feat(filters): put the four built-in filters on the query row

Item 93, the UI half. Unread, Inbox, Flagged and Sent are buttons the
application ships, sitting first on the row, ahead of the user's pinned saved
queries.

runFilter() is runSavedQuery()'s opposite in the one way that matters: it READS
the account box and never writes it. That is item 90's defect. A filter narrows
what the user is already looking at, so the dropdown is its input rather than
something it resets on the way past. A saved query keeps setting the account
from what it stored, because it is a destination and states its own scope.

runQuery() gains an AccountScope parameter. A filter's text arrives already
resolved in the selected account's scope, and scoping it again would put
path:"work/Sent/**" inside path:"work/**".

Two migration changes, both of which unpin rather than delete:

- Sent is no longer migrated from the INI into queries.json. The built-in
  filter covers it, and migrating one too would put two Sent buttons on the
  row, one editable and one not.
- A stored entry naming a known generator is unpinned on load, which is what
  every install upgraded through 0.19.0 carries. It keeps its name and its
  generator and moves to the menu. Deleting it would be data loss on a file
  whose readers are supposed to preserve what they do not own.

The test suite needed the same distinction the design makes.
savedQueryButtonLabels() now skips the filters, and savedQueryButton(window,
label) replaces five positional row->findChild<QPushButton *>() lookups that
were silently returning Unread.

One rendering probe had to be fixed rather than adapted.
replyRowsKeepTheirTextUnderTheThreadLine resized the window to 300px, and four
more buttons pushed the reply row below the viewport: the pixel loop then ran
zero times and reported "0 pixels, the row was painted over", which is a
different defect from the one it exists to catch. It gets 600px and a guard
asserting the row is really inside the viewport, so the next person to shrink
it gets told the truth. Verified by putting 300 back: the guard names the row
at 83..165 in an 82px viewport.

2 files changed, 390 insertions, 31 deletions

diff --git a/tests/test_config.cpp b/tests/test_config.cpp
index 895495d..6c1815c 100644
--- a/tests/test_config.cpp
+++ b/tests/test_config.cpp
@@ -95,6 +95,7 @@ private slots:
     void allSentQueryIsEmptyWhenNoAccountHasOne();
     void allSentQuerySkipsAccountsWithoutTheKey();
     void allSentQueryJoinsEveryConfiguredAccount();
+    void aStoredGeneratedQueryIsUnpinnedNotDropped();
     void everyBuiltinFilterIsAKnownGenerator();
     void aFilterAcrossAllAccountsIsTheUnscopedQuery();
     void aTagFilterScopedToAnAccountCarriesThatAccountsPath();
@@ -1463,6 +1464,55 @@ void TestConfig::jsonWinsOnceItExists()
     QCOMPARE(queries.at(0).name, QStringLiteral("FromTheJson"));
 }
 
