fix(claude): guard thinking tool-call fallback when final text exists

- only parse tool_calls from thinking when finalText is empty

- apply the same guard in stream runtime finalizer

- add regression tests for non-stream and stream paths

internal/adapter/claude/handler_stream_test.go

@@ -209,6 +209,40 @@ func TestHandleClaudeStreamRealtimeToolDetectionFromThinkingFallback(t *testing.
 	}
 }
 
+func TestHandleClaudeStreamRealtimeSkipsThinkingFallbackWhenFinalTextExists(t *testing.T) {
+	h := &Handler{}
+	resp := makeClaudeSSEHTTPResponse(
+		`data: {"p":"response/thinking_content","v":"{\"tool_calls\":[{\"name\":\"search\""}`,
+		`data: {"p":"response/thinking_content","v":",\"input\":{\"q\":\"go\"}}]}"}`,
+		`data: {"p":"response/content","v":"normal answer"}`,
+		`data: [DONE]`,
+	)
+	rec := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodPost, "/anthropic/v1/messages", nil)
+
+	h.handleClaudeStreamRealtime(rec, req, resp, "claude-sonnet-4-5", []any{map[string]any{"role": "user", "content": "use tool"}}, true, false, []string{"search"})
+
+	frames := parseClaudeFrames(t, rec.Body.String())
+	for _, f := range findClaudeFrames(frames, "content_block_start") {
+		contentBlock, _ := f.Payload["content_block"].(map[string]any)
+		if contentBlock["type"] == "tool_use" {
+			t.Fatalf("unexpected tool_use block when final text exists, body=%s", rec.Body.String())
+		}
+	}
+
+	foundEndTurn := false
+	for _, f := range findClaudeFrames(frames, "message_delta") {
+		delta, _ := f.Payload["delta"].(map[string]any)
+		if delta["stop_reason"] == "end_turn" {
+			foundEndTurn = true
+			break
+		}
+	}
+	if !foundEndTurn {
+		t.Fatalf("expected stop_reason=end_turn, body=%s", rec.Body.String())
+	}
+}
+
 func TestHandleClaudeStreamRealtimeUpstreamErrorEvent(t *testing.T) {
 	h := &Handler{}
 	resp := makeClaudeSSEHTTPResponse(

internal/adapter/claude/stream_runtime_finalize.go

@@ -46,7 +46,7 @@ func (s *claudeStreamRuntime) finalize(stopReason string) {
 
 	if s.bufferToolContent {
 		detected := util.ParseToolCalls(finalText, s.toolNames)
-		if len(detected) == 0 && finalThinking != "" {
+		if len(detected) == 0 && finalText == "" && finalThinking != "" {
 			detected = util.ParseToolCalls(finalThinking, s.toolNames)
 		}
 		if len(detected) > 0 {

internal/format/claude/render.go

@@ -9,7 +9,7 @@ import (
 
 func BuildMessageResponse(messageID, model string, normalizedMessages []any, finalThinking, finalText string, toolNames []string) map[string]any {
 	detected := util.ParseToolCalls(finalText, toolNames)
-	if len(detected) == 0 && finalThinking != "" {
+	if len(detected) == 0 && finalText == "" && finalThinking != "" {
 		detected = util.ParseToolCalls(finalThinking, toolNames)
 	}
 	content := make([]map[string]any, 0, 4)

internal/format/claude/render_test.go

@@ -27,3 +27,36 @@ func TestBuildMessageResponseDetectsToolCallsFromThinkingFallback(t *testing.T)
 		t.Fatalf("expected tool name search, got=%#v", last["name"])
 	}
 }
+
+func TestBuildMessageResponseSkipsThinkingFallbackWhenFinalTextExists(t *testing.T) {
+	resp := BuildMessageResponse(
+		"msg_1",
+		"claude-sonnet-4-5",
+		[]any{map[string]any{"role": "user", "content": "hi"}},
+		`{"tool_calls":[{"name":"search","input":{"q":"go"}}]}`,
+		"normal answer",
+		[]string{"search"},
+	)
+
+	if resp["stop_reason"] != "end_turn" {
+		t.Fatalf("expected stop_reason=end_turn, got=%#v", resp["stop_reason"])
+	}
+
+	content, _ := resp["content"].([]map[string]any)
+	foundText := false
+	foundTool := false
+	for _, block := range content {
+		if block["type"] == "text" && block["text"] == "normal answer" {
+			foundText = true
+		}
+		if block["type"] == "tool_use" {
+			foundTool = true
+		}
+	}
+	if !foundText {
+		t.Fatalf("expected text block with finalText, got=%#v", resp["content"])
+	}
+	if foundTool {
+		t.Fatalf("unexpected tool_use block when finalText exists, got=%#v", resp["content"])
+	}
+}