fix: complete username autocomplete on tap, not just show it

Tapping an untouched or partially-typed username field now applies
the suggestion immediately, the same way pressing Enter already did,
instead of only showing the ghost-text hint.

Two bugs were stacking here: find_suggestion() returns nothing for
empty input (by design, to avoid hijacking typing as it's cleared),
so a tap on a blank field never got the field's own suggestion to
begin with. And get_suggestion_suffix() had the same empty-input
guard, so even a suggestion set directly onto current-suggestion
wouldn't have rendered — skipping 0 characters of the suggestion is
just the whole suggestion, which is exactly right to show.

Author: eupn

src/main.rs

@@ -471,11 +471,13 @@ mod autocomplete_handler {
 
         app.global::<AutocompleteHandler>()
             .on_get_suggestion_suffix(|typed, suggestion| {
-                if suggestion.is_empty() || typed.is_empty() {
+                if suggestion.is_empty() {
                     return slint::SharedString::default();
                 }
 
-                // Get the suffix after the typed text
+                // Get the suffix after the typed text (if nothing's typed
+                // yet — e.g. a tap-triggered suggestion — this is the whole
+                // suggestion)
                 let typed_len = typed.chars().count();
                 let suffix: String = suggestion.chars().skip(typed_len).collect();
                 slint::SharedString::from(suffix)

ui/autocomplete_line_edit.slint

@@ -78,7 +78,19 @@ export component AutocompleteLineEdit inherits Rectangle {
     changed has-focus => {
         root.cursor-visible = true;
         if (root.has-focus) {
-            root.refresh-suggestion();
+            if (root.text == "" && root.suggestions.length > 0) {
+                // find-suggestion() intentionally returns nothing for empty
+                // input — that guard is for the typed-and-backspaced-to-empty
+                // case, so it doesn't yank the cursor around mid-edit. A tap
+                // on a still-untouched field should still offer a starting
+                // point, so this bypasses it just for the focus-gained case.
+                root.current-suggestion = root.suggestions[0];
+            } else {
+                root.refresh-suggestion();
+            }
+            // A tap completes the suggestion immediately, same as pressing
+            // Enter — apply-autocomplete() is a no-op if there's none.
+            root.apply-autocomplete();
         }
         AutocompleteHandler.return-key-active = root.has-focus && root.current-suggestion != "";
     }