qml: virtualize debug log output

Author: johnny9

qml/components/DebugLogOutputView.qml

@@ -132,6 +132,11 @@ Page {
                 color: Theme.color.neutral9
                 placeholderTextColor: Theme.color.neutral5
                 placeholderText: qsTr("Search...")
+                // The page is unloaded whenever another Settings section is
+                // selected, while the C++ model intentionally retains its
+                // filter. Mirror that retained value on re-entry so the field
+                // and the rows cannot disagree.
+                text: debugLogModel.filter
                 verticalAlignment: TextInput.AlignVCenter
                 selectByMouse: true
                 Accessible.name: qsTr("Search debug log")
@@ -201,11 +206,13 @@ Page {
             topPadding: 10
             accessibleName: qsTr("Debug log entries")
             autoScrollToBottom: false
-            // DebugLogModel renders newest-first at the top, so y > 0 means
-            // "scrolled away from the newest entries" — which is exactly when
-            // the "N new entries" pill should be offered.
-            onScrolled: function(y) {
-                root.userIsScrolled = (y > 0)
+            // DebugLogModel renders newest-first at the top, so leaving the
+            // beginning is exactly when the "N new entries" pill applies.
+            onScrolled: function() {
+                // A ListView's content origin is not guaranteed to be zero,
+                // particularly with variable-height rows and incremental model
+                // changes. Its boundary state is the authoritative answer.
+                root.userIsScrolled = !logView.atTop
                 if (logView.atTop && root.pendingNewLines > 0) {
                     root.pendingNewLines = 0
                 }
@@ -220,6 +227,7 @@ Page {
             Layout.preferredHeight: 36
 
             TextButton {
+                objectName: "debugLogLoadMoreButton"
                 anchors.centerIn: parent
                 text: qsTr("Load more")
                 textSize: 13

qml/pages/settings/SettingsDebugLog.qml

@@ -6,9 +6,11 @@
 
 Walks through Settings → Debug Log and verifies:
   1. The viewer page loads with a visible search bar and log list.
-  2. The log list is non-empty (entries were actually loaded).
+  2. The initial load is capped while older entries remain available.
   3. Typing in the search field filters the list; clearing it restores
      the full count.
+  4. Auto-refresh replaces the capped tail without growing it unboundedly.
+  5. The list virtualizes offscreen rows and can load older rows on demand.
 
 This test requires the binary to be built with -DENABLE_TEST_AUTOMATION=ON.
 """
@@ -22,7 +24,11 @@
 import tempfile
 
 from qml_test_harness import GUI_STARTUP_TIMEOUT, dump_qml_tree, find_gui_binary, setup_datadir
-from qml_driver import QmlDriver, QmlDriverError
+from qml_driver import QmlDriver
+
+
+INITIAL_LOAD_LIMIT = 1000
+SEEDED_HISTORY_LINES = 1200
 
 
 def assert_close(actual, expected, label, tolerance=1):
@@ -43,6 +49,19 @@ def __init__(self):
         self.process = None
         self.driver = None
         self.datadir = setup_datadir(self.tmpdir)
+        self._seed_debug_log_history()
+
+    def _seed_debug_log_history(self):
+        """Create enough history to exercise the initial cap and Load more."""
+        network_dir = os.path.join(self.datadir, "regtest")
+        os.makedirs(network_dir, exist_ok=True)
+        log_path = os.path.join(network_dir, "debug.log")
+        with open(log_path, "w", encoding="utf-8") as f:
+            for i in range(SEEDED_HISTORY_LINES):
+                f.write(
+                    "2026-01-01T00:00:00Z "
+                    f"test-automation seeded-history marker {i}\n"
+                )
 
     def start(self):
         env = dict(os.environ)
@@ -114,10 +133,15 @@ def test_viewer_visibility(gui):
 
