Code Transfer Skill for Claude

Code Transfer

Transfer code between files with precise line-based control. Dual-mode operation: native tools (1-10 files) or execution mode (10+ files, 90% token savings).

Operation Modes

Basic Mode (Default)

Use Read, Edit, Bash scripts for 1-10 file operations. Works immediately, no setup required.

Execution Mode (10+ files)

from api.filesystem import batch_copy
from api.code_analysis import find_functions

functions = find_functions('app.py', pattern='handle_.*')
operations = [{
    'source_file': 'app.py',
    'start_line': f['start_line'],
    'end_line': f['end_line'],
    'target_file': 'handlers.py',
    'target_line': -1
} for f in functions]
batch_copy(operations)

When to Use

• "copy this code to [file]"
• "move [function/class] to [file]"
• "extract this to a new file"
• "insert at line [number]"
• "reorganize into separate files"

Core Operations

1. Extract Source Code

Read(file_path="src/auth.py")                              # Full file
Read(file_path="src/auth.py", offset=10, limit=20)         # Line range
Grep(pattern="def authenticate", -n=true, -A=10)           # Find function

2. Insert at Specific Line

Use line_insert.py script for line-based insertion:

python3 skills/code-transfer/scripts/line_insert.py <file> <line_number> <code> [--backup]

Examples:

# Insert function at line 50
python3 skills/code-transfer/scripts/line_insert.py src/utils.py 50 "def helper():\n    pass"

# Insert with backup
python3 skills/code-transfer/scripts/line_insert.py src/utils.py 50 "code" --backup

# Insert at beginning
python3 skills/code-transfer/scripts/line_insert.py src/new.py 1 "import os"

When to use:

• User specifies exact line number
• Inserting into new/empty files
• Inserting at beginning/end without context

3. Insert Relative to Content

Use Edit when insertion point is relative to existing code:

Edit(
  file_path="src/utils.py",
  old_string="def existing():\n    pass",
  new_string="def existing():\n    pass\n\ndef new():\n    return True"
)

Workflow Examples

Copy Function Between Files

• Find: Grep(pattern="def validate_user", -n=true, -A=20)
• Extract: Read(file_path="auth.py", offset=45, limit=15)
• Check target: Read(file_path="validators.py")
• Insert: Use line_insert.py or Edit based on context

Extract Class to New File

• Locate: Grep(pattern="class DatabaseConnection", -n=true, -A=50)
• Extract: Read(file_path="original.py", offset=100, limit=50)
• Create: Write(file_path="database.py", content="<extracted>")
• Update imports: Edit in original file
• Remove old class: Edit with replacement

Insert at Specific Line

• Validate: Read(file_path="main.py", offset=20, limit=10)
• Insert: python3 skills/code-transfer/scripts/line_insert.py main.py 25 "logger.info('...')" --backup
• Verify: Read(file_path="main.py", offset=23, limit=5)

Reorganize Into Modules

• Analyze: Read(file_path="utils.py")
• Identify groups: Grep(pattern="^def |^class ", -n=true)
• Extract each category: Write new files
• Update original: Re-export or redirect

Best Practices

Planning:

• Understand dependencies (imports, references)
• Identify exact start/end of code block
• Check target file structure
• Ensure necessary imports included

Preservation:

• Include docstrings and comments
• Transfer related functions together
• Update imports in both files
• Maintain formatting/indentation

Validation:

• Verify insertion placement
• Check syntax
• Test imports
• Suggest running tests

Backups:

• Use --backup for significant changes
• Critical file operations
• Large deletions

Integration

• code-refactor: Refactor after transferring
• test-fixing: Run tests after reorganizing
• feature-planning: Plan large reorganizations