Fission 0.4.1: runtime shell fixes, static server apps, and scoped route actions

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June 17, 2026

Fission 0.4.1: runtime shell fixes, static server apps, and scoped route actions

Fission 0.4.1 is a focused patch release on top of the 0.4 authoring API. It keeps the impl From<Component> for Widget model intact and improves the runtime, shell, server, static-site, and mobile-target behavior needed by production hosts and generated apps.

The main runtime-shell addition is the scoped route/action plumbing needed by host shells. Fission 0.4.0 introduced the low-level scoped raw action primitives with ActionScopeId, ActionScope, and ActionInput::ScopedRaw. Fission 0.4.1 builds on that foundation by adding shell route-change actions, route-location data, route handler registration, and router helpers that host shells can use to connect scoped guest dispatch to normal application reducers.

Scoped route actions for runtime shells

0.4.1 adds RouteLocation and ShellRouteChanged, plus shell builder APIs for registering route handlers.

RouteLocation is a browser-compatible route location structure with a required pathname and optional host, hash, hostname, href, origin, port, protocol, and search fields. ShellRouteChanged is a built-in action that shells can dispatch when the host route changes.

The desktop, mobile, web, and winit shell builders now expose with_route_handler(...), allowing applications and host shells to register a reducer for route changes without inventing their own shell-specific action transport. The router widget also gained builder-style construction helpers for common route table setup.

This matters for shells that mount generated or remote guest UI. Normal applications still use typed actions and reducers. Host shells can combine the 0.4.0 scoped raw action surface with the 0.4.1 route-change layer to keep mounted guest UI associated with the correct runtime and route state.

0.4.1 also fixes the desktop notification-response builder so on_notification_response(...) correctly returns the builder for chained configuration.

Server and static rendering fixes

The server and static site paths received the bulk of the patch work.

0.4.1 adds server static app mounts, SSR environment hooks, cache invalidation APIs, prefix server routes, structured route data, route response status support, and safer server handler execution off runtime threads.

The static and server renderers also gained better lowering for:

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static forms;

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links and responsive images;

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SVG icon coloring;

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animation output;

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text output;

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positioned layout;

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markdown image rendering;

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cache ids.

These changes make the server shell more useful for real apps that mix static pages, server-rendered routes, forms, markdown content, route metadata, and embedded static app surfaces.

Mobile target and package fixes

The CLI target scaffolding and mobile package scripts were tightened.

0.4.1 fixes target feature synchronization when existing projects already contain mobile platform folders, hardens generated Android and iOS scaffolds, and adds executable mobile package script tests. The Android and iOS generated package paths now carry more of the platform metadata and script behavior needed for reliable local packaging and simulator/emulator runs.

Rendering and markdown fixes

The release includes smaller rendering and content fixes that came out of the server/static work:

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Vello clipping helper formatting was cleaned up.

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Off-path image widget expectations were adjusted.

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Markdown viewer tests were expanded.

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Markdown image rendering and SSR image responsiveness were improved.

Verification added in the patch

The tag includes tests or focused verification for the new or fixed behavior:

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mobile scaffold and executable package script coverage;

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markdown viewer behavior;

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image widget behavior around off-path images;

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server/static rendering behavior touched by the SSR changes;

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package verification for every published crate in the workspace.

Migration notes

Most 0.4.0 applications should move to 0.4.1 without code changes.

Applications that need to react to host route changes can register a reducer with with_route_handler(...) and handle ShellRouteChanged. Hosts that mount guest UI can continue using the 0.4 scoped raw action APIs and pair them with route actions where they need route-aware dispatch.

Server-rendered or statically generated sites should prefer 0.4.1 when they rely on route status, structured route metadata, prefixed routes, markdown images, responsive images, static forms, or mounted static app islands.

Mobile projects should regenerate or resync target scaffolds if they need the updated package scripts and target feature handling.

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