diff --git a/internal/translator/antigravity/claude/antigravity_claude_response.go b/internal/translator/antigravity/claude/antigravity_claude_response.go
index 9b0e2756..e6fd810a 100644
--- a/internal/translator/antigravity/claude/antigravity_claude_response.go
+++ b/internal/translator/antigravity/claude/antigravity_claude_response.go
@@ -75,16 +75,13 @@ func ConvertAntigravityResponseToClaude(_ context.Context, _ string, originalReq
 			HasFirstResponse: false,
 			ResponseType:     0,
 			ResponseIndex:    0,
+			ToolNameMap:      util.SanitizedToolNameMap(originalRequestRawJSON),
 		}
 	}
 	modelName := gjson.GetBytes(requestRawJSON, "model").String()
 
 	params := (*param).(*Params)
 
-	if params.ToolNameMap == nil {
-		params.ToolNameMap = util.SanitizedToolNameMap(originalRequestRawJSON)
-	}
-
 	if bytes.Equal(rawJSON, []byte("[DONE]")) {
 		output := make([]byte, 0, 256)
 		// Only send final events if we have actually output content
diff --git a/internal/util/sanitize_test.go b/internal/util/sanitize_test.go
index 3b7714cf..f589aff4 100644
--- a/internal/util/sanitize_test.go
+++ b/internal/util/sanitize_test.go
@@ -93,6 +93,20 @@ func TestSanitizedToolNameMap(t *testing.T) {
 			t.Error("expected nil for nil input")
 		}
 	})
+
+	t.Run("collision keeps first mapping", func(t *testing.T) {
+		raw := []byte(`{"tools":[
+			{"name":"read/file","input_schema":{}},
+			{"name":"read@file","input_schema":{}}
+		]}`)
+		m := SanitizedToolNameMap(raw)
+		if m == nil {
+			t.Fatal("expected non-nil map")
+		}
+		if m["read_file"] != "read/file" {
+			t.Errorf("expected first mapping read/file, got %q", m["read_file"])
+		}
+	})
 }
 
 func TestRestoreSanitizedToolName(t *testing.T) {
diff --git a/internal/util/translator.go b/internal/util/translator.go
index 81400eee..a40609f1 100644
--- a/internal/util/translator.go
+++ b/internal/util/translator.go
@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"strings"
 
+	log "github.com/sirupsen/logrus"
 	"github.com/tidwall/gjson"
 	"github.com/tidwall/sjson"
 )
@@ -298,6 +299,8 @@ func SanitizedToolNameMap(rawJSON []byte) map[string]string {
 		}
 		if _, exists := out[sanitized]; !exists {
 			out[sanitized] = name
+		} else {
+			log.Warnf("sanitized tool name collision: %q and %q both map to %q, keeping first", out[sanitized], name, sanitized)
 		}
 		return true
 	})