feat: dual model support for cost optimization

packages/opencode/src/config/config.ts

@@ -154,6 +154,10 @@ export namespace Config {
           "Model to use in the format of provider/model, eg anthropic/claude-2",
         )
         .optional(),
+      lightweight_model: z
+        .string()
+        .describe("Lightweight model to use for tasks like window title generation")
+        .optional(),
       provider: z
         .record(
           ModelsDev.Provider.partial().extend({
@@ -194,7 +198,7 @@ export namespace Config {
         )
         await fs.unlink(path.join(Global.Path.config, "config"))
       })
-      .catch(() => {})
+      .catch(() => { })
 
     return result
   })

packages/opencode/src/provider/provider.ts

@@ -337,6 +337,41 @@ export namespace Provider {
     }
   }
 
+  export async function getLightweightModel(providerID: string): Promise<{ info: ModelsDev.Model; language: LanguageModel } | null> {
+    const cfg = await Config.get()
+
+    // Check user override
+    if (cfg.lightweight_model) {
+      try {
+        // Parse the lightweight model to get its provider
+        const { providerID: lightweightProviderID, modelID } = parseModel(cfg.lightweight_model)
+        return await getModel(lightweightProviderID, modelID)
+      } catch (e) {
+        log.warn("Failed to get configured lightweight model", { lightweight_model: cfg.lightweight_model, error: e })
+      }
+    }
+
+    const providers = await list()
+    const provider = providers[providerID]
+    if (!provider) return null
+
+    // Select cheapest model whose cost.output <= 4
+    let selected: { info: ModelsDev.Model; language: LanguageModel } | null = null
+    for (const model of Object.values(provider.info.models)) {
+      if (model.cost.output <= 4) {
+        try {
+          const m = await getModel(providerID, model.id)
+          if (!selected || m.info.cost.output < selected.info.cost.output) {
+            selected = m
+          }
+        } catch {
+          // ignore errors and continue searching
+        }
+      }
+    }
+    return selected
+  }
+
   const TOOLS = [
     BashTool,
     EditTool,

packages/opencode/src/provider/transform.ts

@@ -1,4 +1,4 @@
-import type { CoreMessage, LanguageModelV1Prompt } from "ai"
+import type { LanguageModelV1Prompt } from "ai"
 import { unique } from "remeda"
 
 export namespace ProviderTransform {

packages/tui/internal/app/app.go

@@ -5,7 +5,6 @@ import (
 	"fmt"
 	"path/filepath"
 	"sort"
-	"strings"
 
 	"log/slog"
 
@@ -20,24 +19,29 @@ import (
 var RootPath string
 
 type App struct {
-	Info      client.AppInfo
-	Version   string
-	StatePath string
-	Config    *client.ConfigInfo
-	Client    *client.ClientWithResponses
-	State     *config.State
-	Provider  *client.ProviderInfo
-	Model     *client.ModelInfo
-	Session   *client.SessionInfo
-	Messages  []client.MessageInfo
-	Commands  commands.CommandRegistry
+	Info          client.AppInfo
+	Version       string
+	StatePath     string
+	Config        *client.ConfigInfo
+	Client        *client.ClientWithResponses
+	State         *config.State
+	MainProvider  *client.ProviderInfo
+	MainModel     *client.ModelInfo
+	LightProvider *client.ProviderInfo
+	LightModel    *client.ModelInfo
+	Session       *client.SessionInfo
+	Messages      []client.MessageInfo
+	Commands      commands.CommandRegistry
 }
 
 type SessionSelectedMsg = *client.SessionInfo
 type ModelSelectedMsg struct {
-	Provider client.ProviderInfo
-	Model    client.ModelInfo
+	MainProvider        client.ProviderInfo
+	MainModel           client.ModelInfo
+	LightweightProvider client.ProviderInfo
+	LightweightModel    client.ModelInfo
 }
+
 type SessionClearedMsg struct{}
 type CompactSessionMsg struct{}
 type SendMsg struct {
@@ -83,9 +87,10 @@ func New(
 		appState.Theme = *configInfo.Theme
 	}
 	if configInfo.Model != nil {
-		splits := strings.Split(*configInfo.Model, "/")
-		appState.Provider = splits[0]
-		appState.Model = strings.Join(splits[1:], "/")
+		appState.MainProvider, appState.MainModel = util.ParseModel(*configInfo.Model)
+	}
+	if configInfo.LightweightModel != nil {
+		appState.LightProvider, appState.LightModel = util.ParseModel(*configInfo.LightweightModel)
 	}
 
 	// Load themes from all directories
@@ -158,11 +163,11 @@ func (a *App) InitializeProvider() tea.Cmd {
 		var currentProvider *client.ProviderInfo
 		var currentModel *client.ModelInfo
 		for _, provider := range providers {
-			if provider.Id == a.State.Provider {
+			if provider.Id == a.State.MainProvider {
 				currentProvider = &provider
 
 				for _, model := range provider.Models {
-					if model.Id == a.State.Model {
+					if model.Id == a.State.MainModel {
 						currentModel = &model
 					}
 				}
@@ -173,10 +178,40 @@ func (a *App) InitializeProvider() tea.Cmd {
 			currentModel = defaultModel
 		}
 
