fix(core): expose models.dev modes as models (#34714)

packages/core/test/plugin/models-dev.test.ts

@@ -32,6 +32,103 @@ const layer = Layer.mergeAll(catalog.pipe(Layer.provide(connections)), integrati
 const it = testEffect(layer)
 
 describe("ModelsDevPlugin", () => {
+  it.effect("projects models.dev modes as separate models instead of variants", () =>
+    Effect.gen(function* () {
+      const integrations = yield* Integration.Service
+      const catalog = yield* Catalog.Service
+      const models = ModelsDev.Service.of({
+        get: () =>
+          Effect.succeed({
+            acme: {
+              id: "acme",
+              name: "Acme",
+              env: [],
+              npm: "@ai-sdk/openai-compatible",
+              api: "https://api.acme.test/v1",
+              models: {
+                "gpt-5.4": {
+                  id: "gpt-5.4",
+                  name: "GPT-5.4",
+                  family: "gpt",
+                  release_date: "2026-01-01",
+                  attachment: false,
+                  reasoning: true,
+                  temperature: true,
+                  tool_call: true,
+                  cost: {
+                    input: 2.5,
+                    output: 15,
+                    tiers: [
+                      {
+                        tier: { type: "context", size: 272_000 },
+                        input: 3,
+                        output: 18,
+                        cache_read: 0.25,
+                      },
+                    ],
+                    context_over_200k: { input: 5, output: 22.5, cache_read: 0.5 },
+                  },
+                  limit: { context: 1_050_000, input: 922_000, output: 128_000 },
+                  experimental: {
+                    modes: {
+                      fast: {
+                        cost: { input: 5, output: 30, cache_read: 0.5 },
+                        provider: {
+                          headers: { "x-mode": "fast" },
+                          body: { service_tier: "priority" },
+                        },
+                      },
+                    },
+                  },
+                },
+              },
+            },
+          } satisfies Record<string, ModelsDev.Provider>),
+        refresh: () => Effect.void,
+      })
+
+      yield* ModelsDevPlugin.effect(
+        host({
+          catalog: catalogHost(catalog),
+          integration: integrationHost(integrations),
+        }),
+      ).pipe(Effect.provideService(ModelsDev.Service, models))
+
+      const providerID = ProviderV2.ID.make("acme")
+      const base = yield* catalog.model.get(providerID, ModelV2.ID.make("gpt-5.4"))
+      const fast = yield* catalog.model.get(providerID, ModelV2.ID.make("gpt-5.4-fast"))
+
+      expect(base?.variants).toEqual([])
+      expect(base?.request.body).toEqual({})
+      expect(fast).toMatchObject({
+        id: "gpt-5.4-fast",
+        providerID: "acme",
+        name: "GPT-5.4 Fast",
+        api: { id: "gpt-5.4" },
+        request: {
+          headers: { "x-mode": "fast" },
+          body: { service_tier: "priority" },
+        },
+        variants: [],
+      })
+      expect(fast?.cost).toEqual([
+        { input: 5, output: 30, cache: { read: 0.5, write: 0 } },
+        {
+          tier: { type: "context", size: 272_000 },
+          input: 3,
+          output: 18,
+          cache: { read: 0.25, write: 0 },
+        },
+        {
+          tier: { type: "context", size: 200_000 },
+          input: 5,
+          output: 22.5,
+          cache: { read: 0.5, write: 0 },
+        },
+      ])
+    }),
+  )
+
   it.effect("registers key methods for providers with environment variables", () =>
     Effect.acquireUseRelease(
       Effect.sync(() => {