### Summary
The goal is for us to get the latest turn model and reasoning effort on
thread/resume is no override is provided on the thread/resume func call.
This is the part 1 which we write the model and reasoning effort for a
thread to the sqlite db and there will be a followup PR to consume the
two new fields on thread/resume.
[part 2 PR is currently WIP](https://github.com/openai/codex/pull/14888)
and this one can be merged independently.
## Stack Position
3/4. Top-of-stack sibling built on #14830.
## Base
- #14830
## Sibling
- #14827
## Scope
- Extend the realtime startup context with a bounded summary of the
latest thread turns for continuity.
---------
Co-authored-by: Codex <noreply@openai.com>
## Why
PR #13783 moved the `codex.rs` unit tests into `codex_tests.rs`. This
applies the same extraction pattern across the rest of `codex-rs/core`
so the production modules stay focused on runtime code instead of large
inline test blocks.
Keeping the tests in sibling files also makes follow-up edits easier to
review because product changes no longer have to share a file with
hundreds or thousands of lines of test scaffolding.
## What changed
- replaced each inline `mod tests { ... }` in `codex-rs/core/src/**`
with a path-based module declaration
- moved each extracted unit test module into a sibling `*_tests.rs`
file, using `mod_tests.rs` for `mod.rs` modules
- preserved the existing `cfg(...)` guards and module-local structure so
the refactor remains structural rather than behavioral
## Testing
- `cargo test -p codex-core --lib` (`1653 passed; 0 failed; 5 ignored`)
- `just fix -p codex-core`
- `cargo fmt --check`
- `cargo shear`