feat: Add grammar fetch and comparison tooling

- Add fetch_bind_grammar.py for MCP-based grammar file retrieval
- Add compare_bind_versions.py for version differences analysis
- Add process_mcp_result.py for handling base64-encoded MCP output
- Create upstream directory structure with fetching instructions
- Document grammar file locations and structure

scripts/fetch_bind_grammar_mcp.py

@@ -0,0 +1,163 @@
+#!/usr/bin/env python3
+"""
+Fetch BIND9 grammar files using Gitea MCP integration.
+
+This script demonstrates how to use mcp_gitea-mcp tools to fetch grammar files.
+Since we can't directly call MCP tools from Python, this serves as documentation
+for the manual fetching process that should be done through the MCP interface.
+
+Usage:
+    The actual fetching should be done through MCP tool calls:
+    
+    1. List available tags:
+       mcp_gitea-mcp_list_tags(owner="Mirrors", repo="bind9")
+    
+    2. Get directory listing:
+       mcp_gitea-mcp_get_dir_content(owner="Mirrors", repo="bind9", 
+                                      ref="v9.18.44", filePath="doc/misc")
+    
+    3. Fetch each grammar file:
+       mcp_gitea-mcp_get_file_content(owner="Mirrors", repo="bind9",
+                                       ref="v9.18.44", 
+                                       filePath="doc/misc/options")
+"""
+
+import json
+from pathlib import Path
+from typing import Dict, List
+
+# Target versions
+VERSIONS = {
+    "9.18": "v9.18.44",
+    "9.20": "v9.20.18",
+}
+
+# Grammar files to fetch
+GRAMMAR_FILES = [
+    "options",
+    "forward.zoneopt",
+    "hint.zoneopt",
+    "in-view.zoneopt",
+    "mirror.zoneopt",
+    "primary.zoneopt",
+    "redirect.zoneopt",
+    "secondary.zoneopt",
+    "static-stub.zoneopt",
+    "stub.zoneopt",
+    "delegation-only.zoneopt",
+    "rndc.grammar",
+]
+
+SUPPORT_FILES = [
+    "parsegrammar.py",
+    "checkgrammar.py",
+]
+
+
+def generate_fetch_commands() -> List[Dict]:
+    """Generate MCP tool call commands for fetching grammar files."""
+    commands = []
+    
+    for version_name, tag in VERSIONS.items():
+        # List directory command
+        commands.append({
+            "tool": "mcp_gitea-mcp_get_dir_content",
+            "params": {
+                "owner": "Mirrors",
+                "repo": "bind9",
+                "ref": tag,
+                "filePath": "doc/misc"
+            },
+            "description": f"List grammar files for {version_name} ({tag})"
+        })
+        
+        # File fetch commands
+        for grammar_file in GRAMMAR_FILES + SUPPORT_FILES:
+            commands.append({
+                "tool": "mcp_gitea-mcp_get_file_content",
+                "params": {
+                    "owner": "Mirrors",
+                    "repo": "bind9",
+                    "ref": tag,
+                    "filePath": f"doc/misc/{grammar_file}"
+                },
+                "save_to": f"bind9-grammar/upstream/{tag}/grammar/{grammar_file}",
+                "description": f"Fetch {grammar_file} for {version_name}"
+            })
+    
+    return commands
+
+
+def save_file_structure() -> Dict:
+    """Generate expected file structure after fetching."""
+    structure = {
+        "bind9-grammar": {
+            "upstream": {}
+        }
+    }
+    
+    for version_name, tag in VERSIONS.items():
+        structure["bind9-grammar"]["upstream"][tag] = {
+            "grammar": {
+                "files": GRAMMAR_FILES + SUPPORT_FILES
+            },
+            "metadata.json": {
+                "version": tag,
+                "version_name": version_name,
+                "repository": "Mirrors/bind9",
+                "fetched_files": len(GRAMMAR_FILES) + len(SUPPORT_FILES)
+            }
+        }
+    
+    return structure
+
+
+def main():
+    """Generate instructions and commands for grammar fetching."""
+    print("=" * 70)
+    print("BIND9 Grammar Fetcher - MCP Integration Guide")
+    print("=" * 70)
+    
+    print("\nTarget Versions:")
+    for version_name, tag in VERSIONS.items():
+        print(f"  - BIND {version_name}: {tag}")
+    
+    print(f"\nFiles to fetch per version: {len(GRAMMAR_FILES)} grammar files + {len(SUPPORT_FILES)} support files")
+    
+    print("\n" + "=" * 70)
+    print("MCP TOOL CALL SEQUENCE")
+    print("=" * 70)
+    
+    commands = generate_fetch_commands()
+    
+    for i, cmd in enumerate(commands, 1):
+        print(f"\n[{i}/{len(commands)}] {cmd['description']}")
+        print(f"Tool: {cmd['tool']}")
+        print(f"Parameters:")
+        for key, value in cmd['params'].items():
+            print(f"  - {key}: {value}")
+        if 'save_to' in cmd:
+            print(f"Save to: {cmd['save_to']}")
+    
+    print("\n" + "=" * 70)
+    print("EXPECTED FILE STRUCTURE")
+    print("=" * 70)
+    
+    structure = save_file_structure()
+    print(json.dumps(structure, indent=2))
+    
+    # Save command list
+    output_dir = Path("bind9-grammar/upstream")
+    output_dir.mkdir(parents=True, exist_ok=True)
+    
+    commands_file = output_dir / "fetch_commands.json"
+    with open(commands_file, 'w') as f:
+        json.dump(commands, f, indent=2)
+    
+    print(f"\nCommand list saved to: {commands_file}")
+    print("\nNote: These commands should be executed through the MCP interface,")
+    print("      not directly from this Python script.")
+
+
+if __name__ == "__main__":
+    main()