GitNexus/gitnexus/test/unit/chunker.test.ts

/**
 * Unit tests for character chunking and AST-aware chunking logic.
 */
import { describe, it, expect, vi, beforeEach } from 'vitest';
import { characterChunk } from '../../src/core/embeddings/character-chunk.js';

const { createParserForLanguage, resolveLanguageKey } = vi.hoisted(() => ({
  createParserForLanguage: vi.fn(),
  resolveLanguageKey: vi.fn((language: string, filePath?: string) =>
    language === 'typescript' && filePath?.endsWith('.tsx') ? 'typescript:tsx' : language,
  ),
}));

const { getLanguageFromFilename } = vi.hoisted(() => ({
  getLanguageFromFilename: vi.fn((filePath: string) => {
    if (filePath.endsWith('.m') || filePath.endsWith('.mm')) return 'objective-c';
    return filePath.endsWith('.rs') ? 'rust' : 'typescript';
  }),
}));

vi.mock('../../src/core/tree-sitter/parser-loader.js', () => ({
  createParserForLanguage,
  isLanguageAvailable: vi.fn().mockReturnValue(true),
  resolveLanguageKey,
}));

// Partial mock: `ast-utils` now resolves the LanguageProvider registry to apply
// `preprocessSource`, and that graph needs the real shared exports (#2771).
vi.mock('gitnexus-shared', async (importOriginal) => ({
  ...(await importOriginal<typeof import('gitnexus-shared')>()),
  getLanguageFromFilename,
}));

import { chunkNode } from '../../src/core/embeddings/chunker.js';

type FakeNode = {
  type: string;
  startIndex: number;
  endIndex: number;
  namedChildCount: number;
  namedChild: (index: number) => FakeNode | null;
  childForFieldName?: (name: string) => FakeNode | null;
};

const makeFakeNode = (
  type: string,
  startIndex: number,
  endIndex: number,
  children: FakeNode[] = [],
  fields: Record<string, FakeNode> = {},
): FakeNode => ({
  type,
  startIndex,
  endIndex,
  namedChildCount: children.length,
  namedChild: (index: number) => children[index] ?? null,
  childForFieldName: (name: string) => fields[name] ?? null,
});

const makeFunctionTree = (content: string, statementTexts: string[]) => {
  const statementNodes = statementTexts.map((text) => {
    const startIndex = content.indexOf(text);
    return makeFakeNode('expression_statement', startIndex, startIndex + text.length);
  });

  const bodyStart = content.indexOf('{');
  const bodyEnd = content.lastIndexOf('}') + 1;
  const bodyNode = makeFakeNode('statement_block', bodyStart, bodyEnd, statementNodes);
  const fnNode = makeFakeNode('function_declaration', 0, bodyEnd, [], { body: bodyNode });
  const root = makeFakeNode('program', 0, content.length, [fnNode]);

  return {
    rootNode: root,
  };
};

const makeTypedFunctionTree = (nodeType: string, content: string, statementTexts: string[]) => {
  const statementNodes = statementTexts.map((text) => {
    const startIndex = content.indexOf(text);
    return makeFakeNode('expression_statement', startIndex, startIndex + text.length);
  });

  const bodyStart = content.indexOf('{');
  const bodyEnd = content.lastIndexOf('}') + 1;
  const bodyNode = makeFakeNode('statement_block', bodyStart, bodyEnd, statementNodes);
  const fnNode = makeFakeNode(nodeType, 0, bodyEnd, [], { body: bodyNode });
  const root = makeFakeNode('program', 0, content.length, [fnNode]);

  return {
    rootNode: root,
  };
};

const makeDeclarationTree = (
  nodeType: string,
  bodyType: string,
  content: string,
  memberTexts: string[],
) => {
  let searchFrom = 0;
  const memberNodes = memberTexts.map((text) => {
    const startIndex = content.indexOf(text, searchFrom);
    if (startIndex < 0) {
      throw new Error(`Unable to locate member text: ${text}`);
    }
    searchFrom = startIndex + text.length;
    const inferredType =
      text.includes('()') || text.includes(': void') || text.includes(': boolean')
        ? 'method_definition'
        : 'field_definition';
    return makeFakeNode(inferredType, startIndex, startIndex + text.length);
  });

