[6.x] Incorrect templating of tabbed forms

[AtmoFX]

Bug description

In 6.x, it is possible to make any forms with tabs.
However, the form tag does only returns data from the main tab:

• Only fields and sections arrays get defined by the tag
• The above 2 arrays contain only the fields and sections, respectively, form the main tab.

Similar to #11836 (which I created for 5.x profile forms), 6.x should bring tags into {{ form }} + derive sections and fields with:

$data['sections'] = collect($data['tabs'])->flatMap->sections->all();
$data['fields'] = collect($data['sections'])->flatMap->fields->all();

How to reproduce

Create a form with 2 tabs each having 1 section and each section have 1 field (i.e. 2 fields in total) with the blueprint:

tabs:
  main:
    display: Main
    sections:
      -
        fields:
          -
            handle: input_main_tab
            field:
              type: text
              display: 'Input main tab'
  tab_2:
    display: 'Tab 2'
    sections:
      -
        display: 'New Section'
        fields:
          -
            handle: input_tab_2
            field:
              type: text
              display: 'Input tab 2'

The templating snippet available at https://statamic.dev/forms#the-template renders only 1 field.

Logs

Environment

Environment
Application Name: GaiaMine UAT
Laravel Version: 12.44.0
PHP Version: 8.3.6
Composer Version: 2.9.2
Environment: local
Debug Mode: ENABLED
URL: alpha.local/
Maintenance Mode: OFF
Timezone: UTC
Locale: en

Cache
Config: NOT CACHED
Events: NOT CACHED
Routes: NOT CACHED
Views: CACHED

Drivers
Broadcasting: log
Cache: file
Database: mysql
Logs: stack / single
Mail: smtp
Queue: sync
Session: database

Storage
public/storage: NOT LINKED

Livewire
Livewire: v4.0.0-beta.5

Statamic
Addons: 4
Sites: 1
Stache Watcher: Enabled (auto)
Static Caching: Disabled
Version: 6.0.0-alpha.16 PRO

Statamic Addons
alt-design/alt-seo: 1.3.0
jacksleight/statamic-bard-mutator: 3.0.5
pecotamic/sitemap: 1.4.10
statamic/eloquent-driver: 4.35.2

Statamic Eloquent Driver
Asset Containers: file
Assets: file
Blueprints: file
Collection Trees: file
Collections: file
Entries: eloquent
Fieldsets: file
Form Submissions: eloquent
Forms: file
Global Sets: file
Global Variables: file
Navigation Trees: file
Navigations: file
Revisions: file
Sites: file
Taxonomies: file
Terms: file
Tokens: file

Installation

Fresh statamic/statamic site via CLI

Additional details

No response

[duncanmcclean]

Tabs aren't currently supported in form blueprints. We'll fix the UI. 👍

[AtmoFX]

Ohhh... okay....

I had written the below piece of code that seems to work fine for forms too and thought I was missing something.

$formTag = Form::find($handle);
$tabs = $formTag->blueprint()->tabs()->all();
$tabs = array_map(fn($tab) => array($tab->handle() => $tab->contents()), $tabs);

... Well, to be precise, it works fine to return tabs in a form blueprint with sections inside it and fields inside those sections, but the fields were missing most of their usual properties.
Ultimately, I did not find how to get the full field definitions from existing code; had I managed, I would have seen with you if I could have submitted a PR instead of this bug report.