diff --git a/packages/desktop/src/renderer/src/components/sideBar/toc.vue b/packages/desktop/src/renderer/src/components/sideBar/toc.vue
index 20c4b136a6..bb6726155d 100644
--- a/packages/desktop/src/renderer/src/components/sideBar/toc.vue
+++ b/packages/desktop/src/renderer/src/components/sideBar/toc.vue
@@ -7,19 +7,23 @@
       {{ t('sideBar.toc.title') }}
     </div>
     <el-tree
-      v-if="toc.length"
-      :data="toc"
-      :default-expand-all="true"
+      v-if="keyedToc.length"
+      :data="keyedToc"
+      node-key="key"
+      :default-expanded-keys="expandedKeys"
       :props="defaultProps"
       :expand-on-click-node="false"
       :indent="10"
       :icon="ArrowRight"
       @node-click="handleClick"
+      @node-expand="onExpand"
+      @node-collapse="onCollapse"
     />
   </div>
 </template>
 
 <script setup lang="ts">
+import { computed, ref } from 'vue'
 import { useEditorStore } from '@/store/editor'
 import { usePreferencesStore } from '@/store/preferences'
 import bus from '../../bus'
@@ -40,6 +44,67 @@ const defaultProps = {
 const { toc } = storeToRefs(editorStore)
 const { wordWrapInToc } = storeToRefs(preferencesStore)
 
