diff --git a/markitect/associated_files.py b/markitect/associated_files.py
new file mode 100644
index 00000000..3cd4f2c8
--- /dev/null
+++ b/markitect/associated_files.py
@@ -0,0 +1,355 @@
+"""
+Associated Files Manager for Issue #40: Associated Files Management.
+
+This module provides functionality to manage associated markdown and schema files
+with convention-based naming and automatic file placement.
+"""
+
+import os
+from pathlib import Path
+from typing import Dict, List, Optional, Any
+
+
+class AssociatedFilesError(Exception):
+    """Base exception for associated files operations."""
+    pass
+
+
+class InvalidFileTypeError(AssociatedFilesError):
+    """Raised when file has unexpected extension."""
+    pass
+
+
+class DirectoryAccessError(AssociatedFilesError):
+    """Raised when directory cannot be accessed."""
+    pass
+
+
+class AssociatedFilesManager:
+    """
+    Manages associated markdown and schema files with convention-based naming.
+
+    Provides functionality to find, create, and manage pairs of markdown and JSON schema
+    files that follow the convention of having identical basenames with different extensions.
+    """
+
+    def __init__(self, markdown_extension: str = '.md', schema_extension: str = '.json'):
+        """
+        Initialize the associated files manager.
+
+        Args:
+            markdown_extension: File extension for markdown files (default: '.md')
+            schema_extension: File extension for schema files (default: '.json')
+
+        Raises:
+            ValueError: If extensions are invalid or identical
+        """
+        # Validate extensions
+        if not markdown_extension.startswith('.'):
+            raise ValueError("Markdown extension must start with '.'")
+        if not schema_extension.startswith('.'):
+            raise ValueError("Schema extension must start with '.'")
+        if markdown_extension.lower() == schema_extension.lower():
+            raise ValueError("Markdown and schema extensions must be different")
+
+        self.markdown_extension = markdown_extension.lower()
+        self.schema_extension = schema_extension.lower()
+
+    def _validate_file_extension(self, file_path: Path, expected_extension: str, file_type: str) -> None:
+        """
+        Validate file has expected extension.
+
+        Args:
+            file_path: Path to validate
+            expected_extension: Expected extension (e.g., '.md')
+            file_type: Description of file type for error messages
+
+        Raises:
+            InvalidFileTypeError: If file doesn't have expected extension
+        """
+        if file_path.suffix.lower() != expected_extension:
+            raise InvalidFileTypeError(
+                f"Expected {file_type} file with {expected_extension} extension, got {file_path.suffix}"
+            )
+
+    def _validate_markdown_file(self, file_path: Path) -> None:
+        """Validate file is a markdown file."""
+        self._validate_file_extension(file_path, self.markdown_extension, "markdown")
+
+    def _validate_schema_file(self, file_path: Path) -> None:
+        """Validate file is a schema file."""
+        self._validate_file_extension(file_path, self.schema_extension, "schema")
+
+    def _validate_directory(self, directory: Path) -> None:
+        """
+        Validate directory access and permissions.
+
+        Args:
+            directory: Directory path to validate
+
+        Raises:
+            DirectoryAccessError: If directory cannot be accessed
+        """
+        if not directory.exists():
+            raise DirectoryAccessError(f"Directory does not exist: {directory}")
+
+        if not directory.is_dir():
+            raise DirectoryAccessError(f"Path is not a directory: {directory}")
+
+        if not os.access(directory, os.R_OK):
+            raise DirectoryAccessError(f"No read permission for directory: {directory}")
+
+    def get_associated_schema_path(self, markdown_file: Path) -> Path:
+        """
+        Get the path for the associated schema file of a markdown file.
+
+        Args:
+            markdown_file: Path to the markdown file
+
+        Returns:
+            Path where the associated schema should be located
+
+        Raises:
+            InvalidFileTypeError: If the file doesn't have .md extension
+        """
+        self._validate_markdown_file(markdown_file)
+
+        return markdown_file.with_suffix(self.schema_extension)
+
+    def get_associated_markdown_path(self, schema_file: Path) -> Path:
+        """
+        Get the path for the associated markdown file of a schema file.
+
+        Args:
+            schema_file: Path to the schema file
+
+        Returns:
+            Path where the associated markdown should be located
+
+        Raises:
+            InvalidFileTypeError: If the file doesn't have .json extension
+        """
+        self._validate_schema_file(schema_file)
+
+        return schema_file.with_suffix(self.markdown_extension)
+
+    def find_associated_schema(self, markdown_file: Path) -> Optional[Path]:
+        """
+        Find the associated schema file for a markdown file.
+
+        Args:
+            markdown_file: Path to the markdown file
+
+        Returns:
+            Path to associated schema file if it exists, None otherwise
+        """
+        schema_path = self.get_associated_schema_path(markdown_file)
+        return schema_path if schema_path.exists() else None
+
+    def find_associated_markdown(self, schema_file: Path) -> Optional[Path]:
+        """
+        Find the associated markdown file for a schema file.
+
+        Args:
+            schema_file: Path to the schema file
+
+        Returns:
+            Path to associated markdown file if it exists, None otherwise
+        """
+        markdown_path = self.get_associated_markdown_path(schema_file)
+        return markdown_path if markdown_path.exists() else None
+
+    def has_associated_schema(self, markdown_file: Path) -> bool:
+        """
+        Check if a markdown file has an associated schema file.
+
+        Args:
+            markdown_file: Path to the markdown file
+
+        Returns:
+            True if associated schema exists, False otherwise
+        """
+        return self.find_associated_schema(markdown_file) is not None
+
+    def has_associated_markdown(self, schema_file: Path) -> bool:
+        """
+        Check if a schema file has an associated markdown file.
+
+        Args:
+            schema_file: Path to the schema file
+
+        Returns:
+            True if associated markdown exists, False otherwise
+        """
+        return self.find_associated_markdown(schema_file) is not None
+
+    def list_file_pairs(self, directory: Path) -> List[Dict[str, Any]]:
+        """
+        List all associated file pairs in a directory.
+
+        Optimized version that reduces filesystem calls by collecting all files
+        at once and finding pairs through basename intersection.
+
+        Args:
+            directory: Directory to search for file pairs
+
+        Returns:
+            List of dictionaries containing information about each file pair
+        """
+        pairs = []
+
+        # Get all files at once and group by extension (more efficient)
+        try:
+            all_files = [f for f in directory.iterdir() if f.is_file()]
+        except (OSError, PermissionError):
+            # Return empty list if directory cannot be read
+            return pairs
+
+        md_files = {f.stem: f for f in all_files if f.suffix.lower() == self.markdown_extension}
+        json_files = {f.stem: f for f in all_files if f.suffix.lower() == self.schema_extension}
+
+        # Find pairs by checking intersection of basenames (no additional filesystem calls)
+        paired_basenames = set(md_files.keys()) & set(json_files.keys())
+
+        for basename in sorted(paired_basenames):  # Sort for consistent output
+            pairs.append({
+                'basename': basename,
+                'markdown_file': md_files[basename],
+                'schema_file': json_files[basename],
+                'both_exist': True
+            })
+
+        return pairs
+
+    def get_file_pair_info(self, file_path: Path) -> Dict[str, Any]:
+        """
+        Get detailed information about a file pair.
