diff --git a/services/web/frontend/js/features/source-editor/languages/markdown/shortcuts.ts b/services/web/frontend/js/features/source-editor/languages/markdown/shortcuts.ts
index 8ccadc2224..0c8a677b59 100644
--- a/services/web/frontend/js/features/source-editor/languages/markdown/shortcuts.ts
+++ b/services/web/frontend/js/features/source-editor/languages/markdown/shortcuts.ts
@@ -1,6 +1,6 @@
 import { Prec } from '@codemirror/state'
 import { keymap } from '@codemirror/view'
-import { wrapRanges } from '../../commands/ranges'
+import { toggleWrapRanges } from './toggle-marks'
 
 export const shortcuts = () => {
   return Prec.high(
@@ -9,13 +9,13 @@ export const shortcuts = () => {
         key: 'Ctrl-b',
         mac: 'Mod-b',
         preventDefault: true,
-        run: wrapRanges('**', '**'),
+        run: toggleWrapRanges('**', '**', 'StrongEmphasis'),
       },
       {
         key: 'Ctrl-i',
         mac: 'Mod-i',
         preventDefault: true,
-        run: wrapRanges('_', '_'),
+        run: toggleWrapRanges('_', '_', 'Emphasis'),
       },
     ])
   )
diff --git a/services/web/frontend/js/features/source-editor/languages/markdown/toggle-marks.ts b/services/web/frontend/js/features/source-editor/languages/markdown/toggle-marks.ts
new file mode 100644
index 0000000000..53391e2bc0
--- /dev/null
+++ b/services/web/frontend/js/features/source-editor/languages/markdown/toggle-marks.ts
@@ -0,0 +1,190 @@
+import { EditorView } from '@codemirror/view'
+import { EditorSelection, SelectionRange } from '@codemirror/state'
+import { ensureSyntaxTree } from '@codemirror/language'
+import { SyntaxNode } from '@lezer/common'
+import { ancestorOfNodeWithType } from '../../utils/tree-query'
+import { wrapRanges } from '../../commands/ranges'
+
+// Bold parses as `StrongEmphasis`, italic as `Emphasis`; in both cases the
+// delimiters are `EmphasisMark` children of that node.
+type EmphasisNodeType = 'StrongEmphasis' | 'Emphasis'
+
+// The enclosing emphasis node of the requested type that fully contains the
+// range, or null. The exact type is matched so bold and italic aren't confused.
+const enclosingEmphasis = (
+  view: EditorView,
+  range: SelectionRange,
+  nodeType: EmphasisNodeType
+): SyntaxNode | null => {
+  const tree = ensureSyntaxTree(view.state, range.to, 1000)
+  if (!tree) {
+    return null
+  }
+
+  const node = tree.resolveInner(range.from, range.empty ? 0 : 1)
+  const emphasis = ancestorOfNodeWithType(node, nodeType)
+  if (!emphasis) {
+    return null
+  }
+
+  if (range.from < emphasis.from || range.to > emphasis.to) {
+    return null
+  }
+
+  return emphasis
+}
+
+const emphasisMarks = (
+  node: SyntaxNode
+): { open: SyntaxNode; close: SyntaxNode } | null => {
+  let open: SyntaxNode | null = null
+  for (let child = node.firstChild; child; child = child.nextSibling) {
+    if (child.type.is('EmphasisMark')) {
+      open = child
+      break
+    }
+  }
+  let close: SyntaxNode | null = null
+  for (let child = node.lastChild; child; child = child.prevSibling) {
+    if (child.type.is('EmphasisMark')) {
+      close = child
+      break
+    }
+  }
+  if (!open || !close || open === close) {
+    return null
+  }
+  return { open, close }
+}
+
+// Delimiter ranges of same-type spans fully inside the selection, so wrapping
+// can strip them and produce a single flat span instead of nested markup.
+const innerMarksToStrip = (
+  view: EditorView,
+  range: SelectionRange,
+  nodeType: EmphasisNodeType
+): { from: number; to: number }[] => {
+  const result: { from: number; to: number }[] = []
+  if (range.empty) {
+    return result
+  }
+  const tree = ensureSyntaxTree(view.state, range.to, 1000)
+  if (!tree) {
+    return result
+  }
+  tree.iterate({
+    from: range.from,
+    to: range.to,
+    enter: node => {
+      if (
+        node.type.is(nodeType) &&
+        node.from >= range.from &&
+        node.to <= range.to
+      ) {
+        const marks = emphasisMarks(node.node)
+        if (marks) {
+          result.push({ from: marks.open.from, to: marks.open.to })
+          result.push({ from: marks.close.from, to: marks.close.to })
+        }
+      }
+    },
+  })
+  return result
+}
+
+/**
+ * Toggle a markdown inline emphasis delimiter (bold or italic). Unwraps when the
+ * cursor/selection is already inside a span of that type, flattens any same-type
+ * spans contained in the selection, and otherwise wraps via `wrapRanges`.
+ */
+export const toggleWrapRanges = (
+  prefix: string,
+  suffix: string,
+  nodeType: EmphasisNodeType
+) => {
+  const wrap = wrapRanges(prefix, suffix)
+
+  return (view: EditorView): boolean => {
+    if (view.state.readOnly) {
+      return false
+    }
+
+    const ranges = view.state.selection.ranges
+    const needsCustom = ranges.some(
+      range =>
+        enclosingEmphasis(view, range, nodeType) !== null ||
+        innerMarksToStrip(view, range, nodeType).length > 0
+    )
+
+    if (!needsCustom) {
+      return wrap(view)
+    }
+
+    view.dispatch(
+      view.state.changeByRange(range => {
+        const emphasis = enclosingEmphasis(view, range, nodeType)
+        if (!emphasis) {
+          // Strip any same-type spans inside the selection before wrapping so
+          // the result is a single flat span rather than nested markup.
+          const innerMarks = innerMarksToStrip(view, range, nodeType)
+          if (innerMarks.length > 0) {
+            const deletedLength = innerMarks.reduce(
+              (total, mark) => total + (mark.to - mark.from),
+              0
+            )
+            return {
+              range: EditorSelection.range(
+                range.from + prefix.length,
+                range.to + prefix.length - deletedLength
+              ),
+              changes: [
+                { from: range.from, insert: prefix },
+                ...innerMarks.map(mark => ({ from: mark.from, to: mark.to })),
+                { from: range.to, insert: suffix },
+              ],
+            }
+          }
+          const content = view.state.sliceDoc(range.from, range.to)
+          return {
+            range: range.map(
+              view.state.changes([{ from: range.from, insert: prefix }]),
+              1
+            ),
+            changes: [
+              {
+                from: range.from,
+                to: range.to,
+                insert: `${prefix}${content}${suffix}`,
+              },
+            ],
+          }
+        }
+
+        const marks = emphasisMarks(emphasis)
+        if (!marks) {
+          return { range }
+        }
+
+        const { open, close } = marks
+        const innerFrom = open.to
+        const innerTo = close.from
+        const openLength = open.to - open.from
+
+        // Clamp the selection to the inner text, then shift left by the deleted
+        // opening delimiter so it still covers the unwrapped text.
+        const mapPos = (pos: number) =>
+          Math.min(Math.max(pos, innerFrom), innerTo) - openLength
+
+        return {
+          range: EditorSelection.range(mapPos(range.from), mapPos(range.to)),
+          changes: [
+            { from: open.from, to: open.to },
+            { from: close.from, to: close.to },
+          ],
+        }
+      }),
+      { scrollIntoView: true }
+    )
+    return true
+  }
+}