+void TestConfig::aStoredGeneratedQueryIsUnpinnedNotDropped()
+{
+    // An existing install carries a Sent entry in queries.json: 0.19.0 migrated
+    // the hardcoded button into one. Item 93 ships Sent as a built-in filter,
+    // so that stored entry is now a DUPLICATE and would put two Sent buttons on
+    // the row, one editable and one not.
+    //
+    // Unpinned rather than deleted. This file's whole design is that a reader
+    // preserves what it does not own, and the user's instruction for their own
+    // redundant queries was the same: fold them into the menu, do not drop
+    // them. An unpin is reversible from the UI; a delete is not.
+    QTemporaryDir dir;
+    const QString path = writeIni(dir, QStringLiteral(
+        "[account.work]\n"
+        "maildir=work\n"
+        "sent=Sent\n"));
+    writeQueries(dir, QStringLiteral(R"({
+        "version": 1,
+        "queries": [
+            { "name": "Sent", "generated": "sent", "pinned": true },
+            { "name": "Mine", "query": "tag:todo", "pinned": true }
+        ]
+    })"));
+
+    Config config;
+    config.load(path);
+
+    const QList<SavedQuery> queries = config.savedQueries();
+    QCOMPARE(queries.size(), 2);
+
+    bool sawSent = false;
+    for (const SavedQuery &query : queries) {
+        if (query.generated != QStringLiteral("sent"))
+            continue;
+        sawSent = true;
+        QVERIFY2(!query.pinned,
+                 "the stored Sent entry is still a button beside the built-in "
+                 "filter of the same name");
+    }
+    QVERIFY2(sawSent, "the stored Sent entry was DROPPED rather than unpinned");
+
+    // The user's own query is untouched: only the entry duplicating a built-in
+    // filter is unpinned.
+    for (const SavedQuery &query : queries) {
+        if (query.name == QStringLiteral("Mine"))
+            QVERIFY2(query.pinned, "an unrelated pinned query was unpinned");
+    }
+}
+
 void TestConfig::malformedQueriesFileIsAProblemNotACrash()
 {
     QTemporaryDir dir;
@@ -1676,13 +1726,24 @@ void TestConfig::migrationAddsSentWhenAnAccountHasOne()
     Config config;
     config.load(path);
 
+    // The migration used to invent a generated Sent entry here, so the
+    // hardcoded button could be reordered, renamed or removed like any other
+    // row. Item 93 ships Sent as one of four BUILT-IN filters instead, so
+    // migrating one as well would put two Sent buttons on the row: one the
+    // user's to edit and one not.
+    //
+    // Nothing is lost. The built-in resolves through the same generator, so it
+    // still follows the accounts, and it now composes with the account dropdown
+    // rather than resetting it.
     const QList<SavedQuery> queries = config.savedQueries();
-    QCOMPARE(queries.size(), 2);
-    // Last, where the button already sat: after the saved queries.
-    QCOMPARE(queries.at(1).name, QStringLiteral("Sent"));
-    QVERIFY(queries.at(1).isGenerated());
-    QVERIFY(queries.at(1).pinned);
-    QVERIFY(queries.at(1).flat);
+    QCOMPARE(queries.size(), 1);
+    QCOMPARE(queries.at(0).name, QStringLiteral("Inbox"));
+
+    for (const SavedQuery &query : queries) {
+        QVERIFY2(!query.isGenerated(),
+                 "the migration invented a generated entry that now duplicates "
+                 "a built-in filter");
+    }
 }
 
 /// Today the button is hidden entirely when no account configures a sent
diff --git a/tests/test_mainwindow.cpp b/tests/test_mainwindow.cpp
index 228a0bc..4cc9954 100644
--- a/tests/test_mainwindow.cpp
+++ b/tests/test_mainwindow.cpp
@@ -169,6 +169,13 @@ private slots:
     void narrowingAnEmptyQueryBarIsAPlainSearch();
     void aMalformedAccountIsReportedWithoutBlockingTheConstructor();
     void aWorkerBackedWindowReturnsRealThreads();
+    void theFourBuiltinFiltersAreOnTheRowInOrder();
+    void aFilterComposesWithTheSelectedAccount();
+    void aFilterAcrossAllAccountsIsUnscoped();
+    void aFilterDoesNotClearTheAccountSelection();
+    void aSavedQueryStillClearsTheAccountSelection();
+    void aFilterOffersNoEditOrDeleteActions();
+    void changingTheAccountRunsNothing();
     void arrivingBatchesUpdateTheStatusBarWithTheCountSoFar();
     void aRefreshsBatchesLeaveTheStatusBarAlone();
     void selectingAThreadRootShowsItInTheMessagePane();
@@ -1596,7 +1603,11 @@ void TestMainWindow::replyRowsKeepTheirTextUnderTheThreadLine()
     reply.depth = 1;
     model->setThreadMessages(QStringLiteral("t1"), { first, reply });
 
