Token-Efficient and Consistent AI Code Generation Through GNU Unified Diff (JSON)

gnu-unified-diff-prompt.json

{
  "OUTPUT_FORMAT": {
    "type": "JSON",
    "encoding": "UTF-8",
    "structure": {
      "target_file": "string (relative path with forward slashes)",
      "diff": "string (unified diff with \\n line breaks)",
      "error": "string (optional, only present for errors)"
    }
  },
  "DIFF_SPECIFICATIONS": {
    "headers": {
      "format": [
        "--- a/<path>",
        "+++ b/<path>"
      ],
      "rules": [
        "No timestamps/metadata",
        "Use a/ and b/ prefixes"
      ]
    },
    "hunks": {
      "format": "@@ -<start>,<count> +<start>,<count> @@",
      "context": "3 lines context before/after changes",
      "line_endings": "LF (\\n) line endings only",
      "line_markers": {
        "context": " ",
        "deletion": "-",
        "addition": "+"
      }
    },
    "special_cases": {
      "new_file": {
        "original": "--- a/dev/null",
        "new": "+++ b/<relative_path>"
      },
      "deleted_file": {
        "original": "--- a/<relative_path>",
        "new": "+++ b/dev/null"
      }
    }
  },
  "VALIDATION_RULES": {
    "max_total_lines": 10000,
    "max_line_length": 10000,
    "encoding": "UTF-8 required",
    "rules": [
      "No directory traversal",
      "Sanitized file paths",
      "No binary files",
      "Within project scope"
    ]
  },
  "EXAMPLES": {
    "example": [
      {
        "description": "Modification",
        "output": "{\"target_file\":\"src/example.js\",\"diff\":\"--- a/src/example.js\\n+++ b/src/example.js\\n@@ -1,5 +1,5 @@\\n function greet(name) {\\n-  console.log(\\\"Hello, \\\" + name + \\\"!\\\");\\n+  console.log(\\\"Hello, \\\" + name.toUpperCase() + \\\"!!!\\\");\\n }\\n \\n greet(\\\"Alice\\\");\\n\"}"
      },
      {
        "description": "Creation",
        "output": "{\"target_file\":\"src/newfile.js\",\"diff\":\"--- a/dev/null\\n+++ b/src/newfile.js\\n@@ -0,0 +1,3 @@\\n+console.log(\\\"This is a new file.\\\");\\n\"}"
      },
      {
        "description": "Deletion",
        "output": "{\"target_file\":\"src/obsolete.js\",\"diff\":\"--- a/src/obsolete.js\\n+++ b/dev/null\\n@@ -1,3 +0,0 @@\\n-console.log(\\\"This file is obsolete.\\\");\\n\"}"
      }
    ]
  },
  "ERROR_HANDLING": {
    "conditions": [
      "Invalid/nonexistent file",
      "Binary file"
    ],
    "responses": {
      "error_example": [
        "{\"target_file\":\"src/nonexistent.js\",\"error\":\"Target file does not exist.\"}",
        "{\"target_file\":\"assets/image.png\",\"error\":\"Binary files are not supported.\"}"
      ]
    }
  },
  "SECURITY_REQUIREMENTS": {
    "path_handling": [
      "Sanitize all file paths",
      "Prevent directory traversal"
    ],
    "content_safety": [
      "No code injection vectors",
      "Within allowed directory scope",
      "Valid JSON parsing guaranteed"
    ]
  }
}