## Why Model catalog responses can now advertise a nullable `default_service_tier` for each model. Codex needs to preserve three distinct states all the way from config/app-server inputs to inference: - no explicit service tier, so the client may apply the current model catalog default when FastMode is enabled - explicit `default`, meaning the user intentionally wants standard routing - explicit catalog tier ids such as `priority`, `flex`, or future tiers Keeping those states distinct prevents the UI from showing one tier while core sends another, especially after model switches or app-server `thread/start` / `turn/start` updates. ## What Changed - Plumbed `default_service_tier` through model catalog protocol types, app-server model responses, generated schemas, model cache fixtures, and provider/model-manager conversions. - Added the request-only `default` service tier sentinel and normalized legacy config spelling so `fast` in `config.toml` still materializes as the runtime/request id `priority`. - Moved catalog default resolution to the TUI/client side, including recomputing the effective service tier when model/FastMode-dependent surfaces change. - Updated app-server thread lifecycle config construction so `serviceTier: null` preserves explicit standard-routing intent by mapping to `default` instead of internal `None`. - Kept core responsible for validating explicit tiers against the current model and stripping `default` before `/v1/responses`, without applying catalog defaults itself. ## Validation - `CARGO_INCREMENTAL=0 cargo build -p codex-cli` - `CARGO_INCREMENTAL=0 cargo test -p codex-app-server model_list` - `cargo test -p codex-tui service_tier` - `cargo test -p codex-protocol service_tier_for_request` - `cargo test -p codex-core get_service_tier` - `RUST_MIN_STACK=8388608 CARGO_INCREMENTAL=0 cargo test -p codex-core service_tier`
codex-tools
codex-tools is the shared support crate for building, adapting, and executing
model-visible tools outside codex-core.
Today this crate owns the host-facing tool models and helpers that no longer
need to live in core/src/tools/spec.rs or core/src/client_common.rs:
- aggregate host models such as
ToolSpec,ConfiguredToolSpec,LoadableToolSpec,ResponsesApiNamespace, andResponsesApiNamespaceTool - host discovery models used while assembling tool sets, including discoverable-tool models and request-plugin-install helpers
- host adapters such as schema sanitization, MCP/dynamic conversion, code-mode augmentation, and image-detail normalization
- shared executable-tool contracts such as
ToolExecutor,ToolCall, andToolOutput
That extraction is the first step in a longer migration. The goal is not to
move all of core/src/tools into this crate in one shot. Instead, the plan is
to peel off reusable pieces in reviewable increments while keeping
compatibility-sensitive orchestration in codex-core until the surrounding
boundaries are ready.
Vision
Over time, this crate should hold host-side tool machinery that is shared by multiple consumers, for example:
- host-visible aggregate tool models
- tool-set planning and discovery helpers
- MCP and dynamic-tool adaptation into Responses API shapes
- code-mode compatibility shims that do not depend on
codex-core - other narrowly scoped host utilities that multiple crates need
The corresponding non-goals are just as important:
- do not move
codex-coreorchestration here prematurely - do not pull
Session/TurnContext/ approval flow / runtime execution logic into this crate unless those dependencies have first been split into stable shared interfaces - do not turn this crate into a grab-bag for unrelated helper code
Migration approach
The expected migration shape is:
- Keep extension-owned executable-tool authoring in
codex-extension-api. - Move host-side planning/adaptation helpers here when they no longer need to
stay coupled to
codex-core. - Leave compatibility-sensitive adapters in
codex-corewhile downstream call sites are updated. - Only extract higher-level host infrastructure after the crate boundaries are clear and independently testable.
Crate conventions
This crate should start with stricter structure than core/src/tools so it
stays easy to grow:
src/lib.rsshould remain exports-only.- Business logic should live in named module files such as
foo.rs. - Unit tests for
foo.rsshould live in a siblingfoo_tests.rs. - The implementation file should wire tests with:
#[cfg(test)]
#[path = "foo_tests.rs"]
mod tests;
If this crate starts accumulating code that needs runtime state from
codex-core, that is a sign to revisit the extraction boundary before adding
more here.