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.NET MAUI

iOS, Android and Mac Catalyst on .NET 10 and later.

Figma-style comments for a running .NET MAUI app. Tap an element, write a note, and it reaches your coding agent (Claude Code, Codex, Cursor, Gemini CLI, Copilot and others) over MCP with a screenshot, the XAML file and line the element was written at, its page, its view model, and the app's recent log. It is the MAUI client of the same Notato server every other Notato SDK uses: the notes, the board, the MCP tools and the status loop (open, acknowledged, resolved, revert) are the same.

Works on iOS, Android and Mac Catalyst with .NET 10 and later. Windows builds, but has no overlay yet.

Screenshot size. New captures prefer WebP at quality 85 when it is smaller than PNG, after privacy masking and at the same dimensions. PNG remains a fallback, and existing queues and bundles stay readable. See screenshot storage.

Quick start#

npx notato dev           # the server your agent reads, on http://localhost:4747

Add the package to the app (dotnet add package Notato.Maui), and in MauiProgram.cs:

using Notato.Maui;

var builder = MauiApp.CreateBuilder();
builder.UseMauiApp<App>();
#if DEBUG
builder.UseNotato(options => options.Project = "checkout-app");
#endif

Leaving UseNotato out of a build ships nothing of Notato in it. Run the app: a small dark toolbar appears in the corner. Tap Annotate, tap what you want to comment on, write a note, press Send. The number on Annotate is how many notes the screen has; the chevron folds the toolbar into a round button, and ⋯ opens Notato's menu (notes, settings, packaging in test mode, hiding the toolbar), whose header shows the server and whether it is connected. Ask your agent to "watch Notato and fix what comes in".

The app has to be allowed to talk plain http to the development machine:

• iOS and Mac Catalyst: in Platforms/iOS/Info.plist (and MacCatalyst), NSAppTransportSecurity → NSAllowsLocalNetworking = true.
• Android: a network security config that permits cleartext to localhost (see the sample's Platforms/Android/Resources/xml/network_security_config.xml, referenced from AndroidManifest.xml). Then adb reverse tcp:4747 tcp:4747, so localhost:4747 on the emulator or a USB-connected phone is the server on your machine. (10.0.2.2 does not work: notato dev only answers to loopback names.)

The iOS simulator shares the Mac's network, so localhost works there as it is.

On a phone#

A phone cannot reach your machine's localhost (and iOS has no adb reverse). Start the server with a dev tunnel, notato dev --tunnel (see Phones: a dev tunnel; one devtunnel user login first), and there is nothing else to do: it writes the tunnel's https URL and a device token to .notato/device.json at the repository root, and this package's build targets record them in debug builds. When Server is not set, an iPhone, an Android phone and the Android emulator then use the tunnel, sending the device token, and the iOS simulator and Mac Catalyst the server's local address (its port included). Build again after the tunnel's URL changes; Visual Studio's up-to-date check knows the file.

• <NotatoDataDirectory> points the build at another data folder; <NotatoDeviceAccess>false</NotatoDeviceAccess> turns it off, true turns it on in other configurations too (the token then ships in that build).
• The device token opens notato dev on your machine to whoever has it, and anyone with a debug build can read it out of the build. Keep debug builds to yourself; a build for testers goes to a shared server with a capture-only token (below).
• A Server from configuration, or one typed in the toolbar's settings, wins over the tunnel.

Configuration#

UseNotato() binds the Notato section of builder.Configuration when there is one, then applies the delegate. Any configuration source works; the sample embeds an appsettings.json and adds environment variables over it:

{
  "Notato": {
    "Project": "checkout-app",
    "Mode": "Dev",
    "Server": "http://localhost:4747"
  }
}

builder.Configuration.AddJsonStream(appsettingsStream);
builder.UseNotato();                                                   // the "Notato" section
builder.UseNotato(builder.Configuration.GetSection("Feedback"));       // or another section
builder.UseNotato(o => o.AppVersion = "2.1-beta");                     // the section, then code

The configuration is read through IOptionsMonitor, so a source that reloads takes effect without a restart.

For one launch: NOTATO_ENABLED and NOTATO_SERVER#

Two environment variables are read whatever the configuration is, after it and after the code in MauiProgram, so whoever launches the app decides for that launch without changing it: Aspire sets them for an app it runs (WithReference(notato)), and so can an IDE's launch profile, or xcrun simctl launch with the SIMCTL_CHILD_ prefix.

SIMCTL_CHILD_NOTATO_ENABLED=false xcrun simctl launch booted com.example.checkout

Enable() and Disable() still work during the launch and are remembered as before, but the next launch with NOTATO_ENABLED set goes by it again. A server typed into the toolbar's settings still wins over NOTATO_SERVER, as it does over Server. They only matter where UseNotato is in the build: behind #if DEBUG, a release build has nothing of Notato for them to switch on.

