# What
When a normal hook fires inside a thread-spawned subagent, Codex now
includes these optional top-level fields in the hook input:
- `agent_id`: the child thread id
- `agent_type`: the subagent role
Root-agent hook inputs omit these fields. `SubagentStart` and
`SubagentStop` keep their existing required `agent_id` and `agent_type`
fields because those events are inherently subagent-scoped.
This does not change matcher behavior. Tool hooks still match on tool
name, compact hooks still match on trigger, and `UserPromptSubmit` still
ignores matchers. Only `SubagentStart` and `SubagentStop` match on
`agent_type`.
## 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.
## Why
We need `PermissionRequest` hook support!
Also addresses:
- https://github.com/openai/codex/issues/16301
- run a script on Hook to do things like play a sound to draw attention
but actually no-op so user can still approve
- can omit the `decision` object from output or just have the script
exit 0 and print nothing
- https://github.com/openai/codex/issues/15311
- let the script approve/deny on its own
- external UI what will run on Hook and relay decision back to codex
## Reviewer Note
There's a lot of plumbing for the new hook, key files to review are:
- New hook added in `codex-rs/hooks/src/events/permission_request.rs`
- Wiring for network approvals
`codex-rs/core/src/tools/network_approval.rs`
- Wiring for tool orchestrator `codex-rs/core/src/tools/orchestrator.rs`
- Wiring for execve
`codex-rs/core/src/tools/runtimes/shell/unix_escalation.rs`
## What
- Wires shell, unified exec, and network approval prompts into the
`PermissionRequest` hook flow.
- Lets hooks allow or deny approval prompts; quiet or invalid hooks fall
back to the normal approval path.
- Uses `tool_input.description` for user-facing context when it helps:
- shell / `exec_command`: the request justification, when present
- network approvals: `network-access <domain>`
- Uses `tool_name: Bash` for shell, unified exec, and network approval
permission-request hooks.
- For network approvals, passes the originating command in
`tool_input.command` when there is a single owning call; otherwise falls
back to the synthetic `network-access ...` command.
<details>
<summary>Example `PermissionRequest` hook input for a shell
approval</summary>
```json
{
"session_id": "<session-id>",
"turn_id": "<turn-id>",
"transcript_path": "/path/to/transcript.jsonl",
"cwd": "/path/to/cwd",
"hook_event_name": "PermissionRequest",
"model": "gpt-5",
"permission_mode": "default",
"tool_name": "Bash",
"tool_input": {
"command": "rm -f /tmp/example"
}
}
```
</details>
<details>
<summary>Example `PermissionRequest` hook input for an escalated
`exec_command` request</summary>
```json
{
"session_id": "<session-id>",
"turn_id": "<turn-id>",
"transcript_path": "/path/to/transcript.jsonl",
"cwd": "/path/to/cwd",
"hook_event_name": "PermissionRequest",
"model": "gpt-5",
"permission_mode": "default",
"tool_name": "Bash",
"tool_input": {
"command": "cp /tmp/source.json /Users/alice/export/source.json",
"description": "Need to copy a generated file outside the workspace"
}
}
```
</details>
<details>
<summary>Example `PermissionRequest` hook input for a network
approval</summary>
```json
{
"session_id": "<session-id>",
"turn_id": "<turn-id>",
"transcript_path": "/path/to/transcript.jsonl",
"cwd": "/path/to/cwd",
"hook_event_name": "PermissionRequest",
"model": "gpt-5",
"permission_mode": "default",
"tool_name": "Bash",
"tool_input": {
"command": "curl http://codex-network-test.invalid",
"description": "network-access http://codex-network-test.invalid"
}
}
```
</details>
## Follow-ups
- Implement the `PermissionRequest` semantics for `updatedInput`,
`updatedPermissions`, `interrupt`, and suggestions /
`permission_suggestions`
- Add `PermissionRequest` support for the `request_permissions` tool
path
---------
Co-authored-by: Codex <noreply@openai.com>
Abhinav ·
Felipe Coury ·