## What changed
- Centralize the allowlist for bundled MCP cleanup hooks and use it for both local and executor-discovered plugins, including `unified-computer-use` cleanup through `cua_repl`.
- Mark matching cleanup hooks as trusted built-ins so they run without saved hook trust and remain active when regular hooks or their per-hook state are disabled. Plugin enablement and managed-only policy still apply.
- Hide built-in cleanup hooks from hook listings and lifecycle notifications while retaining their metrics. Keep the built-in classification out of serialized protocol data.
## Testing
- Cover allowlist boundaries, trust and enablement behavior, inline and file-based hook declarations, MCP success and error responses, hook listing, lifecycle notifications, metrics, and protocol serialization.
GitOrigin-RevId: f93b7bc99f4ed9694f529def8ec383b45f31430e
## What changed
- Discover inline hooks from executor-provided plugin manifests and accept only
the bundled Computer Use `Stop` hook for `node_repl.turn_ended`.
- Add the accepted hook to the current step's hook engine with
executor-scoped provenance.
- Run executor-scoped hooks in the background after regular stop-hook
decisions, without delaying turn completion, applying control effects, or
exposing them in hook summaries. Skip them when regular hooks only block
continuation.
## Testing
- Added coverage for manifest filtering and option preservation.
- Added coverage for background execution, interaction with regular stop
hooks, and non-blocking turn completion.
GitOrigin-RevId: c0f75f83a23ba8a83bb3a5d5997c4882aacc32d6
## What changed
- Represent configured handlers by handler kind and route execution through the
hooks engine, while preserving command hook behavior.
- Reject MCP tool inputs containing values such as `null` that cannot be
represented in TOML for trust hashing.
## Testing
- Add coverage for rejecting `null` at the top level and within nested MCP tool
input objects and arrays.
GitOrigin-RevId: 3854a349c2a721691450467592f99cf57e6260ef
## Why
Hook configurations can mark command handlers as asynchronous, but Codex previously skipped those handlers outside `SessionEnd`.
## What changed
- Run asynchronous command hooks in the background with a per-session concurrency limit, while keeping `SessionEnd` hooks synchronous.
- Prevent asynchronous hooks from blocking, stopping, rewriting, or otherwise controlling the operation that launched them.
- Deliver warnings and additional context at safe turn boundaries: inject results into an active turn after sampling, or buffer them ahead of the next user prompt when the session is idle.
- Preserve in-flight hooks across configuration reloads, scope spilled output to the thread, and abort outstanding work during session shutdown.
## Testing
Add unit and integration coverage for background scheduling, concurrency, output parsing, active and idle result delivery, configuration reloads, and shutdown cleanup.
GitOrigin-RevId: 8094552e4afe7b47b09a61bb575bb20f4e491d8d
## Why
Timing out a command hook can leave descendant processes running after the hook itself is stopped.
## What changed
- Run hook commands in a process group on Unix and a job object on Windows.
- Terminate the full process tree when hook execution is cancelled or fails, with `taskkill` as a Windows fallback.
- Preserve descendants when a hook completes successfully so intentionally detached helpers can continue running.
GitOrigin-RevId: 1a18653d34c6f1685ef8c4f8e8546663b276292a
## What changed
- Add `additionalContextLimit` to command hook configuration for events that can emit `additionalContext`.
- Apply the limit independently to each hook's context before it is sent to the model. Unset values retain the 2,500-token default, while `0` disables spilling for that hook.
- Expose configured limits through app-server hook and requirements responses, and show them in the TUI hooks browser.
## Testing
- Cover JSON and TOML parsing, discovery and hashing, per-hook spilling behavior, app-server responses, and TUI rendering.
GitOrigin-RevId: 55ddc2dbbdf9067dceee3e1968c03617bbf6bcea
# 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`.
## Why
`PreToolUse` already exposes `updatedInput` in its hook output schema,
but Codex currently rejects it instead of applying the rewrite. That
leaves hook authors unable to make the documented pre-execution
adjustment to a tool call before it runs.
## What
- Accept `updatedInput` from `PreToolUse` hooks when paired with
`permissionDecision: "allow"`.
