Text rules: auto-capitalization, double-space period, backspace repeat

- TextContext: field purpose/hints and text before the cursor, reported by
  the backend (KWin content_type + surrounding_text)
- TextRules: sentence-start and double-space heuristics, deletion helpers
- KeyRepeater: held backspace repeats, then deletes whole words (Ctrl+BS)
- Controller keeps a best-guess of the text before the cursor so rules work
  instantly and in fields that don't report surrounding text
- No auto-capitalization or smart punctuation in password/URL/email fields

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/CMakeLists.txt

@@ -11,6 +11,8 @@ sloposk_add_test(tst_keygeometry)
 sloposk_add_test(tst_controller)
 sloposk_add_test(tst_pointertracker)
 sloposk_add_test(tst_alternatespicker)
+sloposk_add_test(tst_textrules)
+sloposk_add_test(tst_keyrepeater)
 
 # Needs the QML module itself, not just the C++ backing library.
 sloposk_add_test(tst_keyboardsurface)

tests/tst_controller.cpp

@@ -14,10 +14,15 @@ class FakeEngine : public InputEngine
 {
 public:
     void commitText(const QString &text) override { output += text; }
-    void sendKeysym(quint32 keysym) override { keysyms.append(keysym); }
+    void sendKeysym(quint32 keysym, Qt::KeyboardModifiers modifiers) override
+    {
+        keysyms.append(keysym);
+        lastModifiers = modifiers;
+    }
 
     QString output;
     QList<quint32> keysyms;
+    Qt::KeyboardModifiers lastModifiers;
 };
 
 KeyDef makeKey(KeyType type, const QString &label = {})
@@ -105,6 +110,57 @@ private Q_SLOTS:
         QCOMPARE(model.layerName(), u"numbers");
     }
 
+    void backspaceStopsOnRelease()
+    {
+        const KeyDef backspace = makeKey(KeyType::Backspace);
+        controller->keyDown(backspace, 0);
+        controller->keyUp(backspace, KeyOutput::Primary, {}, 50);
+        QTest::qWait(700); // past the repeat delay
+        QCOMPARE(engine.keysyms.size(), 1);
+    }
+
+    void capitalizesAtSentenceStart()
+    {
+        controller->resetContext();
+        QCOMPARE(controller->shiftMode(), KeyboardController::ShiftMode::Once);
+        for (const char *c : {"h", "i", ".", " "})
+            tap(makeKey(KeyType::Character, QString::fromLatin1(c)));
+        QCOMPARE(controller->shiftMode(), KeyboardController::ShiftMode::Once);
+        tap(makeKey(KeyType::Character, u"o"_s));
+        QCOMPARE(engine.output, u"Hi. O");
+    }
+
+    void noCapitalizationInPasswordFields()
+    {
+        TextContext context;
+        context.purpose = TextContext::Purpose::Password;
+        controller->setContext(context);
+        QCOMPARE(controller->shiftMode(), KeyboardController::ShiftMode::Off);
+    }
+
+    void fieldTextDrivesCapitalization()
+    {
+        TextContext context;
+        context.hasSurroundingText = true;
+        context.textBeforeCursor = u"Done! "_s;
+        controller->setContext(context);
+        QCOMPARE(controller->shiftMode(), KeyboardController::ShiftMode::Once);
+        context.textBeforeCursor = u"Done, "_s;
+        controller->setContext(context);
+        QCOMPARE(controller->shiftMode(), KeyboardController::ShiftMode::Off);
+    }
+
+    void doubleSpaceTypesPeriod()
+    {
+        const KeyDef space = makeKey(KeyType::Space);
+        tap(makeKey(KeyType::Character, u"a"_s));
+        tap(space);
+        tap(space);
+        QCOMPARE(engine.output, u"a . ");
+        QCOMPARE(engine.keysyms, QList<quint32>{XKB_KEY_BackSpace}); // removed the first space
+        QCOMPARE(controller->shiftMode(), KeyboardController::ShiftMode::Once);
+    }
+
     void slideTypesSymbolAndSwitchesBack()
     {
         KeyDef layer = makeKey(KeyType::LayerSwitch);

tests/tst_keyboardsurface.cpp

@@ -25,10 +25,15 @@ class FakeEngine : public InputEngine
 {
 public:
     void commitText(const QString &text) override { output += text; }
-    void sendKeysym(quint32 keysym) override { keysyms.append(keysym); }
+    void sendKeysym(quint32 keysym, Qt::KeyboardModifiers modifiers) override
+    {
+        keysyms.append(keysym);
+        lastModifiers = modifiers;
+    }
 
