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diff --git a/src/renderer/src/extensions/latexClosing.ts b/src/renderer/src/extensions/latexClosing.ts
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+++ b/src/renderer/src/extensions/latexClosing.ts
@@ -0,0 +1,230 @@
+// Copyright (c) 2026 Yuren Hao
+// Licensed under AGPL-3.0 - see LICENSE file
+
+import { EditorView, keymap } from '@codemirror/view'
+import { EditorSelection } from '@codemirror/state'
+
+// ── Helpers ──────────────────────────────────────────────────────────
+
+/** Pair definitions for surround/auto-close behavior */
+const PAIRS: Record<string, string> = {
+  '$': '$',
+  '{': '}',
+  '(': ')',
+  '[': ']',
+}
+
+/**
+ * Extract the environment name from a \begin{envname} that ends right
+ * at or before `pos` on the same line.
+ */
+function getBeginEnvBefore(doc: string, pos: number): string | null {
+  // Look backwards from pos to find the line
+  const lineStart = doc.lastIndexOf('\n', pos - 1) + 1
+  const lineBefore = doc.slice(lineStart, pos)
+  // Match \begin{envname} at the end (possibly with trailing whitespace)
+  const m = lineBefore.match(/\\begin\{([^}]+)\}\s*$/)
+  return m ? m[1] : null
+}
+
+// ── 1. Auto-close \begin{env} on Enter ──────────────────────────────
+
+const beginEnvEnterKeymap = keymap.of([
+  {
+    key: 'Enter',
+    run(view) {
+      const { state } = view
+      const { main } = state.selection
+
+      // Only handle when there is no selection
+      if (!main.empty) return false
+
+      const pos = main.head
+      const doc = state.doc.toString()
+      const envName = getBeginEnvBefore(doc, pos)
+      if (!envName) return false
+
+      // Check that there is no existing \end{envName} on the next non-empty lines
+      // that would indicate the environment is already closed nearby
+      const afterCursor = doc.slice(pos)
+      const closingTag = `\\end{${envName}}`
+
+      // Look at the text right after cursor (same line remainder + next few lines)
+      const nextChunk = afterCursor.slice(0, 200)
+      const alreadyClosed = nextChunk.split('\n').some((line) => line.trim() === closingTag)
+      if (alreadyClosed) return false
+
+      // Determine the indentation of the \begin line
+      const line = state.doc.lineAt(pos)
+      const lineText = line.text
+      const indentMatch = lineText.match(/^(\s*)/)
+      const baseIndent = indentMatch ? indentMatch[1] : ''
+      // Use two spaces (or tab) as inner indent — follow the existing indent style
+      const innerIndent = baseIndent + '  '
+
+      // Insert: \n<innerIndent>\n<baseIndent>\end{envName}
+      const insert = `\n${innerIndent}\n${baseIndent}${closingTag}`
+      const cursorPos = pos + 1 + innerIndent.length // after \n + innerIndent
+
+      view.dispatch(
+        state.update({
+          changes: { from: pos, insert },
+          selection: EditorSelection.cursor(cursorPos),
+          scrollIntoView: true,
+          userEvent: 'input',
+        })
+      )
+      return true
+    },
+  },
+])
+
+// ── 2 & 3. Auto-close $ and surround selection ─────────────────────
+
+/**
+ * inputHandler for LaTeX-specific auto-close and surround.
+ *
+ * Handles:
+ *  - `$`: auto-insert matching `$`, or surround selection with `$...$`
+ *  - `{`, `(`, `[`: surround selection (auto-close for `{` is already
+ *    handled by CM6's closeBrackets, so we only add surround behavior)
+ *
+ * Smart behavior:
+ *  - Don't double-close if the character after cursor is already the
+ *    closing counterpart.
+ *  - For `$`, skip over a closing `$` instead of inserting a new one.
