diff --git a/README.md b/README.md
index d864b13d..011a7b28 100644
--- a/README.md
+++ b/README.md
@@ -5,6 +5,12 @@
 
 ## What's new in this fork
 
+### 2026-06-25 — Resizable sidebar
+
+The scripts sidebar can now be resized: drag the handle on its right edge to set
+the width (between 220 and 600 px), or double-click the handle to reset it to the
+default 300 px. The chosen width is persisted in `localStorage`.
+
 ### 2026-06-25 — Search in script output
 
 The output panel now has a find bar (search icon in the "Output" header): type to
diff --git a/web-src/src/common/components/AppLayout.vue b/web-src/src/common/components/AppLayout.vue
index 8f6d69ea..aa13b708 100644
--- a/web-src/src/common/components/AppLayout.vue
+++ b/web-src/src/common/components/AppLayout.vue
@@ -1,8 +1,14 @@
 <template>
   <div class="app-layout">
-    <div ref="appSidebar" :class="{collapsed: !showSidebar}" class="app-sidebar shadow-8dp">
+    <div ref="appSidebar" :class="{collapsed: !showSidebar}" class="app-sidebar shadow-8dp"
+         :style="{width: sidebarWidth + 'px'}">
       <slot name="sidebar"/>
     </div>
+    <div v-show="!narrowView"
+         class="sidebar-resizer"
+         title="Drag to resize · double-click to reset"
+         @mousedown="startResize"
+         @dblclick="resetSidebarWidth"></div>
     <div class="app-content">
       <div ref="contentHeader"
            :class="{borderless: !hasHeader, 'shadow-8dp': hasHeader}" class="content-header">
@@ -34,6 +40,27 @@
 
 import {hasClass, isNull} from '@/common/utils/common';
 
+const SIDEBAR_WIDTH_KEY = 'script_server_sidebar_width';
+const DEFAULT_SIDEBAR_WIDTH = 300;
+const MIN_SIDEBAR_WIDTH = 220;
+const MAX_SIDEBAR_WIDTH = 600;
+
+function clampSidebarWidth(value) {
+  return Math.min(MAX_SIDEBAR_WIDTH, Math.max(MIN_SIDEBAR_WIDTH, value));
+}
+
+function loadSidebarWidth() {
+  try {
+    const stored = parseInt(localStorage.getItem(SIDEBAR_WIDTH_KEY), 10);
+    if (!isNaN(stored)) {
+      return clampSidebarWidth(stored);
+    }
+  } catch (e) {
+    // localStorage unavailable (private mode, jsdom) — use the default
+  }
+  return DEFAULT_SIDEBAR_WIDTH;
+}
+
 export default {
   name: 'AppLayout',
   props: {
@@ -43,10 +70,13 @@ export default {
     return {
       narrowView: false,
       showSidebar: false,
-      hasHeader: false
+      hasHeader: false,
+      sidebarWidth: DEFAULT_SIDEBAR_WIDTH
     }
   },
   mounted() {
+    this.sidebarWidth = loadSidebarWidth();
+
     const contentHeader = this.$refs.contentHeader;
     const contentPanel = this.$refs.contentPanel;
 
@@ -65,9 +95,64 @@ export default {
     resizeListener();
   },
 
+  beforeUnmount() {
+    this._stopResizeListening();
+  },
+
   methods: {
     setSidebarVisibility(visible) {
       this.showSidebar = visible;
+    },
+
+    startResize(event) {
+      if (this.narrowView) {
+        return;
+      }
+      event.preventDefault();
+      this._onResizeMove = (e) => this._doResize(e);
+      this._onResizeUp = () => this._stopResize();
+      document.addEventListener('mousemove', this._onResizeMove);
+      document.addEventListener('mouseup', this._onResizeUp);
+      // Avoid selecting page text and flip the cursor while dragging.
+      document.body.style.userSelect = 'none';
+      document.body.style.cursor = 'col-resize';
+    },
+
+    _doResize(event) {
+      // The sidebar starts at the viewport's left edge, so the pointer's X is
+      // the desired width.
+      this.sidebarWidth = clampSidebarWidth(event.clientX);
+    },
+
+    _stopResize() {
+      this._stopResizeListening();
+      this._persistSidebarWidth();
+    },
+
+    _stopResizeListening() {
+      if (this._onResizeMove) {
+        document.removeEventListener('mousemove', this._onResizeMove);
+        this._onResizeMove = null;
+      }
+      if (this._onResizeUp) {
+        document.removeEventListener('mouseup', this._onResizeUp);
+        this._onResizeUp = null;
+      }
+      document.body.style.userSelect = '';
+      document.body.style.cursor = '';
+    },
+
+    resetSidebarWidth() {
+      this.sidebarWidth = DEFAULT_SIDEBAR_WIDTH;
+      this._persistSidebarWidth();
+    },
+
+    _persistSidebarWidth() {
+      try {
+        localStorage.setItem(SIDEBAR_WIDTH_KEY, String(this.sidebarWidth));
+      } catch (e) {
+        // ignore persistence failures, the in-session width still applies
+      }
     }
   }
 }
@@ -126,12 +211,24 @@ function updatedStylesBasedOnContent(contentHeader, contentPanel, appLayout) {
 }
 
