## Why
`child_agents_md` is a disabled, under-development experiment that adds
a second model-visible explanation of hierarchical `AGENTS.md` behavior.
Keeping it leaves unused prompt, configuration, documentation, and test
surface.
## What changed
- remove the `ChildAgentsMd` feature and `child_agents_md` config schema
entry
- remove the hierarchical prompt asset, export, and instruction
injection
- remove feature-specific tests and documentation
- keep the generic unstable-feature warning coverage using
`apply_patch_streaming_events`
Normal project `AGENTS.md` discovery and composition are unchanged.
## Testing
- `just test -p codex-features`
- `just test -p codex-prompts`
- `just test -p codex-core agents_md`
- `just test -p codex-core unstable_features_warning`
## Why
`codex_core` is consistently a bottleneck for incremental builds during
iteration. The simplest fix is to make the crate smaller.
## Summary
`codex-core` owns several reusable prompt renderers and static prompt
assets, which makes the crate harder to split apart.
Rename `codex-review-prompts` to `codex-prompts` and move shared review,
goal, permissions, compaction, realtime, hierarchical AGENTS.md, and
`apply_patch` prompts into it. Move prompt-only tests and update
consumers and `CODEOWNERS`.
## Validation
- `just test -p codex-prompts -p codex-apply-patch`
- `just test -p codex-core prompt_caching`
- Bazel builds for the affected crates