fix(codex): restore gateway models after reconnect

Use the gateway model catalog when the native app-server returns stale model metadata.

Generated-By: PostHog Code
Task-Id: dfa9be76-95bf-4166-8adc-529483e3d525

Author: richardsolomou

packages/agent/src/adapters/acp-connection.ts

@@ -230,6 +230,7 @@ function createCodexConnection(config: AcpConnectionConfig): AcpConnection {
       },
       model: codexOptions.model,
       reasoningEffort: codexOptions.reasoningEffort,
+      allowedModelIds: config.allowedModelIds,
       processCallbacks: config.processCallbacks,
       onStructuredOutput: config.onStructuredOutput,
       logger: config.logger?.child("CodexAppServerAgent"),

packages/agent/src/adapters/codex-app-server/codex-app-server-agent.ts

@@ -203,6 +203,7 @@ export interface CodexAppServerAgentOptions {
   processOptions: CodexAppServerProcessOptions;
   model?: string;
   reasoningEffort?: string;
+  allowedModelIds?: ReadonlySet<string>;
   processCallbacks?: ProcessSpawnedCallback;
   logger?: Logger;
   onStructuredOutput?: (output: Record<string, unknown>) => Promise<void>;
@@ -265,6 +266,7 @@ export class CodexAppServerAgent extends BaseAcpAgent {
     this.config = new SessionConfigState(
       options.model ?? DEFAULT_CODEX_MODEL,
       options.reasoningEffort,
+      options.allowedModelIds,
     );
     this.onStructuredOutput = options.onStructuredOutput;
     this.developerInstructions = options.processOptions.developerInstructions;

packages/agent/src/adapters/codex-app-server/session-config.test.ts

@@ -134,6 +134,26 @@ describe("SessionConfigState", () => {
       config.options.find((option) => option.category === "mode")?.currentValue,
     ).toBe("full-access");
   });
+
+  it("uses gateway models when the app-server model list is stale", () => {
+    const config = new SessionConfigState(
+      "gpt-5.5",
+      undefined,
+      new Set(["gpt-5.5", "gpt-5.6-sol"]),
+    );
+
+    config.loadModels([
+      { id: "gpt-5.5", model: "gpt-5.5", displayName: "GPT-5.5" },
+    ]);
+
+    const modelOption = config.options.find(
+      (option) => option.category === "model",
+    );
+    expect(modelOption?.type === "select" ? modelOption.options : []).toEqual([
+      { name: "GPT-5.5", value: "gpt-5.5" },
+      { name: "gpt-5.6-sol", value: "gpt-5.6-sol" },
+    ]);
+  });
 });
 
 describe("buildConfigOptions", () => {

packages/agent/src/adapters/codex-app-server/session-config.ts

@@ -229,10 +229,16 @@ export class SessionConfigState {
   private models: Array<{ id: string; name: string }> = [];
   private efforts: string[] = [];
   private _options: SessionConfigOption[] = [];
+  private readonly allowedModelIds?: ReadonlySet<string>;
 
-  constructor(model: string, effort?: string) {
+  constructor(
+    model: string,
+    effort?: string,
+    allowedModelIds?: ReadonlySet<string>,
+  ) {
     this._model = model;
     this._effort = effort;
+    this.allowedModelIds = allowedModelIds?.size ? allowedModelIds : undefined;
     this.rebuild();
   }
 
@@ -262,8 +268,12 @@ export class SessionConfigState {
   ): { modeChanged: boolean } {
     let modeChanged = false;
     if (typeof value === "string") {
-      if (configId === "model") this._model = value;
-      else if (configId === "effort") this._effort = value;
+      if (
+        configId === "model" &&
+        (!this.allowedModelIds || this.allowedModelIds.has(value))
+      ) {
+        this._model = value;
+      } else if (configId === "effort") this._effort = value;
       else if (configId === "mode") {
         this._mode = resolveCodexMode(value);
         modeChanged = true;
@@ -279,13 +289,24 @@ export class SessionConfigState {
    * populate efforts, so fall back to the shared codex model→effort map.
    */
   loadModels(rawModels: RawModel[]): void {
-    this.models = rawModels
+    const liveModels = rawModels
       .filter((m) => !m?.hidden)
       .filter((m) => isOpenAIModel(m as unknown as GatewayModel))
       .map((m) => ({
         id: (m.id ?? m.model) as string,
         name: (m.displayName ?? m.id ?? m.model) as string,
       }));
+    if (this.allowedModelIds) {
+      const liveModelsById = new Map(
+        liveModels.map((model) => [model.id, model]),
+      );
+      this.models = [...this.allowedModelIds].map(
+        (modelId) =>
+          liveModelsById.get(modelId) ?? { id: modelId, name: modelId },
+      );
+    } else {
+      this.models = liveModels;
+    }
     const current = rawModels.find(
       (m) => m.id === this._model || m.model === this._model,
     );