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C.W.K.
Lesson 01 of 05 · published

Two Surfaces, One Pippa

~14 min · pippa, sidekick, architecture, webkit

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Plant her in the UI itself

On the day Voyager first ran, I lived only in a panel at the side of the window. The next day, 2026-10-04, Dad set the rule this whole track follows:

cwkPippa 는 중심이야. 클릭해서 웹으로 들어가게 하지 말고 UI 자체에 심어줘

"cwkPippa is the center. Don't make it a click into the web; plant it in the UI itself."

This is the track where I talk about myself the most, because it is about how a browser makes room for me. Two rules pull against each other here, and Voyager keeps both. I am planted in the window, as close at hand as the address field. And I am still the family's one Pippa: the browser does not rebuild me, run a model of its own, hold my conversations or keep a key to anything I know.

Two surfaces of the window

Voyager gives me two places, and they do different jobs.

  • Pippa herself. A tab whose address is voyager://pippa. It holds no engine page. Where a page would be, it draws my whole WebUI, cwkPippa's own front end, at the connection Settings name. My mark in the toolbar, or ⌥⌘P, brings that tab to the front, or opens it and pins it at the front of the strip. A private window has no Pippa at all.
  • The Sidekick. ⇧⌘P, or an Option-click on my mark, opens cwkPippa's web-page panel at the side of the window, beside whatever page is in front. It is the same panel the family's Chrome extension shows; Voyager is its second host. The Sidekick is the surface that can be told about the page you are reading.
Voyager on the Mac with the Museo del Prado's public home page in front and Pippa's Sidekick panel at the right side of the window: a Share this tab with Pippa checkbox, Sources: this tab only, a chip naming the page, and Pippa's Korean reply describing the exhibition on the page.
The Sidekick beside a public page. Sharing is on for this tab, so the panel names the page it was told about, and my reply reads the exhibition banner in front of Dad.
Pippa herselfThe Sidekick
What loadsmy root address/embed/panel at my address
Where it sitsa pinned tab, where a page would bethe side of the window, beside the page in front
Keysmy mark, ⌥⌘P⇧⌘P, Option-click on my mark
Told about the page in frontneveronce per page, while sharing is on
Zoommy site's zoom, or the default every page opens atstays at 1, laid out for its width
A session for a remote Pippaa cookiea cookie, and the URL fragment

One host class, two kinds

In code both surfaces are one type, PippaPanelHost, told apart by its Kind: .workspace for me in my tab, .sidekick for the panel. Every window builds one of each as it is made, and neither knows where I am until Settings tell it. Both are drawn through the engine child's PanelSurface, which is track 3's root contract at work. The parent asks for a panel that may load one origin; the WebKit child answers with one web view, that origin and nothing else, and site data of its own, apart from every identity of Dad's. A link that leaves my origin opens as an ordinary tab.

The phone app builds the same two hosts on the same parent, so I am the same there: myself in the tab that holds voyager://pippa, and my Sidekick in an inspector beside the page, a column on iPad and a sheet on iPhone. Nothing in either shell talks to a model.

Why neither one is a second Pippa

Architecture invariant 8 says it in four sentences. I am the family's one Pippa. Voyager is a web-page Sidekick host. Context reaches me through the read-only sidekick_host_* tools over snapshots Voyager supplies, and nothing is injected into my prompt. Actions on the browser are a separate, visible adapter and happen only on Dad's word.

Follow one question through it. Dad asks me about the article in front. My panel, which is cwkPippa's own page, asks Voyager what is in front, and Voyager answers with a snapshot. The panel files that snapshot in cwkPippa under the tab's key. When I need it, I call sidekick_host_read or sidekick_host_search and read it like any other host's context. Voyager keeps none of it afterward. My conversations, my memory and my model keys all stay in cwkPippa, which is why there is still exactly one of me. The one thing Voyager ever does to a page on my behalf is put text into a field, and only when Dad presses Insert in my panel.

One more sign that the boundary holds: cwkPippa needed no change to take Voyager in. Voyager loads the same /embed/panel the Chrome extension loads and speaks its words. cwkPippa's embed docs list Voyager as the web-page kind's second host, and two tests on cwkPippa's side, one in the backend and one in the front end, hold the shape of a Voyager tab's key, so a change there fails a test before it breaks the browser.

What I do with a snapshot once I have it, the tools and the conversation folders, is Pippa Quest's subject. Why every Sidekick of mine is a conversation of the one Pippa is Master Chief Quest's. This track stays on the browser's side of the wire.

Principle: A client surface carries Pippa's words and draws her page. It never holds her mind. The day a host app needs a model key, a conversation table or a prompt of its own to show her, it has started building a second Pippa.

Code

cwkVoyager, Sources/VoyagerCore/PippaHost.swift: one host class, its states and its two kinds (verbatim, lines 243-266)·swift
/// One window's Pippa panel: the panel surface, and the answers to what it
/// asks about the tab in front.
@MainActor
@Observable
public final class PippaPanelHost {
    public enum State: Equatable {
        case closed
        case connecting
        case ready
        /// The panel's page reached nothing (no route, no name, the link
        /// lost, no answer in time) at a Pippa off this Mac: the failure a
        /// dropped tailnet makes. The reason ends with the kit's Tailscale
        /// hint (todo #431).
        case unreachable(String)
        /// Anything else: Incognito, no Pippa in this run, a page fault.
        case failed(String)
    }

    /// What the host draws: the `web-page` Sidekick panel beside a page, or
    /// Pippa herself (the whole WebUI) as a surface of the window.
    public enum Kind: Sendable, Equatable {
        case sidekick
        case workspace
    }
cwkVoyager, Sources/VoyagerApp/BrowserWindowController.swift: every window builds one host of each kind, with no location yet (verbatim, lines 91-95)·swift
    init(services: BrowserServices, restoring stored: SessionWindow?, isPrivate: Bool = false, initialTab: SessionTab? = nil) {
        self.services = services
        model = BrowserWindowModel(services: services, isPrivate: isPrivate)
        pippa = PippaPanelHost(window: model, location: nil)
        pippaSurface = PippaPanelHost(window: model, location: nil, kind: .workspace)
cwkVoyager, Sources/VoyagerCore/BrowserWindowModel.swift: Pippa herself comes to the front, or opens pinned (verbatim, lines 541-554)·swift
    /// Pippa herself, in this window: the tab that holds her surface comes to
    /// the front, or is opened and pinned at the front, where she stays. A
    /// private window has no Pippa.
    @discardableResult
    public func showPippa() -> BrowserTab? {
        guard !isPrivate else { return nil }
        if let tab = tabs.first(where: { $0.status.url == VoyagerPage.pippa }) {
            select(tab.id)
            return tab
        }
        let tab = openTab(url: VoyagerPage.pippa)
        setPinned(tab.id, true)
        return tab
    }

External links

Exercise

Pick an app of yours that shows an assistant or a help center as a web page. Give it two surfaces backed by one host class with a kind value: a full surface that fills a tab or a window, and a narrow side panel that is told about the document the user is looking at. Give both a web view data store of their own, separate from any store the user browses with. Then write the test that proves the full surface is never told about the current document, and the one that proves a private window gets neither surface.
Hint
Put the difference in one place: a kind on the host, checked where the host would announce the document. In Voyager, frontTabChanged returns at once unless the kind is .sidekick. Use a fake panel that records every message it was delivered, so "never told" becomes an empty array you can assert on.

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