 .app-sidebar {
-  width: 300px;
-  min-width: 300px;
+  /* width is set inline (resizable, persisted); don't let flex shrink it */
+  flex-shrink: 0;
 
   border-right: 1px solid var(--separator-color);
 }
 
+.sidebar-resizer {
+  flex: 0 0 5px;
+  cursor: col-resize;
+  background: transparent;
+  z-index: 2;
+  transition: background-color 0.15s;
+}
+
+.sidebar-resizer:hover {
+  background-color: var(--primary-color);
+}
+
 .app-content {
   flex: 1 1 0;
 
diff --git a/web-src/tests/unit/common/AppLayout_resize_test.js b/web-src/tests/unit/common/AppLayout_resize_test.js
new file mode 100644
index 00000000..9887ad04
--- /dev/null
+++ b/web-src/tests/unit/common/AppLayout_resize_test.js
@@ -0,0 +1,110 @@
+'use strict';
+import AppLayout from '@/common/components/AppLayout';
+import {mount} from '@vue/test-utils';
+import {attachToDocument} from '../test_utils';
+
+function inMemoryLocalStorage(initial) {
+    const data = Object.assign({}, initial);
+    return {
+        getItem: (k) => (k in data ? data[k] : null),
+        setItem: (k, v) => {
+            data[k] = String(v);
+        },
+        removeItem: (k) => {
+            delete data[k];
+        },
+        _data: data
+    };
+}
+
+const KEY = 'script_server_sidebar_width';
+
+describe('Test AppLayout resizable sidebar', function () {
+    let layout;
+
+    function mountLayout() {
+        return mount(AppLayout, {attachTo: attachToDocument()});
+    }
+
+    afterEach(function () {
+        if (layout) {
+            layout.unmount();
+            layout = null;
+        }
+        vi.unstubAllGlobals();
+    });
+
+    it('defaults to 300px when nothing is stored', function () {
+        vi.stubGlobal('localStorage', inMemoryLocalStorage());
+        layout = mountLayout();
+        expect(layout.vm.sidebarWidth).toBe(300);
+    });
+
+    it('restores a stored width', function () {
+        vi.stubGlobal('localStorage', inMemoryLocalStorage({[KEY]: '450'}));
+        layout = mountLayout();
+        expect(layout.vm.sidebarWidth).toBe(450);
+    });
+
+    it('clamps a too-small stored width up to the minimum', function () {
+        vi.stubGlobal('localStorage', inMemoryLocalStorage({[KEY]: '50'}));
+        layout = mountLayout();
+        expect(layout.vm.sidebarWidth).toBe(220);
+    });
+
+    it('clamps a too-large stored width down to the maximum', function () {
+        vi.stubGlobal('localStorage', inMemoryLocalStorage({[KEY]: '9999'}));
+        layout = mountLayout();
+        expect(layout.vm.sidebarWidth).toBe(600);
+    });
+
+    it('applies the width to the sidebar element', async function () {
+        vi.stubGlobal('localStorage', inMemoryLocalStorage({[KEY]: '420'}));
+        layout = mountLayout();
+        await layout.vm.$nextTick();
+        expect(layout.find('.app-sidebar').attributes('style')).toContain('width: 420px');
+    });
+
+    it('resizing clamps to bounds and updates the width', function () {
+        vi.stubGlobal('localStorage', inMemoryLocalStorage());
+        layout = mountLayout();
+
+        layout.vm._doResize({clientX: 380});
+        expect(layout.vm.sidebarWidth).toBe(380);
+
+        layout.vm._doResize({clientX: 10});
+        expect(layout.vm.sidebarWidth).toBe(220);
+
+        layout.vm._doResize({clientX: 5000});
+        expect(layout.vm.sidebarWidth).toBe(600);
+    });
+
+    it('persists the width when a resize ends', function () {
+        const ls = inMemoryLocalStorage();
+        vi.stubGlobal('localStorage', ls);
+        layout = mountLayout();
+
+        layout.vm._doResize({clientX: 333});
+        layout.vm._stopResize();
+
+        expect(ls._data[KEY]).toBe('333');
+    });
+
+    it('double-click resets to 300px and persists', function () {
+        const ls = inMemoryLocalStorage({[KEY]: '500'});
+        vi.stubGlobal('localStorage', ls);
+        layout = mountLayout();
+        expect(layout.vm.sidebarWidth).toBe(500);
+
+        layout.vm.resetSidebarWidth();
+
+        expect(layout.vm.sidebarWidth).toBe(300);
+        expect(ls._data[KEY]).toBe('300');
+    });
+
+    it('renders a resizer handle', function () {
+        vi.stubGlobal('localStorage', inMemoryLocalStorage());
+        layout = mountLayout();
+        expect(layout.find('.sidebar-resizer').exists()).toBe(true);
+    });
+});