+
+        Args:
+            file_path: Path to either markdown or schema file
+
+        Returns:
+            Dictionary with detailed information about the file pair
+        """
+        if file_path.suffix.lower() == self.markdown_extension:
+            md_file = file_path
+            schema_file = self.get_associated_schema_path(md_file)
+        elif file_path.suffix.lower() == self.schema_extension:
+            schema_file = file_path
+            md_file = self.get_associated_markdown_path(schema_file)
+        else:
+            raise ValueError(f"Unsupported file type: {file_path.suffix}")
+
+        info = {
+            'basename': file_path.stem,
+            'markdown_file': md_file,
+            'schema_file': schema_file,
+            'both_exist': md_file.exists() and schema_file.exists()
+        }
+
+        # Add file sizes if files exist
+        if md_file.exists():
+            info['markdown_size'] = md_file.stat().st_size
+            info['markdown_modified'] = md_file.stat().st_mtime
+
+        if schema_file.exists():
+            info['schema_size'] = schema_file.stat().st_size
+            info['schema_modified'] = schema_file.stat().st_mtime
+
+        return info
+
+    def list_orphaned_files(self, directory: Path) -> Dict[str, List[Path]]:
+        """
+        List orphaned files (files without their associated counterpart).
+
+        Optimized version that reuses file discovery from list_file_pairs logic.
+
+        Args:
+            directory: Directory to search
+
+        Returns:
+            Dictionary with 'orphaned_markdown' and 'orphaned_schemas' lists
+        """
+        orphaned_markdown = []
+        orphaned_schemas = []
+
+        # Get all files at once (reusing optimization pattern)
+        try:
+            all_files = [f for f in directory.iterdir() if f.is_file()]
+        except (OSError, PermissionError):
+            return {
+                'orphaned_markdown': orphaned_markdown,
+                'orphaned_schemas': orphaned_schemas
+            }
+
+        md_files = {f.stem: f for f in all_files if f.suffix.lower() == self.markdown_extension}
+        json_files = {f.stem: f for f in all_files if f.suffix.lower() == self.schema_extension}
+
+        # Find orphaned files by checking set differences
+        orphaned_md_basenames = set(md_files.keys()) - set(json_files.keys())
+        orphaned_json_basenames = set(json_files.keys()) - set(md_files.keys())
+
+        # Collect orphaned files
+        for basename in sorted(orphaned_md_basenames):
+            orphaned_markdown.append(md_files[basename])
+
+        for basename in sorted(orphaned_json_basenames):
+            orphaned_schemas.append(json_files[basename])
+
+        return {
+            'orphaned_markdown': orphaned_markdown,
+            'orphaned_schemas': orphaned_schemas
+        }
+
+    def get_directory_status(self, directory: Path) -> Dict[str, Any]:
+        """
+        Get comprehensive status of associated files in a directory.
+
+        Args:
+            directory: Directory to analyze
+
+        Returns:
+            Dictionary with status information
+        """
+        pairs = self.list_file_pairs(directory)
+        orphaned = self.list_orphaned_files(directory)
+
+        return {
+            'directory': directory,
+            'paired_files': len(pairs),
+            'orphaned_markdown': len(orphaned['orphaned_markdown']),
+            'orphaned_schemas': len(orphaned['orphaned_schemas']),
+            'pairs': pairs,
+            'orphaned': orphaned
+        }
+
+    def suggest_output_path(self, input_file: Path, target_extension: str) -> Path:
+        """
+        Suggest an output path for generating an associated file.
+
+        Args:
+            input_file: Source file path
+            target_extension: Desired extension for output file (e.g., '.json', '.md')
+
+        Returns:
+            Suggested path for the output file
+        """
+        return input_file.with_suffix(target_extension)
+
+    def validate_file_pair_naming(self, markdown_file: Path, schema_file: Path) -> bool:
+        """
+        Validate that two files follow the associated files naming convention.
+
+        Args:
+            markdown_file: Path to markdown file
+            schema_file: Path to schema file
+
+        Returns:
+            True if files follow naming convention, False otherwise
+        """
+        return (
+            markdown_file.stem == schema_file.stem and
+            markdown_file.suffix.lower() == self.markdown_extension and
+            schema_file.suffix.lower() == self.schema_extension and
+            markdown_file.parent == schema_file.parent
+        )
\ No newline at end of file
diff --git a/markitect/cli.py b/markitect/cli.py
index f35b735b..004a853c 100644
--- a/markitect/cli.py
+++ b/markitect/cli.py
@@ -23,8 +23,51 @@ import yaml
 from pathlib import Path
 from typing import Optional
 from tabulate import tabulate
+import builtins
 
 from .database import DatabaseManager
+
+
+def detect_execution_mode():
+    """
+    Detect whether we're running in interactive or automation mode.
+
+    Returns:
+        str: 'interactive' or 'automation'
+
+    Detection logic:
+    - Environment variable MARKITECT_MODE overrides detection
+    - Interactive: TTY present, not in CI, not in pipe
+    - Automation: CI environment, pipe/redirect, or explicit setting
+    """
+    # Explicit mode override
+    mode = os.environ.get('MARKITECT_MODE', '').lower()
+    if mode in ['interactive', 'automation']:
+        return mode
+
+    # Detect CI environments
+    ci_indicators = [
+        'CI', 'CONTINUOUS_INTEGRATION', 'GITHUB_ACTIONS',
+        'GITLAB_CI', 'JENKINS_URL', 'BUILD_NUMBER'
+    ]
+    if any(os.environ.get(var) for var in ci_indicators):
+        return 'automation'
+
+    # Check if output is being piped or redirected
+    if not sys.stdout.isatty():
+        return 'automation'
+
+    # Check if input is being piped
+    if not sys.stdin.isatty():
+        return 'automation'
+
+    # Default to interactive for terminal usage
+    return 'interactive'
+
+
+def should_use_associated_files():
+    """Determine if commands should use associated files behavior."""
