diff --git a/internal/llm/provider_openai.go b/internal/llm/provider_openai.go
index 65125f47cffcb4940dd6e1daa5f037f325c2b27d..9b4685a182e5716148963adda6ac77ab0db45cd1 100644
--- a/internal/llm/provider_openai.go
+++ b/internal/llm/provider_openai.go
@@ -9,6 +9,7 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"sort"
 	"strings"
 	"time"
 
@@ -1122,9 +1123,15 @@ func (c *OpenAIClient) processStreamResponse(body io.Reader, eventChan chan<- St
 		)
 	}
 
-	// Add completed tool calls
-	for i := 0; i < len(toolCallsMap); i++ {
-		if tc, exists := toolCallsMap[i]; exists {
+	// Add completed tool calls in provider index order. Indexes are not
+	// guaranteed to be contiguous across OpenAI-compatible providers.
+	toolCallIndexes := make([]int, 0, len(toolCallsMap))
+	for index := range toolCallsMap {
+		toolCallIndexes = append(toolCallIndexes, index)
+	}
+	sort.Ints(toolCallIndexes)
+	for _, i := range toolCallIndexes {
+		if tc := toolCallsMap[i]; tc != nil {
 			// Parse accumulated arguments
 			if argsBuilder, ok := toolCallArgsMap[i]; ok {
 				argsStr := argsBuilder.String()
diff --git a/internal/llm/provider_openai_stream_sparse_index_test.go b/internal/llm/provider_openai_stream_sparse_index_test.go
new file mode 100644
index 0000000000000000000000000000000000000000..aefb31d5b80ddcbb2744f6e1acf6c7528fb656d2
--- /dev/null
+++ b/internal/llm/provider_openai_stream_sparse_index_test.go
@@ -0,0 +1,31 @@
+package llm
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestProcessStreamPreservesSparseToolCallIndexes(t *testing.T) {
+	chunk := `{"choices":[{"delta":{"tool_calls":[{"index":2,"id":"call_2","function":{"name":"second","arguments":"{}"}},{"index":0,"id":"call_0","function":{"name":"first","arguments":"{}"}}]},"finish_reason":"tool_calls"}]}`
+	stream := "data: " + chunk + "\n\ndata: [DONE]\n\n"
+	events := make(chan StreamEvent, 16)
+
+	response, err := (&OpenAIClient{}).processStreamResponse(strings.NewReader(stream), events)
+	close(events)
+
+	if err != nil {
+		t.Fatalf("processStreamResponse returned error: %v", err)
+	}
+	var calls []*FunctionCall
+	for _, part := range response.Candidates[0].Content.Parts {
+		if part.FunctionCall != nil {
+			calls = append(calls, part.FunctionCall)
+		}
+	}
+	if len(calls) != 2 {
+		t.Fatalf("got %d tool calls, want 2", len(calls))
+	}
+	if calls[0].Name != "first" || calls[1].Name != "second" {
+		t.Fatalf("tool call order = [%q, %q], want [first, second]", calls[0].Name, calls[1].Name)
+	}
+}