-    window.resize(1400, 300);
+    // 600, not 300. The query row carries four built-in filter buttons since
+    // item 93, and at 300 the reply row was pushed below the viewport: the
+    // pixel loop then ran zero times and reported "0 pixels, the row was
+    // painted over", which is a different defect from the one that existed.
+    window.resize(1400, 600);
     window.show();
     QVERIFY(QTest::qWaitForWindowExposed(&window));
 
@@ -1609,6 +1620,21 @@ void TestMainWindow::replyRowsKeepTheirTextUnderTheThreadLine()
     const QRect rect = view->visualRect(child);
     QVERIFY2(rect.height() > 0, "the reply row is not on screen");
 
+    // visualRect reports a height for a row scrolled out of the viewport, so
+    // the check above passes while the loop below has nothing to walk. Assert
+    // the rect is really inside the image, or this measures nothing and says
+    // the row was painted over.
+    QVERIFY2(rect.top() >= 0
+                 && rect.bottom() < view->viewport()->height()
+                 && rect.left() >= 0
+                 && rect.right() <= view->viewport()->width(),
+             qPrintable(QStringLiteral("the reply row at %1..%2 is outside the "
+                                       "%3px viewport, so the pixel count "
+                                       "below would measure nothing")
+                            .arg(rect.top())
+                            .arg(rect.bottom())
+                            .arg(view->viewport()->height())));
+
     QImage shot(view->viewport()->size(), QImage::Format_ARGB32);
     shot.fill(Qt::transparent);
     view->viewport()->render(&shot);
@@ -5464,6 +5490,19 @@ static void loadWithQueries(Config &config, QTemporaryDir &dir,
 }
 
 /// Buttons in the saved-query row, by label, in the order they are laid out.
+/// Whether this is one of the four shipped filters rather than a saved query.
+///
+/// By object name, not by label: the labels are translated, and a user may name
+/// their own query "Unread" too.
+static bool isBuiltinFilterButton(QPushButton *button)
+{
+    for (const SavedQuery &filter : Config::builtinFilters()) {
+        if (button->objectName() == filter.generated + QStringLiteral("Button"))
+            return true;
+    }
+    return false;
+}
+
 static QStringList savedQueryButtonLabels(MainWindow &window)
 {
     QStringList labels;
@@ -5474,12 +5513,40 @@ static QStringList savedQueryButtonLabels(MainWindow &window)
         row->findChildren<QPushButton *>(QString(), Qt::FindDirectChildrenOnly);
     for (QPushButton *button : buttons) {
         // The menu button is not a saved query and must not be counted as one.
-        if (button->objectName() != QStringLiteral("savedQueryMenuButton"))
-            labels.append(button->text());
+        if (button->objectName() == QStringLiteral("savedQueryMenuButton"))
+            continue;
+        // Neither are the four built-in filters (item 93), which sit first on
+        // the row and are not in queries.json at all. Every caller of this
+        // helper is asking about the USER's queries, so counting the filters
+        // would make each of them assert on a number it does not care about.
+        if (isBuiltinFilterButton(button))
+            continue;
+        labels.append(button->text());
     }
     return labels;
 }
 
+/// The user's own pinned button carrying `label`, or null.
+///
+/// Positional lookup does not work any more: the built-in filters occupy the
+/// first four places on the row, so row->findChild<QPushButton *>() returns
+/// Unread rather than the query a test means.
+static QPushButton *savedQueryButton(MainWindow &window, const QString &label)
+{
+    auto *row = window.findChild<QWidget *>(QStringLiteral("savedQueryRow"));
+    if (!row)
+        return nullptr;
+    const QList<QPushButton *> buttons =
+        row->findChildren<QPushButton *>(QString(), Qt::FindDirectChildrenOnly);
+    for (QPushButton *button : buttons) {
+        if (isBuiltinFilterButton(button))
+            continue;
+        if (button->text() == label)
+            return button;
+    }
+    return nullptr;
+}
+
 void TestMainWindow::onlyPinnedQueriesBecomeButtons()
 {
     QTemporaryDir dir;
@@ -5625,7 +5692,7 @@ void TestMainWindow::aScopedSavedQuerySelectsItsAccount()
 
     auto *row = window.findChild<QWidget *>(QStringLiteral("savedQueryRow"));
     QVERIFY(row);
-    auto *button = row->findChild<QPushButton *>();
+    auto *button = savedQueryButton(window, QStringLiteral("Billing"));
     QVERIFY(button);
     button->click();
 