+interface KeyedTocNode {
+  key: string
+  label: unknown
+  slug: unknown
+  children: KeyedTocNode[]
+}
+
+// The TOC nodes carry no stable id, so el-tree (without a node-key) discarded
+// the user's expand/collapse state on every content edit (#3028). Derive a
+// stable key per node — its slug, deduplicated in document order so duplicate
+// headings stay unique — and let el-tree preserve state by that key.
+const keyedToc = computed<KeyedTocNode[]>(() => {
+  const seen = new Map<string, number>()
+  const assign = (nodes: Array<Record<string, unknown>>): KeyedTocNode[] =>
+    nodes.map((node) => {
+      const base = typeof node.slug === 'string' && node.slug ? node.slug : 'heading'
+      const count = seen.get(base) ?? 0
+      seen.set(base, count + 1)
+      return {
+        key: count === 0 ? base : `${base}-${count}`,
+        label: node.label,
+        slug: node.slug,
+        children: assign((node.children as Array<Record<string, unknown>>) ?? [])
+      }
+    })
+  return assign(toc.value as unknown as Array<Record<string, unknown>>)
+})
+
+// Track which headings the user collapsed, by stable key (#3028). Headings are
+// expanded by default; a collapse is remembered here.
+const collapsedKeys = ref<Set<string>>(new Set())
+
+const onCollapse = (data: { key?: string }): void => {
+  if (data.key) collapsedKeys.value = new Set(collapsedKeys.value).add(data.key)
+}
+
+const onExpand = (data: { key?: string }): void => {
+  if (!data.key) return
+  const next = new Set(collapsedKeys.value)
+  next.delete(data.key)
+  collapsedKeys.value = next
+}
+
+// The set el-tree should have expanded: every node that is neither collapsed
+// nor inside a collapsed ancestor. On each content edit el-tree rebuilds and
+// re-applies these keys, so binding the *correct* set makes it paint the right
+// state directly — instead of expanding everything and then collapsing, which
+// flickered.
+const expandedKeys = computed<string[]>(() => {
+  const keys: string[] = []
+  const walk = (nodes: KeyedTocNode[], hiddenByAncestor: boolean): void => {
+    for (const node of nodes) {
+      const collapsed = hiddenByAncestor || collapsedKeys.value.has(node.key)
+      if (!collapsed) keys.push(node.key)
+      walk(node.children, collapsed)
+    }
+  }
+  walk(keyedToc.value, false)
+  return keys
+})
+
 const handleClick = (data: { slug?: unknown }): void => {
   // editor.vue builds a CSS selector with `#${slug}` — bail out if the
   // node has no slug (e.g. unsluggable headings) to avoid emitting
diff --git a/packages/desktop/test/e2e/toc-collapse-state-3028.spec.ts b/packages/desktop/test/e2e/toc-collapse-state-3028.spec.ts
new file mode 100644
index 0000000000..102250f3c4
--- /dev/null
+++ b/packages/desktop/test/e2e/toc-collapse-state-3028.spec.ts
@@ -0,0 +1,113 @@
+import { expect, test } from '@playwright/test'
+import type { ElectronApplication, Page } from 'playwright'
+import { launchWithMarkdown, clickMenuById, waitForEditor } from './helpers'
+
+// #3028 — collapsing a heading in the TOC must survive a document edit.
+//
+// The TOC el-tree was bound with `:default-expand-all` and reseeded from a
+// fresh `listToTree(toc)` on every `json-change`, so any edit re-expanded the
+// whole tree and discarded the user's collapse state.
+//
+//   # A
+//     ## B
+//       ### B1
+//     ## C
+const INITIAL_DOC = '# A\n\n## B\n\n### B1\n\n## C\n'
+
+// Labels of TOC nodes that are actually visible (a collapsed parent hides its
+// children via `display:none`, so they drop out of this list).
+const readVisibleTocLabels = (page: Page): Promise<string[]> =>
+  page.evaluate(() => {
+    const nodes = Array.from(
+      document.querySelectorAll('.side-bar-toc .el-tree .el-tree-node')
+    ) as HTMLElement[]
+    return nodes
+      .filter((n) => n.offsetParent !== null)
+      .map((n) => {
+        const labelEl = n.querySelector(':scope > .el-tree-node__content .el-tree-node__label')
+        return (labelEl?.textContent || '').trim()
+      })
+  })
+
+const collapseNode = (page: Page, label: string): Promise<void> =>
+  page.evaluate((lbl) => {
+    const nodes = Array.from(
+      document.querySelectorAll('.side-bar-toc .el-tree .el-tree-node')
+    ) as HTMLElement[]
+    const node = nodes.find((n) => {
+      const l = n.querySelector(':scope > .el-tree-node__content .el-tree-node__label')
+      return (l?.textContent || '').trim() === lbl
+    })
+    if (!node) throw new Error(`TOC node "${lbl}" not found`)
+    const icon = node.querySelector(
+      ':scope > .el-tree-node__content .el-tree-node__expand-icon'
+    ) as HTMLElement | null
+    if (!icon) throw new Error(`TOC node "${lbl}" has no expand icon`)
+    icon.click()
+  }, label)
+
+const ensureSidebarVisible = async(app: ElectronApplication, page: Page): Promise<void> => {
+  const visible = await page.evaluate(() => {
+    const el = document.querySelector('.side-bar') as HTMLElement | null
+    return !!(el && el.offsetParent !== null)
+  })
+  if (!visible) {
+    await clickMenuById(app, 'sideBarMenuItem')
+    await page.waitForFunction(
