wails V3 Deep-link (Port of v2 feature)

This is a loose port of the v2 Custom Protocol Association feature initially introduced in #3000

There are some modification to how a user will use the API but the logic of gathering it is fairly similar

A unified Golang API for it is provided to the user regardless of OS as opposed to the v2 solution

app.OnApplicationEvent(events.Common.ApplicationLaunchedWithUrl, func(e *application.ApplicationEvent) {
   launchedURL := e.Context().URL() // Retrieve the URL from the event context
   log.Printf("Application launched with URL: %s", launchedURL)
})

I have tested on macOS but will need assistance to confirm/troubleshoot other OS, will include my hardware details below

Setting up custom protocol

Configuring the custom protocol is set inside the wails config file

{
 "name": "My App",
 "description": "An amazing Wails app!",
 "info": {
   "companyName": "My Company",
   "productName": "My Product",
   "protocols": [
     {
       "scheme": "myapp",
       "description": "My Application Custom Protocol"
     },
     {
       "scheme": "anotherprotocol",
       "description": "Another protocol for specific actions"
     }
   ]
 }
}

How it works

The config file will take care of most of the setup for you you will need to run task common:update:build-assets once updating your config file for the changes to take place

In all OS you will need a task package build in order for the custom protocol to work.

MacOS

Values are taken from the config file to populate the correct fields inside the plist

    <key>CFBundleURLTypes</key>
    <array>
        <dict>
            <key>CFBundleURLName</key>
            <string>My Application Custom Protocol</string> <!-- From Protocol.Description in wails.json -->
            <key>CFBundleURLSchemes</key>
            <array>
                <string>myapp</string> <!-- From Protocol.Scheme in wails.json -->
            </array>
        </dict>
    </array>

Windows

**Requires an NSIS install step and makensis ** Windows will add the URL as an argument to the launch args, wails checks this on start up any launch args match your deep link protocol if so the application event is emitted saving you from having to parse and determine yourself.

Linux

Requires an install step

Linux is setup to configure your deep-link via nfpm and a .desktop file, on install the post-install.sh script will update the device database and MIME types to allow for deep linking.

Linux works similar to windows as it passes the url as an argument to the launch. Wails handles is the same way to populate the application event

Hardware details

 Wails (v3.0.0-dev)  Wails Doctor

# System

┌──────────────────────────────────────────────────┐
| Name          | MacOS                            |
| Version       | 15.4.1                           |
| ID            | 24E263                           |
| Branding      | Sequoia                          |
| Platform      | darwin                           |
| Architecture  | arm64                            |
| Apple Silicon | true                             |
| CPU           | Apple M4 Pro                     |
| CPU 1         | Apple M4 Pro                     |
| CPU 2         | Apple M4 Pro                     |
| GPU           | 16 cores, Metal Support: Metal 3 |
| Memory        | 24 GB                            |
└──────────────────────────────────────────────────┘

# Build Environment

┌─────────────────────────────────────────────────────────┐
| Wails CLI    | v3.0.0-dev                               |
| Go Version   | go1.24.1                                 |
| Revision     | 3716acaae4dc0bb6407a7d0a772b32d8509be6d0 |
| Modified     | true                                     |
| -buildmode   | exe                                      |
| -compiler    | gc                                       |
| CGO_CFLAGS   |                                          |
| CGO_CPPFLAGS |                                          |
| CGO_CXXFLAGS |                                          |
| CGO_ENABLED  | 1                                        |
| CGO_LDFLAGS  |                                          |
| GOARCH       | arm64                                    |
| GOARM64      | v8.0                                     |
| GOOS         | darwin                                   |
| vcs          | git                                      |
| vcs.modified | true                                     |
| vcs.revision | 3716acaae4dc0bb6407a7d0a772b32d8509be6d0 |
| vcs.time     | 2025-05-14T20:35:41Z                     |
└─────────────────────────────────────────────────────────┘

Summary by CodeRabbit

New Features
- Added comprehensive support for custom protocol schemes (deep linking) across macOS, Windows, and Linux, enabling applications to handle custom URLs.
- Introduced a new example project demonstrating custom protocol handling, including frontend and backend integration.
- Applications now emit events when launched via custom URLs, allowing frontend components to respond accordingly.
Documentation
- Added detailed guides and README documentation explaining how to configure and use custom protocol schemes in Wails applications.
Chores
- Added configuration files, build scripts, and templates to support packaging, installation, and protocol registration on all major platforms.