  const bodyStart = content.indexOf('{');
  const bodyEnd = content.lastIndexOf('}') + 1;
  const bodyNode = makeFakeNode(bodyType, bodyStart, bodyEnd, memberNodes);
  const declNode = makeFakeNode(nodeType, 0, bodyEnd, [bodyNode], { body: bodyNode });
  const root = makeFakeNode('program', 0, content.length, [declNode]);

  return {
    rootNode: root,
  };
};

const makeObjectiveCDeclarationTree = (
  nodeType: 'protocol_declaration' | 'class_interface',
  content: string,
  memberTexts: string[],
) => {
  const headerName = nodeType === 'protocol_declaration' ? 'Worker' : 'Worker (Tracing)';
  const headerNode = makeFakeNode(
    'identifier',
    content.indexOf(headerName),
    content.indexOf(headerName) + headerName.length,
  );
  let searchFrom = 0;
  const memberNodes = memberTexts.map((text) => {
    const startIndex = content.indexOf(text, searchFrom);
    if (startIndex < 0) throw new Error(`Unable to locate member text: ${text}`);
    searchFrom = startIndex + text.length;
    return makeFakeNode('method_declaration', startIndex, startIndex + text.length);
  });
  const declNode = makeFakeNode(nodeType, 0, content.length, [headerNode, ...memberNodes]);
  return { rootNode: makeFakeNode('program', 0, content.length, [declNode]) };
};

describe('characterChunk', () => {
  it('returns single chunk when content fits', () => {
    const result = characterChunk('short content', 1, 5, 1200, 120);
    expect(result).toHaveLength(1);
    expect(result[0].text).toBe('short content');
    expect(result[0].chunkIndex).toBe(0);
    expect(result[0].startOffset).toBe(0);
    expect(result[0].endOffset).toBe('short content'.length);
    expect(result[0].startLine).toBe(1);
    expect(result[0].endLine).toBe(5);
  });

  it('splits long content into multiple chunks', () => {
    const longContent = 'a'.repeat(3000);
    const result = characterChunk(longContent, 1, 100, 1200, 120);
    expect(result.length).toBeGreaterThan(1);
    for (const chunk of result) {
      expect(chunk.text.length).toBeLessThanOrEqual(1200);
    }
  });

  it('maintains sequential chunkIndex and offsets', () => {
    const longContent = 'x'.repeat(3000);
    const result = characterChunk(longContent, 1, 100, 1200, 120);
    for (let i = 0; i < result.length; i++) {
      expect(result[i].chunkIndex).toBe(i);
      expect(result[i].text).toBe(longContent.slice(result[i].startOffset, result[i].endOffset));
    }
  });

  it('includes overlap between chunks', () => {
    const content = 'abcdefghij'.repeat(200);
    const result = characterChunk(content, 1, 50, 500, 50);
    if (result.length > 1) {
      const endOfFirst = result[0].text.slice(-50);
      expect(result[1].text.startsWith(endOfFirst)).toBe(true);
    }
  });

  it('keeps the first chunk on the real starting line', () => {
    const content = 'alpha\nbeta\ngamma';
    const result = characterChunk(content, 38, 40, 6, 0);
    expect(result[0].startLine).toBe(38);
  });

  it('does not advance endLine when a chunk ends at a newline boundary', () => {
    const content = 'aaa\nbbb\nccc';
    const result = characterChunk(content, 10, 12, 4, 0);
    expect(result[0].text).toBe('aaa\n');
    expect(result[0].startLine).toBe(10);
    expect(result[0].endLine).toBe(10);
  });
});