 
 def test_log_has_entries(gui):
-    """Verify that log entries were actually loaded into the list view."""
+    """Verify that the first snapshot is capped at 1,000 rows."""
     print("\n── test_log_has_entries ──────────────────────────────────────────")
-    count = gui.get_property("debugLogListView", "count")
-    assert count > 0, f"Expected log entries to be loaded, got count={count}"
+    count = gui.wait_for_property(
+        "debugLogListView", "count", INITIAL_LOAD_LIMIT, timeout_ms=5000
+    )
+    assert count == INITIAL_LOAD_LIMIT, (
+        f"Expected the initial load to be capped at {INITIAL_LOAD_LIMIT}, "
+        f"got count={count}"
+    )
     print(f"  PASSED: debugLogListView.count = {count}")
     return count
 
@@ -130,7 +154,6 @@ def test_search_layout_matches_design(gui):
     gui.wait_for_property("debugLogSearchDivider", "height", 1, timeout_ms=3000)
     gui.wait_for_property("debugLogListView", "topPadding", 10, timeout_ms=3000)
     gui.wait_for_property("debugLogListView_row_0", "visible", True, timeout_ms=3000)
-    gui.wait_for_property("debugLogListView_row_0", "y", 10, timeout_ms=3000)
     gui.wait_for_property("debugLogListView_lineNumber_0", "visible", True, timeout_ms=3000)
     gui.wait_for_property("debugLogListView_date_0", "visible", True, timeout_ms=3000)
 
@@ -147,6 +170,13 @@ def test_search_layout_matches_design(gui):
     divider_y = gui.get_property("debugLogSearchDivider", "y")
     divider_height = gui.get_property("debugLogSearchDivider", "height")
     list_y = gui.get_property("debugLogListView", "y")
+    first_row_viewport_y = (
+        gui.get_property("debugLogListView_row_0", "y")
+        - gui.get_property("debugLogListView", "contentY")
+    )
+    effective_line_number_width = gui.get_property(
+        "debugLogListView", "effectiveLineNumberWidth"
+    )
     page_width = gui.get_property("settingsDebugLog", "width")
     content_width = gui.get_property("debugLogContentLayout", "width")
     expected_content_width = max(0, min(page_width - 40, 600))
@@ -197,20 +227,24 @@ def test_search_layout_matches_design(gui):
                  "debug log entry command/content spacing")
     assert_close(gui.get_property("debugLogListView", "lineNumberWidth"), 20,
                  "debug log line number slot width")
-    assert_close(gui.get_property("debugLogListView", "effectiveLineNumberWidth"), 20,
-                 "debug log effective line number slot width")
+    assert effective_line_number_width >= 20, (
+        "Expected the effective line-number slot to honor its 20px minimum"
+    )
     assert_close(gui.get_property("debugLogListView", "fontPixelSize"), 12,
                  "debug log entry font size")
     assert_close(gui.get_property("debugLogListView", "textLineHeight"), 17,
                  "debug log entry line height")
-    assert_close(gui.get_property("debugLogListView_row_0", "y"), 10,
-                 "first debug log row y")
+    assert_close(first_row_viewport_y, 10,
+                 "first debug log row viewport y")
     assert_close(gui.get_property("debugLogListView_row_0", "spacing"), 10,
                  "first debug log row column gap")
     assert_close(gui.get_property("debugLogListView_entryContent_0", "spacing"), 2,
                  "first debug log entry internal gap")
-    assert_close(gui.get_property("debugLogListView_lineNumber_0", "width"), 20,
-                 "first debug log line number width")
+    assert_close(
+        gui.get_property("debugLogListView_lineNumber_0", "width"),
+        effective_line_number_width,
+        "first debug log line number width",
+    )
     first_text_object = (
         "debugLogListView_message_0"
         if first_row_has_command
@@ -236,46 +270,56 @@ def test_refresh_button(gui, original_count):
 
