fix(layout): preserve explicit width when resizing a single column

docs/user/layout.md

@@ -94,7 +94,7 @@ expand_single_column = true
 | `default_width_fraction` | float | unset | Initial strip-axis extent for new columns (0.1-1.0). The packaged config sets `0.5`; a matching output or workspace rule can override it. When it is unset at every level, the client chooses its initial extent. |
 | `center_underfull_strip` | bool | `true` | Center the complete strip when it is shorter than the viewport. Disable to align it at the start edge. |
 | `center_focused` | bool | `false` | Always center the focused column. |
-| `expand_single_column` | bool | `false` | Fill the viewport for a workspace's lone tiled column. Client size hints and viewport bounds still apply. The packaged config enables this. |
+| `expand_single_column` | bool | `false` | Fill the viewport for a workspace's lone tiled column until its width is explicitly changed. Client size hints and viewport bounds still apply. The packaged config enables this. |
 
 ### Horizontal and vertical scrolling
 
@@ -154,10 +154,12 @@ does not resize existing columns, and a column moved to another output retains
 its stored fraction. Re-tiling a floating window or expelling a window into a
 new column creates a column using the current default.
 
-`expand_single_column` affects only how a lone tiled column is displayed. It
-does not rewrite the stored fraction, so the configured or client-selected
-width applies again when a second column appears. Explicit
-`default_maximize` and `default_maximize_to_edges` window rules take precedence.
+`expand_single_column` initially fills the viewport without rewriting the
+column's stored fraction. Explicitly resizing the column, cycling its width, or
+setting its width disables automatic expansion for that column. Otherwise, the
+configured or client-selected width applies again when a second column appears.
+Explicit `default_maximize` and `default_maximize_to_edges` window rules take
+precedence.
 
 When focus moves to a hidden or partially hidden column, Umbriel reveals it by
 the shortest distance needed to show it completely. A column entering from the

docs/user/workspaces.md

@@ -172,7 +172,7 @@ Strut edges are resolved independently. A rule that sets only
 | `layout.scrolling.center_underfull_strip` | bool | Center the complete strip whenever it is narrower than the viewport. Disable to left-align underfull strips. |
 | `layout.scrolling.center_focused` | bool | Always center the focused column, including when the setting changes on config reload. |
 | `layout.scrolling.direction` | string | `"horizontal"` or `"vertical"` scroll axis. |
-| `layout.scrolling.expand_single_column` | bool | Fill the viewport for a workspace's lone tiled column, subject to client size hints and viewport bounds. Disable to keep the configured/default width. |
+| `layout.scrolling.expand_single_column` | bool | Fill the viewport for a workspace's lone tiled column until its width is explicitly changed. Client size hints and viewport bounds still apply. Disable to always keep the configured/default width. |
 | `layout.master.position` | string | Side occupied by the master area: `"left"` or `"right"`. |
 | `layout.master.default_width_fraction` | float | Master area fraction when both areas exist (0.1-0.9). |
 | `layout.master.new_on_top` | bool | Place newly opened windows at the top of the stack. Disable to place them at the bottom. |

examples/config.toml

@@ -412,7 +412,7 @@ bottom = 0
 default_width_fraction = 0.5                    # Initial width for new columns, 0.1-1.0
 center_underfull_strip = true                   # Center a strip narrower than the viewport
 center_focused = false                          # Always center the focused column
-expand_single_column = true                     # Let a lone column fill the viewport
+expand_single_column = true                     # Fill a lone column until its width is explicitly changed
 
 [layout.dwindle]
 # preserve_split = false                        # Keep every split direction fixed after creation

src/layout/layout.h

@@ -120,6 +120,7 @@ namespace umbriel {
     double bottomGapWeight = 0.0;
     double widthFrac = 0.5;
     double savedWidthFrac = 0.0;
+    bool autoExpand = true;
   };
 
   struct LayoutTarget {

src/layout/scrolling.cpp

@@ -31,6 +31,7 @@ namespace umbriel {
         double bottomGapWeight = 0.0;
         double widthFraction = 0.5;
         double savedWidthFraction = 0.0;
+        bool autoExpand = true;
         double viewportCenterFraction = 0.5;
       };
 
