diff --git a/.github/workflows/docs.yml b/.github/workflows/docs.yml
index 35f16c13..7fe0ef31 100644
--- a/.github/workflows/docs.yml
+++ b/.github/workflows/docs.yml
@@ -23,10 +23,10 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup Node.js
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@v6
         with:
           node-version: '22'
           cache: 'npm'
diff --git a/.github/workflows/generators.yml b/.github/workflows/generators.yml
index 4ab4eabb..b88c4701 100644
--- a/.github/workflows/generators.yml
+++ b/.github/workflows/generators.yml
@@ -30,7 +30,7 @@ jobs:
     name: ${{ matrix.framework }} (TS:${{ matrix.typescript }}, TW:${{ matrix.tailwind }}, Inertia:${{ matrix.inertia_version }})
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
@@ -42,7 +42,7 @@ jobs:
         run: bundle exec rspec --tag type:generator
 
       - name: Set up Node
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@v6
         with:
           node-version: ${{ matrix.node }}
 
@@ -69,7 +69,7 @@ jobs:
 
       - name: Upload test artifacts
         if: failure()
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v5
         with:
           name: test-output-${{ matrix.framework }}-ts${{ matrix.typescript }}-tw${{ matrix.tailwind }}-v${{ matrix.inertia_version }}
           path: |
diff --git a/.github/workflows/push.yml b/.github/workflows/push.yml
index e885474c..9860f1a2 100644
--- a/.github/workflows/push.yml
+++ b/.github/workflows/push.yml
@@ -19,11 +19,11 @@ jobs:
     runs-on: ubuntu-latest
     name: Linter
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: "3.3"
+          ruby-version: "3.4"
           bundler: latest
           bundler-cache: true
       - name: Run RuboCop
@@ -53,13 +53,13 @@ jobs:
     name: Test against Ruby ${{ matrix.ruby }} / Rails ${{ matrix.rails }}
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Setup System
         run: sudo apt-get install libsqlite3-dev
 
       - name: Set up Node.js
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@v6
         with:
           node-version: 22.x
 
@@ -67,7 +67,7 @@ jobs:
         uses: ruby/setup-ruby@v1
         with:
           ruby-version: ${{ matrix.ruby }}
-          rubygems: latest
+          rubygems: 'latest'
           bundler-cache: true
         env:
           RAILS_VERSION:  ${{ matrix.rails }}
diff --git a/Gemfile b/Gemfile
index 8e9874e5..8048bfd4 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,7 +8,6 @@ gemspec
 version = ENV.fetch('RAILS_VERSION', '8.1')
 gem 'rails', "~> #{version}.0"
 
-gem 'bundler', '~> 2.0'
 gem 'debug'
 gem 'generator_spec', '~> 0.10'
 gem 'rails-controller-testing'
diff --git a/app/views/inertia.html.erb b/app/views/inertia.html.erb
index e52113b8..8eeec0fc 100644
--- a/app/views/inertia.html.erb
+++ b/app/views/inertia.html.erb
@@ -1 +1 @@
-<div id="app" data-page="<%= page.to_json %>"></div>
+<%= inertia_root(page: page) %>
diff --git a/docs/.vitepress/config.mts b/docs/.vitepress/config.mts
index 7ff43e12..ffc66c9e 100644
--- a/docs/.vitepress/config.mts
+++ b/docs/.vitepress/config.mts
@@ -136,6 +136,7 @@ export default defineConfig({
             { text: 'Prefetching', link: '/guide/prefetching' },
             { text: 'Load when visible', link: '/guide/load-when-visible' },
             { text: 'Merging props', link: '/guide/merging-props' },
+            { text: 'Once props', link: '/guide/once-props' },
             { text: 'Infinite scroll', link: '/guide/infinite-scroll' },
             { text: 'Remembering state', link: '/guide/remembering-state' },
           ],
diff --git a/docs/cookbook/handling-validation-error-types.md b/docs/cookbook/handling-validation-error-types.md
index 475153fc..d7bc4843 100644
--- a/docs/cookbook/handling-validation-error-types.md
+++ b/docs/cookbook/handling-validation-error-types.md
@@ -26,8 +26,10 @@ import type { InertiaFormProps as OriginalProps } from '@inertiajs/vue3'
 type FormDataType = Record<string, FormDataConvertible>
 
 declare module '@inertiajs/vue3' {
-  interface InertiaFormProps<TForm extends FormDataType>
-    extends Omit<OriginalProps<TForm>, 'errors' | 'setError'> {
+  interface InertiaFormProps<TForm extends FormDataType> extends Omit<
+    OriginalProps<TForm>,
+    'errors' | 'setError'
+  > {
     errors: Partial<Record<FormDataKeys<TForm>, string[]>>
 
     setError(field: FormDataKeys<TForm>, value: string[]): this
@@ -60,8 +62,10 @@ import type { InertiaFormProps as OriginalProps } from '@inertiajs/react'
 type FormDataType = Record<string, FormDataConvertible>
 
 declare module '@inertiajs/react' {
-  interface InertiaFormProps<TForm extends FormDataType>
-    extends Omit<OriginalProps<TForm>, 'errors' | 'setError'> {
+  interface InertiaFormProps<TForm extends FormDataType> extends Omit<
+    OriginalProps<TForm>,
+    'errors' | 'setError'
+  > {
     errors: Partial<Record<FormDataKeys<TForm>, string[]>>
 
     setError(field: FormDataKeys<TForm>, value: string[]): void
@@ -92,8 +96,10 @@ import type { Writable } from 'svelte/store'
 type FormDataType = Record<string, FormDataConvertible>
 
 declare module '@inertiajs/svelte' {
-  interface InertiaFormProps<TForm extends FormDataType>
-    extends Omit<OriginalProps<TForm>, 'errors' | 'setError'> {
+  interface InertiaFormProps<TForm extends FormDataType> extends Omit<
+    OriginalProps<TForm>,
+    'errors' | 'setError'
+  > {
     errors: Partial<Record<FormDataKeys<TForm>, string[]>>
 
     setError(field: FormDataKeys<TForm>, value: string[]): this
diff --git a/docs/guide/client-side-setup.md b/docs/guide/client-side-setup.md
index 01732666..98566a7e 100644
--- a/docs/guide/client-side-setup.md
+++ b/docs/guide/client-side-setup.md
@@ -292,3 +292,26 @@ createInertiaApp({
   // ...
 })
 ```
+
+> [!NOTE]
+> Make sure the [`root_dom_id`](/guide/configuration#root_dom_id) configuration option matches the `id` property in your client-side setup.
+
+## Script Element for Page Data
+
+By default, Inertia stores the initial page data in a `data-page` attribute on the root element. You may configure Inertia to use a `<script type="application/json">` element instead, which is slightly faster and easier to inspect in your browser's dev tools.
+
+```js
+createInertiaApp({
+  // ...
+  defaults: {
+    future: {
+      useScriptElementForInitialPage: true,
+    },
+  },
+})
+```
+
+You should also set the [`use_script_element_for_initial_page`](/guide/configuration#use_script_element_for_initial_page) config option to `true`.
+
+> [!NOTE]
+> Be sure to also update your [SSR entry point](/guide/server-side-rendering#add-server-entry-point) if you're using server-side rendering.
diff --git a/docs/guide/configuration.md b/docs/guide/configuration.md
index 0ed0a138..f187d353 100644
--- a/docs/guide/configuration.md
+++ b/docs/guide/configuration.md
@@ -151,3 +151,59 @@ The default value will be changed to `true` in the next major version.
 Specifies the base controller class for the internal `StaticController` used to render [Shorthand routes](/guide/routing#shorthand-routes).
 
 By default, Inertia Rails creates a `StaticController` that inherits from `ApplicationController`. You can use this option to specify a different base controller (for example, to include custom authentication, layout, or before actions).
+
+### `root_dom_id`
+
+**Default**: `'app'`
+**ENV**: `INERTIA_ROOT_DOM_ID`
+
+@available_since rails=master
+
+Specifies the DOM element ID used for the root Inertia.js element.
+
+```ruby
+InertiaRails.configure do |config|
+  config.root_dom_id = 'inertia-app'
+end
+```
+
+> [!NOTE]
+> Make sure your client-side Inertia setup uses the same ID when calling `createInertiaApp`.
+
+### `use_script_element_for_initial_page`
+
+**Default**: `false`
+**ENV**: `INERTIA_USE_SCRIPT_ELEMENT_FOR_INITIAL_PAGE`
+
+@available_since rails=master core=2.2.20
+
+When enabled the initial page data is rendered in a `<script type="application/json">` element instead of the `data-page` attribute on the root `<div>`.
+This provides two main benefits:
+
+1. **Smaller page size**: JSON data doesn't require HTML entity encoding, reducing the overall HTML payload size.
+2. **Faster parsing**: The browser can parse raw JSON directly from the script element, which is more efficient than parsing HTML-encoded JSON from an attribute.
+
+```ruby
+InertiaRails.configure do |config|
+  config.use_script_element_for_initial_page = true
+end
+```
+
+When disabled (default), the HTML output looks like:
+
+```html
+<div id="app" data-page='{"component":"Users/Index",...}'></div>
+```
+
+When enabled, the HTML output looks like:
+
+```html
+<script data-page="app" type="application/json">
+  {"component":"Users/Index",...}
+</script>
+<div id="app"></div>
+```
+
+> [!NOTE]
+> When using this option make sure your client-side Inertia setup is configured to read the page data from the `<script>` element.
+> See the [client side setup](/guide/client-side-setup#script-element-for-page-data) for more details.
diff --git a/docs/guide/deferred-props.md b/docs/guide/deferred-props.md
index 27f99d5e..ac58e00c 100644
--- a/docs/guide/deferred-props.md
+++ b/docs/guide/deferred-props.md
@@ -121,6 +121,8 @@ export default () => (
 
 :::
 
+## Multiple Deferred Props
+
 If you need to wait for multiple deferred props to become available, you can specify an array to the `data` prop.
 
 :::tabs key:frameworks
@@ -189,3 +191,21 @@ export default () => (
 ```
 
 :::
+
+## Combining with Once Props
+
+@available_since rails=master core=2.2.20
+
+You may pass the `once: true` argument to a deferred prop to ensure the data is resolved only once and remembered by the client across subsequent navigations.
+
+```ruby
+class DashboardController < ApplicationController
+  def index
+    render inertia: {
+      stats: InertiaRails.defer(once: true) { Stats.generate },
+    }
+  end
+end
+```
+
+For more information on once props, see the [once props](/guide/once-props) documentation.
diff --git a/docs/guide/merging-props.md b/docs/guide/merging-props.md
index 50e7cdd6..df73da4d 100644
--- a/docs/guide/merging-props.md
+++ b/docs/guide/merging-props.md
@@ -130,7 +130,7 @@ You can also merge props directly on the client side without making a server req
 
 ## Combining with deferred props
 
-You can also combine [deferred props](/guide/deferred-props) with mergeable props to defer the loading of the prop and ultimately mark it as mergeable once it's loaded.
+You may combine [deferred props](/guide/deferred-props) with mergeable props to defer the loading of the prop and ultimately mark it as mergeable once it's loaded.
 
 ```ruby
 class UsersController < ApplicationController
@@ -146,6 +146,24 @@ class UsersController < ApplicationController
 end
 ```
 
