Bring upgrade back

Author: shijie-oai

codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.schemas.json

@@ -10266,6 +10266,12 @@
             "default": false,
             "type": "boolean"
           },
+          "upgrade": {
+            "type": [
+              "string",
+              "null"
+            ]
+          },
           "upgradeInfo": {
             "anyOf": [
               {

codex-rs/app-server-protocol/schema/json/v2/ModelListResponse.json

@@ -63,6 +63,12 @@
           "default": false,
           "type": "boolean"
         },
+        "upgrade": {
+          "type": [
+            "string",
+            "null"
+          ]
+        },
         "upgradeInfo": {
           "anyOf": [
             {

codex-rs/app-server-protocol/schema/typescript/v2/Model.ts

@@ -6,4 +6,4 @@ import type { ReasoningEffort } from "../ReasoningEffort";
 import type { ModelUpgradeInfo } from "./ModelUpgradeInfo";
 import type { ReasoningEffortOption } from "./ReasoningEffortOption";
 
-export type Model = { id: string, model: string, upgradeInfo: ModelUpgradeInfo | null, displayName: string, description: string, hidden: boolean, supportedReasoningEfforts: Array<ReasoningEffortOption>, defaultReasoningEffort: ReasoningEffort, inputModalities: Array<InputModality>, supportsPersonality: boolean, isDefault: boolean, };
+export type Model = { id: string, model: string, upgrade: string | null, upgradeInfo: ModelUpgradeInfo | null, displayName: string, description: string, hidden: boolean, supportedReasoningEfforts: Array<ReasoningEffortOption>, defaultReasoningEffort: ReasoningEffort, inputModalities: Array<InputModality>, supportsPersonality: boolean, isDefault: boolean, };

codex-rs/app-server-protocol/src/protocol/v2.rs

@@ -1395,6 +1395,7 @@ pub struct ModelListParams {
 pub struct Model {
     pub id: String,
     pub model: String,
+    pub upgrade: Option<String>,
     pub upgrade_info: Option<ModelUpgradeInfo>,
     pub display_name: String,
     pub description: String,

codex-rs/app-server/README.md

@@ -142,7 +142,7 @@ Example with notification opt-out:
 - `thread/realtime/stop` — stop the active realtime session for the thread (experimental); returns `{}`.
 - `review/start` — kick off Codex’s automated reviewer for a thread; responds like `turn/start` and emits `item/started`/`item/completed` notifications with `enteredReviewMode` and `exitedReviewMode` items, plus a final assistant `agentMessage` containing the review.
 - `command/exec` — run a single command under the server sandbox without starting a thread/turn (handy for utilities and validation).
-- `model/list` — list available models (set `includeHidden: true` to include entries with `hidden: true`), with reasoning effort options and optional `upgradeInfo` metadata (`model`, `upgradeCopy`, `modelLink`, `migrationMarkdown`). This replaces the previous top-level `upgrade` field.
+- `model/list` — list available models (set `includeHidden: true` to include entries with `hidden: true`), with reasoning effort options, optional legacy `upgrade` model ids, and optional `upgradeInfo` metadata (`model`, `upgradeCopy`, `modelLink`, `migrationMarkdown`).
 - `experimentalFeature/list` — list feature flags with stage metadata (`beta`, `underDevelopment`, `stable`, etc.), enabled/default-enabled state, and cursor pagination. For non-beta flags, `displayName`/`description`/`announcement` are `null`.
 - `collaborationMode/list` — list available collaboration mode presets (experimental, no pagination). This response omits built-in developer instructions; clients should either pass `settings.developer_instructions: null` when setting a mode to use Codex's built-in instructions, or provide their own instructions explicitly.
 - `skills/list` — list skills for one or more `cwd` values (optional `forceReload`).

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

@@ -25,6 +25,7 @@ fn model_from_preset(preset: ModelPreset) -> Model {
     Model {
         id: preset.id.to_string(),
         model: preset.model.to_string(),
+        upgrade: preset.upgrade.as_ref().map(|upgrade| upgrade.id.clone()),
         upgrade_info: preset.upgrade.as_ref().map(|upgrade| ModelUpgradeInfo {
             model: upgrade.id.clone(),
             upgrade_copy: upgrade.upgrade_copy.clone(),

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

@@ -24,6 +24,7 @@ fn model_from_preset(preset: &ModelPreset) -> Model {
     Model {
         id: preset.id.clone(),
         model: preset.model.clone(),
+        upgrade: preset.upgrade.as_ref().map(|upgrade| upgrade.id.clone()),
         upgrade_info: preset.upgrade.as_ref().map(|upgrade| ModelUpgradeInfo {
             model: upgrade.id.clone(),
             upgrade_copy: upgrade.upgrade_copy.clone(),
@@ -166,6 +167,7 @@ async fn list_models_returns_upgrade_info_metadata() -> Result<()> {
         .as_ref()
         .expect("expected upgrade info to be populated");
 
+    assert_eq!(item.upgrade.as_ref(), Some(&upgrade_info.model));
     assert!(!upgrade_info.model.is_empty());
     assert!(
         upgrade_info.upgrade_copy.is_some()

codex-rs/docs/codex_mcp_interface.md

@@ -104,15 +104,14 @@ Each response yields:
   - `inputModalities` – accepted input types for the model
   - `supportsPersonality` – whether the model supports personality-specific instructions
   - `isDefault` – whether the model is recommended for most users
+  - `upgrade` – optional recommended upgrade model id
   - `upgradeInfo` – optional upgrade metadata object with:
     - `model` – recommended upgrade model id
     - `upgradeCopy` – optional display copy for the upgrade recommendation
     - `modelLink` – optional link for the upgrade recommendation
     - `migrationMarkdown` – optional markdown shown when presenting the upgrade
 - `nextCursor` – pass into the next request to continue paging (optional)
 
-Breaking change: `model.upgrade` has been removed. Clients should migrate to `model.upgradeInfo?.model`.
-
 ## Collaboration modes (experimental)
 
 Fetch the built-in collaboration mode presets with `collaborationMode/list`. This endpoint does not accept pagination and returns the full list in one response: