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code-transfer

Development
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Transfer code between files with line-based precision. Use when users request copying code from one location to another, moving functions or classes between files, extracting code blocks, or inserting code at specific line numbers.

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How to use this skill

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  1. Open your project in Codex.
  2. Copy the prompt below and paste it into your agent.
  3. Review the proposed files and risks before you approve installation.
Prompt to paste
I want to install this Agent Skill for this project in Codex.

Source SKILL.md: https://github.com/mhattingpete/claude-skills-marketplace/blob/HEAD/code-operations-plugin/skills/code-transfer/SKILL.md

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First, summarize what it does, its dependencies, license status if identifiable, and any risks. Show the exact files you propose to add under .agents/skills/code-transfer/. Do not write files or run scripts until I approve.

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Copying this prompt does not install or run the skill. Review third-party files before use. Codex skill guide

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

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

Extract Class to New File

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

Insert at Specific Line

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

Reorganize Into Modules

  1. Analyze: Read(file_path="utils.py")
  2. Identify groups: Grep(pattern="^def |^class ", -n=true)
  3. Extract each category: Write new files
  4. 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