【BUG】Codex CLI hooks fail silently on Linux/Windows when editing large files #18067

What version of the Codex App are you using (From “About Codex” dialog)?

latest (0.121.0)

What subscription do you have?

Pro

What platform is your computer?

Linux / Windows

What issue are you seeing?

On Linux and Windows, when Codex edits a large file (roughly >100KB or >1500-2000 lines), the preToolUse/postToolUse hooks fail silently and never execute.

The hook input payload includes the full file content, which exceeds OS-level argument size limits:

• Linux: E2BIG (MAX_ARG_STRLEN = 128KB)
• Windows: ENAMETOOLONG (command-line length limit ~32KB)

This does NOT occur on macOS.

What steps can reproduce the bug?

1. Configure a tool hook (e.g. preToolUse / postToolUse) in hooks.json
2. Use Codex to edit a file with >1500-2000 lines (or >100KB in size)
3. Observe that the hook process is never spawned — no output, no error in the terminal

What is the expected behavior?

Hooks should fire regardless of file size. The hook input should be passed entirely via stdin pipe rather than command-line arguments or environment variables.

Additional information

Editing smaller files (e.g. <50KB) in the same session works correctly — hooks fire successfully. macOS is not affected by this issue.