@@ -167,6 +168,7 @@ namespace umbriel {
           .bottomGapWeight = column.bottomGapWeight,
           .widthFraction = column.widthFrac,
           .savedWidthFraction = column.savedWidthFrac,
+          .autoExpand = column.autoExpand,
           .viewportCenterFraction = 0.5,
       };
       if (viewportPrimary > 0) {
@@ -222,6 +224,7 @@ namespace umbriel {
           .bottomGapWeight = saved.bottomGapWeight,
           .widthFrac = saved.widthFraction,
           .savedWidthFrac = saved.savedWidthFraction,
+          .autoExpand = saved.autoExpand,
       };
       for (const ScrollingSnapshot::Row& row : saved.rows) {
         View* view = (*resolved)[static_cast<size_t>(row.member)];
@@ -309,7 +312,7 @@ namespace umbriel {
       return std::max(1, viewportPrimary + 2 * edgePad);
     }
     int width = 0;
-    if (m_columns.size() == 1 && expandSingleColumn()) {
+    if (m_columns.size() == 1 && expandSingleColumn() && column.autoExpand) {
       // Fill the viewport without touching the stored fraction. Client size hints still apply to tiled columns.
       width = viewportPrimary;
     } else {
@@ -346,6 +349,14 @@ namespace umbriel {
     return true;
   }
 
+  bool ScrollingLayout::setUserWidthFraction(int columnIndex, double fraction) {
+    if (!setWidthFraction(columnIndex, fraction)) {
+      return false;
+    }
+    m_columns[static_cast<size_t>(columnIndex)].autoExpand = false;
+    return true;
+  }
+
   int ScrollingLayout::centeringOffset(int viewportPrimary) const {
     if (!m_config->scrolling.centerUnderfullStrip) {
       return 0;
@@ -792,6 +803,7 @@ namespace umbriel {
     Column& column = m_columns[static_cast<size_t>(columnIndex)];
     column.widthFrac = nextFractionPreset(m_config->widthPresets, column.widthFrac, direction);
     column.savedWidthFrac = 0.0;
+    column.autoExpand = false;
     return true;
   }
 
@@ -800,6 +812,7 @@ namespace umbriel {
       return false;
     }
     Column& column = m_columns[static_cast<size_t>(columnIndex)];
+    column.autoExpand = false;
     if (column.savedWidthFrac > 0.0) {
       column.widthFrac = column.savedWidthFrac;
       column.savedWidthFrac = 0.0;
@@ -1022,7 +1035,7 @@ namespace umbriel {
         const int gap = layout.layoutConfig()->totalGap;
         auto setColumnPrimaryPx = [&](int columnIndex, int extent) {
           const double fraction = static_cast<double>(extent + gap) / static_cast<double>(viewportPrimary + gap);
-          layout.setWidthFraction(columnIndex, fraction);
+          layout.setUserWidthFraction(columnIndex, fraction);
         };
         const bool centerUnderfullStrip =
             m_startStripPrimaryPx < viewportPrimary && layout.layoutConfig()->scrolling.centerUnderfullStrip;

src/layout/scrolling.h

@@ -34,6 +34,7 @@ namespace umbriel {
     [[nodiscard]] int columnX(int columnIndex, int viewportPrimary) const;
     [[nodiscard]] int columnWidth(int columnIndex, int viewportPrimary) const;
     bool setWidthFromPixels(int columnIndex, int viewportPrimary, int width);
+    bool setUserWidthFraction(int columnIndex, double fraction);
     [[nodiscard]] bool isFullWidth(int columnIndex) const override;
     [[nodiscard]] int maxScroll(int viewportPrimary) const {
       return std::max(0, totalWidth(viewportPrimary) - viewportPrimary);

src/workspace/workspace.cpp

@@ -1133,7 +1133,9 @@ namespace umbriel {
       m_focusedView->setMaximizedToEdges(false);
     }
     const int column = m_layout->columnOf(m_focusedView);
-    if (!m_layout->setWidthFraction(column, fraction)) {
+    const bool changed = scrollingLayout() != nullptr ? scrollingLayout()->setUserWidthFraction(column, fraction)
+                                                      : m_layout->setWidthFraction(column, fraction);
+    if (!changed) {
       return false;
     }
     wlr_xdg_toplevel_set_maximized(m_focusedView->toplevel(), false);