+## Combining with Once Props
+
+@available_since rails=master core=2.2.20
+
+You may pass the `once: true` argument to a deferred prop to ensure the data is resolved only once and remembered by the client across subsequent navigations.
+
+```ruby
+class UsersController < ApplicationController
+  def index
+    render inertia: {
+      activity: InertiaRails.merge(once: true) { @user.recent_activity },
+    }
+  end
+end
+```
+
+For more information on once props, see the [once props](/guide/once-props) documentation.
+
 ## Resetting props
 
 On the client side, you can indicate to the server that you would like to reset the prop. This is useful when you want to clear the prop value before merging new data, such as when the user enters a new search query on a paginated list.
diff --git a/docs/guide/once-props.md b/docs/guide/once-props.md
new file mode 100644
index 00000000..78ff2aae
--- /dev/null
+++ b/docs/guide/once-props.md
@@ -0,0 +1,137 @@
+# Once Props
+
+@available_since rails=master core=2.2.20
+
+Some data rarely changes, is expensive to compute, or is simply large. Rather than including this data in every response, you may use _once props_. These props are remembered by the client and reused on subsequent pages that include the same prop. This makes them ideal for [shared data](/guide/shared-data).
+
+## Creating Once Props
+
+To create a once prop, use the `InertiaRails.once` method when returning your response. This method receives a block that returns the prop data.
+
+```ruby
+class BillingController < ApplicationController
+  def index
+    render inertia: {
+      plans: InertiaRails.once { Plan.all },
+    }
+  end
+end
+```
+
+After the client has received this prop, subsequent requests will skip resolving the block and exclude the prop from the response. The client only remembers once props while navigating between pages that include them.
+
+Navigating to a page without the once prop will forget the remembered value, and it will be resolved again on the next page that has it. In practice, this is rarely an issue since once props are typically used as shared data or within a specific section of your application.
+
+## Forcing a Refresh
+
+You may force a once prop to be refreshed using the `fresh` parameter.
+
+```ruby
+class BillingController < ApplicationController
+  def index
+    render inertia: {
+      plans: InertiaRails.once(fresh: true) { Plan.all },
+    }
+  end
+end
+```
+
+## Refreshing from the Client
+
+You may refresh a once prop from the client-side using a [partial reload](/guide/partial-reloads). The server will always resolve a once prop when explicitly requested.
+
+:::tabs key:frameworks
+== Vue
+
+```js
+import { router } from '@inertiajs/vue3'
+
+router.reload({ only: ['plans'] })
+```
+
+== React
+
+```js
+import { router } from '@inertiajs/react'
+
+router.reload({ only: ['plans'] })
+```
+
+== Svelte 4|Svelte 5
+
+```js
+import { router } from '@inertiajs/svelte'
+
+router.reload({ only: ['plans'] })
+```
+
+:::
+
+## Expiration
+
+You may set an expiration time using the `expires_in` parameter. This parameter accepts an `ActiveSupport::Duration` or an integer (seconds). The prop will be refreshed on a subsequent visit after the expiration time has passed.
+
+```ruby
+class DashboardController < ApplicationController
+  def index
+    render inertia: {
+      plans: InertiaRails.once(expires_in: 1.day) { Plan.all },
+    }
+  end
+end
+```
+
+## Custom Keys
+
+You may assign a custom key to the prop using the `key` parameter. This is useful when you want to share data across multiple pages while using different prop names.
+
+```ruby
+class TeamsController < ApplicationController
+  def index
+    render inertia: {
+      memberRoles: InertiaRails.once(key: 'roles') { Role.all },
+    }
+  end
+
+  def invite
+    render inertia: {
+      availableRoles: InertiaRails.once(key: 'roles') { Role.all },
+    }
+  end
+end
+```
+
+Both pages share the same underlying data because they use the same custom key, so the prop is only resolved for whichever page you visit first.
+
+## Sharing Once Props
+
+You may share once props globally using the `inertia_share` controller method.
+
+```ruby
+class ApplicationController < ActionController::Base
+  inertia_share countries: InertiaRails.once { Country.all }
+end
+```
+
+## Prefetching
+
+Once props are compatible with [prefetching](/guide/prefetching). The client automatically includes any remembered once props in prefetched responses, so navigating to a prefetched page will already have the once props available.
+
+Prefetched pages containing an expired once prop will be invalidated from the cache.
+
+## Combining with Other Prop Types
+
+The `once` option can be passed to [deferred](/guide/deferred-props), [merge](/guide/merging-props), and [optional](/guide/partial-reloads#lazy-data-evaluation) props.
+
+```ruby
+class DashboardController < ApplicationController
+  def index
+    render inertia: {
+      memberRoles: InertiaRails.once(key: 'roles') { Role.all },
+      permissions: InertiaRails.defer(once: true) { Permission.all },
+      activity: InertiaRails.merge(once: true) { @user.recent_activity },
+      categories: InertiaRails.optional(once: true) { Category.all },
+    }
+  end
+end
+```
diff --git a/docs/guide/partial-reloads.md b/docs/guide/partial-reloads.md
index e1d75e83..5c2d28f3 100644
--- a/docs/guide/partial-reloads.md
+++ b/docs/guide/partial-reloads.md
@@ -249,29 +249,24 @@ end
 
 Here's a summary of each approach:
 
+| Approach                                                                      | Standard Visits | Partial Reloads | Evaluated        |
+| :---------------------------------------------------------------------------- | :-------------- | :-------------- | :--------------- |
+| <span style="white-space: nowrap">`User.all`</span>                           | Always          | Optionally      | Always           |
+| <span style="white-space: nowrap">`-> { User.all }`</span>                    | Always          | Optionally      | Only when needed |
+| <span style="white-space: nowrap">`InertiaRails.optional { User.all }`</span> | Never           | Optionally      | Only when needed |
+| <span style="white-space: nowrap">`InertiaRails.always { User.all }`</span>   | Always          | Always          | Always           |
+
+## Combining with Once Props
+
+@available_since rails=master core=2.2.20
+
+You may pass the `once: true` argument to a deferred prop to ensure the data is resolved only once and remembered by the client across subsequent navigations.
+
 ```ruby
 class UsersController < ApplicationController
   def index
     render inertia: {
-      # ALWAYS included on standard visits
-      # OPTIONALLY included on partial reloads
-      # ALWAYS evaluated
-      users: User.all,
-
-      # ALWAYS included on standard visits
-      # OPTIONALLY included on partial reloads
-      # ONLY evaluated when needed
-      users: -> { User.all },
-
-      # NEVER included on standard visits
-      # OPTIONALLY included on partial reloads
-      # ONLY evaluated when needed
-      users: InertiaRails.optional { User.all },
-
-      # ALWAYS included on standard visits
-      # ALWAYS included on partial reloads
-      # ALWAYS evaluated
-      users: InertiaRails.always { User.all },
+      users: InertiaRails.optional(once: true) { User.all },
     }
   end
 end
diff --git a/docs/guide/responses.md b/docs/guide/responses.md
index 0963dabe..52b40d8f 100644
--- a/docs/guide/responses.md
+++ b/docs/guide/responses.md
@@ -87,19 +87,85 @@ Please note that if you manually provide a props hash in your render call, the i
 
 ## Root template data
 
-There are situations where you may want to access your prop data in your ERB template. For example, you may want to add a meta description tag, Twitter card meta tags, or Facebook Open Graph meta tags. You can access this data via the `page` method.
+There are situations where you may want to access your prop data in your ERB template. For example, you may want to add a meta description tag, Twitter card meta tags, or Facebook Open Graph meta tags.
+
+Inertia Rails provides several view helpers for working with Inertia data in your templates:
+
+### `inertia_page`
+
+Returns the [page object](/guide/the-protocol#the-page-object) hash containing `component`, `props`, `url`, and other Inertia data. Use this to access page data in your root template.
 
 ```erb
 # app/views/inertia.html.erb
 
 <% content_for(:head) do %>
-<meta name="twitter:title" content="<%= page["props"]["event"].title %>">
+<meta name="twitter:title" content="<%= inertia_page[:props][:event][:title] %>">
 <% end %>
 
-<div id="app" data-page="<%= page.to_json %>"></div>
+<%= inertia_root %>
 ```
 
-Sometimes you may even want to provide data to the root template that will not be sent to your JavaScript page / component. This can be accomplished by passing the `view_data` option.
+### `inertia_rendering?`
+
+Returns `true` when the current request is rendering an Inertia response. This is useful for conditionally rendering content in shared layouts.
+
+```erb
+# app/views/layouts/application.html.erb
+
+<% if inertia_rendering? %>
+  <%= yield %>
+<% else %>
+  <div class="traditional-layout">
+    <%= yield %>
+  </div>
+<% end %>
+```
+
+### `inertia_root`
+
+Renders the root element for the Inertia app. This helper automatically respects the [`root_dom_id`](/guide/configuration#root_dom_id) and [`use_script_element_for_initial_page`](/guide/configuration#use_script_element_for_initial_page) configuration options.
+
+```erb
+<%= inertia_root %>
+```
+
+You can also pass a custom `id` or `page` object if needed:
+
+```erb
+<%= inertia_root(id: 'my-app', page: custom_page_object) %>
+```
+
+### `inertia_ssr_head`
+
+Returns the SSR head content when [server-side rendering](/guide/server-side-rendering) is enabled. This should be included in your layout's `<head>` section to inject SSR-generated meta tags and other head elements.
+
+```erb
+# app/views/layouts/inertia.html.erb
+
+<!DOCTYPE html>
+<html>
+  <head>
+    <%= inertia_ssr_head %>
+  </head>
+  <body>
+    <%= yield %>
+  </body>
+</html>
+```
+
+### `inertia_meta_tags`
+
+Renders meta tags that were defined server-side using the `inertia_meta` configuration. This is useful for SEO when you want to manage meta tags from your Rails controllers. See the [Server-managed meta tags cookbook](/cookbook/server-managed-meta-tags) for a complete guide.
+
+```erb
+<head>
+  <%= inertia_meta_tags %>
+</head>
+```
+
+### Passing additional data to the view
+
+Sometimes you may want to provide data to the root template that will not be sent to your JavaScript page / component. This can be accomplished by passing the `view_data` option.
 
 ```ruby
 def show
@@ -120,7 +186,7 @@ You can then access this variable like a regular local variable.
   content="<%= local_assigns.fetch(:meta, "Default description") %>">
 <% end %>
 
-<div id="app" data-page="<%= page.to_json %>"></div>
+<%= inertia_root %>
 ```
 
 ## Rails generators
diff --git a/docs/guide/shared-data.md b/docs/guide/shared-data.md
index c13abb9d..cac94729 100644
--- a/docs/guide/shared-data.md
+++ b/docs/guide/shared-data.md
@@ -83,6 +83,20 @@ end
 > [!NOTE]
 > Page props and shared data are merged together, so be sure to namespace your shared data appropriately to avoid collisions.
 
+## Sharing Once Props
+
+@available_since rails=master core=2.2.20
+
+You may share data that is resolved only once and remembered by the client across subsequent navigations using [once props](/guide/once-props).
+
+```ruby
+class ApplicationController < ActionController::Base
+  inertia_share countries: InertiaRails.once { Country.all }
+end
+```
+
+For more information on once props, see the [once props](/guide/once-props) documentation.
+
 ## Accessing shared data
 
 Once you have shared the data server-side, you will be able to access it within any of your pages or components. Here's an example of how to access shared data in a layout component.
diff --git a/docs/guide/the-protocol.md b/docs/guide/the-protocol.md
index 481eb161..a4451fe0 100644
--- a/docs/guide/the-protocol.md
+++ b/docs/guide/the-protocol.md
@@ -29,6 +29,33 @@ Content-Type: text/html; charset=utf-8
 </html>
 ```
 
+### Script element alternative
+
+As an alternative the page data can be rendered in a `<script type="application/json">` element instead of the `data-page` attribute.
+This approach provides smaller page sizes (no HTML entity encoding required) and faster JSON parsing by the browser.
+
+```html
+<script data-page="app" type="application/json">
+  {
+    "component": "Event",
+    "props": {
+      "errors": {},
+      "event": {
+        "id": 80,
+        "title": "Birthday party",
+        "start_date": "2019-06-02",
+        "description": "Come out and celebrate Jonathan's 36th birthday party!"
+      }
+    },
+    "url": "/events/80",
+    "version": "c32b8e4965f418ad16eaebba1d4e960f"
+  }
+</script>
+<div id="app"></div>
+```
+
+See the [`use_script_element_for_initial_page`](/guide/configuration#use_script_element_for_initial_page) configuration option to enable this behavior.
+
 While the initial response is HTML, Inertia does not server-side render the JavaScript page components. For information on server-side rendering, see the [SSR documentation](/guide/server-side-rendering).
 
