Add a dda command to automatically sync cursor rules in other coding agent files

src/dda/cli/validate/__init__.py

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+# SPDX-FileCopyrightText: 2025-present Datadog, Inc. <dev@datadoghq.com>
+#
+# SPDX-License-Identifier: MIT
+from __future__ import annotations
+
+from dda.cli.base import dynamic_group
+
+
+@dynamic_group(
+    short_help="Validate tools and utilities",
+)
+def cmd() -> None:
+    """
+    Validate tools and utilities for development workflow.
+    """

src/dda/cli/validate/ai_rules/__init__.py

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+# SPDX-FileCopyrightText: 2025-present Datadog, Inc. <dev@datadoghq.com>
+#
+# SPDX-License-Identifier: MIT
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+import click
+
+from dda.cli.base import dynamic_command, pass_app
+from dda.utils.diff import pretty_diff
+from dda.utils.fs import Path
+
+if TYPE_CHECKING:
+    from dda.cli.application import Application
+
+CURSOR_RULES_DIR = Path(".cursor/rules")
+TARGETS_FILES = [Path("CLAUDE.md")]
+
+
+@dynamic_command(short_help="Validate AI rules are coherent between all the coding agent config files")
+@click.option(
+    "--fix",
+    "-k",
+    "should_fix",
+    is_flag=True,
+    help="Fix the rules if they are not coherent.",
+)
+@pass_app
+def cmd(app: Application, *, should_fix: bool) -> None:
+    cursor_rules_dir = CURSOR_RULES_DIR
+    targets_files = TARGETS_FILES
+
+    # Find all rule files
+    rule_files = get_rule_files(cursor_rules_dir)
+
+    if not rule_files:
+        app.display_warning(f"No rule files found in {cursor_rules_dir}")
+        app.display_info("Add your cursor rules files to the .cursor/rules directory and run this command again.")
+        return
+
+    app.display_debug(f"Found {len(rule_files)} rule files")
+
+    unsynced_targets = []
+    for target_file in targets_files:
+        new_content = generate_content(rule_files, target_file)
+        old_content = ""
+        if target_file.exists() and target_file.is_file():
+            with open(target_file, encoding="utf-8") as f:
+                old_content = f.read()
+        diff = pretty_diff(old_content, new_content)
+        if not diff:
+            continue
+        app.display_info(f"Target file {target_file} is not in sync")
+        app.display_info(diff)
+        if should_fix:
+            with open(target_file, "w", encoding="utf-8") as f:
+                f.write(new_content)
+            app.display_success(f"Successfully fixed {target_file}")
+        else:
+            unsynced_targets.append(str(target_file))
+    if unsynced_targets:
+        app.display_error(f"The following targets are not in sync: {', '.join(unsynced_targets)}")
+        app.abort()
+    app.display_success("All targets are in sync")
+
+
+def get_rule_files(cursor_rules_dir: Path) -> list[Path]:
+    """Find all rule files in cursor rules directory (recursively), excluding personal rules."""
+    return sorted(rule for rule in cursor_rules_dir.glob("**/*.mdc") if "personal" not in rule.parts)
+
+
+def generate_content(rule_files: list[Path], target_file: Path) -> str:
+    """Generate the content to be written to the target file."""
+    # Add header with warning and instructions
+    content_parts = [
+        """<!--
+WARNING: This file is auto-generated by 'dda validate ai-rules'
+Do not edit this file manually. Instead, modify files in the .cursor/rules folder
+and run 'dda validate ai-rules' to update this file.
+-->
+
+# AI Assistant Rules
+
+This file contains concatenated rules from the `.cursor/rules` folder to help Claude understand the project context and coding standards.
+
+## How to Read Metadata in Cursor Rules
+
+Cursor rules contains the following metadata at the begnning of the file between `---` lines.
+ - alwaysApply: boolean, if true, the rule will be applied to all files
+ - globs: array of strings, glob patterns specifying which files to apply the rule to
+ - description: string, a description of the rule
+---
+
+"""
+    ]
+    # Process each rule file
+    content_parts.extend([
+        f"@{rule_file.absolute().relative_to(target_file.parent.absolute(), walk_up=True)}" for rule_file in rule_files
+    ])
+
+    # Add CLAUDE_PERSONAL.md reference
+    content_parts.append("""
+# Personal rules
+@CLAUDE_PERSONAL.md""")
+
+    combined_content = "\n".join(content_parts)
+
+    # Remove trailing separators
+    return combined_content.rstrip("\n-").rstrip() + "\n"

src/dda/utils/diff.py

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+import difflib
+
+
+def pretty_diff(string1: str, string2: str) -> str:
+    lines1 = string1.splitlines()
+    lines2 = string2.splitlines()
+
+    diff = difflib.unified_diff(lines1, lines2, lineterm="")
+
+    result = []
+    for line in diff:
+        if line.startswith("-"):
+            result.append(f"\033[31m{line}\033[0m")  # Red for removals
+        elif line.startswith("+"):
+            result.append(f"\033[32m{line}\033[0m")  # Green for additions
+        else:
+            result.append(line)
+    return "\n".join(result)

tests/cli/validate/__init__.py

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+# SPDX-FileCopyrightText: 2025-present Datadog, Inc. <dev@datadoghq.com>
+#
+# SPDX-License-Identifier: MIT

tests/cli/validate/fixtures/ai_rules/out_of_sync/.cursor/rules/test-rule.mdc

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+This is a test rule.