@@ -5667,7 +5734,7 @@ void TestMainWindow::anUnscopedSavedQueryClearsTheAccount()
 
     auto *row = window.findChild<QWidget *>(QStringLiteral("savedQueryRow"));
     QVERIFY(row);
-    auto *button = row->findChild<QPushButton *>();
+    auto *button = savedQueryButton(window, QStringLiteral("Everywhere"));
     QVERIFY(button);
     button->click();
 
@@ -5888,13 +5955,31 @@ void TestMainWindow::aRenamedSentEntryKeepsWorking()
     })"), oneAccountWithSent());
 
     MainWindow window(config);
-    const QStringList labels = savedQueryButtonLabels(window);
-    QCOMPARE(labels, QStringList{ QStringLiteral("Posta inviata") });
 
+    // The renamed entry is UNPINNED on load now, because item 93 ships Sent as
+    // a built-in filter and two Sent buttons on the row, one editable and one
+    // not, is worse than one of each in its own place. It keeps its name, it
+    // keeps working, and it is in the menu rather than on the row.
+    QVERIFY2(savedQueryButtonLabels(window).isEmpty(),
+             "a stored generated entry is still a button beside the built-in "
+             "filter that duplicates it");
+
+    bool found = false;
+    for (const SavedQuery &saved : config.savedQueries()) {
+        if (saved.name != QStringLiteral("Posta inviata"))
+            continue;
+        found = true;
+        QVERIFY2(saved.isGenerated(),
+                 "the entry lost its generator when renamed");
+        QVERIFY2(!saved.pinned, "the entry was not unpinned");
+    }
+    QVERIFY2(found, "the renamed entry was DROPPED rather than unpinned");
+
+    // The built-in Sent still resolves the same query, so nothing the user
+    // could reach before became unreachable.
     auto *button =
         window.findChild<QPushButton *>(QStringLiteral("sentButton"));
-    QVERIFY2(button, "the generated entry lost its identity when renamed");
-
+    QVERIFY(button);
     auto *queryEdit =
         window.findChild<QLineEdit *>(QStringLiteral("queryEdit"));
     button->click();
@@ -5969,7 +6054,7 @@ void TestMainWindow::aSavedQueryButtonOffersEditUnpinAndDelete()
     MainWindow window(config);
     auto *row = window.findChild<QWidget *>(QStringLiteral("savedQueryRow"));
     QVERIFY(row);
-    auto *button = row->findChild<QPushButton *>();
+    auto *button = savedQueryButton(window, QStringLiteral("Inbox"));
     QVERIFY(button);
 
     // A context menu, so the actions live on the widget itself.
@@ -6017,14 +6102,11 @@ void TestMainWindow::onlyAStoredQueryOffersToBecomeATaggingRule()
     auto *generated = row->findChild<QPushButton *>(
         QStringLiteral("sentButton"));
 
-    QPushButton *stored = nullptr;
-    const QList<QPushButton *> buttons = row->findChildren<QPushButton *>();
-    for (QPushButton *button : buttons) {
-        if (button->text().contains(QStringLiteral("Inbox"))) {
-            stored = button;
-            break;
-        }
-    }
+    // savedQueryButton(), not a scan for the label: item 93 puts a BUILT-IN
+    // Inbox filter on the row too, and it carries no context actions by design,
+    // so a scan finds that one and the assertion below fails against correct
+    // code.
+    QPushButton *stored = savedQueryButton(window, QStringLiteral("Inbox"));
 
