diff --git a/backend/internal/pkg/apicompat/chatcompletions_responses_stream_lifecycle_test.go b/backend/internal/pkg/apicompat/chatcompletions_responses_stream_lifecycle_test.go
index fa058dbd75..b71d1ba78c 100644
--- a/backend/internal/pkg/apicompat/chatcompletions_responses_stream_lifecycle_test.go
+++ b/backend/internal/pkg/apicompat/chatcompletions_responses_stream_lifecycle_test.go
@@ -179,106 +179,6 @@ func TestStream_ToolCallLifecycleComplete(t *testing.T) {
 	require.True(t, sawItemDone, "function_call output_item.done missing")
 }
 
-func TestStream_ReasoningOnlySynthesizesVisibleText(t *testing.T) {
-	events := collectStreamEvents(t, []string{
-		`{"choices":[{"index":0,"delta":{"role":"assistant","content":null,"reasoning_content":""}}]}`,
-		`{"choices":[{"index":0,"delta":{"reasoning_content":"thinking before final"}}]}`,
-		`{"choices":[{"index":0,"delta":{"content":""},"finish_reason":"length"}],"usage":{"prompt_tokens":1,"completion_tokens":2,"total_tokens":3}}`,
-	})
-
-	open := map[int]string{}
-	var sawTextDelta, sawTextDone, sawMessageDone bool
-	for _, e := range events {
-		switch e.Type {
-		case "response.output_item.added":
-			require.NotNil(t, e.Item)
-			open[e.OutputIndex] = e.Item.Type
-		case "response.output_text.delta":
-			sawTextDelta = true
-			require.Equalf(t, "message", open[e.OutputIndex], "fallback text delta before its item was opened")
-			require.Equal(t, "thinking before final", e.Delta)
-		case "response.output_text.done":
-			sawTextDone = true
-			require.Equal(t, "thinking before final", e.Text)
-		case "response.output_item.done":
-			if e.Item != nil && e.Item.Type == "message" {
-				sawMessageDone = true
-				require.Equal(t, "thinking before final", e.Item.Content[0].Text)
-			}
-		case "response.completed":
-			require.NotNil(t, e.Response)
-			require.Equal(t, "incomplete", e.Response.Status)
-			require.NotNil(t, e.Response.IncompleteDetails)
-			require.Equal(t, "max_output_tokens", e.Response.IncompleteDetails.Reason)
-			require.Len(t, e.Response.Output, 2)
-			require.Equal(t, "reasoning", e.Response.Output[0].Type)
-			require.Equal(t, "message", e.Response.Output[1].Type)
-			require.Equal(t, "thinking before final", e.Response.Output[1].Content[0].Text)
-		}
-	}
-	require.True(t, sawTextDelta, "reasoning-only stream must produce visible text delta")
-	require.True(t, sawTextDone, "reasoning-only stream must close visible text part")
-	require.True(t, sawMessageDone, "reasoning-only stream must close synthesized message item")
-}
-
-func TestStream_ReasoningOnlyBlankDoesNotSynthesizeVisibleText(t *testing.T) {
-	events := collectStreamEvents(t, []string{
-		`{"choices":[{"index":0,"delta":{"reasoning_content":"   "}}]}`,
-		`{"choices":[{"index":0,"delta":{},"finish_reason":"stop"}]}`,
-	})
-
-	for _, e := range events {
-		require.NotEqual(t, "response.output_text.delta", e.Type)
-		if e.Type == "response.completed" {
-			require.NotNil(t, e.Response)
-			require.Len(t, e.Response.Output, 2)
-			require.Equal(t, "reasoning", e.Response.Output[0].Type)
-			require.Equal(t, "message", e.Response.Output[1].Type)
-			require.Equal(t, "", e.Response.Output[1].Content[0].Text)
-		}
-	}
-}
-
-func TestStream_ReasoningThenContentDoesNotDuplicateFallbackText(t *testing.T) {
-	events := collectStreamEvents(t, []string{
-		`{"choices":[{"index":0,"delta":{"reasoning_content":"private plan"}}]}`,
-		`{"choices":[{"index":0,"delta":{"content":"final answer"}}]}`,
-		`{"choices":[{"index":0,"delta":{},"finish_reason":"stop"}]}`,
-	})
-
-	var textDeltas []string
-	for _, e := range events {
-		switch e.Type {
-		case "response.output_text.delta":
-			textDeltas = append(textDeltas, e.Delta)
-		case "response.completed":
-			require.NotNil(t, e.Response)
-			require.Len(t, e.Response.Output, 2)
-			require.Equal(t, "private plan", e.Response.Output[0].Summary[0].Text)
-			require.Equal(t, "final answer", e.Response.Output[1].Content[0].Text)
-		}
-	}
-	require.Equal(t, []string{"final answer"}, textDeltas)
-}
-
-func TestStream_ReasoningThenToolCallDoesNotSynthesizeVisibleText(t *testing.T) {
-	events := collectStreamEvents(t, []string{
-		`{"choices":[{"index":0,"delta":{"reasoning_content":"call a tool"}}]}`,
-		`{"choices":[{"index":0,"delta":{"tool_calls":[{"index":0,"id":"call_a","type":"function","function":{"name":"exec","arguments":"{}"}}]}}]}`,
-		`{"choices":[{"index":0,"delta":{},"finish_reason":"tool_calls"}]}`,
-	})
-
-	for _, e := range events {
-		require.NotEqual(t, "response.output_text.delta", e.Type)
-		if e.Type == "response.completed" {
-			require.NotNil(t, e.Response)
-			require.Len(t, e.Response.Output, 2)
-			require.Equal(t, "reasoning", e.Response.Output[0].Type)
-			require.Equal(t, "function_call", e.Response.Output[1].Type)
-		}
-	}
-}
-
 // TestStream_SSEWireComplete drives the full stream through SSE encoding and
 // asserts the function_call events carry complete fields on the wire.
 func TestStream_SSEWireComplete(t *testing.T) {