diff --git a/scripts/lib/shell-split.js b/scripts/lib/shell-split.js
index 39171b149..0a00758cf 100644
--- a/scripts/lib/shell-split.js
+++ b/scripts/lib/shell-split.js
@@ -1,7 +1,8 @@
 'use strict';
 
 // A here-document opener at `index`, but not a here-string (<<<): `<<` or `<<-`, then the
-// delimiter, a shell word whose quotes are removed (`<<'EOF'`, `<<E"OF"`, `<<EOF/END`, `<<123`).
+// delimiter, a shell word whose quotes are removed (`<<'EOF'`, `<<E"OF"`, `<<EOF/END`, `<<123`,
+// and `<<''`, whose body ends at the first empty line).
 function heredocAt(command, index) {
   if (command[index - 1] === '<' || command[index + 2] === '<') return null;
   let i = index + 2;
@@ -10,6 +11,7 @@ function heredocAt(command, index) {
   while (command[i] === ' ' || command[i] === '\t') i++;
   let delimiter = '';
   let quote = null;
+  let quoted = false;
   for (; i < command.length; i++) {
     const ch = command[i];
     if (quote) {
@@ -17,6 +19,7 @@ function heredocAt(command, index) {
       else delimiter += ch;
     } else if (ch === "'" || ch === '"') {
       quote = ch;
+      quoted = true;
     } else if (ch === '\\' && i + 1 < command.length) {
       delimiter += command[++i];
     } else if (/[\s|&;()<>]/.test(ch)) {
@@ -25,7 +28,7 @@ function heredocAt(command, index) {
       delimiter += ch;
     }
   }
-  return delimiter && !quote ? { text: command.slice(index, i), delimiter, stripTabs } : null;
+  return (delimiter || quoted) && !quote ? { text: command.slice(index, i), delimiter, stripTabs } : null;
 }
 
 // The index after the `))` that closes the arithmetic `((` at `index`, or -1.
@@ -64,27 +67,19 @@ function endOfHeredocBodies(command, start, heredocs) {
   return Math.min(end, command.length);
 }
 
-// At the newline at `index` the command ends, after the bodies of the here-documents opened on
-// its line. The bodies are data, so they go with the command that opened the first of them, even
-// when an operator after it (`cat <<EOF &&`) already ended its segment. Returns the index after
-// the bodies.
+// At the newline at `index` the command ends. The bodies of the here-documents opened on its
+// line follow it. They are data, not commands, so they are left out of the segments. Returns the
+// index after the bodies.
 function endLine(command, index, current, heredocs, segments) {
-  const end = endOfHeredocBodies(command, index + 1, heredocs);
-  let bodies = command.slice(index, end);
-  if (heredocs.length > 0 && heredocs[0].segment < segments.length) {
-    segments[heredocs[0].segment] += bodies.trimEnd();
-    bodies = '';
-  }
-  const rest = (current + bodies).trim();
-  if (rest) segments.push(rest);
-  return end;
+  if (current.trim()) segments.push(current.trim());
+  return endOfHeredocBodies(command, index + 1, heredocs);
 }
 
 /**
  * Split a shell command into segments by operators (&&, ||, ;, &) and by
  * newlines, while respecting quoting (single/double) and escaped characters.
  * Redirection operators (&>, >&, 2>&1) are NOT treated as separators, and the
- * body of a here-document stays in the segment of the command that reads it.
+ * body of a here-document, which is data, is left out of the segments.
  */
 function splitShellSegments(command) {
   const segments = [];
@@ -134,7 +129,7 @@ function splitShellSegments(command) {
 
     const heredoc = ch === '<' && next === '<' ? heredocAt(command, i) : null;
     if (heredoc) {
-      heredocs.push({ ...heredoc, segment: segments.length });
+      heredocs.push(heredoc);
       current += heredoc.text;
       i += heredoc.text.length - 1;
       continue;
diff --git a/tests/hooks/pre-bash-dev-server-block.test.js b/tests/hooks/pre-bash-dev-server-block.test.js
index 739da2ad0..4db73f983 100644
--- a/tests/hooks/pre-bash-dev-server-block.test.js
+++ b/tests/hooks/pre-bash-dev-server-block.test.js
@@ -234,6 +234,11 @@ function runTests() {
     assert.strictEqual(result.code, 0, `Expected exit code 0, got ${result.code}`);
   }) ? passed++ : failed++);
 
+  (test('allows a here-document body fed to a package manager command', () => {
+    const result = runScript('npm --version <<EOF && cat\nnpm run dev\nEOF');
+    assert.strictEqual(result.code, 0, `Expected exit code 0, got ${result.code}`);
+  }) ? passed++ : failed++);
+
   // --- Edge cases ---
 
