## Problem
Codex already treated an existing top-level project `./.codex` directory
as protected, but there was a gap on first creation.
If `./.codex` did not exist yet, a turn could create files under it,
such as `./.codex/config.toml`, without going through the same approval
path as later modifications. That meant the initial write could bypass
the intended protection for project-local Codex state.
## What this changes
This PR closes that first-creation gap in the Unix enforcement layers:
- `codex-protocol`
- treat the top-level project `./.codex` path as a protected carveout
even when it does not exist yet
- avoid injecting the default carveout when the user already has an
explicit rule for that exact path
- macOS Seatbelt
- deny writes to both the exact protected path and anything beneath it,
so creating `./.codex` itself is blocked in addition to writes inside it
- Linux bubblewrap
- preserve the same protected-path behavior for first-time creation
under `./.codex`
- tests
- add protocol regressions for missing `./.codex` and explicit-rule
collisions
- add Unix sandbox coverage for blocking first-time `./.codex` creation
- tighten Seatbelt policy assertions around excluded subpaths
## Scope
This change is intentionally scoped to protecting the top-level project
`.codex` subtree from agent writes.
It does not make `.codex` unreadable, and it does not change the product
behavior around loading project skills from `.codex` when project config
is untrusted.
## Why this shape
The fix is pointed rather than broad:
- it preserves the current model of “project `.codex` is protected from
writes”
- it closes the security-relevant first-write hole
- it avoids folding a larger permissions-model redesign into this PR
## Validation
- `cargo test -p codex-protocol`
- `cargo test -p codex-sandboxing seatbelt`
- `cargo test -p codex-exec --test all
sandbox_blocks_first_time_dot_codex_creation -- --nocapture`
---------
Co-authored-by: Michael Bolin <mbolin@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`