+    return detect_execution_mode() == 'interactive'
 from .document_manager import DocumentManager
 from .serializer import ASTSerializer
 from .cache_service import CacheDirectoryService
@@ -80,11 +123,19 @@ def format_output(data, output_format):
         return json.dumps(data, indent=2, default=str)
     elif output_format == 'yaml':
         return yaml.dump(data, default_flow_style=False, allow_unicode=True)
+    elif output_format == 'simple':
+        # Simple format - just basic text output
+        if isinstance(data, builtins.list):
+            return '\n'.join(str(item) for item in data)
+        elif isinstance(data, builtins.dict):
+            return '\n'.join(f"{key}: {value}" for key, value in data.items())
+        else:
+            return str(data)
     elif output_format == 'table':
         try:
             # Check if it's a list type
-            if isinstance(data, (type([]), type(()))):
-                if data and isinstance(data[0], dict):
+            if isinstance(data, (builtins.list, builtins.tuple)):
+                if data and isinstance(data[0], builtins.dict):
                     # List of dictionaries - format as table
                     headers = sorted(data[0].keys())
                     rows = []
@@ -97,7 +148,7 @@ def format_output(data, output_format):
                 else:
                     # List of simple values
                     return tabulate([[item] for item in data], headers=['Value'], tablefmt='grid')
-            elif isinstance(data, dict):
+            elif isinstance(data, builtins.dict):
                 # Single dictionary - format as key-value table
                 rows = [[key, value] for key, value in data.items()]
                 return tabulate(rows, headers=['Key', 'Value'], tablefmt='grid')
@@ -1022,8 +1073,10 @@ def generate_schema(config, file_path, max_depth, output, output_format):
         markitect schema-generate document.md --output schema.json
     """
     try:
-        # Initialize schema generator
+        # Initialize schema generator and associated files manager
         generator = SchemaGenerator()
+        from .associated_files import AssociatedFilesManager
+        associated_files = AssociatedFilesManager()
 
         # Generate schema
         schema = generator.generate_schema_from_file(file_path, max_depth=max_depth)
@@ -1036,6 +1089,15 @@ def generate_schema(config, file_path, max_depth, output, output_format):
         else:
             formatted_output = json.dumps(schema, indent=2, ensure_ascii=False)
 
+        # Mode-based output logic
+        if not output and should_use_associated_files():
+            # Interactive mode: use associated file path
+            from .associated_files import AssociatedFilesManager
+            associated_files = AssociatedFilesManager()
+            output = associated_files.get_associated_schema_path(file_path)
+            if config.get('verbose'):
+                click.echo(f"Interactive mode: using associated file path: {output}", err=True)
+
         # Write to output
         if output:
             output.write_text(formatted_output, encoding='utf-8')
@@ -1100,12 +1162,25 @@ def validate(config, file_path, schema, schema_json, quiet, detailed_errors, err
     """
     try:
         validator = SchemaValidator()
+        from .associated_files import AssociatedFilesManager
+        associated_files = AssociatedFilesManager()
 
-        # Validate exactly one schema source is provided
+        # Validate schema source or auto-discover
         schema_sources = [schema, schema_json]
         provided_sources = [s for s in schema_sources if s is not None]
 
-        if len(provided_sources) != 1:
+        if len(provided_sources) == 0:
+            # Auto-discover associated schema file
+            auto_schema = associated_files.find_associated_schema(file_path)
+            if auto_schema:
+                schema = auto_schema
+                if config.get('verbose'):
+                    click.echo(f"Auto-discovered associated schema: {schema}", err=True)
+            else:
+                click.echo("Error: No schema specified and no associated schema file found", err=True)
+                click.echo("Provide --schema FILE or --schema-json JSON, or ensure an associated .json file exists", err=True)
+                sys.exit(1)
+        elif len(provided_sources) > 1:
             click.echo("Error: Specify exactly one schema source (--schema or --schema-json)", err=True)
             sys.exit(1)
 
@@ -1446,8 +1521,10 @@ def generate_stub(config, schema_file, output, style, title):
             click.echo(f"Generating stub from schema: {schema_file}", err=True)
 
         from .stub_generator import StubGenerator
+        from .associated_files import AssociatedFilesManager
 
         generator = StubGenerator()
+        associated_files = AssociatedFilesManager()
 
         # Load schema and generate stub content
         import json
@@ -1458,6 +1535,13 @@ def generate_stub(config, schema_file, output, style, title):
             schema, placeholder_style=style, title=title
         )
 
+        # Mode-based output logic
+        if not output and should_use_associated_files():
+            # Interactive mode: use associated file path
+            output = associated_files.get_associated_markdown_path(schema_file)
+            if config.get('verbose'):
+                click.echo(f"Interactive mode: using associated file path: {output}", err=True)
+
         # Output to file or stdout
         if output:
             generator.generate_stub_to_file(schema, output, style, title)
@@ -1485,6 +1569,344 @@ def generate_stub(config, schema_file, output, style, title):
         sys.exit(1)
 
 
+@cli.group('associated-files')
+@pass_config
+def associated_files_group(config):
+    """
+    Manage associated markdown and schema file pairs.
+
+    Commands for working with files that follow the convention of having
+    identical basenames with different extensions (e.g., document.md ↔ document.json).
+    """
+    pass
+
+
+@associated_files_group.command('list')
+@click.option('--format', '-f', type=click.Choice(['table', 'json', 'yaml', 'simple']),
+              default=lambda: get_default_format(['table', 'json', 'yaml', 'simple']),
+              help='Output format')
+@click.argument('directory', type=click.Path(exists=True, file_okay=False, path_type=Path), default='.')
+@pass_config
+def list_associated_files(config, format, directory):
+    """
+    List all associated file pairs in a directory.
+
+    Shows markdown/schema file pairs that follow the naming convention.
+
+    Examples:
+        markitect associated-files list
+        markitect associated-files list docs/
+        markitect associated-files list --format json
+    """
+    try:
+        from .associated_files import AssociatedFilesManager
+        manager = AssociatedFilesManager()
+
+        if config.get('verbose'):
+            click.echo(f"Scanning directory: {directory}", err=True)
+
+        pairs = manager.list_file_pairs(directory)
+
+        if not pairs:
+            click.echo("No associated file pairs found.")
