fix: centralize provider thinking profiles

extensions/codex/provider.test.ts

@@ -160,7 +160,11 @@ describe("codex provider", () => {
       reasoning: true,
       compat: { supportsReasoningEffort: true },
     });
-    expect(provider.supportsXHighThinking?.({ provider: "codex", modelId: "o4-mini" })).toBe(true);
+    expect(
+      provider
+        .resolveThinkingProfile?.({ provider: "codex", modelId: "o4-mini" } as never)
+        ?.levels.some((level) => level.id === "xhigh"),
+    ).toBe(true);
   });
 
   it("declares synthetic auth because the harness owns Codex credentials", () => {

extensions/codex/provider.ts

@@ -89,7 +89,16 @@ export function buildCodexProvider(options: BuildCodexProviderOptions = {}): Pro
       source: "codex-app-server",
       mode: "token",
     }),
-    supportsXHighThinking: ({ modelId }) => isKnownXHighCodexModel(modelId),
+    resolveThinkingProfile: ({ modelId }) => ({
+      levels: [
+        { id: "off" },
+        { id: "minimal" },
+        { id: "low" },
+        { id: "medium" },
+        { id: "high" },
+        ...(isKnownXHighCodexModel(modelId) ? [{ id: "xhigh" as const }] : []),
+      ],
+    }),
     isModernModelRef: ({ modelId }) => isModernCodexModel(modelId),
   };
 }