 ## Inertia responses
@@ -97,6 +124,7 @@ The following headers are automatically sent by Inertia when making requests. Yo
 10. `Cache-Control`: Set to `no-cache` for reload requests to prevent serving stale content.
 11. `X-Inertia-Error-Bag`: Specifies which error bag to use for [validation errors](/guide/validation).
 12. `X-Inertia-Infinite-Scroll-Merge-Intent`: Indicates whether the requested data should be appended or prepended when using [Infinite scroll](/guide/infinite-scroll).
+13. `X-Inertia-Except-Once-Props`: Comma-separated list of non-expired [once prop](/guide/once-props) keys already loaded on the client. The server will skip resolving these props unless explicitly requested via a partial reload or force refreshed server-side.
 
 ## Response headers
 
@@ -122,6 +150,7 @@ Inertia shares data between the server and client via a page object. This object
 - `matchPropsOn`: Array of prop keys to use for [matching when merging props](/guide/merging-props#matching-items).
 - `scrollProps`: Configuration for [infinite scroll](/guide/infinite-scroll) prop merging behavior.
 - `deferredProps`: Configuration for client-side [lazy loading of props](/guide/deferred-props).
+- `onceProps`: Configuration for [once props](/guide/once-props) that should only be resolved once and reused on subsequent pages. Each entry maps a key to an object containing the `prop` name and optional `expiresAt` timestamp (in milliseconds).
 
 On standard full page visits, the page object is JSON encoded into the `data-page` attribute in the root `<div>`. On Inertia visits (as indicated by the presence of the `X-Inertia` header), the page object is returned as the JSON payload.
 
