div></div></div> For more information on creating and configuring extensions, refer to <a href="https://developers.cloudflare.com/agents/harnesses/pi/extensions/">Extensions</a>. <div tabindex="-1" class="heading-wrapper level-h4"><h4 id="learn-more">Learn more</h4><a class="anchor-link" href="#learn-more"><svg width="16" height="16" viewBox="0 0 24 24"><path fill="currentcolor" d="m12.11 15.39-3.88 3.88a2.52 2.52 0 0 1-3.5 0 2.47 2.47 0 0 1 0-3.5l3.88-3.88a1 1 0 0 0-1.42-1.42l-3.88 3.89a4.48 4.48 0 0 0 6.33 6.33l3.89-3.88a1 1 0 1 0-1.42-1.42Zm8.58-12.08a4.49 4.49 0 0 0-6.33 0l-3.89 3.88a1 1 0 0 0 1.42 1.42l3.88-3.88a2.52 2.52 0 0 1 3.5 0 2.47 2.47 0 0 1 0 3.5l-3.88 3.88a1 1 0 1 0 1.42 1.42l3.88-3.89a4.49 4.49 0 0 0 0-6.33ZM8.83 15.17a1 1 0 0 0 1.1.22 1 1 0 0 0 .32-.22l4.92-4.92a1 1 0 0 0-1.42-1.42l-4.92 4.92a1 1 0 0 0 0 1.42Z"></path></svg></a></div> <ul> <li><a href="https://developers.cloudflare.com/agents/harnesses/pi/">Pi harness documentation</a></li> <li><a href="https://developers.cloudflare.com/agents/harnesses/pi/extensions/">Pi harness extensions</a></li> <li><a href="https://developers.cloudflare.com/agents/models/pi-ai/">pi-ai model provider</a></li> <li><a href="https://github.com/cloudflare/agents/tree/main/examples/next/harnesses/pi" target="_blank" rel="noopener">Pi harness example ↗︎</a>, with WebSockets, a browser UI, and a <code>@cloudflare/computer</code> Workspace for the model's tools</li> <li><a href="https://github.com/cloudflare/agents/blob/main/docs/agents/lifecycle.md" target="_blank" rel="noopener">Lifecycle ↗︎</a></li> <li><a href="https://earendil.com/posts/pi-durable/" target="_blank" rel="noopener">Pi Durable announcement ↗︎</a> from Earendil</li> </ul>

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