At runtime: INotato#

Take INotato from DI (or Feedback.Current where there is no DI) to switch Notato on and off, and to select things:

public partial class DeveloperSettingsPage(INotato notato) : ContentPage
{
    void OnNotatoToggled(object? sender, ToggledEventArgs e)
    {
        if (e.Value) notato.Enable();   // remembered across launches
        else notato.Disable();          // removes the overlay and closes the connection
    }
}

The sample's Feedback tab does each of these.

What a note carries#

Everything the web SDK sends, in the same schema (environment.platform is maui), so the board, the Markdown and the MCP tools need nothing new:

• Where it is in the code. The XAML file, line and column the element was written at (src/App/Views/ProductCard.xaml:17:14), from MAUI's own XAML diagnostics, with the path from the repository root. Elements made in C# get the nearest element around them that has a location. The component path is the chain of the app's own pages and views around it (AppShell › ProductsPage › ProductCard), with the component's XAML file.
• Which element. A selector (below), its AutomationId (as the test id), x:Name, accessible role and name (from SemanticProperties), its visible text (a container's is the text inside it), and the elements around it.
• How it looks. The values it actually has: colours as hex, font, size, margin, padding, corner radius, stroke, spacing, options, opacity. Defaults are left out.
• What was on screen. The whole window with the element outlined and the pin's number drawn on, and a crop around it. Notato's own toolbar is never in them.
• Context (context.maui): the page and its XAML file, the element's and the page's BindingContext type (usually the view model), the Shell location, the navigation and modal stacks, the device, OS, idiom, orientation, theme, culture and font scale, and the MAUI and .NET versions.
• The app's log (context.console, the web SDK's shape): recent ILogger messages from Information up, and unhandled exceptions.
• Network (context.network), when the app adds NotatoNetworkHandler to its HttpClients: services.AddHttpClient("api").AddHttpMessageHandler(() => new NotatoNetworkHandler()). URLs are recorded without their query strings, or a user name and password in front of the host.

Mark things up in XAML with xmlns:notato="clr-namespace:Notato.Maui;assembly=Notato.Maui": notato:Feedback.Mask="True" makes an element private, and notato:Feedback.Ignore="True" makes the picker look through it.

Feedback is private to its creator by default in Dev mode. The agent starts with that person's notes; choose Shared or All to include project feedback (see the feedback visibility guide). People only notes and asides remain hidden from agents:

• People only, on a note. The composer has a People only switch, off by default ("Keep this between people: the agent won't see it."). A People only note and its whole thread never reach the agent. Its card shows a People only badge, and the same switch there turns it on or off for an existing note: anyone on the thread can, and the server records each change in the thread ("Made this people only: the agent won't see it." or "Shared this with the agent."). Without a server, or before the note has been sent, the change is made on the device with the same thread entry: the note is sent that way, and a test-mode package carries the history. From code, AnnotateOptions.PeopleOnly makes a person's note People only.
• Aside, on a reply. The reply box has an Aside switch ("Just for people: the agent won't see this reply."), off again after each reply. An aside is for the people on the thread, is marked Aside in it, and is never sent to the agent.

@name calls one of the server's mention plugins. None is built in and none is needed to reach the agent, so the composer and the reply box show no chips unless the server adds a plugin.

What a note never carries:

• Password entries, always: covered in every screenshot, and what is in them is never read.
• Android windows marked FLAG_SECURE (one-time codes, card entry): no screenshot is taken of them, unless CaptureSecureWindows is set. The note still says which element it is.
• Inputs, with MaskInputs (on in test and agent mode): the same for every Entry, Editor and SearchBar. notato:Feedback.Mask="False" opts one out, a search box say, so it is shown and recorded.
• Anything marked private with notato:Feedback.Mask="True": covered in every screenshot, and neither its text nor the text of anything inside it goes into a note, whether as its text, its accessible name, a container's text or a match for an agent's :text() selector. The note still says which element it is (its type, AutomationId, x:Name and where it is written). A private container wins over an input inside it that opts out. With MaskInputs, what is typed into an input is no match for :text() either.

Selectors#

A selector is a path through the visual tree, written like CSS so it reads at a glance and the agent can turn it into a search: LoginPage VerticalStackLayout#Form > Button:nth-of-type(2).

Notato writes the shortest selector that finds only that element on its page, and uses selectors to put pins back on elements after a restart. An AutomationId makes the steadiest one.

Pins#

A pin sits on the element its note was made on, follows it as the page scrolls, and goes faint where the element cannot be found (at the place the note was made). Only notes made with this package get a pin: a note from a web page or another SDK is in the Notes list but has no pin, because its selector means nothing here. A screen shows at most the newest 150 pins (as the React Native and Flutter SDKs do); the Notes list has every note. Pins are looked for together, in one pass over the page about once a second while one is missing, and drawn again only when one moved or changed.

