refactor(agent-modal): revamped UI/UX for the agent modal (#1838)

Co-authored-by: Dax Raad <d@ironbay.co>
Co-authored-by: Dax <mail@thdxr.com>

packages/tui/internal/app/app.go

@@ -71,9 +71,11 @@ type ModelSelectedMsg struct {
 	Provider opencode.Provider
 	Model    opencode.Model
 }
+
 type AgentSelectedMsg struct {
-	Agent opencode.Agent
+	AgentName string
 }
+
 type SessionClearedMsg struct{}
 type CompactSessionMsg struct{}
 type SendPrompt = Prompt
@@ -272,6 +274,7 @@ func (a *App) cycleMode(forward bool) (*App, tea.Cmd) {
 	}
 
 	a.State.Agent = a.Agent().Name
+	a.State.UpdateAgentUsage(a.Agent().Name)
 	return a, a.SaveState()
 }
 
@@ -316,6 +319,45 @@ func (a *App) CycleRecentModel() (*App, tea.Cmd) {
 	return a, toast.NewErrorToast("Recent model not found")
 }
 
+func (a *App) SwitchToAgent(agentName string) (*App, tea.Cmd) {
+	// Find the agent index by name
+	for i, agent := range a.Agents {
+		if agent.Name == agentName {
+			a.AgentIndex = i
+			break
+		}
+	}
+
+	// Set up model for the new agent
+	modelID := a.Agent().Model.ModelID
+	providerID := a.Agent().Model.ProviderID
+	if modelID == "" {
+		if model, ok := a.State.AgentModel[a.Agent().Name]; ok {
+			modelID = model.ModelID
+			providerID = model.ProviderID
+		}
+	}
+
+	if modelID != "" {
+		for _, provider := range a.Providers {
+			if provider.ID == providerID {
+				a.Provider = &provider
+				for _, model := range provider.Models {
+					if model.ID == modelID {
+						a.Model = &model
+						break
+					}
+				}
+				break
+			}
+		}
+	}
+
+	a.State.Agent = a.Agent().Name
+	a.State.UpdateAgentUsage(agentName)
+	return a, a.SaveState()
+}
+
 // findModelByFullID finds a model by its full ID in the format "provider/model"
 func findModelByFullID(
 	providers []opencode.Provider,

packages/tui/internal/app/state.go

@@ -16,6 +16,11 @@ type ModelUsage struct {
 	LastUsed   time.Time `toml:"last_used"`
 }
 
+type AgentUsage struct {
+	AgentName string    `toml:"agent_name"`
+	LastUsed  time.Time `toml:"last_used"`
+}
+
 type AgentModel struct {
 	ProviderID string `toml:"provider_id"`
 	ModelID    string `toml:"model_id"`
@@ -29,6 +34,7 @@ type State struct {
 	Model              string                `toml:"model"`
 	Agent              string                `toml:"agent"`
 	RecentlyUsedModels []ModelUsage          `toml:"recently_used_models"`
+	RecentlyUsedAgents []AgentUsage          `toml:"recently_used_agents"`
 	MessagesRight      bool                  `toml:"messages_right"`
 	SplitDiff          bool                  `toml:"split_diff"`
 	MessageHistory     []Prompt              `toml:"message_history"`
@@ -42,6 +48,7 @@ func NewState() *State {
 		Agent:              "build",
 		AgentModel:         make(map[string]AgentModel),
 		RecentlyUsedModels: make([]ModelUsage, 0),
+		RecentlyUsedAgents: make([]AgentUsage, 0),
 		MessageHistory:     make([]Prompt, 0),
 	}
 }
@@ -83,6 +90,42 @@ func (s *State) RemoveModelFromRecentlyUsed(providerID, modelID string) {
 	}
 }
 
+// UpdateAgentUsage updates the recently used agents list with the specified agent
+func (s *State) UpdateAgentUsage(agentName string) {
+	now := time.Now()
+
+	// Check if this agent is already in the list
+	for i, usage := range s.RecentlyUsedAgents {
+		if usage.AgentName == agentName {
+			s.RecentlyUsedAgents[i].LastUsed = now
+			usage := s.RecentlyUsedAgents[i]
+			copy(s.RecentlyUsedAgents[1:i+1], s.RecentlyUsedAgents[0:i])
+			s.RecentlyUsedAgents[0] = usage
+			return
+		}
+	}
+
+	newUsage := AgentUsage{
+		AgentName: agentName,
+		LastUsed:  now,
+	}
+
+	// Prepend to slice and limit to last 20 entries
+	s.RecentlyUsedAgents = append([]AgentUsage{newUsage}, s.RecentlyUsedAgents...)
+	if len(s.RecentlyUsedAgents) > 20 {
+		s.RecentlyUsedAgents = s.RecentlyUsedAgents[:20]
+	}
+}
+
+func (s *State) RemoveAgentFromRecentlyUsed(agentName string) {
+	for i, usage := range s.RecentlyUsedAgents {
+		if usage.AgentName == agentName {
+			s.RecentlyUsedAgents = append(s.RecentlyUsedAgents[:i], s.RecentlyUsedAgents[i+1:]...)
+			return
+		}
+	}
+}
+
 func (s *State) AddPromptToHistory(prompt Prompt) {
 	s.MessageHistory = append([]Prompt{prompt}, s.MessageHistory...)
 	if len(s.MessageHistory) > 50 {