describe('chunkNode', () => {
  beforeEach(() => {
    createParserForLanguage.mockReset();
    resolveLanguageKey.mockReset();
    resolveLanguageKey.mockImplementation(
      (language: string, filePath?: string) => `${language}:${filePath ?? ''}`,
    );
    getLanguageFromFilename.mockImplementation((filePath: string) => {
      if (filePath.endsWith('.m') || filePath.endsWith('.mm')) return 'objective-c';
      return filePath.endsWith('.rs') ? 'rust' : 'typescript';
    });
  });

  it('returns single chunk for short content', async () => {
    const result = await chunkNode('Function', 'short', 'test.ts', 1, 5, 1200, 120);
    expect(result).toHaveLength(1);
    expect(result[0].chunkIndex).toBe(0);
    expect(result[0].text).toBe('short');
    expect(result[0].startOffset).toBe(0);
  });

  it('splits a class by members instead of raw character windows', async () => {
    const content = [
      'class Parser {',
      '  options: ParserOptions;',
      '  cache: Map<string, any>;',
      '  parseJSON() { return JSON.parse("{}"); }',
      '  validate() { return true; }',
      '}',
    ].join('\n');
    const tree = makeDeclarationTree('class_declaration', 'class_body', content, [
      'options: ParserOptions;',
      'cache: Map<string, any>;',
      'parseJSON() { return JSON.parse("{}"); }',
      'validate() { return true; }',
    ]);
    createParserForLanguage.mockResolvedValue({
      parse: vi.fn().mockReturnValue(tree),
    });

    const result = await chunkNode('Class', content, 'test.ts', 1, 6, 90, 0);

    expect(result).toHaveLength(2);
    expect(result[0].text).toContain('class Parser {');
    expect(result[0].text).toContain('options: ParserOptions;');
    expect(result[0].text).toContain('cache: Map<string, any>;');
    expect(result[1].text).toContain('parseJSON()');
    expect(result[1].text).toContain('validate()');
    expect(result[0].startLine).toBe(1);
    expect(result[1].startLine).toBe(4);
  });

  it('preserves interface signatures via declaration-aware chunking', async () => {
    const content = [
      'interface Handler {',
      '  handle(event: Event): void;',
      '  validate(input: string): boolean;',
      '  readonly name: string;',
      '}',
    ].join('\n');
    const tree = makeDeclarationTree('interface_declaration', 'object_type', content, [
      'handle(event: Event): void;',
      'validate(input: string): boolean;',
      'readonly name: string;',
    ]);
    createParserForLanguage.mockResolvedValue({
      parse: vi.fn().mockReturnValue(tree),
    });

    const result = await chunkNode('Interface', content, 'test.ts', 10, 14, 500, 0);

    expect(result).toHaveLength(1);
    expect(result[0].text).toContain('interface Handler {');
    expect(result[0].text).toContain('handle(event: Event): void;');
    expect(result[0].text).toContain('validate(input: string): boolean;');
    expect(result[0].text).toContain('readonly name: string;');
  });

  it('uses declaration-aware chunking for Struct labels', async () => {
    const content = [
      'struct User {',
      '  name: String,',
      '  email: String,',
      '  age: u32,',
      '  address: String,',
      '}',
    ].join('\n');
    const tree = makeDeclarationTree('struct_item', 'declaration_list', content, [
      'name: String,',
      'email: String,',
      'age: u32,',
      'address: String,',
    ]);
    createParserForLanguage.mockResolvedValue({
      parse: vi.fn().mockReturnValue(tree),
    });

    const result = await chunkNode('Struct', content, 'test.rs', 40, 45, 45, 0);

    expect(result).toHaveLength(2);
    expect(result[0].text).toContain('struct User {');
    expect(result[0].text).toContain('name: String,');
    expect(result[0].text).toContain('email: String');
    const combinedText = result.map((chunk) => chunk.text).join('\n');
    expect(combinedText).toContain('email: String');
    expect(combinedText).toContain('age: u32');
    expect(combinedText).toContain('address: String');
    expect(result[0].startLine).toBe(40);
  });

