feat(translator): wrap message-level system roles as user-visible reminders

- Added `ClaudeMessageSystemReminderText` to convert system content into user-readable reminder text.
- Updated translators (Antigravity, Gemini, Codex, OpenAI) to wrap `system` roles as reminders with `<system-reminder>` tags.
- Adjusted related test cases to validate reminder wrapping logic.

internal/translator/antigravity/claude/antigravity_claude_request.go

@@ -12,6 +12,7 @@ import (
 	"github.com/router-for-me/CLIProxyAPI/v7/internal/cache"
 	sigcompat "github.com/router-for-me/CLIProxyAPI/v7/internal/signature"
 	"github.com/router-for-me/CLIProxyAPI/v7/internal/thinking"
+	translatorcommon "github.com/router-for-me/CLIProxyAPI/v7/internal/translator/common"
 	"github.com/router-for-me/CLIProxyAPI/v7/internal/translator/gemini/common"
 	"github.com/router-for-me/CLIProxyAPI/v7/internal/util"
 	log "github.com/sirupsen/logrus"
@@ -370,6 +371,16 @@ func ConvertClaudeRequestToAntigravity(modelName string, inputRawJSON []byte, _
 			clientContentJSON := []byte(`{"role":"","parts":[]}`)
 			clientContentJSON, _ = sjson.SetBytes(clientContentJSON, "role", role)
 			contentsResult := messageResult.Get("content")
+			if originalRole == "system" {
+				if reminderText, ok := translatorcommon.ClaudeMessageSystemReminderText(contentsResult); ok {
+					partJSON := []byte(`{}`)
+					partJSON, _ = sjson.SetBytes(partJSON, "text", reminderText)
+					clientContentJSON, _ = sjson.SetRawBytes(clientContentJSON, "parts.-1", partJSON)
+					contentsJSON, _ = sjson.SetRawBytes(contentsJSON, "-1", clientContentJSON)
+					hasContents = true
+				}
+				continue
+			}
 			if contentsResult.IsArray() {
 				contentResults := contentsResult.Array()
 				numContents := len(contentResults)

internal/translator/antigravity/claude/antigravity_claude_request_test.go

@@ -162,13 +162,13 @@ func TestConvertClaudeRequestToAntigravity_ConvertsMessageSystemRoleToUserConten
 	if got := contents[1].Get("role").String(); got != "user" {
 		t.Fatalf("Expected message-level system content to be downgraded to user role, got %q", got)
 	}
-	if got := contents[1].Get("parts.0.text").String(); got != "String mid-conversation rule" {
+	if got := contents[1].Get("parts.0.text").String(); got != "<system-reminder>\nString mid-conversation rule\n</system-reminder>" {
 		t.Fatalf("Unexpected string message-level system content text: %q", got)
 	}
 	if got := contents[2].Get("role").String(); got != "user" {
 		t.Fatalf("Expected array message-level system content to be downgraded to user role, got %q", got)
 	}
-	if got := contents[2].Get("parts.0.text").String(); got != "Array mid-conversation rule" {
+	if got := contents[2].Get("parts.0.text").String(); got != "<system-reminder>\nArray mid-conversation rule\n</system-reminder>" {
 		t.Fatalf("Unexpected array message-level system content text: %q", got)
 	}
 

internal/translator/codex/claude/codex_claude_request.go

@@ -14,6 +14,7 @@ import (
 
 	sigcompat "github.com/router-for-me/CLIProxyAPI/v7/internal/signature"
 	"github.com/router-for-me/CLIProxyAPI/v7/internal/thinking"
+	translatorcommon "github.com/router-for-me/CLIProxyAPI/v7/internal/translator/common"
 	"github.com/router-for-me/CLIProxyAPI/v7/internal/util"
 	"github.com/tidwall/gjson"
 	"github.com/tidwall/sjson"
@@ -88,7 +89,12 @@ func ConvertClaudeRequestToCodex(modelName string, inputRawJSON []byte, _ bool)
 			messageResult := messageResults[i]
 			messageRole := messageResult.Get("role").String()
 			if messageRole == "system" {
-				messageRole = "developer"
+				if reminderText, ok := translatorcommon.ClaudeMessageSystemReminderText(messageResult.Get("content")); ok {
+					message := []byte(`{"type":"message","role":"user","content":[{"type":"input_text","text":""}]}`)
+					message, _ = sjson.SetBytes(message, "content.0.text", reminderText)
+					template, _ = sjson.SetRawBytes(template, "input.-1", message)
+				}
+				continue
 			}
 
