diff --git a/apps/edge/internal/openai/hot_path_dispatch.go b/apps/edge/internal/openai/hot_path_dispatch.go
index 1f5fbac3..fb4589f5 100644
--- a/apps/edge/internal/openai/hot_path_dispatch.go
+++ b/apps/edge/internal/openai/hot_path_dispatch.go
@@ -695,10 +695,27 @@ func decodeOpenAIPresetSSE(body []byte) (normalizedStageOutput, error) {
 				stage.Deltas = append(stage.Deltas, normalizedStageDelta{Kind: normalizedStageDeltaReasoning, Text: reasoning})
 			}
 			for _, delta := range choice.Delta.ToolCalls {
-				state := tools[delta.Index]
+				toolIndex := delta.Index
+				if toolIndex == 0 && delta.ID != "" {
+					if first := tools[0]; first != nil && first.id != "" && first.id != delta.ID {
+						matched := false
+						for existingIndex, existing := range tools {
+							if existing.id == delta.ID {
+								toolIndex = existingIndex
+								matched = true
+								break
+							}
+						}
+						if !matched {
+							for toolIndex = 1; tools[toolIndex] != nil; toolIndex++ {
+							}
+						}
+					}
+				}
+				state := tools[toolIndex]
 				if state == nil {
 					state = &toolState{}
-					tools[delta.Index] = state
+					tools[toolIndex] = state
 				}
 				if delta.ID != "" {
 					state.id = delta.ID
diff --git a/apps/edge/internal/openai/provider_model_rewrite_test.go b/apps/edge/internal/openai/provider_model_rewrite_test.go
index 782ff586..b1693909 100644
--- a/apps/edge/internal/openai/provider_model_rewrite_test.go
+++ b/apps/edge/internal/openai/provider_model_rewrite_test.go
@@ -102,6 +102,20 @@ func TestGeminiChatProviderResponseAddsMissingParallelToolIndices(t *testing.T)
 	}
 }
 
+func TestOpenAIPresetSSESeparatesNewToolIDsWithoutIndices(t *testing.T) {
+	body := []byte("data: {\"id\":\"chat-1\",\"choices\":[{\"delta\":{\"tool_calls\":[{\"id\":\"call-1\",\"function\":{\"name\":\"read_file\",\"arguments\":\"{\\\"path\\\":\\\"plan.md\\\"}\"}}]}}]}\n\n" +
+		"data: {\"id\":\"chat-1\",\"choices\":[{\"delta\":{\"tool_calls\":[{\"id\":\"call-2\",\"function\":{\"name\":\"read_file\",\"arguments\":\"{\\\"path\\\":\\\"review.md\\\"}\"}}]}}]}\n\n" +
+		"data: {\"id\":\"chat-1\",\"choices\":[{\"delta\":{\"tool_calls\":[{\"id\":\"call-3\",\"function\":{\"name\":\"bash\",\"arguments\":\"{\\\"command\\\":\\\"test -f index.html\\\"}\"}}]}}]}\n\n" +
+		"data: {\"id\":\"chat-1\",\"choices\":[{\"delta\":{},\"finish_reason\":\"tool_calls\"}],\"usage\":{\"prompt_tokens\":1,\"completion_tokens\":1,\"total_tokens\":2}}\n\ndata: [DONE]\n\n")
+	stage, err := decodeOpenAIPresetSSE(body)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(stage.ToolCalls) != 3 {
+		t.Fatalf("decoded tool calls = %+v", stage.ToolCalls)
+	}
+}
+
 func TestProviderChatTokenLimitNormalizationUsesSelectedProfile(t *testing.T) {
 	tests := []struct {
 		name       string