   (test('empty/invalid input passes through (exit code 0)', () => {
diff --git a/tests/lib/shell-split.test.js b/tests/lib/shell-split.test.js
index bd4772305..6c99a00ba 100644
--- a/tests/lib/shell-split.test.js
+++ b/tests/lib/shell-split.test.js
@@ -120,16 +120,10 @@ test('an escaped or quoted newline does not split', () => {
   assert.deepStrictEqual(splitShellSegments('npm run \\\ndev'), ['npm run \\\ndev']);
   assert.deepStrictEqual(splitShellSegments('echo "a\nb"'), ['echo "a\nb"']);
 });
-test('a here-document body stays with its command', () => {
-  assert.deepStrictEqual(
-    splitShellSegments('cat <<EOF > notes.md\na && b\nnpm run dev\nEOF\nls'),
-    ['cat <<EOF > notes.md\na && b\nnpm run dev\nEOF', 'ls']
-  );
-  assert.deepStrictEqual(
-    splitShellSegments("cat <<-'END'\n\tnpm run dev\n\tEND\nls"),
-    ["cat <<-'END'\n\tnpm run dev\n\tEND", 'ls']
-  );
-  assert.deepStrictEqual(splitShellSegments('cat <<A <<B\na\nA\nb\nB\nnext'), ['cat <<A <<B\na\nA\nb\nB', 'next']);
+test('a here-document body is data, left out of the segments', () => {
+  assert.deepStrictEqual(splitShellSegments('cat <<EOF > notes.md\na && b\nnpm run dev\nEOF\nls'), ['cat <<EOF > notes.md', 'ls']);
+  assert.deepStrictEqual(splitShellSegments("cat <<-'END'\n\tnpm run dev\n\tEND\nls"), ["cat <<-'END'", 'ls']);
+  assert.deepStrictEqual(splitShellSegments('cat <<A <<B\na\nA\nb\nB\nnext'), ['cat <<A <<B', 'next']);
 });
 test('a here-string or a shift is not a here-document', () => {
   assert.deepStrictEqual(splitShellSegments('cat <<< x && y'), ['cat <<< x', 'y']);
@@ -143,28 +137,18 @@ test('a << in a comment is not a here-document, and a comment is not split', ()
   assert.deepStrictEqual(splitShellSegments('echo a#b ${#x} && c'), ['echo a#b ${#x}', 'c']);
 });
 test('a here-document delimiter is a shell word, read without its quotes', () => {
-  assert.deepStrictEqual(
-    splitShellSegments('cat <<EOF/END\nnpm run dev\nEOF/END\nls'),
-    ['cat <<EOF/END\nnpm run dev\nEOF/END', 'ls']
-  );
-  assert.deepStrictEqual(splitShellSegments('cat <<E"OF"\nnpm run dev\nEOF\nls'), ['cat <<E"OF"\nnpm run dev\nEOF', 'ls']);
-  assert.deepStrictEqual(splitShellSegments('cat <<123\nnpm run dev\n123\nls'), ['cat <<123\nnpm run dev\n123', 'ls']);
+  assert.deepStrictEqual(splitShellSegments('cat <<EOF/END\nnpm run dev\nEOF/END\nls'), ['cat <<EOF/END', 'ls']);
+  assert.deepStrictEqual(splitShellSegments('cat <<E"OF"\nnpm run dev\nEOF\nls'), ['cat <<E"OF"', 'ls']);
+  assert.deepStrictEqual(splitShellSegments('cat <<123\nnpm run dev\n123\nls'), ['cat <<123', 'ls']);
+  // An empty delimiter ends the body at the first empty line
+  assert.deepStrictEqual(splitShellSegments("cat <<''\nnpm run dev\n\nls"), ["cat <<''", 'ls']);
 });
-test('a here-document body stays with its command after an operator ends the segment', () => {
-  assert.deepStrictEqual(
-    splitShellSegments('cat <<EOF &&\nnpm run dev\nEOF\necho done'),
-    ['cat <<EOF\nnpm run dev\nEOF', 'echo done']
-  );
-  assert.deepStrictEqual(
-    splitShellSegments('cat <<EOF && npm run build\nnpm run dev\nEOF'),
-    ['cat <<EOF\nnpm run dev\nEOF', 'npm run build']
-  );
+test('a here-document body after an operator is left out too', () => {
+  assert.deepStrictEqual(splitShellSegments('cat <<EOF &&\nnpm run dev\nEOF\necho done'), ['cat <<EOF', 'echo done']);
+  assert.deepStrictEqual(splitShellSegments('npm --version <<EOF && cat\nnpm run dev\nEOF'), ['npm --version <<EOF', 'cat']);
 });
 test('a here-document delimiter on a CRLF line still ends the body', () => {
-  assert.deepStrictEqual(
-    splitShellSegments('cat <<EOF\r\ntext\r\nEOF\r\nnpm run dev'),
-    ['cat <<EOF\r\ntext\r\nEOF', 'npm run dev']
-  );
+  assert.deepStrictEqual(splitShellSegments('cat <<EOF\r\ntext\r\nEOF\r\nnpm run dev'), ['cat <<EOF', 'npm run dev']);
 });
 
 console.log(`\n=== Results: ${passed} passed, ${failed} failed ===`);