 			newMessage := func() []byte {

internal/translator/codex/claude/codex_claude_request_test.go

@@ -43,7 +43,7 @@ func TestConvertClaudeRequestToCodex_SystemMessageScenarios(t *testing.T) {
 			wantTexts:        []string{"Be helpful"},
 		},
 		{
-			name: "System role in messages",
+			name: "Message system role does not become developer",
 			inputJSON: `{
 				"model": "claude-3-opus",
 				"messages": [
@@ -51,8 +51,7 @@ func TestConvertClaudeRequestToCodex_SystemMessageScenarios(t *testing.T) {
 					{"role": "user", "content": "hello"}
 				]
 			}`,
-			wantHasDeveloper: true,
-			wantTexts:        []string{"Follow the project instructions"},
+			wantHasDeveloper: false,
 		},
 		{
 			name: "Array system field with filtered billing header",
@@ -102,6 +101,41 @@ func TestConvertClaudeRequestToCodex_SystemMessageScenarios(t *testing.T) {
 	}
 }
 
+func TestConvertClaudeRequestToCodex_MessageSystemRoleWrapsAsUserReminder(t *testing.T) {
+	inputJSON := `{
+		"model": "claude-3-opus",
+		"system": [{"type": "text", "text": "Top-level rules"}],
+		"messages": [
+			{"role": "user", "content": "hello"},
+			{"role": "system", "content": "Follow the project instructions"},
+			{"role": "assistant", "content": [{"type": "text", "text": "ok"}]},
+			{"role": "system", "content": [{"type": "text", "text": "Use the current repo"}]}
+		]
+	}`
+
+	result := ConvertClaudeRequestToCodex("test-model", []byte(inputJSON), false)
+	inputs := gjson.GetBytes(result, "input").Array()
+	if len(inputs) != 5 {
+		t.Fatalf("got %d input items, want 5: %s", len(inputs), gjson.GetBytes(result, "input").Raw)
+	}
+
+	if got := inputs[0].Get("role").String(); got != "developer" {
+		t.Fatalf("top-level system role = %q, want developer", got)
+	}
+	if got := inputs[2].Get("role").String(); got != "user" {
+		t.Fatalf("message-level system role = %q, want user", got)
+	}
+	if got := inputs[2].Get("content.0.text").String(); got != "<system-reminder>\nFollow the project instructions\n</system-reminder>" {
+		t.Fatalf("unexpected first reminder text: %q", got)
+	}
+	if got := inputs[4].Get("role").String(); got != "user" {
+		t.Fatalf("array message-level system role = %q, want user", got)
+	}
+	if got := inputs[4].Get("content.0.text").String(); got != "<system-reminder>\nUse the current repo\n</system-reminder>" {
+		t.Fatalf("unexpected second reminder text: %q", got)
+	}
+}
+
 func TestConvertClaudeRequestToCodex_ParallelToolCalls(t *testing.T) {
 	tests := []struct {
 		name                  string

internal/translator/common/claude_system.go

@@ -0,0 +1,56 @@
+package common
+
+import (
+	"strings"
+
+	"github.com/router-for-me/CLIProxyAPI/v7/internal/util"
+	"github.com/tidwall/gjson"
+)
+
+const (
+	claudeSystemReminderStart = "<system-reminder>"
+	claudeSystemReminderEnd   = "</system-reminder>"
+)
+
+// ClaudeMessageSystemReminderText converts a Claude message-level system value
+// into ordinary user-visible reminder text for non-Claude upstream formats.
+func ClaudeMessageSystemReminderText(content gjson.Result) (string, bool) {
+	parts := claudeSystemTextParts(content)
+	if len(parts) == 0 {
+		return "", false
+	}
+	text := strings.Join(parts, "\n")
+	if strings.TrimSpace(text) == "" {
+		return "", false
+	}
+	return claudeSystemReminderStart + "\n" + text + "\n" + claudeSystemReminderEnd, true
+}
+
+func claudeSystemTextParts(content gjson.Result) []string {
+	if !content.Exists() {
+		return nil
+	}
+	if content.Type == gjson.String {
+		text := content.String()
+		if text == "" || util.IsClaudeCodeAttributionSystemText(text) {
+			return nil
+		}
+		return []string{text}
+	}
+	if !content.IsArray() {
+		return nil
+	}
+	parts := make([]string, 0)
+	content.ForEach(func(_, item gjson.Result) bool {
+		if item.Get("type").String() != "text" {
+			return true
+		}
+		text := item.Get("text").String()
+		if text == "" || util.IsClaudeCodeAttributionSystemText(text) {
+			return true
+		}
+		parts = append(parts, text)
+		return true
+	})
+	return parts
+}