+            return
+
+        # Format output
+        if format == 'table':
+            click.echo(f"Associated File Pairs in {directory}:")
+            click.echo("=" * 60)
+            for pair in pairs:
+                click.echo(f"📄 {pair['basename']}")
+                click.echo(f"   Markdown: {pair['markdown_file'].name}")
+                click.echo(f"   Schema:   {pair['schema_file'].name}")
+                click.echo()
+        elif format == 'json':
+            import json
+            output_data = []
+            for pair in pairs:
+                output_data.append({
+                    'basename': pair['basename'],
+                    'markdown_file': str(pair['markdown_file']),
+                    'schema_file': str(pair['schema_file']),
+                    'both_exist': pair['both_exist']
+                })
+            click.echo(json.dumps(output_data, indent=2))
+        elif format == 'yaml':
+            import yaml
+            output_data = []
+            for pair in pairs:
+                output_data.append({
+                    'basename': pair['basename'],
+                    'markdown_file': str(pair['markdown_file']),
+                    'schema_file': str(pair['schema_file']),
+                    'both_exist': pair['both_exist']
+                })
+            click.echo(yaml.dump(output_data, default_flow_style=False))
+        else:
+            # Simple format
+            for pair in pairs:
+                click.echo(f"{pair['basename']} ({pair['markdown_file'].name} ↔ {pair['schema_file'].name})")
+
+        if config.get('verbose'):
+            click.echo(f"Found {len(pairs)} associated file pairs", err=True)
+
+    except Exception as e:
+        click.echo(f"Error listing associated files: {e}", err=True)
+        if config.get('verbose'):
+            import traceback
+            click.echo(traceback.format_exc(), err=True)
+        sys.exit(1)
+
+
+@associated_files_group.command('info')
+@click.argument('file_path', type=click.Path(exists=True, path_type=Path))
+@click.option('--format', '-f', type=click.Choice(['table', 'json', 'yaml', 'simple']),
+              default=lambda: get_default_format(['table', 'json', 'yaml', 'simple']),
+              help='Output format')
+@pass_config
+def associated_files_info(config, file_path, format):
+    """
+    Show detailed information about associated files.
+
+    Displays information about a file and its associated counterpart.
+
+    Examples:
+        markitect associated-files info document.md
+        markitect associated-files info schema.json --format json
+    """
+    try:
+        from .associated_files import AssociatedFilesManager
+        manager = AssociatedFilesManager()
+
+        info = manager.get_file_pair_info(file_path)
+
+        if format == 'table':
+            click.echo(f"Associated Files Information:")
+            click.echo("=" * 40)
+            click.echo(f"Basename: {info['basename']}")
+            click.echo(f"Markdown: {info['markdown_file']}")
+            click.echo(f"  Exists: {'✅' if info['markdown_file'].exists() else '❌'}")
+            if 'markdown_size' in info:
+                click.echo(f"  Size: {info['markdown_size']} bytes")
+
+            click.echo(f"Schema: {info['schema_file']}")
+            click.echo(f"  Exists: {'✅' if info['schema_file'].exists() else '❌'}")
+            if 'schema_size' in info:
+                click.echo(f"  Size: {info['schema_size']} bytes")
+
+            click.echo(f"Both exist: {'✅' if info['both_exist'] else '❌'}")
+
+        elif format == 'json':
+            import json
+            # Convert Path objects to strings for JSON serialization
+            json_info = {k: str(v) if isinstance(v, Path) else v for k, v in info.items()}
+            click.echo(json.dumps(json_info, indent=2))
+
+        elif format == 'yaml':
+            import yaml
+            # Convert Path objects to strings for YAML serialization
+            yaml_info = {k: str(v) if isinstance(v, Path) else v for k, v in info.items()}
+            click.echo(yaml.dump(yaml_info, default_flow_style=False))
+        else:
+            # Simple format
+            status = "paired" if info['both_exist'] else "orphaned"
+            click.echo(f"{info['basename']}: {status}")
+
+    except Exception as e:
+        click.echo(f"Error getting file info: {e}", err=True)
+        sys.exit(1)
+
+
+@associated_files_group.command('status')
+@click.argument('directory', type=click.Path(exists=True, file_okay=False, path_type=Path), default='.')
+@click.option('--format', '-f', type=click.Choice(['table', 'json', 'yaml', 'simple']),
+              default=lambda: get_default_format(['table', 'json', 'yaml', 'simple']),
+              help='Output format')
+@pass_config
+def associated_files_status(config, directory, format):
+    """
+    Show status of associated files in a directory.
+
+    Displays paired files and orphaned files (files without their counterpart).
+
+    Examples:
+        markitect associated-files status
+        markitect associated-files status docs/
+    """
+    try:
+        from .associated_files import AssociatedFilesManager
+        manager = AssociatedFilesManager()
+
+        status = manager.get_directory_status(directory)
+
+        if format == 'table':
+            click.echo(f"Associated Files Status for {directory}:")
+            click.echo("=" * 50)
+            click.echo(f"📌 Paired files: {status['paired_files']}")
+            click.echo(f"📄 Orphaned markdown: {status['orphaned_markdown']}")
+            click.echo(f"🔧 Orphaned schemas: {status['orphaned_schemas']}")
+
+            if status['pairs']:
+                click.echo("\n📌 Paired Files:")
+                for pair in status['pairs']:
+                    click.echo(f"  • {pair['basename']}")
+
+            if status['orphaned']['orphaned_markdown']:
+                click.echo("\n📄 Orphaned Markdown Files:")
+                for md in status['orphaned']['orphaned_markdown']:
+                    click.echo(f"  • {md.name}")
+
+            if status['orphaned']['orphaned_schemas']:
+                click.echo("\n🔧 Orphaned Schema Files:")
+                for schema in status['orphaned']['orphaned_schemas']:
+                    click.echo(f"  • {schema.name}")
+
+        elif format == 'json':
+            import json
+            # Convert Path objects to strings for JSON serialization
+            json_status = {
+                'directory': str(status['directory']),
+                'paired_files': status['paired_files'],
+                'orphaned_markdown': status['orphaned_markdown'],
+                'orphaned_schemas': status['orphaned_schemas'],
+                'pairs': [{'basename': p['basename'],
+                          'markdown_file': str(p['markdown_file']),
+                          'schema_file': str(p['schema_file'])}
+                         for p in status['pairs']],
+                'orphaned': {
+                    'orphaned_markdown': [str(f) for f in status['orphaned']['orphaned_markdown']],
+                    'orphaned_schemas': [str(f) for f in status['orphaned']['orphaned_schemas']]
+                }
+            }
+            click.echo(json.dumps(json_status, indent=2))
+
+        elif format == 'yaml':
+            import yaml
+            yaml_status = {
+                'directory': str(status['directory']),
+                'paired_files': status['paired_files'],
+                'orphaned_markdown': status['orphaned_markdown'],
+                'orphaned_schemas': status['orphaned_schemas'],
+                'pairs': [{'basename': p['basename'],
+                          'markdown_file': str(p['markdown_file']),
+                          'schema_file': str(p['schema_file'])}
+                         for p in status['pairs']],
+                'orphaned': {
+                    'orphaned_markdown': [str(f) for f in status['orphaned']['orphaned_markdown']],
+                    'orphaned_schemas': [str(f) for f in status['orphaned']['orphaned_schemas']]
+                }
+            }
+            click.echo(yaml.dump(yaml_status, default_flow_style=False))
+        else:
+            # Simple format
+            click.echo(f"Paired: {status['paired_files']}, Orphaned: {status['orphaned_markdown'] + status['orphaned_schemas']}")
+
+    except Exception as e:
+        click.echo(f"Error getting status: {e}", err=True)
+        sys.exit(1)
+
+
+@associated_files_group.command('create-schema')
+@click.argument('markdown_file', type=click.Path(exists=True, path_type=Path))
+@click.option('--max-depth', '-d', type=int, help='Maximum heading depth to include in schema')
+@pass_config
+def create_associated_schema(config, markdown_file, max_depth):
+    """
+    Create an associated schema file for a markdown file.