tests/harness/checks/517_expand_single_resize.sh

@@ -0,0 +1,45 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+readonly BTN_RIGHT=273
+readonly OUTPUT_W=1280
+readonly OUTPUT_H=720
+readonly POINTER="${UMBRIEL_POINTER_CLIENT:-./build-debug/tests/pointer-client}"
+
+cat >> "$UMBRIEL_CONFIG" <<'EOF'
+[animation]
+enabled = false
+[layout.scrolling]
+expand_single_column = true
+center_underfull_strip = true
+EOF
+"$UMBRIEL" msg config-reload > /dev/null
+
+foot --title=expand-single-resize sh -c 'sleep 120' > /dev/null 2>&1 &
+for _ in $(seq 60); do
+  window=$("$UMBRIEL" windows --json | jq -c '.[] | select(.title == "expand-single-resize")')
+  [[ -n $window ]] && break
+  sleep 0.1
+done
+if [[ -z ${window:-} ]]; then
+  echo "timed out waiting for expand-single-resize"
+  exit 1
+fi
+
+before=$window
+"$POINTER" "$OUTPUT_W" "$OUTPUT_H" \
+  move "$(jq -r '.x + .w - 20 | floor' <<< "$before")" "$(jq -r '.y + .h / 2 | floor' <<< "$before")" \
+  mod logo press "$BTN_RIGHT" move 1000 360 release "$BTN_RIGHT" mod none
+
+for _ in $(seq 60); do
+  after=$("$UMBRIEL" windows --json | jq -c '.[] | select(.title == "expand-single-resize")')
+  [[ $(jq -r '.w' <<< "$after") -lt $(jq -r '.w' <<< "$before") ]] && break
+  sleep 0.1
+done
+
+if [[ $(jq -r '.w' <<< "$after") -ge $(jq -r '.w' <<< "$before") ]]; then
+  echo "right-edge drag did not shrink the expanded lone column: before=$before after=$after"
+  exit 1
+fi
+
+echo "right-edge drag resized an automatically expanded lone column: before=$(jq -r '.w' <<< "$before") after=$(jq -r '.w' <<< "$after")"

tests/unit/scrolling_layout.cpp

@@ -314,6 +314,14 @@ UMBRIEL_TEST(expandSingleColumnTrueFillsALoneColumn) {
   CHECK_EQ(fixture.layout.columnWidth(0, kViewport), kViewport);
 }
 
+UMBRIEL_TEST(expandSingleColumnSurvivesInitialWidthSeeding) {
+  Fixture fixture;
+  fixture.config.scrolling.expandSingleColumn = true;
+  fixture.addColumns(1);
+  CHECK(fixture.layout.setWidthFraction(0, 0.5));
+  CHECK_EQ(fixture.layout.columnWidth(0, kViewport), kViewport);
+}
+
 UMBRIEL_TEST(expandSingleColumnTrueHonorsClientMaxWidth) {
   Fixture fixture;
   fixture.config.scrolling.expandSingleColumn = true;
@@ -339,6 +347,20 @@ UMBRIEL_TEST(expandSingleColumnTrueReexpandsTheLastSurvivor) {
   CHECK_EQ(fixture.layout.columnWidth(0, kViewport), kViewport);
 }
 
+UMBRIEL_TEST(pointerResizeOverridesSingleColumnExpansion) {
+  Fixture fixture;
+  fixture.config.scrolling.expandSingleColumn = true;
+  fixture.addColumns(1);
+  fixture.layout.arrange(kUsable);
+
+  auto resize = fixture.layout.beginResize(stub(0), WLR_EDGE_RIGHT, kUsable);
+  CHECK(resize != nullptr);
+  resize->applyDelta(-100.0, 0.0, kUsable);
+  fixture.layout.arrange(kUsable);
+
+  CHECK_EQ(fixture.layout.columnWidth(0, kViewport), kViewport - 100);
+}
+
 UMBRIEL_TEST(twoHalfColumnsTileExactlyAcrossTheViewport) {
   Fixture fixture;
   fixture.addColumns(2);