Summary

Small, focused PR (7 files, +8/−8) that:

1. Renames Ingo\Form\V3 → Horde\Ingo\Form\V3 in the two custom Variable classes
2. Replaces 'ingo:Longemail' / 'ingo:folders' with FQCN ::class references in three legacy forms
3. Bumps horde/form from ^3 to ^3.1 in composer.json and .horde.yml

This aligns ingo with horde/form 3.1.0 FQCN support and with ingo's existing Composer PSR-4 map ("Horde\\Ingo\\": "src/").

What looks good

Namespace correction is necessary. The Variable classes lived under Ingo\Form\V3 while composer.json maps Horde\Ingo\ → src/. Resolution only worked because horde/form 3.1 tries Horde\Ingo\… first (PSR-4 loads the file), then falls back to Ingo\Form\V3\… after the file is already included. Moving to Horde\Ingo\Form\V3 fixes that properly.

Dependency bump is correct. FQCN type strings and vendor-namespaced app:type resolution are new in horde/form 3.1.0. ^3.1 || dev-FRAMEWORK_6_0 is the right constraint.

Call-site coverage is complete. All four custom-variable usages are updated (Forward, Vacation ×2, Spam). Inline \Horde\Ingo\Form\V3\…::class matches the style shown in horde/form's UPGRADING.md.

Blocker: getTypeName() breaks Ingo_Ui_VarRenderer_Html

Ingo still renders through the legacy Horde_Form_Renderer with varrenderer_driver => ['ingo', 'html'] (e.g. spam filtering in lib/Basic/Spam.php). Dispatch is via Horde_Core_Ui_VarRenderer::render(), which builds _renderVarInput_{getTypeName()}.

Ingo_Ui_VarRenderer_Html only implements the legacy names:

• _renderVarInput_ingo_form_type_folders → folder select via Ingo_Flist::select()
• _renderVarInput_ingo_form_type_longemail → delegates to _renderVarInput_longtext()

BaseVariable::getTypeName() derives the type from the class namespace:

After this PR, Forward/Vacation/Spam forms would show warnings instead of folder selectors and email textareas. CI won't catch this — ingo has no form/UI tests for these variables.

Suggested fix (pick one):

1. Override getTypeName() in both Variable classes (matches the BaseVariable docblock: "Override with a simple return 'literal' string"):

public function getTypeName(): string
{
    return 'ingo_form_type_folders'; // or 'ingo_form_type_longemail'
}

2. Update Ingo_Ui_VarRenderer_Html to add _renderVarInput_folders / _renderVarInput_longemail (and keep the old methods for BC).

Option 1 is smaller and keeps the legacy renderer contract explicit.

A broader fix in horde/form's getTypeName() for Horde\{App}\Form\V3\… would help all apps, but ingo still needs a local fix for merge.

Minor nits

• Empty PR description — worth documenting motivation, horde/form ^3.1 requirement, and manual test plan (spam folder picker, forward/vacation address fields)
• Commit typo — second commit says "FCQN"; should be "FQCN"
• Tests — no new coverage; acceptable given ingo's test suite, but manual UI verification is important here

Manual test plan (for author or merger)

• Spam rule page: folder dropdown renders and saves
• Forward rule: multi-line address field renders and validates
• Vacation rule: "My email addresses" and "Addresses to not send responses to" fields render
• With horde/form 3.1.x installed (not only dev-FRAMEWORK_6_0)

Bottom line

Approve the modernization approach, but do not merge until the getTypeName() / VarRenderer mismatch is fixed. Without that, the namespace change is a user-visible regression on three core ingo screens.