+
+    Generates a JSON schema and places it next to the source markdown file
+    with the same basename but .json extension.
+
+    Examples:
+        markitect associated-files create-schema document.md
+        markitect associated-files create-schema doc.md --max-depth 3
+    """
+    try:
+        from .associated_files import AssociatedFilesManager
+        from .schema_generator import SchemaGenerator
+
+        manager = AssociatedFilesManager()
+        generator = SchemaGenerator()
+
+        # Check if associated schema already exists
+        existing_schema = manager.find_associated_schema(markdown_file)
+        if existing_schema:
+            if not click.confirm(f"Associated schema {existing_schema} already exists. Overwrite?"):
+                click.echo("Operation cancelled.")
+                return
+
+        # Generate schema
+        schema = generator.generate_schema_from_file(markdown_file, max_depth=max_depth)
+
+        # Save to associated path
+        schema_path = manager.get_associated_schema_path(markdown_file)
+
+        import json
+        with open(schema_path, 'w', encoding='utf-8') as f:
+            json.dump(schema, f, indent=2, ensure_ascii=False)
+
+        click.echo(f"✅ Created associated schema: {schema_path}")
+
+        if config.get('verbose'):
+            properties = schema.get('properties', {})
+            click.echo(f"Generated schema with {len(properties)} property types", err=True)
+
+    except Exception as e:
+        click.echo(f"Error creating schema: {e}", err=True)
+        sys.exit(1)
+
+
+@associated_files_group.command('create-stub')
+@click.argument('schema_file', type=click.Path(exists=True, path_type=Path))
+@click.option('--style', type=click.Choice(['default', 'custom', 'detailed']),
+              default='default', help='Placeholder content style')
+@click.option('--title', type=str, help='Custom document title')
+@pass_config
+def create_associated_stub(config, schema_file, style, title):
+    """
+    Create an associated markdown stub for a schema file.
+
+    Generates a markdown template and places it next to the source schema file
+    with the same basename but .md extension.
+
+    Examples:
+        markitect associated-files create-stub schema.json
+        markitect associated-files create-stub schema.json --style detailed
+    """
+    try:
+        from .associated_files import AssociatedFilesManager
+        from .stub_generator import StubGenerator
+
+        manager = AssociatedFilesManager()
+        generator = StubGenerator()
+
+        # Check if associated markdown already exists
+        existing_md = manager.find_associated_markdown(schema_file)
+        if existing_md:
+            if not click.confirm(f"Associated markdown {existing_md} already exists. Overwrite?"):
+                click.echo("Operation cancelled.")
+                return
+
+        # Load schema and generate stub
+        import json
+        with open(schema_file, 'r') as f:
+            schema = json.load(f)
+
+        # Save to associated path
+        md_path = manager.get_associated_markdown_path(schema_file)
+        generator.generate_stub_to_file(schema, md_path, style, title)
+
+        click.echo(f"✅ Created associated stub: {md_path}")
+
+        if config.get('verbose'):
+            content = md_path.read_text()
+            click.echo(f"Generated {len(content)} characters of content", err=True)
+
+    except Exception as e:
+        click.echo(f"Error creating stub: {e}", err=True)
+        sys.exit(1)
+
+
 def main():
     """
     Main entry point for the CLI.
diff --git a/tests/test_issue_40_associated_files.py b/tests/test_issue_40_associated_files.py
new file mode 100644
index 00000000..d1733393
--- /dev/null
+++ b/tests/test_issue_40_associated_files.py
@@ -0,0 +1,271 @@
+"""
+Tests for Issue #40: Associated Files Management.
+
+This module tests the functionality for managing associated markdown and schema files
+with convention-based naming and automatic file placement.
+"""
+
+import pytest
+from pathlib import Path
+from tempfile import TemporaryDirectory
+
+from markitect.associated_files import AssociatedFilesManager
+
+
+class TestIssue40AssociatedFiles:
+    """Test suite for associated files management."""
+
+    @pytest.fixture
+    def manager(self):
+        """Create an AssociatedFilesManager instance."""
+        return AssociatedFilesManager()
+
+    @pytest.fixture
+    def temp_dir(self):
+        """Create a temporary directory for testing."""
+        with TemporaryDirectory() as temp_dir:
+            yield Path(temp_dir)
+
+    def test_associated_files_manager_can_be_created(self, manager):
+        """AssociatedFilesManager class should be importable and instantiable."""
+        assert manager is not None
+        assert isinstance(manager, AssociatedFilesManager)
+
+    def test_get_associated_schema_path(self, manager, temp_dir):
+        """Should generate correct associated schema path for markdown file."""
+        md_file = temp_dir / "document.md"
+        md_file.write_text("# Test Document")
+
+        schema_path = manager.get_associated_schema_path(md_file)
+
+        assert schema_path == temp_dir / "document.json"
+        assert schema_path.parent == md_file.parent
+        assert schema_path.stem == md_file.stem
+
+    def test_get_associated_markdown_path(self, manager, temp_dir):
+        """Should generate correct associated markdown path for schema file."""
+        schema_file = temp_dir / "document.json"
+        schema_file.write_text('{"type": "object"}')
+
+        md_path = manager.get_associated_markdown_path(schema_file)
+
+        assert md_path == temp_dir / "document.md"
+        assert md_path.parent == schema_file.parent
+        assert md_path.stem == schema_file.stem
+
+    def test_find_associated_schema(self, manager, temp_dir):
+        """Should find existing associated schema file."""
+        md_file = temp_dir / "blog_post.md"
+        schema_file = temp_dir / "blog_post.json"
+
+        md_file.write_text("# Blog Post")
+        schema_file.write_text('{"type": "object"}')
+
+        found_schema = manager.find_associated_schema(md_file)
+
+        assert found_schema == schema_file
+        assert found_schema.exists()
+
+    def test_find_associated_markdown(self, manager, temp_dir):
+        """Should find existing associated markdown file."""
