fix(core): use catalog small model for session titles

packages/core/src/catalog.ts

@@ -1,7 +1,7 @@
 export * as Catalog from "./catalog"
 
 import { makeLocationNode } from "./effect/app-node"
-import { Array, Context, Effect, Layer, Option, Order, pipe } from "effect"
+import { Array, Context, Effect, Layer, Order, pipe } from "effect"
 import { Catalog } from "@opencode-ai/schema/catalog"
 import { ModelV2 } from "./model"
 import { ProviderV2 } from "./provider"
@@ -21,6 +21,7 @@ export const Event = Catalog.Event
 type Data = {
   providers: Map<ProviderV2.ID, ProviderRecord>
   defaultModel?: DefaultModel
+  smallModels: Map<ProviderV2.ID, ModelV2.ID>
 }
 
 export type Draft = {
@@ -38,6 +39,11 @@ export type Draft = {
       get: () => DefaultModel | undefined
       set: (providerID: ProviderV2.ID, modelID: ModelV2.ID) => void
     }
+    small: {
+      get: (providerID: ProviderV2.ID) => ModelV2.ID | undefined
+      set: (providerID: ProviderV2.ID, modelID: ModelV2.ID) => void
+      remove: (providerID: ProviderV2.ID) => void
+    }
   }
 }
 
@@ -83,7 +89,7 @@ const layer = Layer.effect(
 
     const state = State.create<Data, Draft>({
       name: "catalog",
-      initial: () => ({ providers: new Map() }),
+      initial: () => ({ providers: new Map(), smallModels: new Map() }),
       draft: (draft) => {
         const result: Draft = {
           provider: {
@@ -131,6 +137,15 @@ const layer = Layer.effect(
                 draft.defaultModel = { providerID, modelID }
               },
             },
+            small: {
+              get: (providerID) => draft.smallModels.get(providerID),
+              set: (providerID, modelID) => {
+                draft.smallModels.set(providerID, modelID)
+              },
+              remove: (providerID) => {
+                draft.smallModels.delete(providerID)
+              },
+            },
           },
         }
         return result
@@ -217,48 +232,50 @@ const layer = Layer.effect(
             return
           }
 
-          if (providerID === ProviderV2.ID.opencode) {
-            const gpt5Nano = record.models.get(ModelV2.ID.make("gpt-5-nano"))
-            if (gpt5Nano?.enabled && gpt5Nano.status === "active") return projectModel(gpt5Nano, provider)
+          // Plugin transforms may pin a small model (for example picker-disabled utility models).
+          const configured = state.get().smallModels.get(providerID)
+          if (configured) {
+            const model = record.models.get(configured)
+            if (model?.status === "active") return projectModel(model, provider)
           }
 
-          const candidates = pipe(
+          const priority = providerID.startsWith("opencode")
+            ? ["gpt-nano"]
+            : providerID.startsWith("github-copilot")
+              ? ["gpt-mini", ...SMALL_MODEL_FAMILY_PRIORITY]
+              : SMALL_MODEL_FAMILY_PRIORITY
+
+          const models = pipe(
             Array.fromIterable(record.models.values()),
-            Array.filter(
-              (model) =>
-                model.providerID === providerID &&
-                model.enabled &&
-                model.status === "active" &&
-                model.capabilities.input.some((item) => item.startsWith("text")) &&
-                model.capabilities.output.some((item) => item.startsWith("text")),
-            ),
-            Array.map((model) => ({
-              model,
-              cost: model.cost[0] ? model.cost[0].input + model.cost[0].output : 999,
-              age: (Date.now() - model.time.released) / (1000 * 60 * 60 * 24 * 30),
-              small: SMALL_MODEL_RE.test(`${model.id} ${model.family ?? ""} ${model.name}`.toLowerCase()),
-            })),
-            Array.filter((item) => item.cost > 0 && item.age <= 18),
+            Array.filter((model) => model.enabled && model.status === "active"),
+            Array.sortWith((model) => model.id, Order.flip(Order.String)),
+            Array.sortWith((model) => model.time.released, Order.flip(Order.Number)),
           )
 
-          const pick = (items: typeof candidates) => {
-            const maxCost = Math.max(...items.map((item) => item.cost), 0.01)
-            const maxAge = Math.max(...items.map((item) => item.age), 0.01)
-            return pipe(
-              items,
-              Array.sortWith((item) => (item.cost / maxCost) * 0.8 + (item.age / maxAge) * 0.2, Order.Number),
-              Array.map((item) => projectModel(item.model, provider)),
-              Array.head,
-            )
-          }
+          for (const family of priority) {
+            const candidates = models.filter((model) => model.family === family)
+            if (providerID === ProviderV2.ID.amazonBedrock) {
+              const crossRegionPrefixes = ["global.", "us.", "eu."]
+              const globalMatch = candidates.find((model) => model.id.startsWith("global."))
+              if (globalMatch) return projectModel(globalMatch, provider)
 