  it.each([
    {
      label: 'Protocol',
      nodeType: 'protocol_declaration' as const,
      filePath: 'Worker.m',
      content: [
        '@protocol Worker',
        '- (void)startWithConfiguration:(id)configuration;',
        '- (void)stopWithCompletion:(id)completion;',
        '- (void)reloadWithOptions:(id)options;',
        '@end',
      ].join('\n'),
    },
    {
      label: 'Category',
      nodeType: 'class_interface' as const,
      filePath: 'Worker.mm',
      content: [
        '@interface Worker (Tracing)',
        '- (void)startWithConfiguration:(id)configuration;',
        '- (void)stopWithCompletion:(id)completion;',
        '- (void)reloadWithOptions:(id)options;',
        '@end',
      ].join('\n'),
    },
  ])(
    'chunks Objective-C $label declarations at member boundaries',
    async ({ label, nodeType, filePath, content }) => {
      const members = [
        '- (void)startWithConfiguration:(id)configuration;',
        '- (void)stopWithCompletion:(id)completion;',
        '- (void)reloadWithOptions:(id)options;',
      ];
      createParserForLanguage.mockResolvedValue({
        parse: vi.fn().mockReturnValue(makeObjectiveCDeclarationTree(nodeType, content, members)),
      });

      const result = await chunkNode(label, content, filePath, 1, 5, 90, 0);

      expect(result).toHaveLength(2);
      expect(result[0].text).toContain(members[0]);
      expect(result.slice(1).every((chunk) => chunk.text.startsWith('- (void)'))).toBe(true);
      expect(createParserForLanguage).toHaveBeenCalledWith('objective-c', filePath);
    },
  );

  it('skips Objective-C parameterized interface arguments as declaration members', async () => {
    const content = ['@interface Worker <Runnable>', '- (void)run;', '@end'].join('\n');
    const nameStart = content.indexOf('Worker');
    const argumentsStart = content.indexOf('<Runnable>');
    const methodStart = content.indexOf('- (void)run;');
    const declaration = makeFakeNode('class_interface', 0, content.length, [
      makeFakeNode('identifier', nameStart, nameStart + 'Worker'.length),
      makeFakeNode('parameterized_arguments', argumentsStart, argumentsStart + '<Runnable>'.length),
      makeFakeNode('method_declaration', methodStart, methodStart + '- (void)run;'.length),
    ]);
    createParserForLanguage.mockResolvedValue({
      parse: vi.fn().mockReturnValue({
        rootNode: makeFakeNode('program', 0, content.length, [declaration]),
      }),
    });

    const result = await chunkNode('Class', content, 'ParameterizedWorker.m', 1, 3, 40, 0);

    expect(createParserForLanguage).toHaveBeenCalledWith('objective-c', 'ParameterizedWorker.m');
    expect(result[0].text).toContain('- (void)run');
  });

  it('skips Objective-C generic argument lists as declaration members', async () => {
    const content = ['@interface Worker(Tracing)', '- (void)run;', '@end'].join('\n');
    const nameStart = content.indexOf('Worker');
    const argumentsStart = content.indexOf('(Tracing)');
    const methodStart = content.indexOf('- (void)run;');
    const declaration = makeFakeNode('class_interface', 0, content.length, [
      makeFakeNode('identifier', nameStart, nameStart + 'Worker'.length),
      makeFakeNode('generic_arguments', argumentsStart, argumentsStart + '(Tracing)'.length),
      makeFakeNode('method_declaration', methodStart, methodStart + '- (void)run;'.length),
    ]);
    createParserForLanguage.mockResolvedValue({
      parse: vi.fn().mockReturnValue({
        rootNode: makeFakeNode('program', 0, content.length, [declaration]),
      }),
    });

    const result = await chunkNode('Class', content, 'GenericCategoryWorker.m', 1, 3, 40, 0);

    expect(createParserForLanguage).toHaveBeenCalledWith('objective-c', 'GenericCategoryWorker.m');
    expect(result[0].text).toContain('- (void)run');
    expect(result.some((chunk) => chunk.text === '(Tracing)')).toBe(false);
  });