     QVERIFY2(stored, "no button was built for the stored query");
     QVERIFY2(generated, "no button was built for the generated query");
@@ -6035,11 +6117,14 @@ void TestMainWindow::onlyAStoredQueryOffersToBecomeATaggingRule()
                                  QStringLiteral("queryToRule")),
              "a generated query must not: its query is a snapshot");
 
-    // The guard proving the generated button HAS a menu, so the assertion
-    // above is about this one action and not about a button with no actions.
-    QVERIFY2(contextActionNamed(window, generated,
-                                QStringLiteral("deleteQuery")),
-             "the generated button must still carry its other actions");
+    // The guard, and it has moved since item 93. It used to prove the generated
+    // button HAS a menu, so the assertion above was about one action rather
+    // than about a button with none. `generated` is now the BUILT-IN Sent
+    // filter, which correctly carries no actions at all, so proving the
+    // machinery works has to happen on the button that does have them.
+    QVERIFY2(contextActionNamed(window, stored, QStringLiteral("deleteQuery")),
+             "the stored button lost its other actions, so the assertion above "
+             "is not about queryToRule in particular");
 }
 
 void TestMainWindow::unpinningMovesAQueryToTheMenu()
@@ -6062,7 +6147,7 @@ void TestMainWindow::unpinningMovesAQueryToTheMenu()
     QVERIFY(!window.findChild<QPushButton *>(
         QStringLiteral("savedQueryMenuButton")));
 
-    auto *button = row->findChild<QPushButton *>();
+    auto *button = savedQueryButton(window, QStringLiteral("Inbox"));
     QVERIFY(button);
     QAction *pin = contextActionNamed(window, button, QStringLiteral("pinQuery"));
     QVERIFY(pin);
@@ -6100,7 +6185,7 @@ void TestMainWindow::deletingRemovesTheQueryFromTheFile()
     MainWindow window(config);
     auto *row = window.findChild<QWidget *>(QStringLiteral("savedQueryRow"));
     QVERIFY(row);
-    auto *button = row->findChild<QPushButton *>();
+    auto *button = savedQueryButton(window, QStringLiteral("Doomed"));
     QVERIFY(button);
     QCOMPARE(button->text(), QStringLiteral("Doomed"));
 
@@ -6264,6 +6349,219 @@ void TestMainWindow::aWorkerBackedWindowReturnsRealThreads()
     QTRY_VERIFY_WITH_TIMEOUT(model->rowCount(QModelIndex()) == 1, 15000);
 }
 
