diff --git a/internal/proto/proto.go b/internal/proto/proto.go
index 6dd6c29bd378fa81caa4b4abc849618ef4674036..08c3b3699a129f0e06dc01964656b4fbd615ae49 100644
--- a/internal/proto/proto.go
+++ b/internal/proto/proto.go
@@ -1,14 +1,39 @@
 package proto
 
+import (
+	"github.com/charmbracelet/catwalk/pkg/catwalk"
+	"github.com/charmbracelet/crush/internal/message"
+)
+
 // Instance represents a running app.App instance with its associated resources
 // and state.
 type Instance struct {
-	ID   string `json:"id"`
-	Path string `json:"path"`
-	YOLO bool   `json:"yolo"`
+	ID      string `json:"id"`
+	Path    string `json:"path"`
+	YOLO    bool   `json:"yolo,omitempty"`
+	Debug   bool   `json:"debug,omitempty"`
+	DataDir string `json:"data_dir,omitempty"`
 }
 
 // Error represents an error response.
 type Error struct {
 	Message string `json:"message"`
 }
+
+// AgentInfo represents information about the agent.
+type AgentInfo struct {
+	IsBusy bool          `json:"is_busy"`
+	Model  catwalk.Model `json:"model"`
+}
+
+// IsZero checks if the AgentInfo is zero-valued.
+func (a AgentInfo) IsZero() bool {
+	return a == AgentInfo{}
+}
+
+// AgentMessage represents a message sent to the agent.
+type AgentMessage struct {
+	SessionID   string               `json:"session_id"`
+	Prompt      string               `json:"prompt"`
+	Attachments []message.Attachment `json:"attachments,omitempty"`
+}