 
 def test_auto_refresh(gui, datadir, current_count):
-    """Appending to debug.log triggers auto-refresh and grows the entry count."""
+    """Appending refreshes the capped tail without exceeding its load limit."""
     print("\n── test_auto_refresh ─────────────────────────────────────────────")
     log_path = os.path.join(datadir, "regtest", "debug.log")
     ts = datetime.datetime.now(datetime.timezone.utc).strftime("%Y-%m-%dT%H:%M:%SZ")
     marker_body = "test-automation auto-refresh marker"
     marker = f"{ts} {marker_body}"
     with open(log_path, "a", encoding="utf-8") as f:
         f.write(marker + "\n")
-    try:
-        new_count = gui.wait_for_property(
-            "debugLogListView", "count", lambda c: c > current_count, timeout_ms=5000
-        )
-    except QmlDriverError:
-        gui.click("debugLogRefreshButton")
-        new_count = gui.wait_for_property(
-            "debugLogListView", "count", lambda c: c > current_count, timeout_ms=3000
-        )
-    assert new_count > current_count, (
-        f"Expected count to grow beyond {current_count} after appending to debug.log, "
-        f"got {new_count}"
-    )
-    print(f"  PASSED: count grew from {current_count} to {new_count} after file append")
 
+    # A capped model can insert the new row and remove one old row without
+    # changing count. Filter for the unique marker to observe the actual data
+    # update rather than treating row-count growth as the refresh signal.
     gui.set_text("debugLogSearchField", marker_body)
-    gui.wait_for_property("debugLogListView", "count", lambda c: c >= 1, timeout_ms=3000)
+    gui.wait_for_property("debugLogListView", "count", 1, timeout_ms=5000)
+    gui.wait_for_property(
+        "debugLogListView_commandlessMessage_0",
+        "text",
+        marker_body,
+        timeout_ms=3000,
+    )
+
     gui.wait_for_property("debugLogListView_command_0", "visible", False, timeout_ms=3000)
     gui.wait_for_property("debugLogListView_commandlessMessage_0", "visible", True, timeout_ms=3000)
-    gui.wait_for_property("debugLogListView_commandlessMessage_0", "text", marker_body, timeout_ms=3000)
     gui.wait_for_property("debugLogListView_message_0", "visible", False, timeout_ms=3000)
+    gui.invoke("debugLogListView_commandlessMessage_0", "selectAll")
+    gui.wait_for_property(
+        "debugLogListView_commandlessMessage_0",
+        "selectedText",
+        marker_body,
+        timeout_ms=3000,
+    )
     print("  PASSED: commandless log entry renders inline with the date")
 
     gui.set_text("debugLogSearchField", "")
     restored_count = gui.wait_for_property(
-        "debugLogListView", "count", lambda c: c >= new_count, timeout_ms=3000
+        "debugLogListView", "count", current_count, timeout_ms=3000
+    )
+    assert restored_count == INITIAL_LOAD_LIMIT, (
+        f"Expected auto-refresh to retain the {INITIAL_LOAD_LIMIT}-row cap, "
+        f"got {restored_count}"
+    )
+    print(
+        f"  PASSED: appended entry loaded and count remained capped at "
+        f"{restored_count}"
     )
     return restored_count
 
 
 def test_four_digit_line_numbers_are_not_clipped(gui, datadir, current_count):
-    """Verify the line-number column expands once visible numbers reach four digits."""
+    """Verify virtualized offscreen rows and the four-digit number column."""
     print("\n── test_four_digit_line_numbers_are_not_clipped ────────────────")
     target_count = 1000
     needed = max(0, target_count - current_count)
@@ -293,20 +337,63 @@ def test_four_digit_line_numbers_are_not_clipped(gui, datadir, current_count):
         f"Expected at least {target_count} lines after append, got {count}"
     )
 