  it('chunks an Objective-C implementation at method boundaries', async () => {
    const content = [
      '@implementation Worker',
      '- (void)first {}',
      '- (void)second {}',
      '@end',
    ].join('\n');
    const firstMethod = '- (void)first {}';
    const secondMethod = '- (void)second {}';
    const firstImplementation = makeFakeNode(
      'implementation_definition',
      content.indexOf(firstMethod),
      content.indexOf(firstMethod) + firstMethod.length,
      [
        makeFakeNode(
          'method_definition',
          content.indexOf(firstMethod),
          content.indexOf(firstMethod) + firstMethod.length,
        ),
      ],
    );
    const secondImplementation = makeFakeNode(
      'implementation_definition',
      content.indexOf(secondMethod),
      content.indexOf(secondMethod) + secondMethod.length,
      [
        makeFakeNode(
          'method_definition',
          content.indexOf(secondMethod),
          content.indexOf(secondMethod) + secondMethod.length,
        ),
      ],
    );
    const declaration = makeFakeNode('class_implementation', 0, content.indexOf('@end') + 4, [
      makeFakeNode(
        'identifier',
        content.indexOf('Worker'),
        content.indexOf('Worker') + 'Worker'.length,
      ),
      firstImplementation,
      secondImplementation,
    ]);
    createParserForLanguage.mockResolvedValue({
      parse: vi.fn().mockReturnValue({
        rootNode: makeFakeNode('program', 0, content.length, [declaration]),
      }),
    });

    const result = await chunkNode('Class', content, 'ImplementationWorker.m', 1, 4, 48, 0);

    expect(createParserForLanguage).toHaveBeenCalledWith('objective-c', 'ImplementationWorker.m');
    expect(result).toHaveLength(2);
    expect(result[0].text).toContain(firstMethod);
    expect(result[1].text).toContain(secondMethod);
    expect(result[1].text).not.toContain(firstMethod);
  });

  it('parses distinct Objective-C sources correctly through one cached parser', async () => {
    const protocolMethods = [
      '- (void)startWithConfiguration:(id)configuration;',
      '- (void)stopWithCompletion:(id)completion;',
      '- (void)reloadWithOptions:(id)options;',
    ];
    const categoryMethods = [
      '- (void)traceStartWithConfiguration:(id)configuration;',
      '- (void)traceStopWithCompletion:(id)completion;',
      '- (void)traceReloadWithOptions:(id)options;',
    ];
    const protocolContent = ['@protocol Worker', ...protocolMethods, '@end'].join('\n');
    const categoryContent = ['@interface Worker (Tracing)', ...categoryMethods, '@end'].join('\n');
    const parser = {
      parse: vi.fn((source: string) => {
        if (source === protocolContent) {
          return makeObjectiveCDeclarationTree(
            'protocol_declaration',
            protocolContent,
            protocolMethods,
          );
        }
        if (source === categoryContent) {
          return makeObjectiveCDeclarationTree('class_interface', categoryContent, categoryMethods);
        }
        throw new Error(`Unexpected Objective-C source: ${source}`);
      }),
    };
    createParserForLanguage.mockResolvedValue(parser);

    const protocol = await chunkNode(
      'Protocol',
      protocolContent,
      'CachedObjectiveC.m',
      1,
      5,
      90,
      0,
    );
    const category = await chunkNode(
      'Category',
      categoryContent,
      'CachedObjectiveC.m',
      1,
      5,
      90,
      0,
    );

    expect(createParserForLanguage).toHaveBeenCalledTimes(1);
    expect(protocol.map((chunk) => chunk.text).join('\n')).toContain(protocolMethods[2]);
    expect(category.map((chunk) => chunk.text).join('\n')).toContain(categoryMethods[2]);
    expect(parser.parse.mock.calls.map(([source]) => source)).toEqual([
      protocolContent,
      categoryContent,
    ]);
  });