+ */
+const latexInputHandler = EditorView.inputHandler.of(
+  (view, from, to, inserted) => {
+    // We only care about single-character inserts that are in our pair map
+    if (inserted.length !== 1) return false
+    const close = PAIRS[inserted]
+    if (!close) return false
+
+    const { state } = view
+    const doc = state.doc
+
+    // ── Surround selection ──
+    // If there is a selection (from !== to), wrap it
+    if (from !== to) {
+      // For all pair chars, wrap selection
+      const selectedText = doc.sliceString(from, to)
+      const wrapped = inserted + selectedText + close
+      view.dispatch(
+        state.update({
+          changes: { from, to, insert: wrapped },
+          // Place cursor after the closing char so the selection is visible
+          selection: EditorSelection.range(from + 1, from + 1 + selectedText.length),
+          userEvent: 'input',
+        })
+      )
+      return true
+    }
+
+    // ── No selection: auto-close / skip logic ──
+
+    const pos = from
+    const charAfter = pos < doc.length ? doc.sliceString(pos, pos + 1) : ''
+
+    // For `{`, `(`, `[`: CM6 closeBrackets handles these already.
+    // We only handle surround (above). So skip auto-close for non-$ chars.
+    if (inserted !== '$') return false
+
+    // ── Dollar sign handling ──
+
+    // If the next character is already `$`, skip over it (don't double)
+    if (charAfter === '$') {
+      // But only if it looks like we are at the end of an inline math:
+      // count `$` before cursor; if odd, we're closing
+      const textBefore = doc.sliceString(Math.max(0, pos - 200), pos)
+      const dollarsBefore = (textBefore.match(/\$/g) || []).length
+      if (dollarsBefore % 2 === 1) {
+        // Odd number of $ before → this is a closing $, skip over it
+        view.dispatch(
+          state.update({
+            selection: EditorSelection.cursor(pos + 1),
+            scrollIntoView: true,
+            userEvent: 'input',
+          })
+        )
+        return true
+      }
+    }
+
+    // Don't auto-close if the character before is a backslash (e.g. \$)
+    if (pos > 0) {
+      const charBefore = doc.sliceString(pos - 1, pos)
+      if (charBefore === '\\') return false
+    }
+
+    // Don't auto-close if next char is already $ (and we didn't skip above,
+    // meaning even count → we'd be starting a new pair, but $ is right there)
+    if (charAfter === '$') return false
+
+    // Don't auto-close if we're inside a word (letter/digit right before or after)
+    if (charAfter && /[a-zA-Z0-9]/.test(charAfter)) return false
+
+    // Insert $$ and place cursor in between
+    view.dispatch(
+      state.update({
+        changes: { from: pos, insert: '$$' },
+        selection: EditorSelection.cursor(pos + 1),
+        scrollIntoView: true,
+        userEvent: 'input',
+      })
+    )
+    return true
+  }
+)
+
+// ── Backspace: delete matching pair ─────────────────────────────────
+
+const deletePairKeymap = keymap.of([
+  {
+    key: 'Backspace',
+    run(view) {
+      const { state } = view
+      const { main } = state.selection
+      if (!main.empty) return false
+
+      const pos = main.head
+      if (pos === 0 || pos >= state.doc.length) return false
+
+      const before = state.doc.sliceString(pos - 1, pos)
+      const after = state.doc.sliceString(pos, pos + 1)
+
+      // Check if we're between a matching pair we inserted
+      if (before === '$' && after === '$') {
+        // Delete both
+        view.dispatch(
+          state.update({
+            changes: { from: pos - 1, to: pos + 1 },
+            userEvent: 'delete',
+          })
+        )
+        return true
+      }
+
+      return false
+    },
+  },
+])
+
+// ── Export ────────────────────────────────────────────────────────────
+
+/**
+ * LaTeX-specific closing/surround extension for CodeMirror 6.
+ *
+ * Provides:
+ * - Auto-close `\begin{env}` with `\end{env}` on Enter
+ * - Auto-close `$...$` (smart, no double-close)
+ * - Surround selection with `$`, `{`, `(`, `[`
+ * - Backspace deletes matching `$` pair
+ */
+export function latexClosing() {
+  return [
+    beginEnvEnterKeymap,
+    latexInputHandler,
+    deletePairKeymap,
+  ]
+}