+void TestMainWindow::theFourBuiltinFiltersAreOnTheRowInOrder()
+{
+    // Shipped, not pinned. Nothing in this config names a query, so a row with
+    // four buttons on it can only have got them from the built-in set: before
+    // item 93 a fresh install had an empty query row.
+    QTemporaryDir dir;
+    QVERIFY(dir.isValid());
+    Config config;
+    config.load(writeSentConfig(dir, {
+        {QStringLiteral("work"), QStringLiteral("Sent")},
+    }));
+
+    MainWindow window(config);
+    auto *row = window.findChild<QWidget *>(QStringLiteral("savedQueryRow"));
+    QVERIFY(row);
+
+    QStringList labels;
+    for (QPushButton *button : row->findChildren<QPushButton *>()) {
+        // The overflow menu is a control over the set, not a member of it.
+        if (button->objectName() == QStringLiteral("savedQueryMenuButton"))
+            continue;
+        labels.append(button->text());
+    }
+
+    QCOMPARE(labels, (QStringList{ QStringLiteral("Unread"),
+                                   QStringLiteral("Inbox"),
+                                   QStringLiteral("Flagged"),
+                                   QStringLiteral("Sent") }));
+}
+
+void TestMainWindow::aFilterComposesWithTheSelectedAccount()
+{
+    // Item 90, and the whole point of item 93. Select an account, hit Unread,
+    // and get that account's unread mail rather than everyone's.
+    QTemporaryDir dir;
+    QVERIFY(dir.isValid());
+    Config config;
+    config.load(writeSentConfig(dir, {
+        {QStringLiteral("work"), QStringLiteral("Sent")},
+        {QStringLiteral("personal"), QStringLiteral("Sent")},
+    }));
+
+    MainWindow window(config);
+    auto *queryEdit = window.findChild<QLineEdit *>(QStringLiteral("queryEdit"));
+    QVERIFY(queryEdit);
+
+    window.selectAccountForTesting(QStringLiteral("work"));
+    QCOMPARE(window.selectedAccountForTesting(), QStringLiteral("work"));
+
+    auto *unread =
+        window.findChild<QPushButton *>(QStringLiteral("unreadButton"));
+    QVERIFY2(unread, "no built-in Unread button");
+    unread->click();
+
+    QCOMPARE(queryEdit->text(),
+             QStringLiteral("path:\"work/**\" and (tag:unread)"));
+
+    // Sent under the same account is the account's OWN folder, not the union
+    // wrapped in a scope. See the Config test of the same name for why a row
+    // count cannot tell the two apart.
+    auto *sent = window.findChild<QPushButton *>(QStringLiteral("sentButton"));
+    QVERIFY(sent);
+    sent->click();
+    QCOMPARE(queryEdit->text(), QStringLiteral("path:\"work/Sent/**\""));
+    QVERIFY2(!queryEdit->text().contains(QStringLiteral("personal")),
+             "another account's sent folder leaked into a scoped Sent filter");
+}
+
+void TestMainWindow::aFilterAcrossAllAccountsIsUnscoped()
+{
+    QTemporaryDir dir;
+    QVERIFY(dir.isValid());
+    Config config;
+    config.load(writeSentConfig(dir, {
+        {QStringLiteral("work"), QStringLiteral("Sent")},
+    }));
+
+    MainWindow window(config);
+    auto *queryEdit = window.findChild<QLineEdit *>(QStringLiteral("queryEdit"));
+    QVERIFY(queryEdit);
+
+    // "All accounts" is the default selection, so this is the fresh state.
+    QVERIFY(window.selectedAccountForTesting().isEmpty());
+
+    auto *unread =
+        window.findChild<QPushButton *>(QStringLiteral("unreadButton"));
+    QVERIFY(unread);
+    unread->click();
+
+    QCOMPARE(queryEdit->text(), QStringLiteral("tag:unread"));
+}
+
+void TestMainWindow::aFilterDoesNotClearTheAccountSelection()
+{
+    // The defect item 90 filed: the button used to reset the dropdown to "All
+    // accounts" before running, so the selection was gone before the query ran.
+    // A filter leaves it exactly where the user put it.
+    QTemporaryDir dir;
+    QVERIFY(dir.isValid());
+    Config config;
+    config.load(writeSentConfig(dir, {
+        {QStringLiteral("work"), QStringLiteral("Sent")},
+    }));
+
+    MainWindow window(config);
+    window.selectAccountForTesting(QStringLiteral("work"));
+
+    auto *unread =
+        window.findChild<QPushButton *>(QStringLiteral("unreadButton"));
+    QVERIFY(unread);