@@ -252,6 +281,78 @@ When using [Infinite scroll](/guide/infinite-scroll), the page object includes a
 }
 ```
 
+### Page Object with Once Props
+
+When using [once props](/guide/once-props), the page object includes an `onceProps` configuration. Each entry maps a key to the prop name and an optional expiration timestamp.
+
+```json
+{
+  "component": "Billing/Plans",
+  "props": {
+    "errors": {},
+    "plans": [
+      {
+        "id": 1,
+        "name": "Basic"
+      },
+      {
+        "id": 2,
+        "name": "Pro"
+      }
+    ]
+  },
+  "url": "/billing/plans",
+  "version": "6b16b94d7c51cbe5b1fa42aac98241d5",
+  "clearHistory": false,
+  "encryptHistory": false,
+  "onceProps": {
+    "plans": {
+      "prop": "plans",
+      "expiresAt": null
+    }
+  }
+}
+```
+
+When navigating to a subsequent page that includes the same once prop, the client sends the loaded keys in the `X-Inertia-Except-Once-Props` header. The server skips resolving these props and excludes them from the response. The client reuses the previously loaded values.
+
+```http
+REQUEST
+GET: https://example.com/billing/upgrade
+Accept: text/html, application/xhtml+xml
+X-Requested-With: XMLHttpRequest
+X-Inertia: true
+X-Inertia-Version: 6b16b94d7c51cbe5b1fa42aac98241d5
+X-Inertia-Except-Once-Props: plans
+
+RESPONSE
+HTTP/1.1 200 OK
+Content-Type: application/json
+
+{
+    "component": "Billing/Upgrade",
+    "props": {
+        "errors": {},
+        "currentPlan": {
+            "id": 1,
+            "name": "Basic"
+        }
+    },
+    "url": "/billing/upgrade",
+    "version": "6b16b94d7c51cbe5b1fa42aac98241d5",
+    "clearHistory": false,
+    "encryptHistory": false,
+    "onceProps": {
+        "plans": {
+            "prop": "plans",
+            "expiresAt": null
+        }
+    }
+}
+```
+
+Note that `plans` is included in `onceProps` but not in `props` since it was already loaded on the client. The `onceProps` key identifies the once prop across pages, while `prop` specifies the actual prop name. These may differ when using [custom keys](/guide/once-props#custom-keys).
+
 ## Asset versioning
 
 One common challenge with single-page apps is refreshing site assets when they've been changed. Inertia makes this easy by optionally tracking the current version of the site's assets. In the event that an asset changes, Inertia will automatically make a full-page visit instead of an XHR visit.
diff --git a/docs/package-lock.json b/docs/package-lock.json
index e587c6ec..a6198dfa 100644
--- a/docs/package-lock.json
+++ b/docs/package-lock.json
@@ -21,16 +21,16 @@
       }
     },
     "node_modules/@algolia/abtesting": {
-      "version": "1.11.0",
-      "resolved": "https://registry.npmjs.org/@algolia/abtesting/-/abtesting-1.11.0.tgz",
-      "integrity": "sha512-a7oQ8dwiyoyVmzLY0FcuBqyqcNSq78qlcOtHmNBumRlHCSnXDcuoYGBGPN1F6n8JoGhviDDsIaF/oQrzTzs6Lg==",
+      "version": "1.12.0",
+      "resolved": "https://registry.npmjs.org/@algolia/abtesting/-/abtesting-1.12.0.tgz",
+      "integrity": "sha512-EfW0bfxjPs+C7ANkJDw2TATntfBKsFiy7APh+KO0pQ8A6HYa5I0NjFuCGCXWfzzzLXNZta3QUl3n5Kmm6aJo9Q==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
-        "@algolia/client-common": "5.45.0",
-        "@algolia/requester-browser-xhr": "5.45.0",
-        "@algolia/requester-fetch": "5.45.0",
-        "@algolia/requester-node-http": "5.45.0"
+        "@algolia/client-common": "5.46.0",
+        "@algolia/requester-browser-xhr": "5.46.0",
+        "@algolia/requester-fetch": "5.46.0",
+        "@algolia/requester-node-http": "5.46.0"
       },
       "engines": {
         "node": ">= 14.0.0"
@@ -86,41 +86,41 @@
       }
     },
     "node_modules/@algolia/client-abtesting": {
-      "version": "5.45.0",
-      "resolved": "https://registry.npmjs.org/@algolia/client-abtesting/-/client-abtesting-5.45.0.tgz",
-      "integrity": "sha512-WTW0VZA8xHMbzuQD5b3f41ovKZ0MNTIXkWfm0F2PU+XGcLxmxX15UqODzF2sWab0vSbi3URM1xLhJx+bXbd1eQ==",
+      "version": "5.46.0",
+      "resolved": "https://registry.npmjs.org/@algolia/client-abtesting/-/client-abtesting-5.46.0.tgz",
+      "integrity": "sha512-eG5xV8rujK4ZIHXrRshvv9O13NmU/k42Rnd3w43iKH5RaQ2zWuZO6Q7XjaoJjAFVCsJWqRbXzbYyPGrbF3wGNg==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
-        "@algolia/client-common": "5.45.0",
-        "@algolia/requester-browser-xhr": "5.45.0",
-        "@algolia/requester-fetch": "5.45.0",
-        "@algolia/requester-node-http": "5.45.0"
+        "@algolia/client-common": "5.46.0",
+        "@algolia/requester-browser-xhr": "5.46.0",
+        "@algolia/requester-fetch": "5.46.0",
+        "@algolia/requester-node-http": "5.46.0"
       },
       "engines": {
         "node": ">= 14.0.0"
       }
     },
     "node_modules/@algolia/client-analytics": {
-      "version": "5.45.0",
-      "resolved": "https://registry.npmjs.org/@algolia/client-analytics/-/client-analytics-5.45.0.tgz",
-      "integrity": "sha512-I3g7VtvG/QJOH3tQO7E7zWTwBfK/nIQXShFLR8RvPgWburZ626JNj332M3wHCYcaAMivN9WJG66S2JNXhm6+Xg==",
+      "version": "5.46.0",
+      "resolved": "https://registry.npmjs.org/@algolia/client-analytics/-/client-analytics-5.46.0.tgz",
+      "integrity": "sha512-AYh2uL8IUW9eZrbbT+wZElyb7QkkeV3US2NEKY7doqMlyPWE8lErNfkVN1NvZdVcY4/SVic5GDbeDz2ft8YIiQ==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
-        "@algolia/client-common": "5.45.0",
-        "@algolia/requester-browser-xhr": "5.45.0",
-        "@algolia/requester-fetch": "5.45.0",
-        "@algolia/requester-node-http": "5.45.0"
+        "@algolia/client-common": "5.46.0",
+        "@algolia/requester-browser-xhr": "5.46.0",
+        "@algolia/requester-fetch": "5.46.0",
+        "@algolia/requester-node-http": "5.46.0"
       },
       "engines": {
         "node": ">= 14.0.0"
       }
     },
     "node_modules/@algolia/client-common": {
-      "version": "5.45.0",
-      "resolved": "https://registry.npmjs.org/@algolia/client-common/-/client-common-5.45.0.tgz",
-      "integrity": "sha512-/nTqm1tLiPtbUr+8kHKyFiCOfhRfgC+JxLvOCq471gFZZOlsh6VtFRiKI60/zGmHTojFC6B0mD80PB7KeK94og==",
+      "version": "5.46.0",
+      "resolved": "https://registry.npmjs.org/@algolia/client-common/-/client-common-5.46.0.tgz",
+      "integrity": "sha512-0emZTaYOeI9WzJi0TcNd2k3SxiN6DZfdWc2x2gHt855Jl9jPUOzfVTL6gTvCCrOlT4McvpDGg5nGO+9doEjjig==",
       "dev": true,
       "license": "MIT",
       "engines": {
@@ -128,152 +128,152 @@
       }
     },
     "node_modules/@algolia/client-insights": {
-      "version": "5.45.0",
-      "resolved": "https://registry.npmjs.org/@algolia/client-insights/-/client-insights-5.45.0.tgz",
-      "integrity": "sha512-suQTx/1bRL1g/K2hRtbK3ANmbzaZCi13487sxxmqok+alBDKKw0/TI73ZiHjjFXM2NV52inwwcmW4fUR45206Q==",
+      "version": "5.46.0",
+      "resolved": "https://registry.npmjs.org/@algolia/client-insights/-/client-insights-5.46.0.tgz",
+      "integrity": "sha512-wrBJ8fE+M0TDG1As4DDmwPn2TXajrvmvAN72Qwpuv8e2JOKNohF7+JxBoF70ZLlvP1A1EiH8DBu+JpfhBbNphQ==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
-        "@algolia/client-common": "5.45.0",
-        "@algolia/requester-browser-xhr": "5.45.0",
-        "@algolia/requester-fetch": "5.45.0",
-        "@algolia/requester-node-http": "5.45.0"
+        "@algolia/client-common": "5.46.0",
+        "@algolia/requester-browser-xhr": "5.46.0",
+        "@algolia/requester-fetch": "5.46.0",
+        "@algolia/requester-node-http": "5.46.0"
       },
       "engines": {
         "node": ">= 14.0.0"
       }
     },
     "node_modules/@algolia/client-personalization": {
-      "version": "5.45.0",
-      "resolved": "https://registry.npmjs.org/@algolia/client-personalization/-/client-personalization-5.45.0.tgz",
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-        "@algolia/requester-fetch": "5.45.0",
-        "@algolia/requester-node-http": "5.45.0"
+        "@algolia/client-common": "5.46.0",
+        "@algolia/requester-browser-xhr": "5.46.0",
+        "@algolia/requester-fetch": "5.46.0",
+        "@algolia/requester-node-http": "5.46.0"
       },
       "engines": {
         "node": ">= 14.0.0"
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     },
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-        "@algolia/requester-node-http": "5.45.0"
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+        "@algolia/requester-fetch": "5.46.0",
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         "node": ">= 14.0.0"
@@ -782,9 +782,9 @@
       }
     },
     "node_modules/@iconify-json/simple-icons": {
-      "version": "1.2.60",
-      "resolved": "https://registry.npmjs.org/@iconify-json/simple-icons/-/simple-icons-1.2.60.tgz",
-      "integrity": "sha512-KlwLBKCdMCqfySdkAA+jehdUx6VSjnj6lvzQKus7HjkPSQ6QP58d6xiptkIp0jd/Hw3PW2++nRuGvCvSYaF0Mg==",
+      "version": "1.2.62",
+      "resolved": "https://registry.npmjs.org/@iconify-json/simple-icons/-/simple-icons-1.2.62.tgz",
+      "integrity": "sha512-GpWQ294d4lraB3D2eBSSMROh1x9uKgpmyereLlGzVQjGZ7lbeFzby2ywXxyp4vEODmTDyf1/4WcOYs/yH4rJ5Q==",
       "dev": true,
       "license": "CC0-1.0",
       "dependencies": {
@@ -1303,9 +1303,9 @@
       "license": "MIT"
     },
     "node_modules/@sveltejs/acorn-typescript": {
-      "version": "1.0.7",
-      "resolved": "https://registry.npmjs.org/@sveltejs/acorn-typescript/-/acorn-typescript-1.0.7.tgz",
-      "integrity": "sha512-znp1A/Y1Jj4l/Zy7PX5DZKBE0ZNY+5QBngiE21NJkfSTyzzC5iKNWOtwFXKtIrn7MXEFBck4jD95iBNkGjK92Q==",
+      "version": "1.0.8",
+      "resolved": "https://registry.npmjs.org/@sveltejs/acorn-typescript/-/acorn-typescript-1.0.8.tgz",
+      "integrity": "sha512-esgN+54+q0NjB0Y/4BomT9samII7jGwNy/2a3wNZbT2A2RpmXsXwUt24LvLhx6jUq2gVk4cWEvcRO6MFQbOfNA==",
       "dev": true,
       "license": "MIT",
       "peerDependencies": {
@@ -1417,30 +1417,30 @@
       }
     },
     "node_modules/@volar/language-core": {
-      "version": "2.4.23",
-      "resolved": "https://registry.npmjs.org/@volar/language-core/-/language-core-2.4.23.tgz",
-      "integrity": "sha512-hEEd5ET/oSmBC6pi1j6NaNYRWoAiDhINbT8rmwtINugR39loROSlufGdYMF9TaKGfz+ViGs1Idi3mAhnuPcoGQ==",
+      "version": "2.4.26",
+      "resolved": "https://registry.npmjs.org/@volar/language-core/-/language-core-2.4.26.tgz",
+      "integrity": "sha512-hH0SMitMxnB43OZpyF1IFPS9bgb2I3bpCh76m2WEK7BE0A0EzpYsRp0CCH2xNKshr7kacU5TQBLYn4zj7CG60A==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
-        "@volar/source-map": "2.4.23"
+        "@volar/source-map": "2.4.26"
       }
     },
     "node_modules/@volar/source-map": {
-      "version": "2.4.23",
-      "resolved": "https://registry.npmjs.org/@volar/source-map/-/source-map-2.4.23.tgz",
-      "integrity": "sha512-Z1Uc8IB57Lm6k7q6KIDu/p+JWtf3xsXJqAX/5r18hYOTpJyBn0KXUR8oTJ4WFYOcDzWC9n3IflGgHowx6U6z9Q==",
+      "version": "2.4.26",
+      "resolved": "https://registry.npmjs.org/@volar/source-map/-/source-map-2.4.26.tgz",
+      "integrity": "sha512-JJw0Tt/kSFsIRmgTQF4JSt81AUSI1aEye5Zl65EeZ8H35JHnTvFGmpDOBn5iOxd48fyGE+ZvZBp5FcgAy/1Qhw==",
       "dev": true,
       "license": "MIT"
     },
     "node_modules/@volar/typescript": {
-      "version": "2.4.23",
-      "resolved": "https://registry.npmjs.org/@volar/typescript/-/typescript-2.4.23.tgz",
-      "integrity": "sha512-lAB5zJghWxVPqfcStmAP1ZqQacMpe90UrP5RJ3arDyrhy4aCUQqmxPPLB2PWDKugvylmO41ljK7vZ+t6INMTag==",
+      "version": "2.4.26",