Modes#

• Dev: notes go live to notato dev, pins turn amber when the agent acknowledges them and green when it resolves them, and replies arrive in the pin's card. On a resolved pin, Ask the agent to revert asks for the change to be undone. A note made while the server is down (or that the server cannot take yet: an unknown project, a missing credential, a busy server) is kept on the device, screenshots and all, and sent when it can be, in order, before the project's notes are read again; its pin's card shows what the server said, the menu says when the server cannot be reached, and Retry tries it again at once. A note the server refuses outright (too large, or not valid) says why on its pin's card and does not hold up the ones after it. On connecting, the app reads the project's notes without what only the agent needs (their context and steps), page by page.
• Test: feedback defaults to shared and is sent live into a review session when a server is configured. Notes also stay on the device (they survive a restart), out of the device's backups: in Android's no-backup folder, and on iOS and Mac Catalyst in a folder marked to be left out of them (on iOS, also unreadable while the device is locked unless open). Package and share in the toolbar's menu makes the bundle zip notato_import_bundle reads (feedback.md, annotations.json, shots/), opens the share sheet, and uploads it when a server is set. With a server set, the zip has the screenshots only while the server says it takes them. A zip over the server's 100 MB limit is shared but not uploaded, and the menu says so.
• Agent: like dev, and the app also takes notato_annotate requests from the agent: notato_annotate { target: "#PromoBanner", comment: "…" } is relayed to the app, which finds the element by its selector, takes the screenshot and files the note as the agent.

How the overlay works#

Notato draws its UI with MAUI controls, in a layer of its own above the app, so it needs nothing from the app's pages and works over Shell, tabs, navigation, modal pages, popups and alerts:

• iOS and Mac Catalyst: a transparent window above the app's window in the same scene. Touches that are not on Notato's controls go to the app. Being a separate window keeps the overlay above modal pages and alerts and out of the screenshots, which are taken of the app's window only.
• Android: a view in the decor view of the window that is on top. MAUI shows a modal page in a dialog window of its own, and the overlay moves into it while it shows. A screenshot is the window drawn with the overlay left out, so the overlay never disappears; only a window it cannot be drawn from that way (a SurfaceView or TextureView, such as a camera or a map, or a hardware bitmap) is copied from the screen instead, with the overlay hidden while it is.

Notato's controls carry explicit styles, so the app's implicit styles do not reach them, and its handler customisations apply only to the app's own controls.

The picker hit-tests the visual tree with the native views' real positions (scroll views and clipping included), topmost first. Parent in the note widens the selection to the element around it.

Physical devices and shared servers#

notato dev listens on loopback only. Your own phones reach it through a dev tunnel (On a phone), and a USB-connected Android phone also with adb reverse. For testers elsewhere, run a shared server (notato serve, see the main README) and give the app its address and a project token in configuration. The token only ever goes to that server (its scheme, host and port): a server typed into the toolbar's settings gets no token, so a note sent there goes without one.

A build you hand out (TestFlight, an internal track, a device farm) holds whatever is in it, and anyone with it can read that out. Give it a capture-only token, which can send notes and nothing else, so one read out of the app cannot read, change or delete anyone's feedback:

npx notato token create checkout-app --purpose app --capture-only --expires 30

Notato asks the server what the token may do before it connects. With a capture-only token it sends notes (and those kept on the device) without following the project, the notes' cards point to the board for replies, status and revert, and a test-mode package uploads its captured notes when a server is configured.

Known limits#

• Windows has no overlay yet: the package builds there, and INotato calls that need a window fail with a message.
• XAML line numbers need MAUI's XAML diagnostics, which are on in Debug builds. A Release build gets the component and its XAML file where the XAML compiler records it (from the project's folder, unless ProjectPath is set), and selectors.
• Items in a CollectionView are recycled, so a selector to one item can point at another after scrolling. A pin in a list stays on its element only while that element still shows the note's item (the same BindingContext, or the same text); when a row is reused for another item, the pin is looked for again, and goes faint where it was until its item is back on screen.
• Variants (comparing versions in the page) are web only.
• Shaking does not reach the iOS simulator. Use INotato.ShowToolbar() there.
• Verified on the iPhone 17 Pro simulator (iOS 26.5) and an Android 16 emulator, against notato dev, by tapping and typing through the whole loop on both. Not yet run: Mac Catalyst, physical devices, a notato serve server with a token.

Hiding completed annotations#

On a resolved or reverted note, open More options → Hide from this app to hide its pin and card on this device. In Settings, Hide completed annotations hides completed notes across every screen at once, including notes beyond the 150 drawn pins. Restore hidden annotations brings them back.

Hiding keeps the feedback, screenshots and thread in the dashboard and exports. It never changes the note on the server. Reopened tasks and new agent questions remain visible. The preference is scoped to the server, project, mode, credential and name, and survives app restarts when runtime preferences are remembered.