+        md_file = temp_dir / "article.md"
+        schema_file = temp_dir / "article.json"
+
+        md_file.write_text("# Article")
+        schema_file.write_text('{"type": "object"}')
+
+        found_md = manager.find_associated_markdown(schema_file)
+
+        assert found_md == md_file
+        assert found_md.exists()
+
+    def test_find_associated_files_returns_none_when_not_found(self, manager, temp_dir):
+        """Should return None when associated files don't exist."""
+        md_file = temp_dir / "lonely.md"
+        md_file.write_text("# Lonely Document")
+
+        schema_file = temp_dir / "orphan.json"
+        schema_file.write_text('{"type": "object"}')
+
+        assert manager.find_associated_schema(md_file) is None
+        assert manager.find_associated_markdown(schema_file) is None
+
+    def test_has_associated_schema(self, manager, temp_dir):
+        """Should correctly detect if markdown file has associated schema."""
+        md_file = temp_dir / "test.md"
+        schema_file = temp_dir / "test.json"
+
+        md_file.write_text("# Test")
+
+        # No schema initially
+        assert not manager.has_associated_schema(md_file)
+
+        # Create schema
+        schema_file.write_text('{"type": "object"}')
+        assert manager.has_associated_schema(md_file)
+
+    def test_has_associated_markdown(self, manager, temp_dir):
+        """Should correctly detect if schema file has associated markdown."""
+        md_file = temp_dir / "guide.md"
+        schema_file = temp_dir / "guide.json"
+
+        schema_file.write_text('{"type": "object"}')
+
+        # No markdown initially
+        assert not manager.has_associated_markdown(schema_file)
+
+        # Create markdown
+        md_file.write_text("# Guide")
+        assert manager.has_associated_markdown(schema_file)
+
+    def test_list_file_pairs(self, manager, temp_dir):
+        """Should list all associated file pairs in directory."""
+        # Create some paired files
+        (temp_dir / "doc1.md").write_text("# Doc 1")
+        (temp_dir / "doc1.json").write_text('{"type": "object"}')
+
+        (temp_dir / "doc2.md").write_text("# Doc 2")
+        (temp_dir / "doc2.json").write_text('{"type": "object"}')
+
+        # Create orphaned files
+        (temp_dir / "orphan.md").write_text("# Orphan")
+        (temp_dir / "lonely.json").write_text('{"type": "object"}')
+
+        pairs = manager.list_file_pairs(temp_dir)
+
+        assert len(pairs) == 2
+        pair_names = {pair['basename'] for pair in pairs}
+        assert 'doc1' in pair_names
+        assert 'doc2' in pair_names
+
+    def test_get_file_pair_info(self, manager, temp_dir):
+        """Should provide detailed information about file pairs."""
+        md_file = temp_dir / "example.md"
+        schema_file = temp_dir / "example.json"
+
+        md_file.write_text("# Example Document\n\nContent here.")
+        schema_file.write_text('{"type": "object", "title": "Example Schema"}')
+
+        pair_info = manager.get_file_pair_info(md_file)
+
+        assert pair_info['basename'] == 'example'
+        assert pair_info['markdown_file'] == md_file
+        assert pair_info['schema_file'] == schema_file
+        assert pair_info['both_exist'] is True
+        assert 'markdown_size' in pair_info
+        assert 'schema_size' in pair_info
+
+    def test_supports_nested_directories(self, manager, temp_dir):
+        """Should work correctly with nested directory structures."""
+        nested_dir = temp_dir / "docs" / "architecture"
+        nested_dir.mkdir(parents=True)
+
+        md_file = nested_dir / "system.md"
+        schema_file = nested_dir / "system.json"
+
+        md_file.write_text("# System Architecture")
+
+        schema_path = manager.get_associated_schema_path(md_file)
+        assert schema_path == schema_file
+        assert not manager.has_associated_schema(md_file)
+
+        schema_file.write_text('{"type": "object"}')
+        assert manager.has_associated_schema(md_file)
+
+    def test_handles_complex_filenames(self, manager, temp_dir):
+        """Should handle complex filenames with special characters."""
+        complex_name = "my-complex_file.name-v2"
+        md_file = temp_dir / f"{complex_name}.md"
+
+        md_file.write_text("# Complex File")
+
+        schema_path = manager.get_associated_schema_path(md_file)
+        expected_schema = temp_dir / f"{complex_name}.json"
+
+        assert schema_path == expected_schema
+        assert schema_path.stem == complex_name
+
+    def test_validate_file_extensions(self, manager, temp_dir):
+        """Should validate that files have correct extensions."""
+        txt_file = temp_dir / "document.txt"
+        txt_file.write_text("Not markdown")
+
+        from markitect.associated_files import InvalidFileTypeError
+
+        with pytest.raises(InvalidFileTypeError, match="Expected markdown file"):
+            manager.get_associated_schema_path(txt_file)
+
+        xml_file = temp_dir / "schema.xml"
+        xml_file.write_text("<schema/>")
+
+        with pytest.raises(InvalidFileTypeError, match="Expected schema file"):
+            manager.get_associated_markdown_path(xml_file)
+
+
+class TestAssociatedFilesIntegration:
+    """Test integration of associated files with existing commands."""
+
+    @pytest.fixture
+    def manager(self):
+        return AssociatedFilesManager()
+
+    @pytest.fixture
+    def temp_dir(self):
+        with TemporaryDirectory() as temp_dir:
+            yield Path(temp_dir)
+
+    def test_schema_generate_default_output_placement(self, manager, temp_dir):
+        """Schema generation should default to placing output next to source."""
+        md_file = temp_dir / "article.md"
+        md_file.write_text("# Article\n\n## Introduction\n\nContent here.")
+
+        expected_schema_path = manager.get_associated_schema_path(md_file)
+
+        # This would be the expected behavior for schema-generate command
+        assert expected_schema_path == temp_dir / "article.json"
+
+    def test_stub_generate_default_output_placement(self, manager, temp_dir):
+        """Stub generation should default to placing output next to schema."""
+        schema_file = temp_dir / "template.json"
+        schema_file.write_text('''{
+            "$schema": "http://json-schema.org/draft-07/schema#",
+            "type": "object",
+            "title": "Template Schema"
+        }''')
+
+        expected_md_path = manager.get_associated_markdown_path(schema_file)
+
+        # This would be the expected behavior for generate-stub command
+        assert expected_md_path == temp_dir / "template.md"
+
+    def test_validation_auto_discovery(self, manager, temp_dir):
+        """Validation should auto-discover associated schema files."""
+        md_file = temp_dir / "document.md"
+        schema_file = temp_dir / "document.json"
+
+        md_file.write_text("# Document")
+        schema_file.write_text('{"type": "object"}')
+
+        # Validation command should find schema automatically
+        found_schema = manager.find_associated_schema(md_file)
+        assert found_schema == schema_file
+
+    def test_workflow_roundtrip(self, manager, temp_dir):
+        """Test complete workflow: markdown → schema → stub."""
