Support direct file read/write APIs instead of shell commands

What feature would you like to see?

Support direct file read/write APIs (e.g. readFile/writeFile) instead of relying on shell commands for filesystem access.

Additional information

Additional context

• Using PowerShell/bash commands for file I/O leads to multiple cross-platform issues:
• CRLF vs LF line endings
• Encoding mismatches (UTF-8 vs system codepages)
• Shell escaping for paths with spaces/special characters
• Inconsistent behavior across Windows / macOS / Linux

Why it matters

• Agents and tools often need to write multi-line files (source code, configs, serialized data)
• Shell-based writes easily corrupt or reformat content unintentionally
• Beginners struggle with shell quirks → worse onboarding UX

Proposed direction

• Introduce a direct file API surface (e.g. readFile, writeFile, appendFile)
• Ensure consistent behavior across CLI and other Codex surfaces
• Avoid shell entirely for non-interactive filesystem operations

Willing to contribute

I’m interested in contributing a prototype implementation (especially Windows support).
Happy to help with API design, cross-platform behavior, and testing.