+      "resolved": "https://registry.npmjs.org/@volar/typescript/-/typescript-2.4.26.tgz",
+      "integrity": "sha512-N87ecLD48Sp6zV9zID/5yuS1+5foj0DfuYGdQ6KHj/IbKvyKv1zNX6VCmnKYwtmHadEO6mFc2EKISiu3RDPAvA==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
-        "@volar/language-core": "2.4.23",
+        "@volar/language-core": "2.4.26",
         "path-browserify": "^1.0.1",
         "vscode-uri": "^3.0.8"
       }
@@ -1549,13 +1549,13 @@
       }
     },
     "node_modules/@vue/language-core": {
-      "version": "3.1.5",
-      "resolved": "https://registry.npmjs.org/@vue/language-core/-/language-core-3.1.5.tgz",
-      "integrity": "sha512-FMcqyzWN+sYBeqRMWPGT2QY0mUasZMVIuHvmb5NT3eeqPrbHBYtCP8JWEUCDCgM+Zr62uuWY/qoeBrPrzfa78w==",
+      "version": "3.1.8",
+      "resolved": "https://registry.npmjs.org/@vue/language-core/-/language-core-3.1.8.tgz",
+      "integrity": "sha512-PfwAW7BLopqaJbneChNL6cUOTL3GL+0l8paYP5shhgY5toBNidWnMXWM+qDwL7MC9+zDtzCF2enT8r6VPu64iw==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
-        "@volar/language-core": "2.4.23",
+        "@volar/language-core": "2.4.26",
         "@vue/compiler-dom": "^3.5.0",
         "@vue/shared": "^3.5.0",
         "alien-signals": "^3.0.0",
@@ -1748,27 +1748,27 @@
       }
     },
     "node_modules/algoliasearch": {
-      "version": "5.45.0",
-      "resolved": "https://registry.npmjs.org/algoliasearch/-/algoliasearch-5.45.0.tgz",
-      "integrity": "sha512-wrj4FGr14heLOYkBKV3Fbq5ZBGuIFeDJkTilYq/G+hH1CSlQBtYvG2X1j67flwv0fUeQJwnWxxRIunSemAZirA==",
+      "version": "5.46.0",
+      "resolved": "https://registry.npmjs.org/algoliasearch/-/algoliasearch-5.46.0.tgz",
+      "integrity": "sha512-7ML6fa2K93FIfifG3GMWhDEwT5qQzPTmoHKCTvhzGEwdbQ4n0yYUWZlLYT75WllTGJCJtNUI0C1ybN4BCegqvg==",
       "dev": true,
       "license": "MIT",
       "peer": true,
       "dependencies": {
-        "@algolia/abtesting": "1.11.0",
-        "@algolia/client-abtesting": "5.45.0",
-        "@algolia/client-analytics": "5.45.0",
-        "@algolia/client-common": "5.45.0",
-        "@algolia/client-insights": "5.45.0",
-        "@algolia/client-personalization": "5.45.0",
-        "@algolia/client-query-suggestions": "5.45.0",
-        "@algolia/client-search": "5.45.0",
-        "@algolia/ingestion": "1.45.0",
-        "@algolia/monitoring": "1.45.0",
-        "@algolia/recommend": "5.45.0",
-        "@algolia/requester-browser-xhr": "5.45.0",
-        "@algolia/requester-fetch": "5.45.0",
-        "@algolia/requester-node-http": "5.45.0"
+        "@algolia/abtesting": "1.12.0",
+        "@algolia/client-abtesting": "5.46.0",
+        "@algolia/client-analytics": "5.46.0",
+        "@algolia/client-common": "5.46.0",
+        "@algolia/client-insights": "5.46.0",
+        "@algolia/client-personalization": "5.46.0",
+        "@algolia/client-query-suggestions": "5.46.0",
+        "@algolia/client-search": "5.46.0",
+        "@algolia/ingestion": "1.46.0",
+        "@algolia/monitoring": "1.46.0",
+        "@algolia/recommend": "5.46.0",
+        "@algolia/requester-browser-xhr": "5.46.0",
+        "@algolia/requester-fetch": "5.46.0",
+        "@algolia/requester-node-http": "5.46.0"
       },
       "engines": {
         "node": ">= 14.0.0"
@@ -1863,9 +1863,9 @@
       }
     },
     "node_modules/birpc": {
-      "version": "2.8.0",
-      "resolved": "https://registry.npmjs.org/birpc/-/birpc-2.8.0.tgz",
-      "integrity": "sha512-Bz2a4qD/5GRhiHSwj30c/8kC8QGj12nNDwz3D4ErQ4Xhy35dsSDvF+RA/tWpjyU0pdGtSDiEk6B5fBGE1qNVhw==",
+      "version": "2.9.0",
+      "resolved": "https://registry.npmjs.org/birpc/-/birpc-2.9.0.tgz",
+      "integrity": "sha512-KrayHS5pBi69Xi9JmvoqrIgYGDkD6mcSe/i6YKi3w5kekCLzrX4+nawcXqrj2tIp50Kw/mT/s3p+GVK0A0sKxw==",
       "dev": true,
       "license": "MIT",
       "funding": {
@@ -2163,9 +2163,9 @@
       }
     },
     "node_modules/devalue": {
-      "version": "5.5.0",
-      "resolved": "https://registry.npmjs.org/devalue/-/devalue-5.5.0.tgz",
-      "integrity": "sha512-69sM5yrHfFLJt0AZ9QqZXGCPfJ7fQjvpln3Rq5+PS03LD32Ost1Q9N+eEnaQwGRIriKkMImXD56ocjQmfjbV3w==",
+      "version": "5.6.0",
+      "resolved": "https://registry.npmjs.org/devalue/-/devalue-5.6.0.tgz",
+      "integrity": "sha512-BaD1s81TFFqbD6Uknni42TrolvEWA1Ih5L+OiHWmi4OYMJVwAYPGtha61I9KxTf52OvVHozHyjPu8zljqdF3uA==",
       "dev": true,
       "license": "MIT"
     },
@@ -2308,9 +2308,9 @@
       }
     },
     "node_modules/esrap": {
-      "version": "2.2.0",
-      "resolved": "https://registry.npmjs.org/esrap/-/esrap-2.2.0.tgz",
-      "integrity": "sha512-WBmtxe7R9C5mvL4n2le8nMUe4mD5V9oiK2vJpQ9I3y20ENPUomPcphBXE8D1x/Bm84oN1V+lOfgXxtqmxTp3Xg==",
+      "version": "2.2.1",
+      "resolved": "https://registry.npmjs.org/esrap/-/esrap-2.2.1.tgz",
+      "integrity": "sha512-GiYWG34AN/4CUyaWAgunGt0Rxvr1PTMlGC0vvEov/uOQYWne2bpN03Um+k8jT+q3op33mKouP2zeJ6OlM+qeUg==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
@@ -3769,9 +3769,9 @@
       }
     },
     "node_modules/preact": {
-      "version": "10.27.2",
-      "resolved": "https://registry.npmjs.org/preact/-/preact-10.27.2.tgz",
-      "integrity": "sha512-5SYSgFKSyhCbk6SrXyMpqjb5+MQBgfvEKE/OC+PujcY34sOpqtr+0AZQtPYx5IA6VxynQ7rUPCtKzyovpj9Bpg==",
+      "version": "10.28.0",
+      "resolved": "https://registry.npmjs.org/preact/-/preact-10.28.0.tgz",
+      "integrity": "sha512-rytDAoiXr3+t6OIP3WGlDd0ouCUG1iCWzkcY3++Nreuoi17y6T5i/zRhe6uYfoVcxq6YU+sBtJouuRDsq8vvqA==",
       "dev": true,
       "license": "MIT",
       "funding": {
@@ -3780,9 +3780,9 @@
       }
     },
     "node_modules/prettier": {
-      "version": "3.6.2",
-      "resolved": "https://registry.npmjs.org/prettier/-/prettier-3.6.2.tgz",
-      "integrity": "sha512-I7AIg5boAr5R0FFtJ6rCfD+LFsWHp81dolrFD8S79U9tb8Az2nGrJncnMSnys+bpQJfRUzqs9hnA81OAA3hCuQ==",
+      "version": "3.7.4",
+      "resolved": "https://registry.npmjs.org/prettier/-/prettier-3.7.4.tgz",
+      "integrity": "sha512-v6UNi1+3hSlVvv8fSaoUbggEM5VErKmmpGA7Pl3HF8V6uKY7rvClBOJlH6yNwQtfTueNkGVpOv/mtWL9L4bgRA==",
       "dev": true,
       "license": "MIT",
       "peer": true,
@@ -3827,9 +3827,9 @@
       }
     },
     "node_modules/prettier-plugin-tailwindcss": {
-      "version": "0.7.1",
-      "resolved": "https://registry.npmjs.org/prettier-plugin-tailwindcss/-/prettier-plugin-tailwindcss-0.7.1.tgz",
-      "integrity": "sha512-Bzv1LZcuiR1Sk02iJTS1QzlFNp/o5l2p3xkopwOrbPmtMeh3fK9rVW5M3neBQzHq+kGKj/4LGQMTNcTH4NGPtQ==",
+      "version": "0.7.2",
+      "resolved": "https://registry.npmjs.org/prettier-plugin-tailwindcss/-/prettier-plugin-tailwindcss-0.7.2.tgz",
+      "integrity": "sha512-LkphyK3Fw+q2HdMOoiEHWf93fNtYJwfamoKPl7UwtjFQdei/iIBoX11G6j706FzN3ymX9mPVi97qIY8328vdnA==",
       "dev": true,
       "license": "MIT",
       "engines": {
@@ -3966,9 +3966,9 @@
       }
     },
     "node_modules/regex": {
-      "version": "6.0.1",
-      "resolved": "https://registry.npmjs.org/regex/-/regex-6.0.1.tgz",
-      "integrity": "sha512-uorlqlzAKjKQZ5P+kTJr3eeJGSVroLKoHmquUj4zHWuR+hEyNqlXsSKlYYF5F4NI6nl7tWCs0apKJ0lmfsXAPA==",
+      "version": "6.1.0",
+      "resolved": "https://registry.npmjs.org/regex/-/regex-6.1.0.tgz",
+      "integrity": "sha512-6VwtthbV4o/7+OaAF9I5L5V3llLEsoPyq9P1JVXkedTP33c7MfCG0/5NOPcSJn0TzXcG9YUrR0gQSWioew3LDg==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
@@ -4365,9 +4365,9 @@
       }
     },
     "node_modules/superjson": {
-      "version": "2.2.5",
-      "resolved": "https://registry.npmjs.org/superjson/-/superjson-2.2.5.tgz",
-      "integrity": "sha512-zWPTX96LVsA/eVYnqOM2+ofcdPqdS1dAF1LN4TS2/MWuUpfitd9ctTa87wt4xrYnZnkLtS69xpBdSxVBP5Rm6w==",
+      "version": "2.2.6",
+      "resolved": "https://registry.npmjs.org/superjson/-/superjson-2.2.6.tgz",
+      "integrity": "sha512-H+ue8Zo4vJmV2nRjpx86P35lzwDT3nItnIsocgumgr0hHMQ+ZGq5vrERg9kJBo5AWGmxZDhzDo+WVIJqkB0cGA==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
@@ -4378,9 +4378,9 @@
       }
     },
     "node_modules/svelte": {
-      "version": "5.44.1",
-      "resolved": "https://registry.npmjs.org/svelte/-/svelte-5.44.1.tgz",
-      "integrity": "sha512-8VnkRXpa6tJ9IqiwKvzZBNnBy9tZg0N63duDz0EJqiozsmBEAZfHiZzWWWAneIN+cAWkK1JkafW1xIbC4YrdBA==",
+      "version": "5.45.8",
+      "resolved": "https://registry.npmjs.org/svelte/-/svelte-5.45.8.tgz",
+      "integrity": "sha512-1Jh7FwVh/2Uxg0T7SeE1qFKMhwYH45b2v53bcZpW7qHa6O8iU1ByEj56PF0IQ6dU4HE5gRkic6h+vx+tclHeiw==",
       "dev": true,
       "license": "MIT",
       "peer": true,
@@ -4395,7 +4395,7 @@
         "clsx": "^2.1.1",
         "devalue": "^5.5.0",
         "esm-env": "^1.2.1",
-        "esrap": "^2.1.0",
+        "esrap": "^2.2.1",
         "is-reference": "^3.0.3",
         "locate-character": "^3.0.0",
         "magic-string": "^0.30.11",
@@ -4816,15 +4816,15 @@
       }
     },
     "node_modules/vue-tsc": {
-      "version": "3.1.5",
-      "resolved": "https://registry.npmjs.org/vue-tsc/-/vue-tsc-3.1.5.tgz",
-      "integrity": "sha512-L/G9IUjOWhBU0yun89rv8fKqmKC+T0HfhrFjlIml71WpfBv9eb4E9Bev8FMbyueBIU9vxQqbd+oOsVcDa5amGw==",
+      "version": "3.1.8",
+      "resolved": "https://registry.npmjs.org/vue-tsc/-/vue-tsc-3.1.8.tgz",
+      "integrity": "sha512-deKgwx6exIHeZwF601P1ktZKNF0bepaSN4jBU3AsbldPx9gylUc1JDxYppl82yxgkAgaz0Y0LCLOi+cXe9HMYA==",
       "dev": true,
       "license": "MIT",
       "peer": true,
       "dependencies": {
-        "@volar/typescript": "2.4.23",
-        "@vue/language-core": "3.1.5"
+        "@volar/typescript": "2.4.26",
+        "@vue/language-core": "3.1.8"
       },
       "bin": {
         "vue-tsc": "bin/vue-tsc.js"
diff --git a/lib/generators/inertia/install/templates/initializer.rb b/lib/generators/inertia/install/templates/initializer.rb
index 83ef4b25..c8430fd1 100644
--- a/lib/generators/inertia/install/templates/initializer.rb
+++ b/lib/generators/inertia/install/templates/initializer.rb
@@ -4,4 +4,5 @@
   config.version = ViteRuby.digest
   config.encrypt_history = true
   config.always_include_errors_hash = true
+  config.use_script_element_for_initial_page = true
 end
diff --git a/lib/generators/inertia/install/templates/react/inertia.jsx b/lib/generators/inertia/install/templates/react/inertia.jsx
index ef676f37..40e0c804 100644
--- a/lib/generators/inertia/install/templates/react/inertia.jsx
+++ b/lib/generators/inertia/install/templates/react/inertia.jsx
@@ -44,6 +44,7 @@ createInertiaApp({
       forceIndicesArrayFormatInFormData: false,
     },
     future: {
+      useScriptElementForInitialPage: true,
       useDataInertiaHeadAttribute: true,
       useDialogForErrorModal: true,
       preserveEqualProps: true,
diff --git a/lib/generators/inertia/install/templates/react/inertia.tsx b/lib/generators/inertia/install/templates/react/inertia.tsx
index 7bd3c6ae..da8b75c8 100644
--- a/lib/generators/inertia/install/templates/react/inertia.tsx
+++ b/lib/generators/inertia/install/templates/react/inertia.tsx
@@ -44,6 +44,7 @@ void createInertiaApp({
       forceIndicesArrayFormatInFormData: false,
     },
     future: {
+      useScriptElementForInitialPage: true,
       useDataInertiaHeadAttribute: true,
       useDialogForErrorModal: true,
       preserveEqualProps: true,
diff --git a/lib/generators/inertia/install/templates/svelte/inertia.ts b/lib/generators/inertia/install/templates/svelte/inertia.ts
index 11ed3de6..58d19f92 100644
--- a/lib/generators/inertia/install/templates/svelte/inertia.ts