+        # Start with markdown
+        original_md = temp_dir / "workflow_test.md"
+        original_md.write_text("# Workflow Test\n\n## Section 1\n\nContent.")
+
+        # Generate schema (should place next to original)
+        schema_path = manager.get_associated_schema_path(original_md)
+        assert schema_path == temp_dir / "workflow_test.json"
+
+        # Create the schema (simulating schema-generate command)
+        schema_path.write_text('{"type": "object", "title": "Workflow Test"}')
+
+        # Generate stub from schema (should use different name to avoid conflict)
+        stub_path = temp_dir / "workflow_test_stub.md"  # Avoiding conflict with original
+
+        # Verify the association logic works
+        assert manager.has_associated_schema(original_md)
+        assert manager.has_associated_markdown(schema_path)
\ No newline at end of file
diff --git a/tests/test_issue_40_cli_integration.py b/tests/test_issue_40_cli_integration.py
new file mode 100644
index 00000000..23674b6a
--- /dev/null
+++ b/tests/test_issue_40_cli_integration.py
@@ -0,0 +1,326 @@
+"""
+CLI Integration Tests for Issue #40: Associated Files Management.
+
+Tests the enhanced CLI commands that work with associated files.
+"""
+
+import json
+import pytest
+from pathlib import Path
+from tempfile import TemporaryDirectory
+from click.testing import CliRunner
+
+from markitect.cli import cli
+
+
+class TestIssue40CLIIntegration:
+    """Test CLI integration for associated files management."""
+
+    @pytest.fixture
+    def runner(self):
+        """Create CLI test runner."""
+        return CliRunner()
+
+    @pytest.fixture
+    def temp_dir(self):
+        """Create a temporary directory for testing."""
+        with TemporaryDirectory() as temp_dir:
+            yield Path(temp_dir)
+
+    def test_schema_generate_with_explicit_associated_path(self, runner, temp_dir):
+        """schema-generate can use explicit associated .json file path."""
+        md_file = temp_dir / "document.md"
+        md_file.write_text("# Document\n\n## Introduction\n\nContent here.")
+
+        # Explicitly specify associated file path
+        expected_schema = temp_dir / "document.json"
+        result = runner.invoke(cli, [
+            'schema-generate', str(md_file), '--output', str(expected_schema)
+        ])
+
+        assert result.exit_code == 0
+
+        # Should create associated schema file
+        assert expected_schema.exists()
+
+        # Verify it's valid JSON
+        schema_content = json.loads(expected_schema.read_text())
+        assert schema_content['type'] == 'object'
+
+    def test_schema_generate_interactive_mode_defaults_to_associated_path(self, runner, temp_dir):
+        """schema-generate in interactive mode should default to associated path."""
+        md_file = temp_dir / "document.md"
+        md_file.write_text("# Document\n\n## Introduction\n\nContent here.")
+
+        # Run schema-generate without --output in interactive mode
+        result = runner.invoke(cli, [
+            'schema-generate', str(md_file)
+        ], env={'MARKITECT_MODE': 'interactive'})
+
+        assert result.exit_code == 0
+
+        # Should create associated schema file
+        expected_schema = temp_dir / "document.json"
+        assert expected_schema.exists()
+
+        # Verify it's valid JSON
+        schema_content = json.loads(expected_schema.read_text())
+        assert schema_content['type'] == 'object'
+
+    def test_generate_stub_with_explicit_associated_path(self, runner, temp_dir):
+        """generate-stub can use explicit associated .md file path."""
+        schema_file = temp_dir / "template.json"
+        schema_content = {
+            "$schema": "http://json-schema.org/draft-07/schema#",
+            "type": "object",
+            "title": "Template Schema",
+            "properties": {
+                "headings": {
+                    "type": "object",
+                    "properties": {
+                        "level_1": {"type": "array", "minItems": 1, "maxItems": 1}
+                    }
+                }
+            }
+        }
+        schema_file.write_text(json.dumps(schema_content))
+
+        # Explicitly specify associated file path
+        expected_md = temp_dir / "template.md"
+        result = runner.invoke(cli, [
+            'generate-stub', str(schema_file), '--output', str(expected_md)
+        ])
+
+        assert result.exit_code == 0
+
+        # Should create associated markdown file
+        assert expected_md.exists()
+
+        # Verify it's valid markdown
+        md_content = expected_md.read_text()
+        assert md_content.startswith('# ')
+
+    def test_generate_stub_interactive_mode_defaults_to_associated_path(self, runner, temp_dir):
+        """generate-stub in interactive mode should default to associated path."""
+        schema_file = temp_dir / "template.json"
+        schema_content = {
+            "$schema": "http://json-schema.org/draft-07/schema#",
+            "type": "object",
+            "title": "Template Schema",
+            "properties": {
+                "headings": {
+                    "type": "object",
+                    "properties": {
+                        "level_1": {"type": "array", "minItems": 1, "maxItems": 1}
+                    }
+                }
+            }
+        }
+        schema_file.write_text(json.dumps(schema_content))
+
+        # Run generate-stub without --output in interactive mode
+        result = runner.invoke(cli, [
+            'generate-stub', str(schema_file)
+        ], env={'MARKITECT_MODE': 'interactive'})
+
+        assert result.exit_code == 0
+
+        # Should create associated markdown file
+        expected_md = temp_dir / "template.md"
+        assert expected_md.exists()
+
+        # Verify it's valid markdown
+        md_content = expected_md.read_text()
+        assert md_content.startswith('# ')
+
+    def test_validate_auto_discovers_associated_schema(self, runner, temp_dir):
+        """validate should auto-discover associated schema when not specified."""
+        md_file = temp_dir / "article.md"
+        schema_file = temp_dir / "article.json"
+
+        md_file.write_text("# Article\n\n## Introduction\n\nContent.")
+        schema_file.write_text('{"$schema": "http://json-schema.org/draft-07/schema#", "type": "object", "title": "Article Schema"}')
+
+        # Run validate with only markdown file (should find associated schema)
+        result = runner.invoke(cli, [
+            'validate', str(md_file)
+        ])
+
+        assert result.exit_code == 0
+        # Should indicate successful validation using auto-discovered schema
+
+    def test_new_associated_files_list_command(self, runner, temp_dir):
+        """Should have new command to list associated file pairs."""
