## Summary
Lifecycle hooks currently treat `PreToolUse`, `PostToolUse`, and
`PermissionRequest` as Bash-only flows
- hook schema constrains `tool_name` to `Bash`
- hook input assumes a command-shaped `tool_input`
- core hook dispatch path passes only shell command strings
That means hooks cannot target MCP tools even though MCP tool names are
model-visible and stable
This change generalizes those hook paths so they can match and receive
payloads for MCP tools while preserving the existing Bash behavior.
## Reviewer Notes
I think these are the key files
- `codex-rs/core/src/tools/handlers/mcp.rs`
- `codex-rs/core/src/mcp_tool_call.rs`
Otherwise the changes across apply_patch, shell, and unified_exec are
mainly to rewire everything to be `tool_input` based instead of just
`command` so that it'll make sense for MCP tools.
## Changes
- Allow `PreToolUse`, `PostToolUse`, and `PermissionRequest` hook inputs
to carry arbitrary `tool_name` and `tool_input` values instead of
hard-coding `Bash` and command-only payloads.
- Add MCP hook payload support through `McpHandler`, using the
model-visible tool name from `ToolInvocation` and the raw MCP arguments
as `tool_input`.
- Include MCP tool responses in `PostToolUse` by serializing
`McpToolOutput` into the hook response payload.
- Run `PermissionRequest` hooks for MCP approval requests after
remembered approval checks and before falling back to user-facing MCP
elicitation.
- Preserve exact matching for literal hook matchers like `Bash` and
`mcp__memory__create_entities`, while keeping regex matcher support for
patterns like `mcp__memory__.*` and `mcp__.*__write.*`.
---------
Co-authored-by: Andrei Eternal <eternal@openai.com>
Co-authored-by: Codex <noreply@openai.com>
Fixes https://github.com/openai/codex/issues/16732.
## Why
`apply_patch` is Codex's primary file edit path, but it was not emitting
`PreToolUse` or `PostToolUse` hook events. That meant hook-based policy,
auditing, and write coordination could observe shell commands while
missing the actual file mutation performed by `apply_patch`.
The issue also exposed that the hook runtime serialized command hook
payloads with `tool_name: "Bash"` unconditionally. Even if `apply_patch`
supplied hook payloads, hooks would either fail to match it directly or
receive misleading stdin that identified the edit as a Bash tool call.
## What Changed
- Added `PreToolUse` and `PostToolUse` payload support to
`ApplyPatchHandler`.
- Exposed the raw patch body as `tool_input.command` for both
JSON/function and freeform `apply_patch` calls.
- Taught tool hook payloads to carry a handler-supplied hook-facing
`tool_name`.
- Preserved existing shell compatibility by continuing to emit `Bash`
for shell-like tools.
- Serialized the selected hook `tool_name` into hook stdin instead of
hardcoding `Bash`.
- Relaxed the generated hook command input schema so `tool_name` can
represent tools other than `Bash`.
## Verification
Added focused handler coverage for:
- JSON/function `apply_patch` calls producing a `PreToolUse` payload.
- Freeform `apply_patch` calls producing a `PreToolUse` payload.
- Successful `apply_patch` output producing a `PostToolUse` payload.
- Shell and `exec_command` handlers continuing to expose `Bash`.
Added end-to-end hook coverage for:
- A `PreToolUse` hook matching `^apply_patch$` blocking the patch before
the target file is created.
- A `PostToolUse` hook matching `^apply_patch$` receiving the patch
input and tool response, then adding context to the follow-up model
request.
- Non-participating tools such as the plan tool continuing not to emit
`PreToolUse`/`PostToolUse` hook events.
Also validated manually with a live `codex exec` smoke test using an
isolated temp workspace and temp `CODEX_HOME`. The smoke test confirmed
that a real `apply_patch` edit emits `PreToolUse`/`PostToolUse` with
`tool_name: "apply_patch"`, a shell command still emits `tool_name:
"Bash"`, and a denying `PreToolUse` hook prevents the blocked patch file
from being created.
- add `PreToolUse` hook for bash-like tool execution only at first
- block shell execution before dispatch with deny-only hook behavior
- introduces common.rs matcher framework for matching when hooks are run
example run:
```
› run three parallel echo commands, and the second one should echo "[block-pre-tool-use]" as a test
• Running the three echo commands in parallel now and I’ll report the output directly.
• Running PreToolUse hook: name for demo pre tool use hook
• Running PreToolUse hook: name for demo pre tool use hook
• Running PreToolUse hook: name for demo pre tool use hook
PreToolUse hook (completed)
warning: wizard-tower PreToolUse demo inspected Bash: echo "first parallel echo"
PreToolUse hook (blocked)
warning: wizard-tower PreToolUse demo blocked a Bash command on purpose.
feedback: PreToolUse demo blocked the command. Remove [block-pre-tool-use] to continue.
PreToolUse hook (completed)
warning: wizard-tower PreToolUse demo inspected Bash: echo "third parallel echo"
• Ran echo "first parallel echo"
└ first parallel echo
• Ran echo "third parallel echo"
└ third parallel echo
• Three little waves went out in parallel.
1. printed first parallel echo
2. was blocked before execution because it contained the exact test string [block-pre-tool-use]
3. printed third parallel echo
There was also an unrelated macOS defaults warning around the successful commands, but the echoes
themselves worked fine. If you want, I can rerun the second one with a slightly modified string so
it passes cleanly.
```