+++ b/lib/generators/inertia/install/templates/svelte/inertia.ts
@@ -42,6 +42,7 @@ createInertiaApp({
       forceIndicesArrayFormatInFormData: false,
     },
     future: {
+      useScriptElementForInitialPage: true,
       useDataInertiaHeadAttribute: true,
       useDialogForErrorModal: true,
       preserveEqualProps: true,
diff --git a/lib/generators/inertia/install/templates/vue/inertia.ts b/lib/generators/inertia/install/templates/vue/inertia.ts
index d4073351..e2968cf0 100644
--- a/lib/generators/inertia/install/templates/vue/inertia.ts
+++ b/lib/generators/inertia/install/templates/vue/inertia.ts
@@ -41,6 +41,7 @@ createInertiaApp({
       forceIndicesArrayFormatInFormData: false,
     },
     future: {
+      useScriptElementForInitialPage: true,
       useDataInertiaHeadAttribute: true,
       useDialogForErrorModal: true,
       preserveEqualProps: true,
diff --git a/lib/inertia_rails/base_prop.rb b/lib/inertia_rails/base_prop.rb
index 1ee723b8..f8b75cae 100644
--- a/lib/inertia_rails/base_prop.rb
+++ b/lib/inertia_rails/base_prop.rb
@@ -3,7 +3,7 @@
 module InertiaRails
   # Base class for all props.
   class BaseProp
-    def initialize(&block)
+    def initialize(**, &block)
       @block = block
     end
 
diff --git a/lib/inertia_rails/configuration.rb b/lib/inertia_rails/configuration.rb
index 482802c3..e8603b9d 100644
--- a/lib/inertia_rails/configuration.rb
+++ b/lib/inertia_rails/configuration.rb
@@ -34,6 +34,12 @@ class Configuration
 
       # Whether to include empty `errors` hash to the props when no errors are present.
       always_include_errors_hash: nil,
+
+      # Whether to use `<script>` element for initial page rendering instead of the `data-page` attribute.
+      use_script_element_for_initial_page: false,
+
+      # DOM id to use for the root Inertia.js element.
+      root_dom_id: 'app',
     }.freeze
 
     OPTION_NAMES = DEFAULTS.keys.freeze
diff --git a/lib/inertia_rails/defer_prop.rb b/lib/inertia_rails/defer_prop.rb
index eb235536..83d40c43 100644
--- a/lib/inertia_rails/defer_prop.rb
+++ b/lib/inertia_rails/defer_prop.rb
@@ -2,6 +2,7 @@
 
 module InertiaRails
   class DeferProp < IgnoreOnFirstLoadProp
+    prepend PropOnceable
     prepend PropMergeable
 
     DEFAULT_GROUP = 'default'
diff --git a/lib/inertia_rails/helper.rb b/lib/inertia_rails/helper.rb
index 6701835b..04b09a2e 100644
--- a/lib/inertia_rails/helper.rb
+++ b/lib/inertia_rails/helper.rb
@@ -32,5 +32,19 @@ def inertia_meta_tags
 
       safe_join(meta_tags, "\n")
     end
+
+    def inertia_root(id: nil, page: inertia_page)
+      config = controller.send(:inertia_configuration)
+      id ||= config.root_dom_id
+
+      if config.use_script_element_for_initial_page
+        safe_join([
+                    tag.script(page.to_json.html_safe, 'data-page': id, type: 'application/json'),
+                    tag.div(id: id)
+                  ], "\n")
+      else
+        tag.div(id: id, 'data-page': page.to_json)
+      end
+    end
   end
 end
diff --git a/lib/inertia_rails/inertia_rails.rb b/lib/inertia_rails/inertia_rails.rb
index 85c19dd2..80ea85a2 100644
--- a/lib/inertia_rails/inertia_rails.rb
+++ b/lib/inertia_rails/inertia_rails.rb
@@ -1,5 +1,6 @@
 # frozen_string_literal: true
 
+require 'inertia_rails/prop_onceable'
 require 'inertia_rails/prop_mergeable'
 require 'inertia_rails/base_prop'
 require 'inertia_rails/ignore_on_first_load_prop'
@@ -8,6 +9,7 @@
 require 'inertia_rails/optional_prop'
 require 'inertia_rails/defer_prop'
 require 'inertia_rails/merge_prop'
+require 'inertia_rails/once_prop'
 require 'inertia_rails/scroll_prop'
 require 'inertia_rails/configuration'
 require 'inertia_rails/meta_tag'
@@ -36,6 +38,10 @@ def always(&block)
       AlwaysProp.new(&block)
     end
 
+    def once(...)
+      OnceProp.new(...)
+    end
+
     def merge(...)
       MergeProp.new(...)
     end
@@ -44,8 +50,8 @@ def deep_merge(match_on: nil, &block)
       MergeProp.new(deep_merge: true, match_on: match_on, &block)
     end
 
-    def defer(group: nil, merge: nil, deep_merge: nil, match_on: nil, &block)
-      DeferProp.new(group: group, merge: merge, deep_merge: deep_merge, match_on: match_on, &block)
+    def defer(...)
+      DeferProp.new(...)
     end
 
     def scroll(metadata = nil, **options, &block)
diff --git a/lib/inertia_rails/merge_prop.rb b/lib/inertia_rails/merge_prop.rb
index e3172af4..8a756302 100644
--- a/lib/inertia_rails/merge_prop.rb
+++ b/lib/inertia_rails/merge_prop.rb
@@ -2,6 +2,7 @@
 
 module InertiaRails
   class MergeProp < BaseProp
+    prepend PropOnceable
     prepend PropMergeable
 
     def initialize(**_props, &block)
diff --git a/lib/inertia_rails/once_prop.rb b/lib/inertia_rails/once_prop.rb
new file mode 100644
index 00000000..98f21b42
--- /dev/null
+++ b/lib/inertia_rails/once_prop.rb
@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+module InertiaRails
+  class OnceProp < BaseProp
+    prepend PropOnceable
+
+    def initialize(**, &block)
+      @once = true
+      super(&block)
+    end
+  end
+end
diff --git a/lib/inertia_rails/optional_prop.rb b/lib/inertia_rails/optional_prop.rb
index 0d650964..59624467 100644
--- a/lib/inertia_rails/optional_prop.rb
+++ b/lib/inertia_rails/optional_prop.rb
@@ -2,5 +2,6 @@
 
 module InertiaRails
   class OptionalProp < IgnoreOnFirstLoadProp
+    prepend PropOnceable
   end
 end
diff --git a/lib/inertia_rails/prop_onceable.rb b/lib/inertia_rails/prop_onceable.rb
new file mode 100644
index 00000000..f5d06715
--- /dev/null
+++ b/lib/inertia_rails/prop_onceable.rb
@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+module InertiaRails
+  module PropOnceable
+    attr_reader :once_key, :once_expires_in
+
+    def initialize(**props, &block)
+      @once = props.fetch(:once, false)
+      @once_key = props[:key]
+      @once_expires_in = props[:expires_in]
+      @fresh = props.fetch(:fresh, false)
+
+      super
+    end
+
+    def once?
+      @once
+    end
+
+    def fresh?
+      @fresh
+    end
+
+    def expires_at
+      return nil unless @once_expires_in
+
+      timestamp = case @once_expires_in
+                  when ActiveSupport::Duration
+                    (Time.current + @once_expires_in).to_f
+                  when Numeric
+                    Time.current.to_f + @once_expires_in
+                  else
+                    raise ArgumentError, "Invalid `expires_in` value: #{@once_expires_in.inspect}"
+                  end
+
+      (timestamp * 1000).to_i
+    end
+  end
+end
diff --git a/lib/inertia_rails/renderer.rb b/lib/inertia_rails/renderer.rb
index 88735337..5ee50a34 100644
--- a/lib/inertia_rails/renderer.rb
+++ b/lib/inertia_rails/renderer.rb
@@ -48,7 +48,7 @@ def render
                                   else
                                     "#{@response.headers['Vary']}, X-Inertia"
                                   end
-      if @request.headers['X-Inertia']
+      if @request.inertia?
         @response.set_header('X-Inertia', 'true')
         @render_method.call json: page.to_json, status: @response.status, content_type: Mime[:json]
       else
@@ -97,15 +97,17 @@ def merge_props(shared_props, props, deep_merge)
     def computed_props
       # rubocop:disable Style/MultilineBlockChain
       @props
-        .tap do |merged_props| # Always keep errors in the props
-          if merged_props.key?(:errors) && !merged_props[:errors].is_a?(BaseProp)
-            errors = merged_props[:errors]
-            merged_props[:errors] = InertiaRails.always { errors }
-          end
+        .tap do |merged_props|
+        # Always keep errors in the props
+        if merged_props.key?(:errors) && !merged_props[:errors].is_a?(BaseProp)
+          errors = merged_props[:errors]
+          merged_props[:errors] = InertiaRails.always { errors }
         end
+      end
         .then { |props| deep_transform_props(props) } # Internal hydration/filtering
         .then { |props| @configuration.prop_transformer(props: props) } # Apply user-defined prop transformer
-        .tap do |props| # Add meta tags last (never transformed)
+        .tap do |props|
+        # Add meta tags last (never transformed)
         props[:_inertia_meta] = meta_tags if meta_tags.present?
       end
       # rubocop:enable Style/MultilineBlockChain
@@ -128,6 +130,9 @@ def page
       @page[:scrollProps] = scroll_props if scroll_props.present?
       @page.merge!(resolve_merge_props)
 
+      once_props = resolve_once_props
+      @page[:onceProps] = once_props if once_props.present?
+
       @page
     end
 
@@ -173,6 +178,17 @@ def resolve_merge_props
       }.delete_if { |_, v| v.blank? }
     end
 
+    def resolve_once_props
+      @props.each_with_object({}) do |(key, prop), result|
+        next unless prop.try(:once?)
+        next if excluded_by_partial_request?([key.to_s])
+
+        once_key = (prop.once_key || key).to_s
+
+        result[once_key] = { prop: key.to_s, expiresAt: prop.expires_at }.compact
+      end
+    end
+
     def resolve_match_on_props
       all_merge_props.filter_map do |key, prop|
         prop.match_on.map! { |ms| "#{key}.#{ms}" } if prop.match_on.present?
@@ -251,6 +267,10 @@ def partial_except_keys
       @partial_except_keys ||= (@request.headers['X-Inertia-Partial-Except'] || '').split(',').compact_blank!
     end
 
+    def except_once_keys
+      @except_once_keys ||= (@request.headers['X-Inertia-Except-Once-Props'] || '').split(',').compact_blank!
+    end
+
     def rendering_partial_component?
       @request.headers['X-Inertia-Partial-Component'] == @component
     end
@@ -265,12 +285,8 @@ def resolve_component(component)
 
     def keep_prop?(prop, path)
       return true if prop.is_a?(AlwaysProp)
-
-      if rendering_partial_component? && (partial_keys.present? || partial_except_keys.present?)
-        path_with_prefixes = path_prefixes(path)
-        return false if excluded_by_only_partial_keys?(path_with_prefixes)
-        return false if excluded_by_except_partial_keys?(path_with_prefixes)
-      end
+      return false if excluded_by_once_cache?(prop, path)
+      return false if excluded_by_partial_request?(path)
 
       # Precedence: Evaluate IgnoreOnFirstLoadProp only after partial keys have been checked
       return false if prop.is_a?(IgnoreOnFirstLoadProp) && !rendering_partial_component?
@@ -278,6 +294,29 @@ def keep_prop?(prop, path)
       true
     end
 
+    def excluded_by_once_cache?(prop, path)
+      return false unless prop.try(:once?)
+      return false if prop.try(:fresh?)
+      return false if explicitly_requested?(path)
+
+      once_key = (prop.once_key || path.join('.')).to_s
+      except_once_keys.include?(once_key)
+    end
+
+    def explicitly_requested?(path)
+      return false unless rendering_partial_component? && partial_keys.present?
+
+      path_with_prefixes = path_prefixes(path)
+      (path_with_prefixes & partial_keys).any?
+    end
+
+    def excluded_by_partial_request?(path)
+      return false unless rendering_partial_component? && (partial_keys.present? || partial_except_keys.present?)
+
+      path_with_prefixes = path_prefixes(path)
+      excluded_by_only_partial_keys?(path_with_prefixes) || excluded_by_except_partial_keys?(path_with_prefixes)
+    end
+
     def path_prefixes(parts)
       (0...parts.length).map do |i|
         parts[0..i].join('.')
diff --git a/spec/dummy/app/controllers/inertia_render_test_controller.rb b/spec/dummy/app/controllers/inertia_render_test_controller.rb