+        # Create some file pairs
+        (temp_dir / "doc1.md").write_text("# Doc 1")
+        (temp_dir / "doc1.json").write_text('{"type": "object"}')
+
+        (temp_dir / "doc2.md").write_text("# Doc 2")
+        (temp_dir / "doc2.json").write_text('{"type": "object"}')
+
+        # Create orphaned files
+        (temp_dir / "orphan.md").write_text("# Orphan")
+
+        result = runner.invoke(cli, [
+            'associated-files', 'list', str(temp_dir)
+        ])
+
+        assert result.exit_code == 0
+        assert 'doc1' in result.output
+        assert 'doc2' in result.output
+        # Should show paired status
+
+    def test_new_associated_files_info_command(self, runner, temp_dir):
+        """Should have command to show info about associated files."""
+        md_file = temp_dir / "example.md"
+        schema_file = temp_dir / "example.json"
+
+        md_file.write_text("# Example\n\nContent here.")
+        schema_file.write_text('{"type": "object", "title": "Example"}')
+
+        result = runner.invoke(cli, [
+            'associated-files', 'info', str(md_file)
+        ])
+
+        assert result.exit_code == 0
+        assert 'example' in result.output
+        assert 'paired' in result.output.lower()
+
+    def test_new_associated_files_create_command(self, runner, temp_dir):
+        """Should have command to create missing associated files."""
+        md_file = temp_dir / "lonely.md"
+        md_file.write_text("# Lonely Document\n\n## Section\n\nContent.")
+
+        # Create associated schema
+        result = runner.invoke(cli, [
+            'associated-files', 'create-schema', str(md_file)
+        ])
+
+        assert result.exit_code == 0
+
+        expected_schema = temp_dir / "lonely.json"
+        assert expected_schema.exists()
+
+        # Verify it's a valid schema
+        schema = json.loads(expected_schema.read_text())
+        assert schema['type'] == 'object'
+
+    def test_new_associated_files_create_stub_command(self, runner, temp_dir):
+        """Should have command to create stub from existing schema."""
+        schema_file = temp_dir / "template.json"
+        schema_content = {
+            "$schema": "http://json-schema.org/draft-07/schema#",
+            "type": "object",
+            "title": "Template",
+            "properties": {
+                "headings": {
+                    "type": "object",
+                    "properties": {
+                        "level_1": {"type": "array", "minItems": 1}
+                    }
+                }
+            }
+        }
+        schema_file.write_text(json.dumps(schema_content))
+
+        # Create associated markdown stub
+        result = runner.invoke(cli, [
+            'associated-files', 'create-stub', str(schema_file)
+        ])
+
+        assert result.exit_code == 0
+
+        expected_md = temp_dir / "template.md"
+        assert expected_md.exists()
+
+        # Verify it's valid markdown
+        md_content = expected_md.read_text()
+        assert md_content.startswith('# ')
+
+    def test_associated_files_status_command(self, runner, temp_dir):
+        """Should show status of associated files in directory."""
+        # Create mixed scenarios
+        (temp_dir / "paired.md").write_text("# Paired")
+        (temp_dir / "paired.json").write_text('{"type": "object"}')
+
+        (temp_dir / "lonely.md").write_text("# Lonely")
+        (temp_dir / "orphan.json").write_text('{"type": "object"}')
+
+        result = runner.invoke(cli, [
+            'associated-files', 'status', str(temp_dir)
+        ])
+
+        assert result.exit_code == 0
+        assert 'paired' in result.output.lower() or 'orphaned' in result.output.lower()
+
+    def test_enhanced_commands_preserve_explicit_output(self, runner, temp_dir):
+        """Enhanced commands should still respect explicit --output options."""
+        md_file = temp_dir / "source.md"
+        md_file.write_text("# Source\n\n## Content")
+
+        custom_output = temp_dir / "custom_name.json"
+
+        # Use explicit output path (should override associated file logic)
+        result = runner.invoke(cli, [
+            'schema-generate', str(md_file), '--output', str(custom_output)
+        ])
+
+        assert result.exit_code == 0
+        assert custom_output.exists()
+        assert not (temp_dir / "source.json").exists()
+
+    def test_associated_files_help_commands(self, runner):
+        """Associated files commands should provide helpful usage information."""
+        result = runner.invoke(cli, ['associated-files', '--help'])
+        assert result.exit_code == 0
+        assert 'associated' in result.output.lower()
+        assert 'files' in result.output.lower()
+
+        # Test subcommand help
+        result = runner.invoke(cli, ['associated-files', 'list', '--help'])
+        assert result.exit_code == 0
+
+    def test_error_handling_for_non_existent_files(self, runner, temp_dir):
+        """Should handle non-existent files gracefully."""
+        non_existent = temp_dir / "does_not_exist.md"
+
+        result = runner.invoke(cli, [
+            'associated-files', 'info', str(non_existent)
+        ])
+
+        assert result.exit_code != 0
+        assert 'not found' in result.output.lower() or 'error' in result.output.lower()
+
+    def test_workflow_integration_complete_cycle(self, runner, temp_dir):
+        """Test complete workflow with associated files."""
+        original_md = temp_dir / "workflow.md"
+        original_md.write_text("# Workflow Example\n\n## Introduction\n\nTest content.")
+
+        # Step 1: Generate schema explicitly to workflow.json
+        schema_file = temp_dir / "workflow.json"
+        result1 = runner.invoke(cli, [
+            'schema-generate', str(original_md), '--output', str(schema_file)
+        ])
+        assert result1.exit_code == 0
+        assert schema_file.exists()
+
+        # Step 2: Generate stub with different name to avoid conflict
+        stub_name = temp_dir / "workflow_template.md"
+        result2 = runner.invoke(cli, [
+            'generate-stub', str(schema_file), '--output', str(stub_name)
+        ])
+        assert result2.exit_code == 0
+        assert stub_name.exists()
+
+        # Step 3: Validate original against its schema
+        result3 = runner.invoke(cli, [
+            'validate', str(original_md)
+        ])
+        assert result3.exit_code == 0
+
+        # Step 4: List associated files
+        result4 = runner.invoke(cli, [
+            'associated-files', 'status', str(temp_dir)
+        ])
+        assert result4.exit_code == 0
+        assert 'paired' in result4.output.lower() or 'orphaned' in result4.output.lower()
\ No newline at end of file
diff --git a/tests/test_l4_service_output_formatting.py b/tests/test_l4_service_output_formatting.py
index f90c40a7..c53d4596 100644
--- a/tests/test_l4_service_output_formatting.py
+++ b/tests/test_l4_service_output_formatting.py
@@ -140,6 +140,9 @@ class TestOutputFormatting:
             # Without specifying format
             result = self.runner.invoke(cli, ['query', 'SELECT * FROM markdown_files'])
 
+            if result.exit_code != 0:
+                print("Command output:", result.output)
+                print("Command exception:", result.exception)
             assert result.exit_code == 0
             # Should look like table format (not JSON or YAML)
             assert not result.output.strip().startswith('[')  # Not JSON array