`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`.
The debug output listed non-file-backed layers such as session flags and
MDM managed config, but it did not show their values. That made it
difficult to explain unexpected effective settings because users could
not inspect those layers on disk.
Now `/debug-config` might include output like this:
```
Config layer stack (lowest precedence first):
1. system (/etc/codex/config.toml) (enabled)
2. user (/Users/mbolin/.codex/config.toml) (enabled)
3. legacy managed_config.toml (mdm) (enabled)
MDM value:
# Production Codex configuration file.
[otel]
log_user_prompt = true
environment = "prod"
exporter = { otlp-http = {
endpoint = "https://example.com/otel",
protocol = "binary"
}}
```
**Before:**
```
Error loading configuration: value `Never` is not in the allowed set [OnRequest]
```
**After:**
```
Error loading configuration: invalid value for `approval_policy`: `Never` is not in the
allowed set [OnRequest] (set by MDM com.openai.codex:requirements_toml_base64)
```
Done by introducing a new struct `ConfigRequirementsWithSources` onto
which we `merge_unset_fields` now. Also introduces a pair of requirement
value and its `RequirementSource` (inspired by `ConfigLayerSource`):
```rust
pub struct Sourced<T> {
pub value: T,
pub source: RequirementSource,
}
```
Load managed requirements from MDM key `requirements_toml_base64`.
Tested on my Mac (using `defaults` to set the preference, though this
would be set by MDM in production):
```
➜ codex git:(gt/mdm-requirements) defaults read com.openai.codex requirements_toml_base64 | base64 -d
allowed_approval_policies = ["on-request"]
➜ codex git:(gt/mdm-requirements) just c --yolo
cargo run --bin codex -- "$@"
Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.26s
Running `target/debug/codex --yolo`
Error loading configuration: value `Never` is not in the allowed set [OnRequest]
error: Recipe `codex` failed on line 11 with exit code 1
➜ codex git:(gt/mdm-requirements) defaults delete com.openai.codex requirements_toml_base64
➜ codex git:(gt/mdm-requirements) just c --yolo
cargo run --bin codex -- "$@"
Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.24s
Running `target/debug/codex --yolo`
╭──────────────────────────────────────────────────────────╮
│ >_ OpenAI Codex (v0.0.0) │
│ │
│ model: codex-auto-balanced medium /model to change │
│ directory: ~/code/codex/codex-rs │
╰──────────────────────────────────────────────────────────╯
Tip: Start a fresh idea with /new; the previous session stays in history.
```
## Summary
- Factor `load_config_as_toml` into `core::config_loader` so config
loading is reusable across callers.
- Layer `~/.codex/config.toml`, optional `~/.codex/managed_config.toml`,
and macOS managed preferences (base64) with recursive table merging and
scoped threads per source.
## Config Flow
```
Managed prefs (macOS profile: com.openai.codex/config_toml_base64)
▲
│
~/.codex/managed_config.toml │ (optional file-based override)
▲
│
~/.codex/config.toml (user-defined settings)
```
- The loader searches under the resolved `CODEX_HOME` directory
(defaults to `~/.codex`).
- Managed configs let administrators ship fleet-wide overrides via
device profiles which is useful for enforcing certain settings like
sandbox or approval defaults.
- For nested hash tables: overlays merge recursively. Child tables are
merged key-by-key, while scalar or array values replace the prior layer
entirely. This lets admins add or tweak individual fields without
clobbering unrelated user settings.
Michael Bolin