index 04123e32..06f3979f 100644
--- a/spec/dummy/app/controllers/inertia_render_test_controller.rb
+++ b/spec/dummy/app/controllers/inertia_render_test_controller.rb
@@ -189,4 +189,80 @@ def reset_test
       regular_prop: 'regular value',
     }
   end
+
+  def once_props
+    render inertia: 'TestComponent', props: {
+      cached_data: InertiaRails.once { 'expensive data' },
+      regular: 'regular prop',
+    }
+  end
+
+  def once_props_with_expires_in
+    render inertia: 'TestComponent', props: {
+      cached_data: InertiaRails.once(expires_in: 1.hour) { 'expensive data with expiration' },
+    }
+  end
+
+  def once_props_with_custom_key
+    render inertia: 'TestComponent', props: {
+      cached_data: InertiaRails.once(key: 'my_custom_key') { 'expensive data with custom key' },
+    }
+  end
+
+  def deferred_once_props
+    render inertia: 'TestComponent', props: {
+      name: 'Brian',
+      deferred_cached: InertiaRails.defer(once: true) { 'deferred and cached' },
+    }
+  end
+
+  inertia_share only: [:shared_once_props] do
+    {
+      shared_cached: InertiaRails.once { 'shared once data' },
+    }
+  end
+
+  def shared_once_props
+    render inertia: 'TestComponent', props: {
+      name: 'Brian',
+    }
+  end
+
+  def nested_once_props
+    render inertia: 'TestComponent', props: {
+      nested: {
+        cached: InertiaRails.once { 'nested cached data' },
+      },
+      regular: 'regular prop',
+    }
+  end
+
+  def multiple_once_props
+    render inertia: 'TestComponent', props: {
+      cached_one: InertiaRails.once { 'first cached' },
+      cached_two: InertiaRails.once { 'second cached' },
+      regular: 'regular prop',
+    }
+  end
+
+  def once_props_not_fresh
+    render inertia: 'TestComponent', props: {
+      cached_data: InertiaRails::OnceProp.new { 'cached data' },
+      regular: 'regular prop',
+    }
+  end
+
+  def once_props_fresh
+    render inertia: 'TestComponent', props: {
+      cached_data: InertiaRails::OnceProp.new(fresh: true) { 'fresh data' },
+      regular: 'regular prop',
+    }
+  end
+
+  def once_props_fresh_and_non_fresh
+    render inertia: 'TestComponent', props: {
+      foo: InertiaRails::OnceProp.new(fresh: true) { 'bar' },
+      baz: InertiaRails::OnceProp.new { 'qux' },
+    }
+  end
 end
diff --git a/spec/dummy/config/routes.rb b/spec/dummy/config/routes.rb
index 7cc18cd9..c1c4d818 100644
--- a/spec/dummy/config/routes.rb
+++ b/spec/dummy/config/routes.rb
@@ -44,6 +44,16 @@
   get 'prepend_merge_test' => 'inertia_render_test#prepend_merge_test'
   get 'nested_paths_test' => 'inertia_render_test#nested_paths_test'
   get 'reset_test' => 'inertia_render_test#reset_test'
+  get 'once_props' => 'inertia_render_test#once_props'
+  get 'once_props_with_expires_in' => 'inertia_render_test#once_props_with_expires_in'
+  get 'once_props_with_custom_key' => 'inertia_render_test#once_props_with_custom_key'
+  get 'deferred_once_props' => 'inertia_render_test#deferred_once_props'
+  get 'shared_once_props' => 'inertia_render_test#shared_once_props'
+  get 'nested_once_props' => 'inertia_render_test#nested_once_props'
+  get 'multiple_once_props' => 'inertia_render_test#multiple_once_props'
+  get 'once_props_not_fresh' => 'inertia_render_test#once_props_not_fresh'
+  get 'once_props_fresh' => 'inertia_render_test#once_props_fresh'
+  get 'once_props_fresh_and_non_fresh' => 'inertia_render_test#once_props_fresh_and_non_fresh'
   get 'non_inertiafied' => 'inertia_test#non_inertiafied'
   get 'deeply_nested_props' => 'inertia_render_test#deeply_nested_props'
 
diff --git a/spec/inertia/once_prop_spec.rb b/spec/inertia/once_prop_spec.rb
new file mode 100644
index 00000000..1861b29c
--- /dev/null
+++ b/spec/inertia/once_prop_spec.rb
@@ -0,0 +1,111 @@
+# frozen_string_literal: true
+
+RSpec.describe InertiaRails::OnceProp do
+  it_behaves_like 'base prop'
+
+  describe '#once?' do
+    subject { prop.once? }
+
+    let(:prop) { described_class.new { 'value' } }
+
+    it { is_expected.to be true }
+  end
+
+  describe '#once_key' do
+    subject { prop.once_key }
+
+    context 'without custom key' do
+      let(:prop) { described_class.new { 'value' } }
+
+      it { is_expected.to be_nil }
+    end
+
+    context 'with custom key via constructor' do
+      let(:prop) { described_class.new(key: 'custom_key') { 'value' } }
+
+      it { is_expected.to eq('custom_key') }
+    end
+  end
+
+  describe '#once_expires_in' do
+    subject { prop.once_expires_in }
+
+    context 'without expires_in' do
+      let(:prop) { described_class.new { 'value' } }
+
+      it { is_expected.to be_nil }
+    end
+
+    context 'with expires_in via constructor' do
+      let(:prop) { described_class.new(expires_in: 3600) { 'value' } }
+
+      it { is_expected.to eq(3600) }
+    end
+  end
+
+  describe '#expires_at' do
+    subject { prop.expires_at }
+
+    let(:freeze_time) { Time.current }
+
+    before do
+      allow(Time).to receive(:current).and_return(freeze_time)
+    end
+
+    context 'without expires_in' do
+      let(:prop) { described_class.new { 'value' } }
+
+      it { is_expected.to be_nil }
+    end
+
+    context 'with Numeric (seconds)' do
+      let(:prop) { described_class.new(expires_in: 3600) { 'value' } }
+
+      it 'returns expiration timestamp in milliseconds' do
+        expected = ((freeze_time.to_f + 3600) * 1000).to_i
+        expect(prop.expires_at).to eq(expected)
+      end
+    end
+
+    context 'with ActiveSupport::Duration' do
+      let(:prop) { described_class.new(expires_in: 1.hour) { 'value' } }
+
+      it 'returns expiration timestamp in milliseconds' do
+        expected = ((freeze_time + 1.hour).to_f * 1000).to_i
+        expect(prop.expires_at).to eq(expected)
+      end
+    end
+  end
+
+  describe '#once? is independent of fresh' do
+    subject { prop.once? }
+
+    context 'when fresh is false (default)' do
+      let(:prop) { described_class.new { 'value' } }
+
+      it { is_expected.to be true }
+    end
+
+    context 'when fresh is true' do
+      let(:prop) { described_class.new(fresh: true) { 'value' } }
+
+      it { is_expected.to be true }
+    end
+  end
+
+  describe '#fresh?' do
+    subject { prop.fresh? }
+
+    context 'when fresh is false (default)' do
+      let(:prop) { described_class.new { 'value' } }
+
+      it { is_expected.to be false }
+    end
+
+    context 'when fresh is true' do
+      let(:prop) { described_class.new(fresh: true) { 'value' } }
+
+      it { is_expected.to be true }
+    end
+  end
+end
diff --git a/spec/inertia/prop_onceable_spec.rb b/spec/inertia/prop_onceable_spec.rb
new file mode 100644
index 00000000..329433eb
--- /dev/null
+++ b/spec/inertia/prop_onceable_spec.rb
@@ -0,0 +1,125 @@
+# frozen_string_literal: true
+
+RSpec.describe InertiaRails::PropOnceable do
+  describe 'via DeferProp' do
+    let(:prop_class) { InertiaRails::DeferProp }
+
+    describe '#once?' do
+      it 'defaults to false' do
+        prop = prop_class.new { 'value' }
+        expect(prop.once?).to be false
+      end
+
+      it 'can be set to true' do
+        prop = prop_class.new(once: true) { 'value' }
+        expect(prop.once?).to be true
+      end
+
+      context 'once? is independent of fresh' do
+        it 'returns true when once is true regardless of fresh' do
+          prop = prop_class.new(once: true, fresh: true) { 'value' }
+          expect(prop.once?).to be true
+        end
+
+        it 'returns false when once is false regardless of fresh' do
+          prop = prop_class.new(once: false, fresh: true) { 'value' }
+          expect(prop.once?).to be false
+        end
+      end
+    end
+
+    describe '#fresh?' do
+      it 'defaults to false' do
+        prop = prop_class.new(once: true) { 'value' }
+        expect(prop.fresh?).to be false
+      end
+
+      it 'can be set to true' do
+        prop = prop_class.new(once: true, fresh: true) { 'value' }
+        expect(prop.fresh?).to be true
+      end
+    end
+
+    describe '#once_key' do
+      it 'defaults to nil' do
+        prop = prop_class.new { 'value' }
+        expect(prop.once_key).to be_nil
+      end
+
+      it 'can be set via constructor' do
+        prop = prop_class.new(once: true, key: 'custom') { 'value' }
+        expect(prop.once_key).to eq('custom')
+      end
+    end
+
+    describe '#once_expires_in' do
+      it 'defaults to nil' do
+        prop = prop_class.new { 'value' }
+        expect(prop.once_expires_in).to be_nil
+      end
+
+      it 'can be set via constructor' do
+        prop = prop_class.new(once: true, expires_in: 3600) { 'value' }
+        expect(prop.once_expires_in).to eq(3600)
+      end
+    end
+
+    describe '#expires_at' do
+      let(:freeze_time) { Time.current }
+
+      before do
+        allow(Time).to receive(:current).and_return(freeze_time)
+      end
+
+      it 'returns nil without expires_in' do
+        prop = prop_class.new(once: true) { 'value' }
+        expect(prop.expires_at).to be_nil
+      end
+
+      it 'returns expiration timestamp in milliseconds with expires_in' do
+        prop = prop_class.new(once: true, expires_in: 3600) { 'value' }
+        expected = ((freeze_time.to_f + 3600) * 1000).to_i
+        expect(prop.expires_at).to eq(expected)
+      end
+    end
+
+    it 'preserves existing DeferProp functionality' do
+      prop = prop_class.new(group: 'custom', once: true) { 'value' }
+      expect(prop.group).to eq('custom')
+      expect(prop.once?).to be true
+    end
+  end
+
+  describe 'via OptionalProp' do
+    let(:prop_class) { InertiaRails::OptionalProp }
+
+    it 'supports once functionality' do
+      prop = prop_class.new(once: true, key: 'opt_key', expires_in: 1800) { 'value' }
+      expect(prop.once?).to be true
+      expect(prop.once_key).to eq('opt_key')
+      expect(prop.once_expires_in).to eq(1800)
+    end
+
+    it 'defaults to not once' do
+      prop = prop_class.new { 'value' }
+      expect(prop.once?).to be false
+    end
+  end
+
+  describe 'via MergeProp' do
+    let(:prop_class) { InertiaRails::MergeProp }
+
+    it 'supports once functionality' do
+      prop = prop_class.new(once: true, key: 'merge_key', expires_in: 7200) { 'value' }
+      expect(prop.once?).to be true
+      expect(prop.once_key).to eq('merge_key')
+      expect(prop.once_expires_in).to eq(7200)
+    end
+
+    it 'preserves merge functionality' do
+      prop = prop_class.new(once: true) { 'value' }
+      expect(prop.merge?).to be true
+      expect(prop.once?).to be true
+    end
+  end
+end
diff --git a/spec/inertia/rendering_spec.rb b/spec/inertia/rendering_spec.rb
index 62eadb6e..24a8494b 100644
--- a/spec/inertia/rendering_spec.rb
+++ b/spec/inertia/rendering_spec.rb
@@ -797,6 +797,373 @@
       end
     end
   end
+
+  context 'view configuration options' do
+    after do
+      InertiaRails.configure do |config|
+        config.use_script_element_for_initial_page = false
+        config.root_dom_id = 'app'
+      end
+    end
+
+    describe 'root_dom_id' do
+      let(:page) { InertiaRails::Renderer.new('TestComponent', controller, request, response, '').send(:page) }
+
+      context 'with default root_dom_id' do
+        before { get component_path }
+
+        it 'renders div with id="app"' do
+          expect(response.body).to include('<div id="app" data-page=')