+      () => {
+        const el = document.querySelector('.side-bar') as HTMLElement | null
+        return !!(el && el.offsetParent !== null)
+      },
+      null,
+      { timeout: 5000 }
+    )
+  }
+}
+
+test.describe('TOC collapse state survives edits (#3028)', () => {
+  let app: ElectronApplication
+  let page: Page
+
+  test.beforeAll(async() => {
+    const launched = await launchWithMarkdown(INITIAL_DOC)
+    app = launched.app
+    page = launched.page
+    await waitForEditor(page)
+    await ensureSidebarVisible(app, page)
+    await clickMenuById(app, 'tocMenuItem')
+    await page.waitForSelector('.side-bar-toc .el-tree', { state: 'visible', timeout: 10000 })
+    await page.waitForFunction(
+      () => document.querySelectorAll('.side-bar-toc .el-tree-node__label').length >= 4,
+      null,
+      { timeout: 10000 }
+    )
+  })
+
+  test.afterAll(async() => {
+    if (app) await app.close()
+  })
+
+  test('a collapsed heading stays collapsed after a content edit', async() => {
+    // Everything expanded initially.
+    await expect.poll(() => readVisibleTocLabels(page), { timeout: 8000 })
+      .toEqual(['A', 'B', 'B1', 'C'])
+
+    // Collapse "B": its child "B1" disappears.
+    await collapseNode(page, 'B')
+    await expect.poll(() => readVisibleTocLabels(page), { timeout: 5000 })
+      .toEqual(['A', 'B', 'C'])
+
+    // Edit a different heading ("C" -> "C2"), triggering UPDATE_TOC.
+    const cContent = page
+      .locator('.mu-container h2 .mu-atxheading-content')
+      .filter({ hasText: 'C' })
+      .last()
+    await cContent.click()
+    await page.keyboard.press('End')
+    await page.keyboard.type('2', { delay: 20 })
+
+    // After the live TOC update, "B" must still be collapsed (B1 hidden).
+    await expect.poll(() => readVisibleTocLabels(page), { timeout: 8000 })
+      .toEqual(['A', 'B', 'C2'])
+  })
+})
diff --git a/packages/muya/e2e/tests/drag/image-resize-bar-reflow-2939.spec.ts b/packages/muya/e2e/tests/drag/image-resize-bar-reflow-2939.spec.ts
new file mode 100644
index 0000000000..73870402e8
--- /dev/null
+++ b/packages/muya/e2e/tests/drag/image-resize-bar-reflow-2939.spec.ts
@@ -0,0 +1,56 @@
+import type { Locator } from '@playwright/test';
+import { expect, test } from '../fixtures/muya';
+import { editor, floats } from '../helpers/selectors';
+
+/**
+ * #2939 — the ImageResizeBar positioned its left/right handles once on image
+ * click and never tracked layout reflow (unlike imageToolbar, which rides
+ * baseFloat's `autoUpdate`). When the surrounding layout shifted — the desktop
+ * sidebar toggling, or any window/ancestor resize — the handles stayed at their
+ * stale coordinates, detached from the image.
+ *
+ * Reproduce the reflow with a viewport resize (the muya container is centered,
+ * so narrowing the viewport moves the image's left edge) and assert the left
+ * handle stays aligned with the image.
+ */
+
+const DATA_URI =
+    'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mNkAAIAAAoAAv/lxKUAAAAASUVORK5CYII=';
+
+test.describe('ImageResizeBar reflow (#2939)', () => {
+    test('left handle tracks the image when the viewport resizes', async ({ page }) => {
+        await page.setViewportSize({ width: 1400, height: 900 });
+        await page.evaluate(uri => window.muya!.setContent(`![alt](${uri})`), DATA_URI);
+
+        const image = page.locator(editor.image).first();
+        await expect(image).toBeVisible();
+        await expect.poll(async () => image.evaluate(el =>
+            el.classList.contains('mu-image-success')), { timeout: 5_000 }).toBe(true);
+
+        const innerImg = image.locator('img').first();
+        await innerImg.click();
+
+        const leftHandle = page.locator(`${floats.imageTransformer} .bar.left`);
+        await expect(leftHandle).toBeVisible();
+
+        const offsetBefore = await getHandleOffset(innerImg, leftHandle);
+        expect(Math.abs(offsetBefore)).toBeLessThan(4);
+
+        // Narrow the viewport: the centered container — and the image — shift right.
+        await page.setViewportSize({ width: 760, height: 900 });
+
+        await expect.poll(async () => Math.abs(await getHandleOffset(innerImg, leftHandle)), {
+            timeout: 5_000,
+            intervals: [50, 100, 250, 500],
+        }).toBeLessThan(4);
+    });
+});
+
+async function getHandleOffset(img: Locator, handle: Locator): Promise<number> {
+    const imgBox = await img.boundingBox();
+    const handleBox = await handle.boundingBox();
+    if (!imgBox || !handleBox)
+        throw new Error('missing bounding box');
+    // The left handle sits at `image.left - 5` (CIRCLE_RADIO); compare centers.
+    return (handleBox.x + handleBox.width / 2) - imgBox.x;
+}
diff --git a/packages/muya/src/assets/styles/blockSyntax.css b/packages/muya/src/assets/styles/blockSyntax.css
index 7291952a57..2eb1eed6c1 100644
--- a/packages/muya/src/assets/styles/blockSyntax.css
+++ b/packages/muya/src/assets/styles/blockSyntax.css
@@ -815,6 +815,20 @@ figure.mu-diagram-block .mu-diagram-preview svg path[stroke='#000000'] {
     stroke: var(--editor-color);
 }
 