+		// Initialize lightweight model based on config or defaults
+		lightProvider := currentProvider
+		lightModel := currentModel
+
+		if a.State.LightProvider != "" && a.State.LightModel != "" {
+			lightProviderID, lightModelID := a.State.LightProvider, a.State.LightModel
+			// Find provider/model
+			for _, provider := range providers {
+				if provider.Id == lightProviderID {
+					lightProvider = &provider
+					for _, model := range provider.Models {
+						if model.Id == lightModelID {
+							lightModel = &model
+							break
+						}
+					}
+					break
+				}
+			}
+		} else {
+			// Try to find a default lightweight model for the provider
+			lightModel = getDefaultLightweightModel(*currentProvider)
+			if lightModel == nil {
+				// Fall back to the main model
+				lightModel = currentModel
+			}
+		}
+
 		// TODO: handle no provider or model setup, yet
 		return ModelSelectedMsg{
-			Provider: *currentProvider,
-			Model:    *currentModel,
+			MainProvider:        *currentProvider,
+			MainModel:           *currentModel,
+			LightweightProvider: *lightProvider,
+			LightweightModel:    *lightModel,
 		}
 	}
 }
@@ -193,6 +228,20 @@ func getDefaultModel(response *client.PostProviderListResponse, provider client.
 	return nil
 }
 
+func getDefaultLightweightModel(provider client.ProviderInfo) *client.ModelInfo {
+	// Select the cheapest model whose Cost.Output <= 4
+	var selected *client.ModelInfo
+	for _, model := range provider.Models {
+		if model.Cost.Output <= 4 {
+			if selected == nil || model.Cost.Output < selected.Cost.Output {
+				tmp := model // create copy to take address of loop variable safely
+				selected = &tmp
+			}
+		}
+	}
+	return selected
+}
+
 type Attachment struct {
 	FilePath string
 	FileName string
@@ -231,8 +280,8 @@ func (a *App) InitializeProject(ctx context.Context) tea.Cmd {
 	go func() {
 		response, err := a.Client.PostSessionInitialize(ctx, client.PostSessionInitializeJSONRequestBody{
 			SessionID:  a.Session.Id,
-			ProviderID: a.Provider.Id,
-			ModelID:    a.Model.Id,
+			ProviderID: a.MainProvider.Id,
+			ModelID:    a.MainModel.Id,
 		})
 		if err != nil {
 			slog.Error("Failed to initialize project", "error", err)
@@ -248,10 +297,17 @@ func (a *App) InitializeProject(ctx context.Context) tea.Cmd {
 }
 
 func (a *App) CompactSession(ctx context.Context) tea.Cmd {
+	providerID := a.MainProvider.Id
+	modelID := a.MainModel.Id
+	if a.LightProvider != nil && a.LightModel != nil {
+		providerID = a.LightProvider.Id
+		modelID = a.LightModel.Id
+	}
+
 	response, err := a.Client.PostSessionSummarizeWithResponse(ctx, client.PostSessionSummarizeJSONRequestBody{
 		SessionID:  a.Session.Id,
-		ProviderID: a.Provider.Id,
-		ModelID:    a.Model.Id,
+		ProviderID: providerID,
+		ModelID:    modelID,
 	})
 	if err != nil {
 		slog.Error("Failed to compact session", "error", err)
@@ -315,8 +371,8 @@ func (a *App) SendChatMessage(ctx context.Context, text string, attachments []At
 		response, err := a.Client.PostSessionChat(ctx, client.PostSessionChatJSONRequestBody{
 			SessionID:  a.Session.Id,
 			Parts:      parts,
-			ProviderID: a.Provider.Id,
-			ModelID:    a.Model.Id,
+			ProviderID: a.MainProvider.Id,
+			ModelID:    a.MainModel.Id,
 		})
 		if err != nil {
 			slog.Error("Failed to send message", "error", err)

packages/tui/internal/components/chat/editor.go

@@ -121,8 +121,17 @@ func (m *editorComponent) Content() string {
 	}
 
 	model := ""
-	if m.app.Model != nil {
-		model = muted(m.app.Provider.Name) + base(" "+m.app.Model.Name)
+	if m.app.MainModel != nil && m.app.MainProvider != nil {
+		model = muted(m.app.MainProvider.Name) + base(" "+m.app.MainModel.Name)
+
+		// show lightweight model if configured
+		if m.app.LightModel != nil && m.app.LightProvider != nil {
+			if m.app.LightProvider.Id == m.app.MainProvider.Id {
+				model = model + muted(" (⚡"+m.app.LightModel.Name+")")
+			} else {
+				model = model + muted(" (⚡"+m.app.LightProvider.Name+"/"+m.app.LightModel.Name+")")
+			}
+		}
 	}
 
 	space := m.width - 2 - lipgloss.Width(model) - lipgloss.Width(hint)