  it('expands Objective-C protocol optional and required sections', async () => {
    const content = [
      '@protocol P',
      '@optional',
      '- (void)first;',
      '- (void)second;',
      '@required',
      '- (void)third;',
      '- (void)fourth;',
      '@end',
    ].join('\n');
    const members = ['- (void)first;', '- (void)second;', '- (void)third;', '- (void)fourth;'];
    let searchFrom = 0;
    const methodNodes = members.map((text) => {
      const startIndex = content.indexOf(text, searchFrom);
      searchFrom = startIndex + text.length;
      return makeFakeNode('method_declaration', startIndex, startIndex + text.length);
    });
    const optionalStart = content.indexOf('@optional');
    const requiredStart = content.indexOf('@required');
    const optional = makeFakeNode(
      'qualified_protocol_interface_declaration',
      optionalStart,
      methodNodes[1].endIndex,
      methodNodes.slice(0, 2),
    );
    const required = makeFakeNode(
      'qualified_protocol_interface_declaration',
      requiredStart,
      methodNodes[3].endIndex,
      methodNodes.slice(2),
    );
    const header = makeFakeNode('identifier', content.indexOf('P'), content.indexOf('P') + 1);
    const declaration = makeFakeNode('protocol_declaration', 0, content.length, [
      header,
      optional,
      required,
    ]);
    createParserForLanguage.mockResolvedValue({
      parse: vi.fn().mockReturnValue({
        rootNode: makeFakeNode('program', 0, content.length, [declaration]),
      }),
    });

    const result = await chunkNode('Protocol', content, 'ProtocolSections.m', 1, 8, 36, 0);
    const combined = result.map((chunk) => chunk.text).join('\n');
    const requiredChunk = result.find((chunk) => chunk.text.includes(members[2]));

    expect(result.length).toBeGreaterThan(1);
    for (const member of members) expect(combined).toContain(member);
    expect(
      result.some((chunk) => chunk.text.includes(members[0]) && chunk.text.includes(members[1])),
    ).toBe(false);
    expect(requiredChunk?.text).toContain('@required');
    expect(requiredChunk?.text).not.toContain(members[1]);
    expect(createParserForLanguage).toHaveBeenCalledWith('objective-c', 'ProtocolSections.m');
  });

  it('expands Objective-C instance variables before chunking a class declaration', async () => {
    const content = [
      '@interface Worker {',
      '  id _first;',
      '  id _second;',
      '}',
      '- (void)run;',
      '@end',
    ].join('\n');
    const firstIvar = 'id _first;';
    const secondIvar = 'id _second;';
    const method = '- (void)run;';
    const firstIvarStart = content.indexOf(firstIvar);
    const secondIvarStart = content.indexOf(secondIvar);
    const methodStart = content.indexOf(method);
    const instanceVariables = makeFakeNode(
      'instance_variables',
      content.indexOf('{'),
      content.indexOf('}') + 1,
      [
        makeFakeNode('instance_variable', firstIvarStart, firstIvarStart + firstIvar.length),
        makeFakeNode('instance_variable', secondIvarStart, secondIvarStart + secondIvar.length),
      ],
    );
    const declaration = makeFakeNode('class_interface', 0, content.length, [
      makeFakeNode(
        'identifier',
        content.indexOf('Worker'),
        content.indexOf('Worker') + 'Worker'.length,
      ),
      instanceVariables,
      makeFakeNode('method_declaration', methodStart, methodStart + method.length),
    ]);
    createParserForLanguage.mockResolvedValue({
      parse: vi.fn().mockReturnValue({
        rootNode: makeFakeNode('program', 0, content.length, [declaration]),
      }),
    });

    const result = await chunkNode('Class', content, 'Worker.m', 1, 6, 48, 0);
    const combined = result.map((chunk) => chunk.text).join('\n');

    expect(result.length).toBeGreaterThan(1);
    expect(combined).toContain(firstIvar);
    expect(combined).toContain(secondIvar);
    expect(combined).toContain(method);
    expect(combined).toContain('}');
    expect(
      result.some((chunk) => chunk.text.includes(firstIvar) && chunk.text.includes(secondIvar)),
    ).toBe(true);
    expect(
      result.some((chunk) => chunk.text.includes(secondIvar) && chunk.text.includes('}')),
    ).toBe(true);
  });

