.NET MAUI is a C# and XAML framework for building native mobile and desktop applications from one shared codebase. Developers use it to create apps for Android, iOS, iPadOS, macOS, and Windows. The catalogue entries provide skills, instructions, and agents for working with .NET MAUI.
Borrowing it
Nothing to install: this file belongs to dotnet/maui. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/dotnet/maui/main/.github/instructions/handler-patterns.instructions.mdgit clone --depth 1 https://github.com/dotnet/mauiWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/instructions/dotnet/maui/handler-patterns)<a href="https://agentmods.dev/instructions/dotnet/maui/handler-patterns"><img src="https://agentmods.dev/badge/instructions/dotnet/maui/handler-patterns/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/instructions/dotnet/maui/handler-patterns"><img src="https://agentmods.dev/badge/instructions/dotnet/maui/handler-patterns.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00464 | $0.00464 |
| Opus 5.5 | $0.00186 | $0.00186 |
| Sonnet 5.5 | $0.00093 | $0.00093 |
| Haiku 4.5 | $0.00046 | $0.00046 |
Grade A, and why
maui handler-patterns.instructions.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 37 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Handler Mapper and Property Patterns
Property Update Flow
- Property updates MUST go through
Handler.UpdateValue(nameof(Property))— never call mapper methods directly - Direct calls bypass user-registered
AppendToMapping/PrependToMappingcustomizations - Map dependencies before dependents — if property B reads property A, A's mapper must run first
CommandMapperentries return void and use the(handler, view, args)signature
Lifecycle Management
- ConnectHandler: Register listeners, subscribe to events, capture native defaults BEFORE applying cross-platform properties
- DisconnectHandler: Unsubscribe all events, dispose platform resources, null out references
- Call
base.ConnectHandler/base.DisconnectHandler— base class performs platform hookup/teardown (NOT mapper initialization, which happens inSetVirtualView)
Null Safety in Callbacks
- Null-check
VirtualViewbefore access in every mapper method and platform callback — it is null during disconnect - Validate
MauiContextbefore use — throwInvalidOperationExceptionwith descriptive message if null - After async operations, verify the handler is still connected before applying results
Native Defaults Preservation
- Capture native default values (colors, fonts, styles) in
ConnectHandlerBEFORE any cross-platform property is applied - Clearing a cross-platform property (setting to null/default) must restore the captured native default, not a hardcoded fallback
- On Windows, preserve WinUI XAML style-applied values; on Android, cache theme-inherited drawables; on iOS, capture UIAppearance defaults
Mapper Extensibility
- When extending existing mappers, ensure the base mapper chain is called — do not silently replace
- Static mapper methods should be
public staticto enable platform-specific overrides - Use
nameof()for property keys — avoid magic strings
Fire-and-Forget Async
- Use
.FireAndForget(handler)for async operations in mapper methods — never use bareasync void - The
FireAndForgetoverload accepting a handler logs exceptions through the handler's service provider
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 1mo ago First seen · 37 lines · 464 tokens per session scan A cb2d7da041a3
maui handler-patterns.instructions.md is an instructions file published in the GitHub repository dotnet/maui (23,322 stars, last pushed today), licensed MIT. It adds 464 tokens to every session, about $0.0019 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
Other instructions, from other repositories
plan-forge api-patterns.instructions.md
API patterns for .NET — REST conventions, ProblemDetails, pagination, versioning, error responses.
plan-forge swiftui.instructions.md
SwiftUI patterns — state management, navigation, async data loading, previews.
vscode buildNext.instructions.md
Working notes and architecture documentation for the new esbuild-based build system in build/next. Use when making changes to the new build pipeline (transpile/bundle commands, NLS plugin, source-map handling, resource copying, or self-hosting watch tasks).
next.js AGENTS.md
AGENTS.md instructions for vercel/next.js, covering next.js development guide, codebase structure, monorepo overview, core package: packages/next and other important packages.
vscode oss-third-party-notices.instructions.md
Instructions for microsoft/vscode, covering vs code oss third-party-notices pipeline, architecture, pipeline flow in ci, cache eligibility and rollout and applying the notice (cutover).
langchain AGENTS.md
AGENTS.md instructions for langchain-ai/langchain, covering global development guidelines for the langchain monorepo, corridor security analysis, project architecture and context, monorepo structure and development tools & commands.