feat(keyboard): harden polish/clipboard guards and ship 1.6.6 (build 59)

Keep marketing version at 1.6.6 and bump build to 59. Strengthen never-answer
polish safeguards, clipboard reply-intent continuity, voice undo UX, device
UITests harness, eval fixtures, and What's New assets.

OSGKeyboardExt/Services/KeyboardTextInserter.swift

@@ -2,7 +2,8 @@
 // OSGKeyboard · Keyboard Extension
 //
 // Inserts Flow transcripts from the host app and surfaces polish warnings
-// without re-running LLM polish in the extension.
+// without re-running LLM polish in the extension. Also tracks the last
+// voice insertion so the undo button can roll it back safely.
 
 import OSGKeyboardShared
 
@@ -14,6 +15,14 @@ final class KeyboardTextInserter {
     private let contextBeforeInput: () -> String?
     private let scheduleAutoClearError: () -> Void
 
+    /// Exact string last inserted by voice (including any word-boundary
+    /// separator). Cleared after a successful undo or when the caret no
+    /// longer sits after that text.
+    private var lastInsertedText: String?
+    /// Suppresses availability refresh while we walk `deleteBackward`
+    /// for undo, so intermediate contexts don't flicker the button.
+    private var isUndoing = false
+
     init(
         state: KeyboardState,
         insertText: @escaping (String) -> Void,
@@ -55,7 +64,9 @@ final class KeyboardTextInserter {
             previousContext: contextBeforeInput(),
             insertion: trimmed
         )
-        insertText(separator + trimmed)
+        let inserted = separator + trimmed
+        insertText(inserted)
+        recordLastInsertion(inserted)
         state.lastTranscript = ""
         state.level = 0
         if let warning = delivery.polishWarning {
@@ -66,4 +77,50 @@ final class KeyboardTextInserter {
         }
         OSGLog.keyboardExt.info("flow insert length=\(trimmed.count, privacy: .public)")
     }
+
+    /// Roll back the last voice insertion when it is still at the caret.
+    func undoLastInsertion() {
+        guard let text = lastInsertedText, !text.isEmpty else { return }
+        guard let preceding = contextBeforeInput(), preceding.hasSuffix(text) else {
+            clearLastInsertion()
+            return
+        }
+
+        isUndoing = true
+        defer { isUndoing = false }
+
+        for _ in 0..<text.count {
+            deleteBackward()
+        }
+        clearLastInsertion()
+        OSGLog.keyboardExt.info("voice undo length=\(text.count, privacy: .public)")
+    }
+
+    /// Re-evaluate whether the recorded insertion is still undoable.
+    /// Call from `textDidChange` / `selectionDidChange`.
+    func refreshUndoAvailability() {
+        guard !isUndoing else { return }
+        guard let text = lastInsertedText, !text.isEmpty else {
+            if state.undoAvailable { state.undoAvailable = false }
+            return
+        }
+        let available = contextBeforeInput()?.hasSuffix(text) == true
+        if !available {
+            // Caret moved or the user edited the insertion — drop the record.
+            lastInsertedText = nil
+        }
+        if state.undoAvailable != available {
+            state.undoAvailable = available
+        }
+    }
+
+    private func recordLastInsertion(_ text: String) {
+        lastInsertedText = text
+        state.undoAvailable = true
+    }
+
+    private func clearLastInsertion() {
+        lastInsertedText = nil
+        state.undoAvailable = false
+    }
 }