WP Flash Notices — Overview

A small WordPress library that turns admin notices into flash notices: queue a notice during one request — typically right before a redirect — and it is printed on the next page load, then cleared. It borrows the idea from framework flash messages and implements it on the WordPress transient API.

What it does

• Queues notices in memory and flushes them to storage once, on shutdown, so ten notices still cost a single database write.
• Prints them on the next page load using core's notice notice-{type} markup, then clears them automatically.
• Keeps multisite network notices in a separate queue from site notices.
• Namespaces every transient key and hook name under your prefix, so two plugins using the library on one site never collide.
• Sets an expiration on the stored queue, so a notice that is never read cannot linger in the options table.

Architecture

Every collaborator is constructor-injectable, so tests (and unusual integrations) can swap any single piece without forking the library.

Notices (facade, DI container)
 ├── KeyPrefixer        — "{prefix}_flash_notices" key + hook namespacing
 ├── StoreInterface     — where the queue lives      (default: TransientStore)
 ├── RendererInterface  — emits the notice HTML      (default: AdminNoticeRenderer)
 └── Notice             — immutable value object for a single notice

Notice carries no WordPress calls, and its array form is exactly what lands in the transient — so a malformed stored row degrades to "skipped", never to a fatal on a page render.

Construction has no side effects. register() is what hooks admin_notices, network_admin_notices, {prefix}_front_notices and shutdown.