internal/translator/gemini/claude/gemini_claude_request.go

@@ -10,6 +10,7 @@ import (
 	"strings"
 
 	"github.com/router-for-me/CLIProxyAPI/v7/internal/registry"
+	translatorcommon "github.com/router-for-me/CLIProxyAPI/v7/internal/translator/common"
 	"github.com/router-for-me/CLIProxyAPI/v7/internal/translator/gemini/common"
 	"github.com/router-for-me/CLIProxyAPI/v7/internal/util"
 	"github.com/tidwall/gjson"
@@ -79,6 +80,15 @@ func ConvertClaudeRequestToGemini(modelName string, inputRawJSON []byte, _ bool)
 			contentJSON, _ = sjson.SetBytes(contentJSON, "role", role)
 
 			contentsResult := messageResult.Get("content")
+			if roleResult.String() == "system" {
+				if reminderText, ok := translatorcommon.ClaudeMessageSystemReminderText(contentsResult); ok {
+					part := []byte(`{"text":""}`)
+					part, _ = sjson.SetBytes(part, "text", reminderText)
+					contentJSON, _ = sjson.SetRawBytes(contentJSON, "parts.-1", part)
+					out, _ = sjson.SetRawBytes(out, "contents.-1", contentJSON)
+				}
+				return true
+			}
 			if contentsResult.IsArray() {
 				contentsResult.ForEach(func(_, contentResult gjson.Result) bool {
 					switch contentResult.Get("type").String() {

internal/translator/gemini/claude/gemini_claude_request_test.go

@@ -134,13 +134,13 @@ func TestConvertClaudeRequestToGemini_ConvertsMessageSystemRoleToUserContent(t *
 	if got := contents[1].Get("role").String(); got != "user" {
 		t.Fatalf("Expected message-level string system content to be downgraded to user role, got %q", got)
 	}
-	if got := contents[1].Get("parts.0.text").String(); got != "String mid-conversation rule" {
+	if got := contents[1].Get("parts.0.text").String(); got != "<system-reminder>\nString mid-conversation rule\n</system-reminder>" {
 		t.Fatalf("Unexpected string message-level system content text: %q", got)
 	}
 	if got := contents[2].Get("role").String(); got != "user" {
 		t.Fatalf("Expected message-level array system content to be downgraded to user role, got %q", got)
 	}
-	if got := contents[2].Get("parts.0.text").String(); got != "Array mid-conversation rule" {
+	if got := contents[2].Get("parts.0.text").String(); got != "<system-reminder>\nArray mid-conversation rule\n</system-reminder>" {
 		t.Fatalf("Unexpected array message-level system content text: %q", got)
 	}
 