+/* js-sequence-diagrams creates its <text> with no fill attribute and its
+   note/actor boxes with the 3-char `#fff`, so the attribute-keyed rules above
+   miss them and the labels/boxes stay black-on-white on dark themes (#3047).
+   Recolor the sequence SVG by element, scoped to `svg.sequence` so mermaid /
+   vega / flowchart (which set fills via attributes) are untouched. */
+figure.mu-diagram-block .mu-diagram-preview svg.sequence text {
+    fill: var(--editor-color);
+}
+
+figure.mu-diagram-block .mu-diagram-preview svg.sequence rect[fill='#fff'],
+figure.mu-diagram-block .mu-diagram-preview svg.sequence path[fill='#fff'] {
+    fill: var(--editor-bg-color);
+}
+
 figure.mu-active.mu-math-block > div.mu-math-preview,
 figure.mu-active.mu-diagram-block > div.mu-diagram-preview {
     position: absolute;
diff --git a/packages/muya/src/block/content/codeBlockContent/index.ts b/packages/muya/src/block/content/codeBlockContent/index.ts
index c4c05a2452..6c57fc4200 100644
--- a/packages/muya/src/block/content/codeBlockContent/index.ts
+++ b/packages/muya/src/block/content/codeBlockContent/index.ts
@@ -417,7 +417,7 @@ class CodeBlockContent extends Content {
             // transform alias to original language
             const fullLengthLang = transformAliasToOrigin([lang])[0];
             if (fullLengthLang && /\S/.test(text) && loadedLanguages.has(fullLengthLang)) {
-                const tokens = prism.tokenize(text, prism.languages[lang]);
+                const tokens = prism.tokenize(text, prism.languages[fullLengthLang]);
                 let offset = start.offset;
                 let code = '';
                 let needRender = false;
diff --git a/packages/muya/src/ui/imageResizeBar/index.ts b/packages/muya/src/ui/imageResizeBar/index.ts
index 1354a966f6..887b1ba6b4 100644
--- a/packages/muya/src/ui/imageResizeBar/index.ts
+++ b/packages/muya/src/ui/imageResizeBar/index.ts
@@ -1,6 +1,7 @@
 import type Format from '../../block/base/format';
 import type { Muya } from '../../index';
 import type { ImageToken } from '../../inlineRenderer/types';
+import { autoUpdate } from '@floating-ui/dom';
 
