feat(keyboard): show closest word suggestion on invalid command #640

Keyboards/KeyboardsBase/KeyboardViewController.swift

@@ -2069,7 +2069,13 @@ class KeyboardViewController: UIInputViewController {
                 autoCapAtStartOfProxy()
 
                 if commandState == .invalid {
-                    commandBar.text = commandPromptSpacing + invalidCommandMsgWikidata
+                    // wordToTranslate is set by queryTranslation, verbToConjugate by triggerVerbConjugation.
+                    let failedWord = wordToTranslate.isEmpty ? verbToConjugate : wordToTranslate
+                    if let suggestion = didYouMeanSuggestion(for: failedWord) {
+                        commandBar.text = commandPromptSpacing + suggestion
+                    } else {
+                        commandBar.text = commandPromptSpacing + invalidCommandMsgWikidata
+                    }
                     commandBar.isShowingInfoButton = true
                 } else {
                     commandBar.isShowingInfoButton = false
@@ -2096,7 +2102,11 @@ class KeyboardViewController: UIInputViewController {
                     loadKeys()
                     proxy.insertText(selectedText)
                     autoCapAtStartOfProxy()
-                    commandBar.text = commandPromptSpacing + invalidCommandMsgWiktionary
+                    if let suggestion = didYouMeanSuggestion(for: selectedText) {
+                        commandBar.text = commandPromptSpacing + suggestion
+                    } else {
+                        commandBar.text = commandPromptSpacing + invalidCommandMsgWiktionary
+                    }
                     commandBar.isShowingInfoButton = true
                     commandBar.textColor = keyCharColor
                     return
@@ -2130,7 +2140,11 @@ class KeyboardViewController: UIInputViewController {
                     loadKeys()
                     proxy.insertText(selectedText)
                     autoCapAtStartOfProxy()
-                    commandBar.text = commandPromptSpacing + invalidCommandMsgWikidata
+                    if let suggestion = didYouMeanSuggestion(for: selectedText) {
+                        commandBar.text = commandPromptSpacing + suggestion
+                    } else {
+                        commandBar.text = commandPromptSpacing + invalidCommandMsgWikidata
+                    }
                     commandBar.isShowingInfoButton = true
                     commandBar.textColor = keyCharColor
                     return
@@ -2152,7 +2166,11 @@ class KeyboardViewController: UIInputViewController {
 
                     if commandState == .invalid {
                         proxy.insertText(selectedText)
-                        commandBar.text = commandPromptSpacing + invalidCommandMsgWikidata
+                        if let suggestion = didYouMeanSuggestion(for: selectedText) {
+                            commandBar.text = commandPromptSpacing + suggestion
+                        } else {
+                            commandBar.text = commandPromptSpacing + invalidCommandMsgWikidata
+                        }
                         commandBar.isShowingInfoButton = true
                     } else {
                         commandBar.isShowingInfoButton = false

Keyboards/KeyboardsBase/ScribeFunctionality/CommandVariables.swift

@@ -182,3 +182,25 @@ var alreadyPluralMsg = ""
 
 /// The message shown on the download data button when no language data has been downloaded.
 var downloadDataMsg = "Please download language data"
+
+/// Returns a "Did you mean: X?" suggestion string for an invalid command input.
+/// Progressively shortens the word to find the closest prefix match in the autocomplete lexicon.
+///
+/// - Parameter word: the word that was not found.
+/// - Returns: a suggestion string, or nil if no close match exists.
+func didYouMeanSuggestion(for word: String) -> String? {
+    guard !word.isEmpty else { return nil }
+
+    // Try progressively shorter prefixes (minimum 2 chars) to find a close match.
+    var prefix = word.lowercased()
+    while prefix.count >= 2 {
+        let suggestions = LanguageDBManager.shared.queryAutocompletions(word: prefix)
+        if let first = suggestions.first, !first.isEmpty {
+            // Only suggest if it's actually different from what was typed.
+            guard first.lowercased() != word.lowercased() else { return nil }
+            return "Did you mean: \(first)?"
+        }
+        prefix = String(prefix.dropLast())
+    }
+    return nil
+}