internal/translator/openai/claude/openai_claude_request.go

@@ -10,6 +10,7 @@ import (
 
 	sigcompat "github.com/router-for-me/CLIProxyAPI/v7/internal/signature"
 	"github.com/router-for-me/CLIProxyAPI/v7/internal/thinking"
+	translatorcommon "github.com/router-for-me/CLIProxyAPI/v7/internal/translator/common"
 	"github.com/router-for-me/CLIProxyAPI/v7/internal/util"
 	"github.com/tidwall/gjson"
 	"github.com/tidwall/sjson"
@@ -131,14 +132,6 @@ func ConvertClaudeRequestToOpenAI(modelName string, inputRawJSON []byte, stream
 	if system := root.Get("system"); system.Exists() {
 		appendSystemContent(system)
 	}
-	if messages := root.Get("messages"); messages.Exists() && messages.IsArray() {
-		messages.ForEach(func(_, message gjson.Result) bool {
-			if message.Get("role").String() == "system" {
-				appendSystemContent(message.Get("content"))
-			}
-			return true
-		})
-	}
 	// Only add system message if it has content
 	if hasSystemContent {
 		messagesJSON, _ = sjson.SetRawBytes(messagesJSON, "-1", systemMsgJSON)
@@ -148,10 +141,15 @@ func ConvertClaudeRequestToOpenAI(modelName string, inputRawJSON []byte, stream
 	if messages := root.Get("messages"); messages.Exists() && messages.IsArray() {
 		messages.ForEach(func(_, message gjson.Result) bool {
 			role := message.Get("role").String()
+			contentResult := message.Get("content")
 			if role == "system" {
+				if reminderText, ok := translatorcommon.ClaudeMessageSystemReminderText(contentResult); ok {
+					msgJSON := []byte(`{"role":"user","content":[{"type":"text","text":""}]}`)
+					msgJSON, _ = sjson.SetBytes(msgJSON, "content.0.text", reminderText)
+					messagesJSON, _ = sjson.SetRawBytes(messagesJSON, "-1", msgJSON)
+				}
 				return true
 			}
-			contentResult := message.Get("content")
 
 			// Handle content
 			if contentResult.Exists() && contentResult.IsArray() {

internal/translator/openai/claude/openai_claude_request_test.go

@@ -357,7 +357,7 @@ func validGPTChatReasoningSignature() string {
 	return base64.URLEncoding.EncodeToString(raw)
 }
 
-func TestConvertClaudeRequestToOpenAI_MidConversationSystemMessagesMoveToInitialSystem(t *testing.T) {
+func TestConvertClaudeRequestToOpenAI_MessageSystemRoleWrapsAsUserReminder(t *testing.T) {
 	inputJSON := `{
 		"model": "claude-sonnet-4-5",
 		"system": [{"type": "text", "text": "Top-level rules"}],
@@ -374,27 +374,30 @@ func TestConvertClaudeRequestToOpenAI_MidConversationSystemMessagesMoveToInitial
 	resultJSON := gjson.ParseBytes(result)
 	messages := resultJSON.Get("messages").Array()
 
-	if len(messages) != 4 {
-		t.Fatalf("Expected 4 messages, got %d: %s", len(messages), resultJSON.Get("messages").Raw)
+	if len(messages) != 6 {
+		t.Fatalf("Expected 6 messages, got %d: %s", len(messages), resultJSON.Get("messages").Raw)
 	}
 
 	roles := make([]string, 0, len(messages))
 	for _, message := range messages {
 		roles = append(roles, message.Get("role").String())
 	}
-	if got, want := roles, []string{"system", "user", "assistant", "user"}; fmt.Sprintf("%v", got) != fmt.Sprintf("%v", want) {
+	if got, want := roles, []string{"system", "user", "user", "assistant", "user", "user"}; fmt.Sprintf("%v", got) != fmt.Sprintf("%v", want) {
 		t.Fatalf("Unexpected message roles: got %v, want %v", got, want)
 	}
 
 	systemContent := messages[0].Get("content").Array()
-	if len(systemContent) != 3 {
-		t.Fatalf("Expected 3 system content items, got %d: %s", len(systemContent), messages[0].Get("content").Raw)
+	if len(systemContent) != 1 {
+		t.Fatalf("Expected only top-level system content, got %d items: %s", len(systemContent), messages[0].Get("content").Raw)
 	}
-	wantTexts := []string{"Top-level rules", "String mid-conversation rule", "Array mid-conversation rule"}
-	for i, want := range wantTexts {
-		if got := systemContent[i].Get("text").String(); got != want {
-			t.Fatalf("system content[%d] = %q, want %q", i, got, want)
-		}
+	if got := systemContent[0].Get("text").String(); got != "Top-level rules" {
+		t.Fatalf("system content = %q, want Top-level rules", got)
+	}
+	if got := messages[2].Get("content.0.text").String(); got != "<system-reminder>\nString mid-conversation rule\n</system-reminder>" {
+		t.Fatalf("unexpected string reminder text: %q", got)
+	}
+	if got := messages[4].Get("content.0.text").String(); got != "<system-reminder>\nArray mid-conversation rule\n</system-reminder>" {
+		t.Fatalf("unexpected array reminder text: %q", got)
 	}
 }