 import { isHTMLElement, isMouseEvent } from '../../utils';
 import { findScrollContainer } from '../../utils/dom';
@@ -26,6 +27,8 @@ export class ImageResizeBar {
     private _eventId: string[] = [];
     private _lastScrollTop: number | null = null;
     private _resizing: boolean = false;
+    // Stops the autoUpdate reposition loop set up in `_render`.
+    private _cleanup: (() => void) | null = null;
     // A container for storing drag strips
     private _container: HTMLDivElement;
 
@@ -89,6 +92,9 @@ export class ImageResizeBar {
 
         this._createElements();
         this._update();
+        // Reposition the handles whenever the image moves (window/ancestor
+        // resize, sidebar toggle, scroll), so they stay attached to it (#2939).
+        this._cleanup = autoUpdate(this._reference!, this._container, () => this._update());
         eventCenter.emit('muya-float', this, true);
     }
 
@@ -202,6 +208,8 @@ export class ImageResizeBar {
 
     hide() {
         const { eventCenter } = this.muya;
+        this._cleanup?.();
+        this._cleanup = null;
         const circles = this._container.querySelectorAll('.bar');
         Array.from(circles).forEach(c => c.remove());
         this._status = false;
@@ -211,6 +219,8 @@ export class ImageResizeBar {
     // Remove the `.mu-transformer` container appended to document.body in the
     // constructor; invoked by `Muya.destroy()` so it is not leaked (#3315).
     destroy() {
+        this._cleanup?.();
+        this._cleanup = null;
         this._container.remove();
     }
 }
diff --git a/packages/muya/src/utils/prism/__tests__/languageAlias.spec.ts b/packages/muya/src/utils/prism/__tests__/languageAlias.spec.ts
new file mode 100644
index 0000000000..d9edd5ea7e
--- /dev/null
+++ b/packages/muya/src/utils/prism/__tests__/languageAlias.spec.ts
@@ -0,0 +1,30 @@
+// @vitest-environment happy-dom
+import { describe, expect, it } from 'vitest';
+import prism, { loadLanguage, transformAliasToOrigin } from '../index';
+
+describe('c++ language alias (#2910)', () => {
+    it('resolves `c++` to the cpp grammar', () => {
+        expect(transformAliasToOrigin(['c++'])[0]).toBe('cpp');
+    });
+
+    it('resolves `h++` to the cpp grammar', () => {
+        expect(transformAliasToOrigin(['h++'])[0]).toBe('cpp');
+    });
+
+    it('leaves the canonical `cpp` id untouched', () => {
+        expect(transformAliasToOrigin(['cpp'])[0]).toBe('cpp');
+    });
+
+    // The runtime grammar is registered under the resolved id (`cpp`), never the
+    // alias, so code paths must tokenize with `transformAliasToOrigin(lang)` —
+    // tokenizing with the raw `c++` grammar is `undefined` and crashes (the
+    // backspaceHandler regression this alias exposed).
+    it('exposes a runtime grammar for the resolved id but not the raw alias', async () => {
+        await loadLanguage('c++');
+        const resolved = transformAliasToOrigin(['c++'])[0];
+        expect(resolved).toBe('cpp');
+        expect(prism.languages[resolved]).toBeTruthy();
+        expect(prism.languages['c++']).toBeUndefined();
+        expect(() => prism.tokenize('int main(){}', prism.languages[resolved])).not.toThrow();
+    });
+});
diff --git a/packages/muya/src/utils/prism/__tests__/latexEscapedPercent.spec.ts b/packages/muya/src/utils/prism/__tests__/latexEscapedPercent.spec.ts
new file mode 100644
index 0000000000..e0683245f8
--- /dev/null
+++ b/packages/muya/src/utils/prism/__tests__/latexEscapedPercent.spec.ts
@@ -0,0 +1,29 @@
+// @vitest-environment happy-dom
+import { beforeAll, describe, expect, it } from 'vitest';
+import prism, { loadLanguage, patchLatexEscapedPercent } from '../index';
+
+function hasCommentToken(code: string): boolean {
+    const tokens = prism.tokenize(code, prism.languages.latex);
+    return tokens.some(
+        t => typeof t === 'object' && (t as { type?: string }).type === 'comment',
+    );
+}
+
+describe('latex escaped percent highlighting (#3037)', () => {
+    beforeAll(async () => {
+        await loadLanguage('latex');
+        patchLatexEscapedPercent(prism);
+    });
+
+    it('does not treat `\\%` as the start of a comment', () => {
+        expect(hasCommentToken('1\\%+2\\%=3\\%')).toBe(false);
+    });
+
+    it('still treats a bare `%` as a comment', () => {
+        expect(hasCommentToken('100% done')).toBe(true);
+    });
+
+    it('still treats a line-leading `%` as a comment', () => {
+        expect(hasCommentToken('%a real comment')).toBe(true);
+    });
+});
diff --git a/packages/muya/src/utils/prism/index.ts b/packages/muya/src/utils/prism/index.ts
index 665c4770c1..ce9c4f1daf 100644
--- a/packages/muya/src/utils/prism/index.ts
+++ b/packages/muya/src/utils/prism/index.ts
@@ -7,6 +7,22 @@ const prism = Prism;
 window.Prism = Prism;
 import('prismjs/plugins/keep-markup/prism-keep-markup');
 
+// prismjs ships C++ without a `c++`/`h++` alias, so fenced blocks tagged
+// ```c++ never resolve to the cpp grammar and stay unhighlighted (#2910).
+// Add each alias only once — `components.languages` is a shared singleton and
+// this module may be evaluated more than once (tests, HMR); pushing duplicates
+// makes prism's dependency loader throw "c++ cannot be alias for both cpp and
+// cpp".
+if (languages.cpp) {
+    const existing = languages.cpp.alias;
+    const alias = Array.isArray(existing) ? [...existing] : existing ? [existing] : [];
+    for (const name of ['c++', 'h++']) {
+        if (!alias.includes(name))
+            alias.push(name);
+    }
+    languages.cpp.alias = alias;
+}
+
 const langs: {
     name: string;
     [key: string]: string;
@@ -50,8 +66,19 @@ function search(text: string) {
     return fuse.search(text).map(i => i.item).slice(0, 5);
 }
 
+// In LaTeX `\%` is an escaped literal percent, not a line comment, but
+// prismjs's default latex `comment` token (`/%.*/`) swallows everything after
+// it. Require the `%` to not follow a backslash so `\%` highlights as a normal
+// control sequence (#3037). tex/context alias the same grammar object, so this
+// one override covers all three.
+export function patchLatexEscapedPercent(prismInstance: typeof Prism) {
+    const latex = prismInstance.languages.latex as { comment?: unknown } | undefined;
+    if (latex?.comment)
+        latex.comment = { pattern: /(^|[^\\])%.*/, lookbehind: true };
+}
+
 // pre load latex and yaml and html for `math block` \ `front matter` and `html block`
-loadLanguage('latex');
+loadLanguage('latex').then(() => patchLatexEscapedPercent(prism));
 loadLanguage('yaml');
 
 export { walkTokens } from './walkToken';