Clipboard
Clipboard access is for explicit user transfer: Copy, Paste, Copy link, Clear copied value, or writing typed content the user intentionally asked to share with other apps.
By the end of this guide, you will know how to build a Copy link button that writes text and shows a success message. The same pattern applies to larger apps: declare the capability when native configuration is needed, store the result in typed app state, request the host operation from a reducer, and test both success and failure with a memory host.
Avoid background clipboard reads. Users expect clipboard access to be tied to a visible action, and browsers or operating systems may require focus, a secure origin, or a direct user gesture.
1. Start with the state the screen needs
Add the smallest state fields the screen needs to render honestly. For this flow, useful state is:
#[derive(Default)]
struct ClipboardState {
// Add these fields to your existing app state.
share_url: String,
copied: bool,
clipboard_error: Option<String>,
}
impl GlobalState for ClipboardState {}
State is the source of truth for the UI. Do not store whether the host "probably" succeeded; wait for the typed success action and store the returned value.
2. Configure the target and host
There is no single safe add-capability value for this feature because the product owns the route/provider details, or because the default host can expose the feature without generated permission files. You still configure the shell explicitly and review target packaging before release.
Clipboard does not need generated Android or iOS permission entries in the built-in declaration. The default shell can provide a clipboard host on common desktop paths, but custom shells and web targets still need an implementation that respects focus, gesture, and security rules.
This is the difference between the Fission API, a provider, and packaging configuration:
•
The Fission API is the typed Rust contract your reducer calls, such as ctx.effects.camera().capture_photo(...).
•
The provider is the shell-side Rust implementation that turns that typed request into the correct OS, browser, or hardware call.
•
Packaging configuration is the manifest, plist, entitlement, service-worker, protocol, domain, or store metadata that lets the platform permit that call in a real installed app.
If the API exists but the provider is missing, the request returns a typed unsupported error. If the provider exists but packaging is missing, the operating system or browser may deny the request before the provider can complete it.
3. Define reducers for success and failure
Capability work finishes later, after the reducer that started it has returned. You therefore need one reducer for the successful result and one reducer for the error path.
#[fission_reducer(LinkCopied)]
fn on_link_copied(state: &mut ClipboardState) {
state.copied = true;
state.clipboard_error = None;
}
#[fission_reducer(CopyFailed)]
fn on_copy_failed(state: &mut ClipboardState, error: ClipboardError) {
state.copied = false;
state.clipboard_error = Some(error.message);
}
Keep both paths explicit. A denied permission, unavailable device, unsupported host, or cancelled prompt is not an exceptional mystery; it is normal product behavior the UI should explain.
4. Request the capability from a reducer
Call the capability from the reducer that handles the user's intent. The reducer queues a host effect and returns. The runtime later dispatches either the success reducer or the failure reducer.
ctx.effects
.clipboard()
.write_text(ClipboardWriteTextRequest {
text: state.share_url.clone(),
})
.on_ok(ctx.effects.bind(
LinkCopied,
reduce_with!(on_link_copied),
))
.on_err(ctx.effects.bind(
CopyFailed(ClipboardError::default()),
reduce_with!(on_copy_failed),
));
The call does not run the OS API directly. It records a typed host request. That keeps shared app logic portable across Fission targets where the capability applies, plus static-site previews and tests.
5. Trigger the reducer from the UI
Wire the user-facing control with the normal Fission action pattern. This example uses a small widget so the binding has one clear home.
struct CopyShareLinkButton;
impl From<CopyShareLinkButton> for Widget {
fn from(component: CopyShareLinkButton) -> Self {
let (ctx, view) = fission::build::current::<ClipboardState>();
let run = with_reducer!(ctx, CopyShareLink, on_copy_share_link);
Button::new("Copy link")
.disabled(false)
.on_press(run)
.into()
}
}
Rename the widget and action for your product, but keep the shape: the widget dispatches one typed action, the reducer starts the capability request, and the success or failure reducer updates state.
6. Provide and test the host behavior
Register a ClipboardHost with .with_clipboard_host(...) when the default shell is not enough. Use MemoryClipboardHost in tests. The provider should return typed errors for denied gestures, missing focus, unsupported rich content, or unavailable host clipboard.
Test write success, read-empty, read-text, read-rich-content, clear, and gesture-denied errors. Reducer tests should prove the app does not claim Copy succeeded when the provider returns an error.
A useful first test creates the app with the memory host, dispatches the start action, feeds the queued effect through the host, and asserts that the reducer updates state from the returned payload. Add a second test for the error path before you ship the screen.
Platform expectations
Clipboard is broadly available on macOS, Windows, Linux, Web, Android, and iOS. Browser clipboard access usually requires a secure context and user gesture. Linux depends on the active display server and clipboard backend.
For a cross-platform summary, read the capability matrix. For exact request fields, provider traits, and generated configuration, see the Clipboard reference.
Finished capability flow
A complete Clipboard integration has all of these pieces in place:
Piece | What should exist |
|---|---|
Configuration | fission.toml declares the capability and generated platform files contain the permission text, manifest entry, entitlement, domain, or protocol metadata the target needs. |
State | App state records the in-flight flag, the successful value, and the user-facing error separately. |
Reducers | One reducer starts the host request, one handles success, and one handles denial, unsupported hosts, cancellation, or provider errors. |
Provider | The shell registers a real provider for production and a memory provider for tests. |
Tests | At least one test covers success and one covers permission denial or unsupported host behavior. |
Diagnose capability failures
Capability failures should be safe to retry and easy to explain. Start by checking fission.toml, then run fission doctor, then inspect the generated target files. If the provider is missing, the request should return an unsupported error. If the provider exists but the platform configuration is wrong, the OS or browser will usually deny the request before the provider can complete it. Keep those cases distinct in the UI so users know whether they can retry, change settings, connect hardware, or choose another path.
Fission
A cross-platform, GPU-accelerated user interface framework for Rust. MIT licensed.
Copyright (c) 2026 Fission
Ready to use today. Widget APIs are expected to remain stable; some runtime and shell APIs may change before 1.0.0.
Fission 0.7.0