## Why
The legacy `AfterToolUse` hook path was still wired through core tool
dispatch even though the hooks registry never populated any handlers for
it. The supported hook surface is `PostToolUse`, so the old
infrastructure was dead code on the hot path.
## What changed
- Removed the legacy `AfterToolUse` dispatch from `codex-core` tool
execution.
- Removed the unused legacy hook payload types and exports from
`codex-hooks`.
- Simplified legacy notify handling now that `HookEvent` only carries
`AfterAgent`.
## Validation
- `cargo test -p codex-hooks`
- `cargo test -p codex-core registry`
(Experimental)
This PR adds a first MVP for hooks, with SessionStart and Stop
The core design is:
- hooks live in a dedicated engine under codex-rs/hooks
- each hook type has its own event-specific file
- hook execution is synchronous and blocks normal turn progression while
running
- matching hooks run in parallel, then their results are aggregated into
a normalized HookRunSummary
On the AppServer side, hooks are exposed as operational metadata rather
than transcript-native items:
- new live notifications: hook/started, hook/completed
- persisted/replayed hook results live on Turn.hookRuns
- we intentionally did not add hook-specific ThreadItem variants
Hooks messages are not persisted, they remain ephemeral. The context
changes they add are (they get appended to the user's prompt)
pakrym-oai