refactor(core): Extract thought parsing logic into a dedicated utility (#9503)

packages/core/src/utils/thoughtUtils.test.ts

@@ -0,0 +1,80 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, it, expect } from 'vitest';
+import { parseThought } from './thoughtUtils.js';
+
+describe('parseThought', () => {
+  it.each([
+    {
+      name: 'a standard thought with subject and description',
+      rawText: '**Subject:** This is the description.',
+      expected: {
+        subject: 'Subject:',
+        description: 'This is the description.',
+      },
+    },
+    {
+      name: 'leading and trailing whitespace in the raw string',
+      rawText: '  **Subject** description with spaces   ',
+      expected: { subject: 'Subject', description: 'description with spaces' },
+    },
+    {
+      name: 'whitespace surrounding the subject content',
+      rawText: '** Subject  **',
+      expected: { subject: 'Subject', description: '' },
+    },
+    {
+      name: 'a thought with only a subject',
+      rawText: '**Only Subject**',
+      expected: { subject: 'Only Subject', description: '' },
+    },
+    {
+      name: 'a thought with only a description (no subject)',
+      rawText: 'This is just a description.',
+      expected: { subject: '', description: 'This is just a description.' },
+    },
+    {
+      name: 'an empty string input',
+      rawText: '',
+      expected: { subject: '', description: '' },
+    },
+    {
+      name: 'newlines within the subject and description',
+      rawText:
+        '**Multi-line\nSubject**\nHere is a description\nspread across lines.',
+      expected: {
+        subject: 'Multi-line\nSubject',
+        description: 'Here is a description\nspread across lines.',
+      },
+    },
+    {
+      name: 'only the first subject if multiple are present',
+      rawText: '**First** some text **Second**',
+      expected: { subject: 'First', description: 'some text **Second**' },
+    },
+    {
+      name: 'text before and after the subject',
+      rawText: 'Prefix text **Subject** Suffix text.',
+      expected: {
+        subject: 'Subject',
+        description: 'Prefix text  Suffix text.',
+      },
+    },
+    {
+      name: 'an unclosed subject tag',
+      rawText: 'Text with **an unclosed subject',
+      expected: { subject: '', description: 'Text with **an unclosed subject' },
+    },
+    {
+      name: 'an empty subject tag',
+      rawText: 'A thought with **** in the middle.',
+      expected: { subject: '', description: 'A thought with  in the middle.' },
+    },
+  ])('should correctly parse $name', ({ rawText, expected }) => {
+    expect(parseThought(rawText)).toEqual(expected);
+  });
+});