May 18 '25 21:05 atterpac

Walkthrough

This change introduces comprehensive support for custom protocol schemes (deep linking) in Wails applications across macOS, Windows, and Linux. It includes new documentation, example projects, configuration files, build scripts, and runtime logic. The update adds event types, context handling, and platform-specific implementations to enable applications to register and respond to custom URL schemes, emitting events to the frontend when launched via a registered protocol.

Changes

Files/Paths	Change Summary
docs/src/content/docs/guides/custom-protocol-association.mdx	Added a detailed guide for implementing custom protocol schemes (deep linking) in Wails apps across all major platforms.
v3/examples/custom-protocol-example/* (README.md, .gitignore, Taskfile.yml, greetservice.go, main.go, etc.)	Introduced a new example project demonstrating custom protocol usage, including Go backend, frontend assets, build scripts, configuration, and documentation.
v3/examples/custom-protocol-example/build/* (darwin, linux, windows, config.yml, etc.)	Added cross-platform build and packaging scripts, configuration files, Info.plist templates, NSIS installer scripts, and Linux packaging support for the example.
v3/examples/custom-protocol-example/frontend/* (index.html, src/*, package.json, .gitignore, etc.)	Added frontend implementation for the example, including event handling for URLs, UI, CSS, and generated JS bindings.
v3/internal/commands/build-assets.go	Added `ProtocolConfig` struct and integrated protocol support into build/update config structs and asset update logic.
v3/internal/commands/build_assets/linux/nfpm/scripts/postinstall.sh	Replaced empty script with logic to update desktop and MIME databases post-installation, with error handling.
v3/internal/commands/updatable_build_assets/darwin/Info.dev.plist.tmpl, Info.plist.tmpl	Updated Info.plist templates to conditionally include custom URL scheme declarations based on provided protocols.
v3/internal/commands/updatable_build_assets/linux/desktop.tmpl	Added a Linux desktop entry template supporting protocol MIME type handlers.
v3/internal/commands/updatable_build_assets/linux/nfpm/nfpm.yaml.tmpl	Activated postinstall script in nfpm YAML template for Linux packaging.
v3/internal/runtime/desktop/@wailsio/runtime/src/event_types.ts	Added new event type constant `ApplicationLaunchedWithUrl` to the `Common` event category.
v3/pkg/application/application_darwin.go, application_darwin_delegate.h, application_darwin_delegate.m	Added macOS support for handling custom protocol Apple Events, including new handler class, initialization, and event emission.
v3/pkg/application/application_linux.go	Extended Linux app to detect and handle custom protocol URLs from command-line arguments, emitting launch events.
v3/pkg/application/application_windows.go	Enhanced Windows app to detect and handle custom protocol URLs from command-line arguments, emitting launch events.
v3/pkg/application/context_application_event.go	Added/renamed constants and methods to support URL context in application events, including getter/setter for URL.
v3/pkg/events/events.txt, events.go	Added new event identifier and struct field for `ApplicationLaunchedWithUrl`; incremented event IDs accordingly.

Sequence Diagram(s)

sequenceDiagram
    participant OS as Operating System
    participant App as Wails Application
    participant Backend as Go Backend
    participant Frontend as JS Frontend

    OS->>App: Launch via custom URL (e.g., myapp://...)
    App->>Backend: Emit ApplicationLaunchedWithUrl event with URL context
    Backend->>Frontend: Emit frontend event (e.g., "ShowURL") with URL data
    Frontend->>Frontend: Display or process received URL

Poem

🐇
A protocol hops through the door,
With URLs it brings to explore.
Mac, Windows, and Linux in sync,
Now apps can respond in a blink!
Events and handlers, all in a row—
Deep linking magic, ready to go.
Let’s celebrate with a joyful wink!

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GitHub Check: Run Go Tests v3 (ubuntu-latest, 1.24)
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