  it('keeps ivar attributes attached to the following instance variable', async () => {
    const extraMethods = ['- (void)alpha;', '- (void)bravo;', '- (void)charlie;'];
    const content = [
      '@interface Worker {',
      '  __attribute__((unused)) id _first;',
      '}',
      ...extraMethods,
      '@end',
    ].join('\n');
    const attribute = '__attribute__((unused))';
    const firstIvar = 'id _first;';
    const attrStart = content.indexOf(attribute);
    const firstIvarStart = content.indexOf(firstIvar);
    const instanceVariables = makeFakeNode(
      'instance_variables',
      content.indexOf('{'),
      content.indexOf('}') + 1,
      [
        makeFakeNode('attribute_specifier', attrStart, attrStart + attribute.length),
        makeFakeNode('instance_variable', firstIvarStart, firstIvarStart + firstIvar.length),
      ],
    );
    const methodNodes = extraMethods.map((method) => {
      const methodStart = content.indexOf(method);
      return makeFakeNode('method_declaration', methodStart, methodStart + method.length);
    });
    const declaration = makeFakeNode('class_interface', 0, content.length, [
      makeFakeNode(
        'identifier',
        content.indexOf('Worker'),
        content.indexOf('Worker') + 'Worker'.length,
      ),
      instanceVariables,
      ...methodNodes,
    ]);
    createParserForLanguage.mockResolvedValue({
      parse: vi.fn().mockReturnValue({
        rootNode: makeFakeNode('program', 0, content.length, [declaration]),
      }),
    });

    // First-chunk prefix starts at `@interface`, so size must cover that
    // prefix plus the ivar unit. Smaller sizes fall into characterChunk and
    // can split the attribute token itself.
    const chunkSize = content.indexOf('}') + 2;
    const result = await chunkNode(
      'Class',
      content,
      'WorkerAttr.m',
      1,
      extraMethods.length + 4,
      chunkSize,
      0,
    );

    expect(content.length).toBeGreaterThan(chunkSize);
    expect(
      result.some((chunk) => chunk.text.includes(attribute) && !chunk.text.includes(firstIvar)),
    ).toBe(false);
    expect(
      result.some((chunk) => chunk.text.includes(attribute) && chunk.text.includes(firstIvar)),
    ).toBe(true);
  });

  it('keeps Objective-C declaration modifiers in the class prefix', async () => {
    const content = ['NS_ROOT_CLASS @interface Worker', '- (void)run;', '@end'].join('\n');
    const modifier = 'NS_ROOT_CLASS';
    const method = '- (void)run;';
    const methodStart = content.indexOf(method);
    const declaration = makeFakeNode('class_interface', 0, content.length, [
      makeFakeNode('storage_class_specifier', 0, modifier.length),
      makeFakeNode(
        'identifier',
        content.indexOf('Worker'),
        content.indexOf('Worker') + 'Worker'.length,
      ),
      makeFakeNode('method_declaration', methodStart, methodStart + method.length),
    ]);
    createParserForLanguage.mockResolvedValue({
      parse: vi.fn().mockReturnValue({
        rootNode: makeFakeNode('program', 0, content.length, [declaration]),
      }),
    });

    const result = await chunkNode('Class', content, 'RootClass.m', 1, 3, 80, 0);

    expect(result[0].text).toContain(method);
    expect(result.some((chunk) => chunk.text.trim() === modifier)).toBe(false);
  });

  it('keeps Objective-C protocol inheritance in the declaration prefix', async () => {
    const content = ['@protocol Worker <Runnable, Observable>', '- (void)run;', '@end'].join('\n');
    const protocolNameStart = content.indexOf('Worker');
    const inheritanceStart = content.indexOf('<Runnable, Observable>');
    const methodStart = content.indexOf('- (void)run;');
    const declaration = makeFakeNode('protocol_declaration', 0, content.length, [
      makeFakeNode('identifier', protocolNameStart, protocolNameStart + 'Worker'.length),
      makeFakeNode(
        'protocol_reference_list',
        inheritanceStart,
        inheritanceStart + '<Runnable, Observable>'.length,
      ),
      makeFakeNode('method_declaration', methodStart, methodStart + '- (void)run;'.length),
    ]);
    createParserForLanguage.mockResolvedValue({
      parse: vi.fn().mockReturnValue({
        rootNode: makeFakeNode('program', 0, content.length, [declaration]),
      }),
    });

