fix(core): resolve hidden title models internally

packages/core/src/session/runner/model.ts

@@ -88,12 +88,23 @@ export interface Resolved {
 
 export interface Interface {
   readonly resolve: (session: SessionSchema.Info) => Effect.Effect<Resolved, Error>
+  readonly resolveCatalogModel: (
+    session: SessionSchema.Info,
+    model: ModelV2.Info,
+  ) => Effect.Effect<Resolved, Error>
 }
 
 export class Service extends Context.Service<Service, Interface>()("@opencode/v2/SessionRunnerModel") {}
 
 /** Test or embedding seam for supplying a model resolver directly. */
-export const layerWith = (resolve: Interface["resolve"]) => Layer.succeed(Service, Service.of({ resolve }))
+export const layerWith = (
+  resolve: Interface["resolve"],
+  resolveCatalogModel: Interface["resolveCatalogModel"] = (session, model) =>
+    resolve({
+      ...session,
+      model: ModelV2.Ref.make({ id: model.id, providerID: model.providerID }),
+    }),
+) => Layer.succeed(Service, Service.of({ resolve, resolveCatalogModel }))
 
 /** Builds a Resolved whose catalog identity mirrors the route model. Test or embedding seam. */
 export const resolved = (model: Model, variant?: ModelV2.VariantID, cost: ModelV2.Info["cost"] = []): Resolved => ({
@@ -307,7 +318,43 @@ const layer = Layer.effect(
     const integrations = yield* Integration.Service
     const npm = yield* Npm.Service
     const aisdk = yield* AISDK.Service
+    const resolveCatalogModel = Effect.fn("SessionRunnerModel.resolveCatalogModel")(function* (
+      session: SessionSchema.Info,
+      selected: ModelV2.Info,
+      variant?: ModelV2.VariantID,
+    ) {
+      const provider = yield* catalog.provider.get(selected.providerID)
+      const connection = yield* integrations.connection.active(
+        provider?.integrationID ?? Integration.ID.make(selected.providerID),
+      )
+      const model = yield* resolve(
+        {
+          ...session,
+          model: ModelV2.Ref.make({
+            id: selected.id,
+            providerID: selected.providerID,
+            ...(variant === undefined ? {} : { variant }),
+          }),
+        },
+        selected,
+        connection ? yield* integrations.connection.resolve(connection) : undefined,
+        {
+          loadPackage: (specifier) => ProviderV2.loadPackage(specifier, npm),
+          loadAISDK: (model) => aisdk.model(model),
+        },
+      )
+      return {
+        model,
+        ref: ModelV2.Ref.make({
+          id: selected.id,
+          providerID: selected.providerID,
+          ...(variant === undefined ? {} : { variant }),
+        }),
+        cost: selected.cost,
+      }
+    })
     return Service.of({
+      resolveCatalogModel,
       resolve: Effect.fn("SessionRunnerModel.resolve")(function* (session) {
         // Location plugins populate and filter the catalog asynchronously during layer startup.
         const defaultModel = session.model ? undefined : yield* catalog.model.default()
@@ -324,28 +371,7 @@ const layer = Layer.effect(
             modelID: session.model.id,
           })
         if (!selected) return yield* new ModelNotSelectedError({ sessionID: session.id })
-        const provider = yield* catalog.provider.get(selected.providerID)
+        return yield* resolveCatalogModel(session, selected, session.model?.variant)
-        const connection = yield* integrations.connection.active(
-          provider?.integrationID ?? Integration.ID.make(selected.providerID),
-        )
-        const model = yield* resolve(
-          session,
-          selected,
-          connection ? yield* integrations.connection.resolve(connection) : undefined,
-          {
-            loadPackage: (specifier) => ProviderV2.loadPackage(specifier, npm),
-            loadAISDK: (model) => aisdk.model(model),
-          },
-        )
-        return {
-          model,
-          ref: ModelV2.Ref.make({
-            id: selected.id,
-            providerID: selected.providerID,
-            ...(session.model?.variant === undefined ? {} : { variant: session.model.variant }),
-          }),
-          cost: selected.cost,
-        }
       }),
     })
   }),