+    unread->click();
+
+    QCOMPARE(window.selectedAccountForTesting(), QStringLiteral("work"));
+}
+
+void TestMainWindow::aSavedQueryStillClearsTheAccountSelection()
+{
+    // The other half of the design, and the reason item 90 was not fixed in
+    // place. A saved query is a DESTINATION: it states its own scope, so an
+    // unscoped one clears the selection rather than inheriting it. That is the
+    // behaviour the rules preview depends on and it must survive item 93.
+    QTemporaryDir dir;
+    QVERIFY(dir.isValid());
+    Config config;
+    const QString path = writeSentConfig(dir, {
+        {QStringLiteral("work"), QStringLiteral("Sent")},
+    });
+    {
+        QSettings s(path, QSettings::IniFormat);
+        s.beginGroup(QStringLiteral("queries"));
+        s.setValue(QStringLiteral("Mine"), QStringLiteral("tag:todo"));
+        s.endGroup();
+        s.sync();
+    }
+    config.load(path);
+
+    MainWindow window(config);
+    window.selectAccountForTesting(QStringLiteral("work"));
+
+    // The migrated [queries] entry is pinned, so it is a button beside the
+    // filters. Found by its label, since only the filters have stable object
+    // names.
+    QPushButton *mine = nullptr;
+    auto *row = window.findChild<QWidget *>(QStringLiteral("savedQueryRow"));
+    QVERIFY(row);
+    for (QPushButton *button : row->findChildren<QPushButton *>()) {
+        if (button->text() == QStringLiteral("Mine"))
+            mine = button;
+    }
+    QVERIFY2(mine, "the user's own pinned query is not on the row");
+
+    mine->click();
+    QVERIFY2(window.selectedAccountForTesting().isEmpty(),
+             "an unscoped saved query no longer clears the account selection");
+}
+
+void TestMainWindow::aFilterOffersNoEditOrDeleteActions()
+{
+    // A filter is not the user's to edit, rename or delete: it is shipped, and
+    // it is not in queries.json at all. Offering the actions would produce a
+    // dialog that writes an entry the row does not read.
+    QTemporaryDir dir;
+    QVERIFY(dir.isValid());
+    Config config;
+    config.load(writeSentConfig(dir, {
+        {QStringLiteral("work"), QStringLiteral("Sent")},
+    }));
+
+    MainWindow window(config);
+    auto *unread =
+        window.findChild<QPushButton *>(QStringLiteral("unreadButton"));
+    QVERIFY(unread);
+
+    for (QAction *action : unread->actions()) {
+        QVERIFY2(action->objectName() != QStringLiteral("editQuery"),
+                 "a built-in filter offered Edit");
+        QVERIFY2(action->objectName() != QStringLiteral("pinQuery"),
+                 "a built-in filter offered a pin toggle");
+        QVERIFY2(action->objectName() != QStringLiteral("deleteQuery"),
+                 "a built-in filter offered Delete");
+    }
+}
+
+void TestMainWindow::changingTheAccountRunsNothing()
+{
+    // The user's decision, 2026-08-15: "changing the account should not run the
+    // query, hitting the button after changing the account is what queries."
+    // The dropdown selects scope; the button is the verb.
+    //
+    // Today m_accountBox has no signal connected at all, so this guards against
+    // wiring one up by reflex while making the filters compose.
+    QTemporaryDir dir;
+    QVERIFY(dir.isValid());
+    Config config;
+    config.load(writeSentConfig(dir, {
+        {QStringLiteral("work"), QStringLiteral("Sent")},
+    }));
+
+    MainWindow window(config);
+    auto *queryEdit = window.findChild<QLineEdit *>(QStringLiteral("queryEdit"));
+    QVERIFY(queryEdit);
+
+    // A known starting point, so "nothing happened" is distinguishable from
+    // "it was empty all along", which would pass against a re-run that clears.
+    queryEdit->setText(QStringLiteral("tag:todo"));
+    const quint64 before = window.currentGenerationForTesting();
+
+    window.selectAccountForTesting(QStringLiteral("work"));
+
+    QCOMPARE(queryEdit->text(), QStringLiteral("tag:todo"));
+    QCOMPARE(window.currentGenerationForTesting(), before);
+}
+
 void TestMainWindow::arrivingBatchesUpdateTheStatusBarWithTheCountSoFar()
 {
     // Item 74: "Searching..." was set once by runQuery and cleared only on