- Apply the rewritten input before dispatch so the tool executes the
updated payload, not the original one.
- Preserve the stable hook-facing compatibility shapes that
participating tool handlers expose:
- Bash-like tools (`shell`, `container.exec`, `local_shell`,
`shell_command`, `exec_command`) use `{ "command": ... }`.
- `apply_patch` exposes its patch body through the same command-shaped
hook contract.
- MCP tools expose their JSON argument object directly.
- Keep each participating tool handler responsible for translating
hook-facing `updatedInput` back into its concrete invocation shape.
## Verification
Direct Bash-like rewrite coverage:
- `pre_tool_use_rewrites_shell_before_execution`
- `pre_tool_use_rewrites_container_exec_before_execution`
- `pre_tool_use_rewrites_local_shell_before_execution`
- `pre_tool_use_rewrites_shell_command_before_execution`
- `pre_tool_use_rewrites_exec_command_before_execution`
These cases assert that each supported Bash-like surface runs only the
rewritten command while the hook still observes the original `{
"command": ... }` input.
`pre_tool_use_rewrites_apply_patch_before_execution`
- Model emits one patch.
- Hook swaps in a different patch.
- Asserts only the rewritten file is created, and the hook saw the
original patch.
`pre_tool_use_rewrites_code_mode_nested_exec_command_before_execution`
- Model runs one nested shell command from code mode.
- Hook rewrites it.
- Asserts only the rewritten command runs, and the hook saw the original
nested input.
`pre_tool_use_rewrites_mcp_tool_before_execution`
- Model calls the RMCP echo tool.
- Hook rewrites the MCP arguments.
- Asserts the MCP server receives and returns the rewritten message, not
the original one.
Based on work from Vincent K -
https://github.com/openai/codex/pull/19060
<img width="1836" height="642" alt="CleanShot 2026-04-29 at 20 47 40@2x"
src="https://github.com/user-attachments/assets/b647bb89-65fe-40c8-80b0-7a6b7c984634"
/>
## Why
Compaction rewrites the conversation context that future model turns
receive, but hooks currently have no deterministic lifecycle point
around that rewrite. This adds compact lifecycle hooks so users can
audit manual and automatic compaction, surface hook messages in the UI,
and run post-compaction follow-up without overloading tool or prompt
hooks.
## What Changed
- Added `PreCompact` and `PostCompact` hook events across hook config,
discovery, dispatch, generated schemas, app-server notifications,
analytics, and TUI hook rendering.
- Added trigger matching for compact hooks with the documented `manual`
and `auto` matcher values.
- Wired `PreCompact` before both local and remote compaction, and
`PostCompact` after successful local or remote compaction.
- Kept compact hook command input to lifecycle metadata: session id,
Codex turn id, transcript path, cwd, hook event name, model, and
trigger.
- Made compact stdout handling consistent with other hooks: plain stdout
is ignored as debug output, while malformed JSON-looking stdout is
reported as failed hook output.
- Added integration coverage for compact hook dispatch, trigger
matching, post-compact execution, and the audited behavior that
`decision:"block"` does not block compaction.
## Out of Scope
- Hook-specific compaction blocking is not implemented;
`decision:"block"` and exit-code-2 blocking semantics are intentionally
unsupported for `PreCompact`.
- Custom compaction instructions are not exposed to compact hooks in
this PR.
- Compact summaries, summary character counts, and summary previews are
not exposed to compact hooks in this PR.
## Verification
- `cargo test -p codex-hooks`
- `cargo test -p codex-core
manual_pre_compact_block_decision_does_not_block_compaction`
- `cargo test -p codex-app-server hooks_list`
- `cargo test -p codex-core config_schema_matches_fixture`
- `cargo test -p codex-tui hooks_browser`
## Docs
The developer documentation for Codex hooks should be updated alongside
this feature to document `PreCompact` and `PostCompact`, the
`manual`/`auto` matcher values, and the compact hook payload fields.
---------
Co-authored-by: Vincent Koc <vincentkoc@ieee.org>
teddywyly-oai