[Feature request] Extend PreToolUse hooks beyond Bash + implement updatedInput rewrite

Summary

The PreToolUse hook in ~/.codex/hooks.json currently fires for Bash/shell tool calls only. Two related requests that together unlock full-parity middleware integrations:

1. Expand PreToolUse to all tool calls — specifically read_file and grep, which are the other high-volume tools with the highest potential to overflow context when left unconstrained (apply_patch is now fixed — see progress below)
2. Implement updatedInput in the hook response — the runtime currently rejects it with "PreToolUse hook returned unsupported updatedInput". Implementing this would let hooks enforce programmatic budgets (e.g. cap limit on a file read, cap head_limit on a grep) rather than relying on model compliance

Motivation

I'm the author of squeez, an external compression middleware that integrates with Claude Code, Copilot CLI, OpenCode, Gemini CLI, and Codex CLI via their respective hook systems.

For Codex specifically, I can compress Bash output via the existing PreToolUse + PostToolUse hooks — that part works today. But read_file / grep results routinely push sessions past the context budget, and without a hook surface on those tools the only fallback is a prose hint in AGENTS.md, which the model may or may not honour.

If the hook surface expanded, middleware could uniformly enforce output-size budgets across every tool call, the same way Claude Code's PreToolUse + tool-input rewrite does today.

Progress

✅ Fixed in 0.123.0 (PR #18391, 2026-04-23)

• apply_patch now emits PreToolUse and PostToolUse hook events
• tool_name in hook stdin is now handler-supplied (no longer always "Bash")

❌ Still blocked

• read_file and grep have no ToolHandler with pre_tool_use_payload/post_tool_use_payload — only test files exist, no hook dispatch
• updatedInput is explicitly rejected by output_parser.rs:

``
if output.updated_input.is_some() {
Some("PreToolUse hook returned unsupported updatedInput".to_string())
}
``

Suggested acceptance criteria

• PreToolUse fires for read_file and grep in addition to Bash/shell and apply_patch
• A hook emitting {"decision":"allow","updatedInput":{...}} has the rewritten input passed to the tool
• Documentation updated to reflect both

Downstream tracker

squeez CodexCliAdapter stays at BUDGET_SOFT (prose hints in AGENTS.md) until both remaining items land. Will flip to BUDGET_HARD once confirmed. Happy to test a dev branch.

Additional context

Related discussion: openai/codex#2150