1- Add model service tiers metadata (#20969)

## Why

The model list needs to carry display-ready service tier metadata so
clients can render tier choices with stable IDs, names, and
descriptions. A raw speed-tier string list is not enough for richer UI
copy or future tier labels.

## What changed

- Added `ModelServiceTier` to shared model metadata with string `id`,
`name`, and `description` fields.
- Added `service_tiers` to `ModelInfo` and `ModelPreset`, preserving
empty defaults for older cached model payloads.
- Exposed `serviceTiers` on app-server v2 `Model` responses and threaded
it through TUI app-server model conversion.
- Marked legacy `additional_speed_tiers` / `additionalSpeedTiers`
metadata as deprecated in source and generated schema output.
- Regenerated app-server protocol JSON schema and TypeScript fixtures,
including `ModelServiceTier.ts`.

## Verification

- Ran `just write-app-server-schema`.
- Did not run local tests per repo instruction; relying on PR CI.

---------

Co-authored-by: Codex <noreply@openai.com>

codex-rs/app-server/src/models.rs

@@ -1,6 +1,7 @@
 use std::sync::Arc;
 
 use codex_app_server_protocol::Model;
+use codex_app_server_protocol::ModelServiceTier;
 use codex_app_server_protocol::ModelUpgradeInfo;
 use codex_app_server_protocol::ReasoningEffortOption;
 use codex_core::ThreadManager;
@@ -43,6 +44,15 @@ fn model_from_preset(preset: ModelPreset) -> Model {
         input_modalities: preset.input_modalities,
         supports_personality: preset.supports_personality,
         additional_speed_tiers: preset.additional_speed_tiers,
+        service_tiers: preset
+            .service_tiers
+            .into_iter()
+            .map(|service_tier| ModelServiceTier {
+                id: service_tier.id,
+                name: service_tier.name,
+                description: service_tier.description,
+            })
+            .collect(),
         is_default: preset.is_default,
     }
 }

codex-rs/app-server/tests/common/models_cache.rs

@@ -29,6 +29,7 @@ fn preset_to_info(preset: &ModelPreset, priority: i32) -> ModelInfo {
         supported_in_api: preset.supported_in_api,
         priority,
         additional_speed_tiers: preset.additional_speed_tiers.clone(),
+        service_tiers: preset.service_tiers.clone(),
         upgrade: preset.upgrade.as_ref().map(Into::into),
         base_instructions: "base instructions".to_string(),
         model_messages: None,

codex-rs/app-server/tests/suite/v2/model_list.rs

@@ -9,6 +9,7 @@ use codex_app_server_protocol::JSONRPCResponse;
 use codex_app_server_protocol::Model;
 use codex_app_server_protocol::ModelListParams;
 use codex_app_server_protocol::ModelListResponse;
+use codex_app_server_protocol::ModelServiceTier;
 use codex_app_server_protocol::ModelUpgradeInfo;
 use codex_app_server_protocol::ReasoningEffortOption;
 use codex_app_server_protocol::RequestId;
@@ -51,6 +52,15 @@ fn model_from_preset(preset: &ModelPreset) -> Model {
         // todo(sayan): fix, maybe make roundtrip use ModelInfo only
         supports_personality: false,
         additional_speed_tiers: preset.additional_speed_tiers.clone(),
+        service_tiers: preset
+            .service_tiers
+            .iter()
+            .map(|service_tier| ModelServiceTier {
+                id: service_tier.id.clone(),
+                name: service_tier.name.clone(),
+                description: service_tier.description.clone(),
+            })
+            .collect(),
         is_default: preset.is_default,
     }
 }