tests/cli/validate/fixtures/ai_rules/out_of_sync/CLAUDE.md

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+Old content

tests/cli/validate/fixtures/ai_rules/simple_rules_no_target/.cursor/rules/coding-standards.mdc

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+Use TypeScript for all frontend code.

tests/cli/validate/fixtures/ai_rules/simple_rules_no_target/.cursor/rules/nested/my-nested-rule.mdc

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+---
+alwaysApply: true
+---

tests/cli/validate/fixtures/ai_rules/simple_rules_no_target/.cursor/rules/personal/mypersonal-rules.mdc

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+---
+alwaysApply: true
+---

tests/cli/validate/fixtures/ai_rules/simple_rules_no_target/.cursor/rules/security.mdc

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+Always validate input parameters.

tests/cli/validate/fixtures/ai_rules/simple_rules_no_target/.cursor/rules/testing.mdc

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+Write unit tests for all functions.

tests/cli/validate/test_ai_rules.py

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+# SPDX-FileCopyrightText: 2025-present Datadog, Inc. <dev@datadoghq.com>
+#
+# SPDX-License-Identifier: MIT
+from __future__ import annotations
+
+import os
+import shutil
+from typing import TYPE_CHECKING
+
+import pytest
+
+from dda.utils.fs import Path
+
+if TYPE_CHECKING:
+    from collections.abc import Callable
+
+    from tests.conftest import CliRunner
+
+
+@pytest.fixture(name="use_temp_fixture_folder")
+def fixt_use_temp_folder(temp_dir: Path) -> Callable[[str], Path]:
+    def _use_temp_folder(folder_name: str) -> Path:
+        shutil.copytree(Path(__file__).parent / "fixtures" / "ai_rules" / folder_name, temp_dir / folder_name)
+        return Path(temp_dir) / folder_name
+
+    return _use_temp_folder
+
+
+def test_validate_rule_files_no_target_file(
+    dda: CliRunner,
+    use_temp_fixture_folder: Callable[[str], Path],
+) -> None:
+    """Test validation with multiple rule files."""
+
+    path = use_temp_fixture_folder("simple_rules_no_target")
+    with path.as_cwd():
+        result = dda("validate", "ai-rules")
+
+    result.check_exit_code(exit_code=1)
+
+
+def test_validate_with_fix_flag(
+    dda: CliRunner,
+    use_temp_fixture_folder: Callable[[str], Path],
+) -> None:
+    """Test validation with fix flag when files are out of sync."""
+    path = use_temp_fixture_folder("simple_rules_no_target")
+    with path.as_cwd():
+        result = dda("validate", "ai-rules", "--fix")
+
+    result.check_exit_code(exit_code=0)
+    assert (path / "CLAUDE.md").exists()
+    content = (path / "CLAUDE.md").read_text(encoding="utf-8")
+    assert f"@{os.path.join('.cursor', 'rules', 'coding-standards.mdc')}" in content
+    assert f"@{os.path.join('.cursor', 'rules', 'security.mdc')}" in content
+    assert f"@{os.path.join('.cursor', 'rules', 'testing.mdc')}" in content
+    assert "imhere.txt" not in content
+    assert f"@{os.path.join('.cursor', 'rules', 'personal', 'my-rule.mdc')}" not in content
+    assert f"@{os.path.join('.cursor', 'rules', 'nested', 'my-nested-rule.mdc')}" in content
+    assert "@CLAUDE_PERSONAL.md" in content
+
+
+def test_validate_no_cursor_rules_directory(
+    dda: CliRunner,
+    use_temp_fixture_folder: Callable[[str], Path],
+) -> None:
+    """Test validation when cursor rules directory doesn't exist."""
+    path = use_temp_fixture_folder("no_cursor_rules")
+    with path.as_cwd():
+        result = dda("validate", "ai-rules")
+
+    result.check_exit_code(exit_code=0)
+    # Should not create target file if no rules directory
+    target_file = path / "CLAUDE.md"
+    assert not target_file.exists()
+
+
+def test_validate_in_sync(
+    dda: CliRunner,
+    use_temp_fixture_folder: Callable[[str], Path],
+) -> None:
+    """Test validation when files are already in sync."""
+    path = use_temp_fixture_folder("simple_rules_no_target")
+
+    with path.as_cwd():
+        # First fix the files
+        result = dda("validate", "ai-rules", "--fix")
+        result.check_exit_code(exit_code=0)
+
+        # Then validate without fix
+        result = dda("validate", "ai-rules")
+        result.check_exit_code(exit_code=0)
+
+
+def test_validate_out_of_sync(
+    dda: CliRunner,
+    use_temp_fixture_folder: Callable[[str], Path],
+) -> None:
+    """Test validation when files are out of sync."""
+    path = use_temp_fixture_folder("out_of_sync")
+
+    with path.as_cwd():
+        result = dda("validate", "ai-rules")
+        result.check_exit_code(exit_code=1)