test(02-tree-sitter-02): add symbol chunk merge regression

- index a temp project with two small exported functions
- assert symbol-aware chunks for a and b remain separate and unmerged

Author: PatrickSys

tests/symbol-chunk-merge.test.ts

@@ -0,0 +1,79 @@
+import { afterEach, beforeEach, describe, expect, it } from 'vitest';
+import { promises as fs } from 'fs';
+import os from 'os';
+import path from 'path';
+import { CodebaseIndexer } from '../src/core/indexer.js';
+import { analyzerRegistry } from '../src/core/analyzer-registry.js';
+import { GenericAnalyzer } from '../src/analyzers/generic/index.js';
+import {
+  CODEBASE_CONTEXT_DIRNAME,
+  KEYWORD_INDEX_FILENAME
+} from '../src/constants/codebase-context.js';
+
+describe('Symbol-aware chunk merge guard', () => {
+  let tempDir: string;
+
+  beforeEach(async () => {
+    analyzerRegistry.register(new GenericAnalyzer());
+    tempDir = await fs.mkdtemp(path.join(os.tmpdir(), 'symbol-chunk-merge-'));
+    await fs.writeFile(
+      path.join(tempDir, 'package.json'),
+      JSON.stringify({ name: 'symbol-chunk-test' })
+    );
+  });
+
+  afterEach(async () => {
+    await fs.rm(tempDir, { recursive: true, force: true });
+  });
+
+  it('keeps small symbol chunks separate during indexing', async () => {
+    await fs.writeFile(
+      path.join(tempDir, 'utils.ts'),
+      [
+        'export function a(): number {',
+        '  return 1;',
+        '}',
+        '',
+        'export function b(): number {',
+        '  return 2;',
+        '}'
+      ].join('\n')
+    );
+
+    const indexer = new CodebaseIndexer({
+      rootPath: tempDir,
+      config: { skipEmbedding: true }
+    });
+
+    await indexer.index();
+
+    const indexPath = path.join(tempDir, CODEBASE_CONTEXT_DIRNAME, KEYWORD_INDEX_FILENAME);
+    const allChunks = JSON.parse(await fs.readFile(indexPath, 'utf-8')) as Array<{
+      filePath: string;
+      relativePath: string;
+      metadata?: {
+        componentName?: string;
+        symbolAware?: boolean;
+        merged?: boolean;
+      };
+    }>;
+
+    const utilsChunks = allChunks.filter((chunk) => {
+      const fileNameFromFilePath = chunk.filePath.split(/[\\/]/).pop();
+      const fileNameFromRelativePath = chunk.relativePath.split(/[\\/]/).pop();
+      return fileNameFromFilePath === 'utils.ts' || fileNameFromRelativePath === 'utils.ts';
+    });
+
+    expect(utilsChunks.length).toBeGreaterThanOrEqual(2);
+
+    const aChunk = utilsChunks.find((chunk) => chunk.metadata?.componentName === 'a');
+    const bChunk = utilsChunks.find((chunk) => chunk.metadata?.componentName === 'b');
+
+    expect(aChunk).toBeDefined();
+    expect(bChunk).toBeDefined();
+    expect(aChunk?.metadata?.symbolAware).toBe(true);
+    expect(bChunk?.metadata?.symbolAware).toBe(true);
+    expect(aChunk?.metadata?.merged).not.toBe(true);
+    expect(bChunk?.metadata?.merged).not.toBe(true);
+  });
+});