## What
This change introduces a new `ReadOnlyAccess` model and threads it through
sandbox policy consumers so read access is explicit instead of implicit.
- Added `ReadOnlyAccess` to protocol:
- `Restricted { include_platform_defaults, readable_roots }`
- `FullAccess`
- Changed `SandboxPolicy` shape:
- `ReadOnly` is now `ReadOnly { access: ReadOnlyAccess }`
- `WorkspaceWrite` now carries `read_only_access: ReadOnlyAccess`
- Kept existing behavior for now by defaulting to `ReadOnlyAccess::FullAccess`
in constructors and current config/app-server mappings.
- Added helper methods to compute effective readable roots (including optional
platform defaults + cwd) and to detect full read access.
- Updated seatbelt policy generation to honor restricted read roots by emitting
scoped `(allow file-read* ...)` entries when full read access is not granted.
- Updated Linux backends (`bwrap`, legacy landlock path) to fail closed with an
explicit `UnsupportedOperation` when restricted read access is requested but
not yet implemented there.
- Updated Windows sandbox backends (standard, elevated, and runner paths) to
fail closed in the same way for restricted read access.
- Updated all call sites/tests/pattern matches for the new structured variants
and regenerated app-server protocol schema/types.
## Why
The previous `SandboxPolicy::ReadOnly` implied full-disk read access and left
no way to express a narrower read surface.
This refactor establishes the policy model needed to support user-configurable
read restrictions in a follow-up without changing current runtime behavior.
It also ensures we do not silently ignore future restricted-read policies on
platform backends that do not support them yet. Failing closed keeps sandbox
semantics predictable and avoids accidental over-permission.
## Compatibility and rollout notes
- Existing behavior is preserved by default (`FullAccess`).
- Existing config/app-server flows continue to serialize/deserialize cleanly.
- New schema artifacts are included to keep generated protocol outputs in sync.
## Validation
- `just fmt`
- `just fix -p codex-protocol -p codex-core -p codex-linux-sandbox -p codex-windows-sandbox -p codex-app-server-protocol`
- `cargo check -p codex-windows-sandbox`
- Targeted crate/test runs were executed during development for protocol/core/
sandbox-related crates.
`codex-core` had accumulated config loading, requirements parsing,
constraint logic, and config-layer state handling in a single crate.
This change extracts that subsystem into `codex-config` to reduce
`codex-core` rebuild/test surface area and isolate future config work.
## What Changed
### Added `codex-config`
- Added new workspace crate `codex-rs/config` (`codex-config`).
- Added workspace/build wiring in:
- `codex-rs/Cargo.toml`
- `codex-rs/config/Cargo.toml`
- `codex-rs/config/BUILD.bazel`
- Updated lockfiles (`codex-rs/Cargo.lock`, `MODULE.bazel.lock`).
- Added `codex-core` -> `codex-config` dependency in
`codex-rs/core/Cargo.toml`.
### Moved config internals from `core` into `config`
Moved modules to `codex-rs/config/src/`:
- `core/src/config/constraint.rs` -> `config/src/constraint.rs`
- `core/src/config_loader/cloud_requirements.rs` ->
`config/src/cloud_requirements.rs`
- `core/src/config_loader/config_requirements.rs` ->
`config/src/config_requirements.rs`
- `core/src/config_loader/fingerprint.rs` -> `config/src/fingerprint.rs`
- `core/src/config_loader/merge.rs` -> `config/src/merge.rs`
- `core/src/config_loader/overrides.rs` -> `config/src/overrides.rs`
- `core/src/config_loader/requirements_exec_policy.rs` ->
`config/src/requirements_exec_policy.rs`
- `core/src/config_loader/state.rs` -> `config/src/state.rs`
`codex-config` now re-exports this surface from `config/src/lib.rs` at
the crate top level.
### Updated `core` to consume/re-export `codex-config`
- `core/src/config_loader/mod.rs` now imports/re-exports config-loader
types/functions from top-level `codex_config::*`.
- Local moved modules were removed from `core/src/config_loader/`.
- `core/src/config/mod.rs` now re-exports constraint types from
`codex_config`.
Michael Bolin