fix(hooks): decode the escapes that Bash removes in a double-quoted commit message

In double quotes, Bash drops the backslash before $, `, ", \ and a newline, so git receives fix: say "hello" for -m "fix: say \"hello\"". The check kept the backslashes, so an escaped backslash before a newline counted twice. These escapes are now decoded, and a backslash before any other character stays. The test that pinned the escaped quotes now expects the message git records.

scripts/hooks/pre-bash-commit-quality.js

@@ -204,8 +204,9 @@ function validateCommitMessage(command) {
   const heredoc = messageMatch[1]?.startsWith('$(')
     ? heredocBody(command.slice(messageMatch.index + messageMatch[0].indexOf('"') + 1))
     : null;
-  // In double quotes, Bash drops a backslash-newline, a line continuation
-  const doubleQuoted = messageMatch[1]?.replace(/\\(\r?\n|[\s\S])/g, (escape, next) => (next.endsWith('\n') ? '' : escape));
+  // In double quotes, Bash drops the backslash before $ ` " \ and drops a backslash-newline,
+  // a line continuation, altogether. Before any other character the backslash stays.
+  const doubleQuoted = messageMatch[1]?.replace(/\\(\r?\n|[$`"\\])/g, (escape, next) => (next.endsWith('\n') ? '' : next));
   const message = heredoc ?? doubleQuoted ?? messageMatch[2] ?? messageMatch[3];
   // The format rules apply to the subject: git drops leading blank lines and trailing
   // whitespace, and the first line left is the subject.

tests/hooks/pre-bash-commit-quality.test.js

@@ -495,7 +495,7 @@ if (test('captures full single-quoted -m message containing a double quote', ()
 if (test('captures full double-quoted -m message with escaped inner quotes (not truncated)', () => {
   const res = hook.validateCommitMessage('git commit -m "fix: say \\"hello\\" to the user"');
   assert.ok(res, 'expected a validation result');
-  assert.strictEqual(res.message, 'fix: say \\"hello\\" to the user');
+  assert.strictEqual(res.message, 'fix: say "hello" to the user');
 })) passed++; else failed++;
 
 if (test('measures length of the full message past an apostrophe (not the truncated prefix)', () => {
@@ -529,8 +529,10 @@ if (test('drops a line continuation from a double-quoted message, as Bash does',
   const res = hook.validateCommitMessage('git commit -m "\\\nfix: handle empty input"');
   assert.strictEqual(res.message, 'fix: handle empty input');
   assert.deepStrictEqual(res.issues, []);
-  // An escaped backslash before a newline is a backslash, and the newline stays
-  assert.strictEqual(hook.validateCommitMessage('git commit -m "fix: path C:\\\\\nbody"').message, 'fix: path C:\\\\\nbody');
+  // An escaped backslash before a newline is one backslash, and the newline stays
+  assert.strictEqual(hook.validateCommitMessage('git commit -m "fix: path C:\\\\\nbody"').message, 'fix: path C:\\\nbody');
+  // Bash removes the backslash only before $ ` " \ and a newline
+  assert.strictEqual(hook.validateCommitMessage('git commit -m "fix: cost \\$5 in \\d+ steps"').message, 'fix: cost $5 in \\d+ steps');
 })) passed++; else failed++;
 
 if (test('reads a here-document whose body has a backslash at the end of a line', () => {