+        end
+      end
+
+      context 'with custom root_dom_id' do
+        before do
+          InertiaRails.configure { |c| c.root_dom_id = 'custom-root' }
+          get component_path
+        end
+
+        it 'renders div with custom id' do
+          expect(response.body).to include('<div id="custom-root" data-page=')
+        end
+      end
+    end
+
+    describe 'use_script_element_for_initial_page' do
+      let(:page) { InertiaRails::Renderer.new('TestComponent', controller, request, response, '').send(:page) }
+
+      context 'when false (default)' do
+        before { get component_path }
+
+        it 'renders div with data-page attribute' do
+          expect(response.body).to include('<div id="app" data-page=')
+        end
+
+        it 'does not render script element for page data' do
+          expect(response.body).not_to include('<script data-page=')
+        end
+      end
+
+      context 'when true' do
+        before do
+          InertiaRails.configure { |c| c.use_script_element_for_initial_page = true }
+          get component_path
+        end
+
+        it 'renders script element with page data' do
+          expect(response.body).to include('<script data-page="app" type="application/json">')
+          expect(response.body).to include(page.to_json)
+          expect(response.body).to include('</script>')
+        end
+
+        it 'renders div without data-page attribute' do
+          expect(response.body).to include('<div id="app"></div>')
+        end
+      end
+
+      context 'when true with custom root_dom_id' do
+        before do
+          InertiaRails.configure do |c|
+            c.use_script_element_for_initial_page = true
+            c.root_dom_id = 'inertia-app'
+          end
+          get component_path
+        end
+
+        it 'renders script element with custom data-page attribute' do
+          expect(response.body).to include('<script data-page="inertia-app" type="application/json">')
+        end
+
+        it 'renders div with custom id' do
+          expect(response.body).to include('<div id="inertia-app"></div>')
+        end
+      end
+    end
+  end
+
+  context 'once prop rendering' do
+    let(:headers) { { 'X-Inertia' => true } }
+
+    context 'on first load' do
+      before { get once_props_path, headers: headers }
+
+      it 'returns props on first load' do
+        expect(response.parsed_body['props']).to include('cached_data' => 'expensive data', 'regular' => 'regular prop')
+      end
+
+      it 'returns onceProps metadata' do
+        expect(response.parsed_body['onceProps']).to eq(
+          'cached_data' => { 'prop' => 'cached_data' }
+        )
+      end
+    end
+
+    context 'with expires_in' do
+      before { get once_props_with_expires_in_path, headers: headers }
+
+      it 'includes expiresAt in onceProps' do
+        once_props = response.parsed_body['onceProps']
+        expect(once_props['cached_data']['expiresAt']).to be_a(Integer)
+        expect(once_props['cached_data']['expiresAt']).to be > (Time.current.to_f * 1000).to_i
+      end
+    end
+
+    context 'with custom key' do
+      before { get once_props_with_custom_key_path, headers: headers }
+
+      it 'uses custom key in onceProps' do
+        expect(response.parsed_body['onceProps']).to have_key('my_custom_key')
+        expect(response.parsed_body['onceProps']['my_custom_key']['prop']).to eq('cached_data')
+      end
+    end
+
+    context 'with X-Inertia-Except-Once-Props header' do
+      let(:headers) do
+        {
+          'X-Inertia' => true,
+          'X-Inertia-Except-Once-Props' => 'cached_data',
+        }
+      end
+
+      before { get once_props_path, headers: headers }
+
+      it 'excludes cached once props from props' do
+        expect(response.parsed_body['props']).not_to have_key('cached_data')
+        expect(response.parsed_body['props']).to include('regular' => 'regular prop')
+      end
+
+      it 'still includes once props in onceProps metadata' do
+        expect(response.parsed_body['onceProps']).to eq(
+          'cached_data' => { 'prop' => 'cached_data' }
+        )
+      end
+    end
+
+    context 'with custom key and X-Inertia-Except-Once-Props header' do
+      let(:headers) do
+        {
+          'X-Inertia' => true,
+          'X-Inertia-Except-Once-Props' => 'my_custom_key',
+        }
+      end
+
+      before { get once_props_with_custom_key_path, headers: headers }
+
+      it 'excludes prop by custom key' do
+        expect(response.parsed_body['props']).not_to have_key('cached_data')
+      end
+    end
+
+    context 'when refreshing once prop via partial reload' do
+      let(:headers) do
+        {
+          'X-Inertia' => true,
+          'X-Inertia-Partial-Data' => 'cached_data',
+          'X-Inertia-Partial-Component' => 'TestComponent',
+          'X-Inertia-Except-Once-Props' => 'cached_data',
+        }
+      end
+
+      before { get once_props_path, headers: headers }
+
+      it 'returns the once prop when explicitly requested' do
+        expect(response.parsed_body['props']).to include('cached_data' => 'expensive data')
+      end
+
+      it 'includes prop in onceProps metadata' do
+        expect(response.parsed_body['onceProps']).to eq(
+          'cached_data' => { 'prop' => 'cached_data' }
+        )
+      end
+    end
+
+    context 'with deferred once props' do
+      before { get deferred_once_props_path, headers: headers }
+
+      it 'returns deferredProps on first load' do
+        expect(response.parsed_body['deferredProps']).to eq('default' => ['deferred_cached'])
+      end
+
+      it 'returns onceProps metadata' do
+        expect(response.parsed_body['onceProps']).to eq(
+          'deferred_cached' => { 'prop' => 'deferred_cached' }
+        )
+      end
+
+      context 'with a partial reload' do
+        let(:headers) do
+          {
+            'X-Inertia' => true,
+            'X-Inertia-Partial-Data' => 'deferred_cached',
+            'X-Inertia-Partial-Component' => 'TestComponent',
+          }
+        end
+
+        it 'returns the deferred prop value' do
+          expect(response.parsed_body['props']).to include('deferred_cached' => 'deferred and cached')
+        end
+      end
+
+      context 'with a partial reload and prop already cached' do
+        let(:headers) do
+          {
+            'X-Inertia' => true,
+            'X-Inertia-Partial-Data' => 'deferred_cached',
+            'X-Inertia-Partial-Component' => 'TestComponent',
+            'X-Inertia-Except-Once-Props' => 'deferred_cached',
+          }
+        end
+
+        it 'returns the prop when explicitly requested (bypasses cache)' do
+          expect(response.parsed_body['props']).to include('deferred_cached' => 'deferred and cached')
+        end
+      end
+    end
+
+    context 'with shared once props' do
+      before { get shared_once_props_path, headers: headers }
+
+      it 'returns shared once props' do
+        expect(response.parsed_body['props']).to include('shared_cached' => 'shared once data')
+      end
+
+      it 'returns onceProps metadata for shared props' do
+        expect(response.parsed_body['onceProps']).to eq(
+          'shared_cached' => { 'prop' => 'shared_cached' }
+        )
+      end
+    end
+
+    context 'with partial reload requesting only specific props' do
+      let(:headers) do
+        {
+          'X-Inertia' => true,
+          'X-Inertia-Partial-Data' => 'cached_one',
+          'X-Inertia-Partial-Component' => 'TestComponent',
+        }
+      end
+
+      before { get multiple_once_props_path, headers: headers }
+
+      it 'only includes requested props in props' do
+        expect(response.parsed_body['props']).to eq('cached_one' => 'first cached')
+      end
+
+      it 'only includes requested once props in onceProps' do
+        expect(response.parsed_body['onceProps']).to eq(
+          'cached_one' => { 'prop' => 'cached_one' }
+        )
+      end
+    end
+
+    context 'with partial reload excluding specific props' do
+      let(:headers) do
+        {
+          'X-Inertia' => true,
+          'X-Inertia-Partial-Except' => 'cached_two',
+          'X-Inertia-Partial-Component' => 'TestComponent',
+        }
+      end
+
+      before { get multiple_once_props_path, headers: headers }
+
+      it 'excludes specified props from props' do
+        expect(response.parsed_body['props']).to eq(
+          'cached_one' => 'first cached',
+          'regular' => 'regular prop'
+        )
+      end
+
+      it 'excludes specified once props from onceProps' do
+        expect(response.parsed_body['onceProps']).to eq(
+          'cached_one' => { 'prop' => 'cached_one' }
+        )
+      end
+    end
+
+    context 'with fresh: false (default behavior)' do
+      before { get once_props_not_fresh_path, headers: headers }
+
+      it 'returns the prop value on first load' do
+        expect(response.parsed_body['props']).to include('cached_data' => 'cached data')
+      end
+
+      it 'includes prop in onceProps metadata' do
+        expect(response.parsed_body['onceProps']).to eq(
+          'cached_data' => { 'prop' => 'cached_data' }
+        )
+      end
+
+      context 'when client has prop cached' do
+        let(:headers) do
+          {
+            'X-Inertia' => true,
+            'X-Inertia-Except-Once-Props' => 'cached_data',
+          }
+        end
+
+        it 'excludes the prop from response' do
+          expect(response.parsed_body['props']).not_to have_key('cached_data')
+        end
+      end
+    end
+
+    context 'with fresh: true (force refresh)' do
+      before { get once_props_fresh_path, headers: headers }
+
+      it 'returns the prop value' do
+        expect(response.parsed_body['props']).to include('cached_data' => 'fresh data')
+      end
+
+      it 'includes prop in onceProps metadata' do
+        expect(response.parsed_body['onceProps']).to eq(
+          'cached_data' => { 'prop' => 'cached_data' }
+        )
+      end
+
+      context 'when client has prop cached' do
+        let(:headers) do
+          {
+            'X-Inertia' => true,
+            'X-Inertia-Except-Once-Props' => 'cached_data',
+          }
+        end
+
+        it 'still includes the prop (bypasses cache)' do
+          expect(response.parsed_body['props']).to include('cached_data' => 'fresh data')
+        end
+
+        it 'includes prop in onceProps so client updates cache' do
+          expect(response.parsed_body['onceProps']).to eq(
+            'cached_data' => { 'prop' => 'cached_data' }
+          )
+        end
+      end
+    end
+
+    context 'with mixed fresh and non-fresh once props' do
+      let(:headers) do
+        {
+          'X-Inertia' => true,
+          'X-Inertia-Except-Once-Props' => 'foo,baz',
+        }
+      end
+
+      before { get once_props_fresh_and_non_fresh_path, headers: headers }
+
+      it 'includes fresh prop but excludes non-fresh prop from props' do
+        expect(response.parsed_body['props']).to include('foo' => 'bar')
+        expect(response.parsed_body['props']).not_to have_key('baz')
+      end
+
+      it 'includes both props in onceProps metadata' do
+        expect(response.parsed_body['onceProps']).to eq(
+          'foo' => { 'prop' => 'foo' },
+          'baz' => { 'prop' => 'baz' }
+        )
+      end
+    end
+  end
 end
 
 def inertia_div(page)