-          return Option.getOrUndefined(
-            pipe(
-              candidates,
-              Array.filter((item) => item.small),
-              (items) => (items.length > 0 ? pick(items) : pick(candidates)),
-            ),
-          )
+              const region = typeof provider.settings?.region === "string" ? provider.settings.region : undefined
+              if (region) {
+                const regionPrefix = region.split("-")[0]
+                if (regionPrefix === "us" || regionPrefix === "eu") {
+                  const regionalMatch = candidates.find((model) => model.id.startsWith(`${regionPrefix}.`))
+                  if (regionalMatch) return projectModel(regionalMatch, provider)
+                }
+              }
+
+              const unprefixed = candidates.find(
+                (model) => !crossRegionPrefixes.some((prefix) => model.id.startsWith(prefix)),
+              )
+              if (unprefixed) return projectModel(unprefixed, provider)
+              continue
+            }
+            if (candidates[0]) return projectModel(candidates[0], provider)
+          }
         }),
       },
     }
@@ -267,6 +284,6 @@ const layer = Layer.effect(
   }),
 )
 
-const SMALL_MODEL_RE = /\b(nano|flash|lite|mini|haiku|small|fast)\b/
+const SMALL_MODEL_FAMILY_PRIORITY = ["gemini-flash", "gpt-nano", "claude-haiku"]
 
 export const node = makeLocationNode({ service: Service, layer, deps: [EventV2.node, Integration.node] })

packages/core/src/plugin/host.ts

@@ -148,6 +148,12 @@ export const make = Effect.fn("PluginHost.make")(function* (plugin: PluginV2.Int
                 set: (providerID, modelID) =>
                   draft.model.default.set(ProviderV2.ID.make(providerID), ModelV2.ID.make(modelID)),
               },
+              small: {
+                get: (providerID) => draft.model.small.get(ProviderV2.ID.make(providerID)),
+                set: (providerID, modelID) =>
+                  draft.model.small.set(ProviderV2.ID.make(providerID), ModelV2.ID.make(modelID)),
+                remove: (providerID) => draft.model.small.remove(ProviderV2.ID.make(providerID)),
+              },
             },
           })
         }),

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

@@ -119,6 +119,8 @@ function shouldUseResponses(modelID: string) {
   return Number(match[1]) >= 5 && !modelID.startsWith("gpt-5-mini")
 }
 
+const UTILITY_MODELS = ["gpt-5.4-nano", "gpt-4.1", "gpt-4o", "gpt-4o-mini"]
+
 export const GithubCopilotPlugin = define({
   id: "opencode.provider.github-copilot",
   effect: Effect.fn(function* (ctx) {
@@ -192,6 +194,13 @@ export const GithubCopilotPlugin = define({
           model.enabled = false
         })
       }
+      // GitHub exposes utility models for title generation without including them in the picker.
+      const utility = UTILITY_MODELS.map((id) => ModelV2.ID.make(id)).find((id) => {
+        const model = evt.model.get(item.provider.id, id)
+        return model?.status === "active"
+      })
+      if (utility) evt.model.small.set(item.provider.id, utility)
+      else evt.model.small.remove(item.provider.id)
     })
     const refresh = () => loading.withPermit(load().pipe(Effect.andThen(ctx.catalog.reload())))
     yield* events.subscribe(Integration.Event.ConnectionUpdated).pipe(

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)
-        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,
-        }
+        return yield* resolveCatalogModel(session, selected, session.model?.variant)
       }),
     })
   }),

packages/core/src/session/title.ts

@@ -3,6 +3,7 @@ export * as SessionTitle from "./title"
 import { LLM, LLMClient, LLMError, LLMEvent, Message, type LLMRequest } from "@opencode-ai/llm"
 import { Context, DateTime, Effect, Layer, Stream } from "effect"
 import { AgentV2 } from "../agent"
+import { Catalog } from "../catalog"
 import { Database } from "../database/database"
 import { EventV2 } from "../event"
 import { makeLocationNode } from "../effect/app-node"
@@ -21,6 +22,7 @@ type Dependencies = {
   }
   readonly agents: AgentV2.Interface
   readonly models: SessionRunnerModel.Interface
+  readonly catalog: Catalog.Interface
 }
 
 export interface Interface {
@@ -45,7 +47,14 @@ const make = (dependencies: Dependencies) => {
     const resolved = yield* (
       agent.model
         ? dependencies.models.resolve({ ...session, model: agent.model })
-        : dependencies.models.resolve(session)
+        : Effect.gen(function* () {
+            const providerID = session.model?.providerID ?? (yield* dependencies.catalog.model.default())?.providerID
+            const small = providerID ? yield* dependencies.catalog.model.small(providerID) : undefined
+            if (!small) return yield* dependencies.models.resolve(session)
+            return yield* dependencies.models
+              .resolveCatalogModel(session, small)
+              .pipe(Effect.catch(() => dependencies.models.resolve(session)))
+          })
     ).pipe(Effect.catch(() => Effect.succeed(undefined)))
     if (!resolved) return
     const chunks: string[] = []
@@ -90,8 +99,9 @@ export const layer = Layer.effect(
     const llm = yield* LLMClient.Service
     const agents = yield* AgentV2.Service
     const models = yield* SessionRunnerModel.Service
+    const catalog = yield* Catalog.Service
     const database = yield* Database.Service
-    const title = make({ events, llm, agents, models })
+    const title = make({ events, llm, agents, models, catalog })
     return Service.of({
       generateForFirstPrompt: (session) => title.generateForFirstPrompt(database.db, session),
     })
@@ -101,5 +111,5 @@ export const layer = Layer.effect(
 export const node = makeLocationNode({
   service: Service,
   layer,
-  deps: [EventV2.node, llmClient, AgentV2.node, SessionRunnerModel.node, Database.node],
+  deps: [EventV2.node, llmClient, AgentV2.node, SessionRunnerModel.node, Catalog.node, Database.node],
 })