    const result = await chunkNode('Protocol', content, 'ProtocolInheritance.m', 1, 3, 50, 0);

    expect(createParserForLanguage).toHaveBeenCalledWith('objective-c', 'ProtocolInheritance.m');
    expect(result[0].text).toContain('- (void)');
    expect(result[0].text).not.toBe('@protocol Worker <Runnable, Observable>');
  });

  it('splits a function into multiple AST-aware chunks using snippet offsets', async () => {
    const content = [
      'function example() {',
      '  const first = 1;',
      '',
      '  const second = 2;',
      '  return first + second;',
      '}',
    ].join('\n');
    const tree = makeFunctionTree(content, [
      'const first = 1;',
      'const second = 2;',
      'return first + second;',
    ]);
    createParserForLanguage.mockResolvedValue({
      parse: vi.fn().mockReturnValue(tree),
    });

    const result = await chunkNode('Function', content, 'test.ts', 38, 43, 68, 0);

    expect(result).toHaveLength(2);
    expect(result[0].startOffset).toBe(0);
    expect(result[0].endOffset).toBeGreaterThan(content.indexOf('const second = 2;'));
    expect(result[0].startLine).toBe(38);
    expect(result[0].endLine).toBe(42);
    expect(result[0].text).toContain('function example() {');
    expect(result[0].text).toContain('\n\n  const second = 2;');
    expect(result[1].startOffset).toBeGreaterThan(content.indexOf('const second = 2;'));
    expect(result[1].startLine).toBeGreaterThanOrEqual(42);
    expect(result[1].endLine).toBe(43);
    expect(result[1].text.length).toBeGreaterThan(0);
  });

  it('uses AST-aware chunking for Constructor labels too', async () => {
    const content = [
      'constructor() {',
      '  this.ready = true;',
      '  this.mode = "prod";',
      '  this.start();',
      '}',
    ].join('\n');
    const tree = makeFunctionTree(content, [
      'this.ready = true;',
      'this.mode = "prod";',
      'this.start();',
    ]);
    createParserForLanguage.mockResolvedValue({
      parse: vi.fn().mockReturnValue(tree),
    });

    const result = await chunkNode('Constructor', content, 'test.ts', 12, 16, 55, 0);

    expect(result).toHaveLength(2);
    expect(result[0].text).toContain('constructor() {');
    expect(result[0].startLine).toBe(12);
    expect(result[1].startLine).toBe(14);
  });

  it('recognizes Rust function_item nodes for AST-aware chunking', async () => {
    const content = [
      'fn build_user() {',
      '    let first = 1;',
      '    let second = 2;',
      '    return first + second;',
      '}',
    ].join('\n');
    const tree = makeTypedFunctionTree('function_item', content, [
      'let first = 1;',
      'let second = 2;',
      'return first + second;',
    ]);
    createParserForLanguage.mockResolvedValue({
      parse: vi.fn().mockReturnValue(tree),
    });

    const result = await chunkNode('Function', content, 'test.rs', 20, 24, 52, 0);

    expect(result).toHaveLength(2);
    expect(result[0].text).toContain('fn build_user() {');
    expect(result[0].startLine).toBe(20);
    expect(result[1].text).toContain('return first + second;');
  });

  it('falls back to character chunks when AST parsing fails', async () => {
    createParserForLanguage.mockRejectedValueOnce(new Error('no parser'));

    const content = 'x'.repeat(3000);
    const result = await chunkNode('Function', content, 'test.tsx', 1, 100, 1200, 120);
    expect(result.length).toBeGreaterThan(1);
    expect(result[0].startOffset).toBe(0);
  });
});