diff --git a/internal/translator/codex/claude/codex_claude_request.go b/internal/translator/codex/claude/codex_claude_request.go
index 20241bf24..6b5bfb0bc 100644
--- a/internal/translator/codex/claude/codex_claude_request.go
+++ b/internal/translator/codex/claude/codex_claude_request.go
@@ -26,7 +26,7 @@ import (
 // The function performs the following transformations:
 // 1. Sets up a template with the model name and empty instructions field
 // 2. Processes system messages and converts them to developer input content
-// 3. Transforms message contents (text, image, tool_use, tool_result) to appropriate formats
+// 3. Transforms message contents (text, image, document, tool_use, tool_result) to appropriate formats
 // 4. Converts tools declarations to the expected format
 // 5. Adds additional configuration parameters for the Codex API
 // 6. Maps Claude thinking configuration to Codex reasoning settings
@@ -129,6 +129,12 @@ func ConvertClaudeRequestToCodex(modelName string, inputRawJSON []byte, _ bool)
 				contentItems = append(contentItems, content)
 			}
 
+			appendDocumentContent := func(dataURL string) {
+				content := []byte(`{"type":"input_file","file_data":"","filename":"document.pdf"}`)
+				content, _ = sjson.SetBytes(content, "file_data", dataURL)
+				contentItems = append(contentItems, content)
+			}
+
 			appendReasoningContent := func(part gjson.Result) {
 				if messageRole != "assistant" {
 					return
@@ -182,6 +188,22 @@ func ConvertClaudeRequestToCodex(modelName string, inputRawJSON []byte, _ bool)
 								appendImageContent(dataURL)
 							}
 						}
+					case "document":
+						sourceResult := messageContentResult.Get("source")
+						if sourceResult.Get("type").String() != "base64" {
+							continue
+						}
+						mediaType := strings.TrimSpace(sourceResult.Get("media_type").String())
+						if !strings.EqualFold(mediaType, "application/pdf") {
+							continue
+						}
+						data := sourceResult.Get("data").String()
+						if data == "" {
+							data = sourceResult.Get("base64").String()
+						}
+						if data != "" {
+							appendDocumentContent(fmt.Sprintf("data:%s;base64,%s", mediaType, data))
+						}
 					case "tool_use":
 						flushMessage()
 						functionCallMessage := []byte(`{"type":"function_call"}`)
diff --git a/internal/translator/codex/claude/codex_claude_request_test.go b/internal/translator/codex/claude/codex_claude_request_test.go
index 446e1376e..9db9c069f 100644
--- a/internal/translator/codex/claude/codex_claude_request_test.go
+++ b/internal/translator/codex/claude/codex_claude_request_test.go
@@ -508,6 +508,44 @@ func TestConvertClaudeRequestToCodex_AssistantThinkingSignatureToReasoningItem(t
 	}
 }
 
+func TestConvertClaudeRequestToCodex_PreservesBase64PDFDocumentContent(t *testing.T) {
+	inputJSON := `{
+		"messages": [{
+			"role": "user",
+			"content": [
+				{"type": "text", "text": "before"},
+				{"type": "document", "source": {"type": "base64", "media_type": "application/pdf", "data": "JVBERi0xLjQK"}},
+				{"type": "text", "text": "after"}
+			]
+		}]
+	}`
+
+	result := ConvertClaudeRequestToCodex("gpt-5.6-sol", []byte(inputJSON), false)
+	content := gjson.GetBytes(result, "input.0.content").Array()
+	if len(content) != 3 {
+		t.Fatalf("got %d content items, want 3. Output: %s", len(content), result)
+	}
+
+	wantTypes := []string{"input_text", "input_file", "input_text"}
+	for i, wantType := range wantTypes {
+		if got := content[i].Get("type").String(); got != wantType {
+			t.Fatalf("content[%d].type = %q, want %q. Output: %s", i, got, wantType, result)
+		}
+	}
+	if got := content[0].Get("text").String(); got != "before" {
+		t.Fatalf("content[0].text = %q, want %q", got, "before")
+	}
+	if got := content[1].Get("file_data").String(); got != "data:application/pdf;base64,JVBERi0xLjQK" {
+		t.Fatalf("content[1].file_data = %q, want PDF data URL", got)
+	}
+	if got := content[1].Get("filename").String(); got != "document.pdf" {
+		t.Fatalf("content[1].filename = %q, want %q", got, "document.pdf")
+	}
+	if got := content[2].Get("text").String(); got != "after" {
+		t.Fatalf("content[2].text = %q, want %q", got, "after")
+	}
+}
+
 func TestConvertClaudeRequestToCodex_PreservesContentOrderAcrossToolAndReasoningItems(t *testing.T) {
 	signature := validCodexReasoningSignature()
 	inputJSON := `{