## Why
Plugins can bundle lifecycle hooks, but Codex previously only discovered
hooks from user, project, and managed config layers. This adds the
plugin discovery and runtime plumbing needed for plugin-bundled hooks
while keeping execution behind the `plugin_hooks` feature flag.
## What
- Discovers plugin hook sources from each plugin's default
`hooks/hooks.json`.
- Supports `plugin.json` manifest `hooks` entries as either relative
paths or inline hook objects.
- Plumbs discovered plugin hook sources through plugin loading into the
hook runtime when `plugin_hooks` is enabled.
- Marks plugin-originated hook runs as `HookSource::Plugin`.
- Injects `PLUGIN_ROOT` and `CLAUDE_PLUGIN_ROOT` into plugin hook
command environments.
- Updates generated schemas and hook source metadata for the plugin hook
source.
## Stack
1. This PR - openai/codex#19705
2. openai/codex#19778
3. openai/codex#19840
4. openai/codex#19882
## Reviewer Notes
- Core logic is in `codex-rs/core-plugins/src/loader.rs` and
`codex-rs/hooks/src/engine/discovery.rs`
- Moved existing / adding new tests to
`codex-rs/core-plugins/src/loader_tests.rs` hence the large diff there
- Otherwise mostly plumbing and minor schema updates
### Core Changes
The `codex-rs/core` changes are limited to wiring plugin hook support
into existing core flows:
- `core/src/session/session.rs` conditionally pulls effective plugin
hook sources and plugin hook load warnings from `PluginsManager` when
`plugin_hooks` is enabled, then passes them into `HooksConfig`.
- `core/src/hook_runtime.rs` adds the `plugin` metric tag for
`HookSource::Plugin`.
- `core/config.schema.json` picks up the new `plugin_hooks` feature
flag, and `core/src/plugins/manager_tests.rs` updates fixtures for the
added plugin hook fields.
---------
Co-authored-by: Codex <noreply@openai.com>
Load plugin manifests through a shared discoverable-path helper so
manifest reads, installs, and skill names all see the same alternate
manifest location.
## Summary
- move skill loading and management into codex-core-skills
- leave codex-core with the thin integration layer and shared wiring
## Testing
- CI
---------
Co-authored-by: Codex <noreply@openai.com>
## Summary
- extract plugin identifiers and load-outcome types into codex-plugin
- update codex-core to consume the new plugin crate
## Testing
- CI
---------
Co-authored-by: Codex <noreply@openai.com>