-    gui.wait_for_property(
-        "debugLogListView_lineNumber_999", "text", str(target_count), timeout_ms=3000
-    )
-    line_number_width = gui.get_property("debugLogListView_lineNumber_999", "width")
-    line_number_implicit_width = gui.get_property(
-        "debugLogListView_lineNumber_999", "implicitWidth"
+    last_index = count - 1
+    last_line_number = f"debugLogListView_lineNumber_{last_index}"
+    gui.invoke("debugLogListView", "scrollToTop")
+    gui.wait_for_property("debugLogListView", "atTop", True, timeout_ms=3000)
+    assert not gui.object_exists(last_line_number), (
+        f"Expected offscreen row {last_index} not to be instantiated at the top"
     )
+
+    gui.invoke("debugLogListView", "scrollToBottom")
+    gui.wait_for_property("debugLogListView", "atBottom", True, timeout_ms=3000)
+    gui.wait_for_property(last_line_number, "text", str(count), timeout_ms=3000)
+    line_number_width = gui.get_property(last_line_number, "width")
+    line_number_implicit_width = gui.get_property(last_line_number, "implicitWidth")
     assert line_number_width >= line_number_implicit_width, (
         f"Expected four-digit line number width {line_number_width} to fit "
         f"implicit width {line_number_implicit_width}"
     )
     assert gui.get_property("debugLogListView", "effectiveLineNumberWidth") > 20, \
         "Expected effective line-number slot to expand beyond the design minimum"
-    print("  PASSED: four-digit line numbers fit expanded line-number slot")
+    print("  PASSED: offscreen rows are virtualized and four-digit line numbers fit")
+
+
+def test_load_more_at_bottom(gui, current_count):
+    """The bottom affordance appends older rows without moving the viewport."""
+    print("\n── test_load_more_at_bottom ───────────────────────")
+    gui.invoke("debugLogListView", "scrollToBottom")
+    gui.wait_for_property("debugLogListView", "atBottom", True, timeout_ms=3000)
+    gui.wait_for_property("debugLogLoadMoreButton", "visible", True, timeout_ms=3000)
+    content_y_before = gui.get_property("debugLogListView", "contentY")
+
+    gui.click("debugLogLoadMoreButton")
+    expanded_count = gui.wait_for_property(
+        "debugLogListView", "count", lambda c: c > current_count, timeout_ms=5000
+    )
+    content_y_after = gui.get_property("debugLogListView", "contentY")
+    assert_close(
+        content_y_after,
+        content_y_before,
+        "load-more viewport anchor",
+        tolerance=2,
+    )
+    gui.wait_for_property("debugLogLoadMoreButton", "visible", False, timeout_ms=3000)
+
+    oldest_index = expanded_count - 1
+    oldest_message = f"debugLogListView_commandlessMessage_{oldest_index}"
+    gui.invoke("debugLogListView", "scrollToBottom")
+    gui.wait_for_property(
+        oldest_message,
+        "text",
+        "test-automation seeded-history marker 0",
+        timeout_ms=3000,
+    )
+    print(
+        f"  PASSED: loaded {expanded_count - current_count} older rows without "
+        "moving the viewport, including the oldest seeded row"
+    )
+    return expanded_count
 
 
 def test_close_settings(gui):
@@ -363,9 +450,10 @@ def run_tests():
         total = test_log_has_entries(gui)
         test_search_layout_matches_design(gui)
         test_search_filter(gui, total)
-        total = test_refresh_button(gui, total)
         total = test_auto_refresh(gui, harness.datadir, total)
+        total = test_refresh_button(gui, total)
         test_four_digit_line_numbers_are_not_clipped(gui, harness.datadir, total)
+        total = test_load_more_at_bottom(gui, total)
         test_close_settings(gui)
 
         print("\n" + "=" * 50)

test/functional/qml_test_debug_log.py

@@ -14,6 +14,7 @@
         <file>tst_createpassword.qml</file>
         <file>tst_createtypeselector.qml</file>
         <file>tst_createwalletwizard.qml</file>
+        <file>tst_debuglogoutputview.qml</file>
         <file>tst_desktopwallets.qml</file>
         <file>tst_displaysettings.qml</file>
         <file>tst_dropdownbutton.qml</file>