packages/core/src/session/title.ts

@@ -8,7 +8,6 @@ import { Database } from "../database/database"
 import { EventV2 } from "../event"
 import { makeLocationNode } from "../effect/app-node"
 import { llmClient } from "../effect/app-node-platform"
-import { ModelV2 } from "../model"
 import { SessionEvent } from "./event"
 import { SessionHistory } from "./history"
 import { SessionRunnerModel } from "./runner/model"
@@ -53,10 +52,7 @@ const make = (dependencies: Dependencies) => {
             const small = providerID ? yield* dependencies.catalog.model.small(providerID) : undefined
             if (!small) return yield* dependencies.models.resolve(session)
             return yield* dependencies.models
-              .resolve({
+              .resolveCatalogModel(session, small)
-                ...session,
-                model: ModelV2.Ref.make({ id: small.id, providerID: small.providerID }),
-              })
               .pipe(Effect.catch(() => dependencies.models.resolve(session)))
           })
     ).pipe(Effect.catch(() => Effect.succeed(undefined)))

packages/core/test/catalog.test.ts

@@ -411,6 +411,9 @@ describe("CatalogV2", () => {
       })
 
       expect((yield* catalog.model.small(providerID))?.id).toBe(ModelV2.ID.make("gpt-5.4-nano"))
+      expect((yield* catalog.model.available()).some((model) => model.id === ModelV2.ID.make("gpt-5.4-nano"))).toBe(
+        false,
+      )
     }),
   )
 

packages/core/test/plugin/provider-github-copilot.test.ts

@@ -289,6 +289,28 @@ describe("GithubCopilotPlugin", () => {
     }),
   )
 
+  it.effect("pins picker-hidden utility models for internal small-model work", () =>
+    Effect.gen(function* () {
+      const catalog = yield* Catalog.Service
+      const providerID = ProviderV2.ID.githubCopilot
+      yield* catalog.transform((catalog) => {
+        catalog.provider.update(providerID, () => {})
+        catalog.model.update(providerID, ModelV2.ID.make("gpt-4.1"), (model) => {
+          model.enabled = false
+        })
+        catalog.model.update(providerID, ModelV2.ID.make("gpt-5.4-nano"), (model) => {
+          model.enabled = false
+        })
+      })
+      yield* addPlugin()
+
+      expect((yield* catalog.model.small(providerID))?.id).toBe(ModelV2.ID.make("gpt-5.4-nano"))
+      expect((yield* catalog.model.available()).some((model) => model.id === ModelV2.ID.make("gpt-5.4-nano"))).toBe(
+        false,
+      )
+    }),
+  )
+
   it.effect("does not disable gpt-5-chat-latest for non-Copilot providers", () =>
     Effect.gen(function* () {
       const catalog = yield* Catalog.Service

packages/core/test/session-title.test.ts

@@ -55,6 +55,21 @@ const models = Layer.mock(SessionRunnerModel.Service)({
       : model
     return Effect.succeed(SessionRunnerModel.resolved(selected))
   },
+  resolveCatalogModel: (session, selected) => {
+    resolvedModels.push({ id: selected.id, provider: selected.providerID })
+    if (failSmallResolve && selected.id === ModelV2.ID.make("mini")) {
+      return Effect.fail(new Error("small unavailable") as never)
+    }
+    return Effect.succeed(
+      SessionRunnerModel.resolved(
+        Model.make({
+          id: selected.id,
+          provider: selected.providerID,
+          route: OpenAIChat.route.with({ limits: { context: 10_000, output: 1_000 } }),
+        }),
+      ),
+    )
+  },
 })
 const it = testEffect(
   AppNodeBuilder.build(
@@ -152,9 +167,11 @@ const seedSmallModel = () =>
         model.time.released = Date.now()
       })
       catalog.model.update(providerID, ModelV2.ID.make("mini"), (model) => {
+        model.enabled = false
         model.family = ModelV2.Family.make("gpt-nano")
         model.time.released = Date.now()
       })
+      catalog.model.small.set(providerID, ModelV2.ID.make("mini"))
     })
   })