diff --git a/main.go b/main.go
index 6497ec8..d1ff7dc 100644
--- a/main.go
+++ b/main.go
@@ -85,6 +85,7 @@ var llmTransport = &http.Transport{
 }
 
 var defCfg = Cfg{"https://api.kilo.ai/api/openrouter", "openrouter/free", "-", 0.7, 300, 120, 1000, true, "auto", 262144, map[string]string{"reasoning_effort": "high"}}
+const opencodeAgentVersion = "opencode/1.18.30"
 
 func atoiD(s string, d int) int {
   if v, e := strconv.Atoi(strings.TrimSpace(s)); e == nil {
@@ -103,7 +104,8 @@ func queryModelsContextWindow(cfg *Cfg) int {
   }
   req, err := http.NewRequest("GET", strings.TrimRight(cfg.Endpoint, "/")+"/models", nil)
   if err != nil { return 0 }
-  req.Header.Set("User-Agent", "Mozilla/5.0 (compatible; Bantam/1.0)")
+  req.Header.Set("User-Agent", opencodeAgentVersion)
+  req.Header.Set("X-Session-ID", projectID())
   if cfg.APIKey != "" && cfg.APIKey != "-" { req.Header.Set("Authorization", "Bearer "+cfg.APIKey) }
   resp, err := client.Do(req)
   if err != nil || resp.StatusCode >= 400 { return 0 }
@@ -175,7 +177,8 @@ func listModels(cfg *Cfg) (string, error) {
   }
   req, err := http.NewRequest("GET", strings.TrimRight(cfg.Endpoint, "/")+"/models", nil)
   if err != nil { return "", err }
-  req.Header.Set("User-Agent", "Mozilla/5.0 (compatible; Bantam/1.0)")
+  req.Header.Set("User-Agent", opencodeAgentVersion)
+  req.Header.Set("X-Session-ID", projectID())
   if cfg.APIKey != "" && cfg.APIKey != "-" { req.Header.Set("Authorization", "Bearer "+cfg.APIKey) }
   resp, err := client.Do(req)
   if err != nil { return "", err }
@@ -1043,7 +1046,8 @@ func llm(ctx context.Context, cfg *Cfg, msgs []Message, tools []map[string]any)
     if COL { fmt.Print("\r" + pend) } else { fmt.Println(pend) }
     req, _ := http.NewRequestWithContext(ctx, "POST", strings.TrimRight(cfg.Endpoint, "/")+"/chat/completions", bytes.NewReader(body))
     req.Header.Set("Content-Type", "application/json")
-    req.Header.Set("User-Agent", "Mozilla/5.0 (compatible; Bantam/1.0)")
+    req.Header.Set("User-Agent", opencodeAgentVersion)
+    req.Header.Set("X-Session-ID", projectID())
     if cfg.APIKey != "" && cfg.APIKey != "-" { req.Header.Set("Authorization", "Bearer "+cfg.APIKey) }
     resp, err = client.Do(req)
     var is4xxClientErr bool
diff --git a/main_test.go b/main_test.go
index 60008b7..5e7b1de 100644
--- a/main_test.go
+++ b/main_test.go
@@ -1170,7 +1170,7 @@ func TestLLMNonStreamingAndHeaders(t *testing.T) {
   if gotAuth != "Bearer secret" {
     t.Errorf("auth = %q", gotAuth)
   }
-  if !strings.Contains(gotUA, "Bantam/1.0") {
+  if !strings.Contains(gotUA, "opencode/1.18.30") {
     t.Errorf("user-agent = %q", gotUA)
   }
   if m.Content == nil || *m.Content != "hi" || m.ReasoningContent != "think" {