     QString output;
     QList<quint32> keysyms;
+    Qt::KeyboardModifiers lastModifiers;
 };
 
 constexpr QPoint KeyboardOffset(0, 100); // room above for popups

tests/tst_keyrepeater.cpp

@@ -0,0 +1,31 @@
+#include "input/KeyRepeater.h"
+
+#include <QSignalSpy>
+#include <QTest>
+
+class TestKeyRepeater : public QObject
+{
+    Q_OBJECT
+
+private Q_SLOTS:
+    void repeatsThenSwitchesToWords()
+    {
+        KeyRepeater repeater({.initialDelayMs = 50, .intervalMs = 10, .wordModeAfterMs = 150, .wordIntervalMs = 20});
+        QSignalSpy spy(&repeater, &KeyRepeater::repeat);
+        repeater.start();
+
+        QTest::qWait(40);
+        QCOMPARE(spy.count(), 0); // still in the initial delay
+        QTRY_VERIFY(spy.count() >= 3);
+        QCOMPARE(spy.first().first().toBool(), false);
+        QTRY_VERIFY(spy.last().first().toBool()); // word mode eventually
+
+        repeater.stop();
+        const auto count = spy.count();
+        QTest::qWait(60);
+        QCOMPARE(spy.count(), count);
+    }
+};
+
+QTEST_GUILESS_MAIN(TestKeyRepeater)
+#include "tst_keyrepeater.moc"

tests/tst_textrules.cpp

@@ -0,0 +1,53 @@
+#include "input/TextRules.h"
+
+#include <QTest>
+
+using namespace Qt::StringLiterals;
+
+class TestTextRules : public QObject
+{
+    Q_OBJECT
+
+private Q_SLOTS:
+    void startsSentence_data()
+    {
+        QTest::addColumn<QString>("text");
+        QTest::addColumn<bool>("expected");
+        QTest::newRow("empty") << QString() << true;
+        QTest::newRow("after period and space") << u"Hi. "_s << true;
+        QTest::newRow("after question, two spaces") << u"Why?  "_s << true;
+        QTest::newRow("after newline") << u"Hi\n"_s << true;
+        QTest::newRow("only spaces") << u"  "_s << true;
+        QTest::newRow("period without space") << u"Hi."_s << false;
+        QTest::newRow("mid sentence") << u"Hi there "_s << false;
+        QTest::newRow("after comma") << u"Hi, "_s << false;
+        QTest::newRow("mid word") << u"Hel"_s << false;
+    }
+
+    void startsSentence()
+    {
+        QFETCH(QString, text);
+        QFETCH(bool, expected);
+        QCOMPARE(TextRules::startsSentence(text), expected);
+    }
+
+    void doubleSpacePeriod()
+    {
+        QVERIFY(TextRules::wantsDoubleSpacePeriod(u"word "_s));
+        QVERIFY(TextRules::wantsDoubleSpacePeriod(u"42 "_s));
+        QVERIFY(!TextRules::wantsDoubleSpacePeriod(u"word. "_s));
+        QVERIFY(!TextRules::wantsDoubleSpacePeriod(u"word  "_s));
+        QVERIFY(!TextRules::wantsDoubleSpacePeriod(u" "_s));
+    }
+
+    void deletion()
+    {
+        QCOMPARE(TextRules::withoutLastCharacter(u"ab"_s), u"a");
+        QCOMPARE(TextRules::withoutLastCharacter(u"a👍"_s), u"a");
+        QCOMPARE(TextRules::withoutLastWord(u"one two  "_s), u"one ");
+        QCOMPARE(TextRules::withoutLastWord(u"one"_s), QString());
+    }
+};
+
+QTEST_GUILESS_MAIN(TestTextRules)
+#include "tst_textrules.moc"