fix: /response端点移除强制注入大量instructions内容

backend/internal/service/openai_codex_transform.go

 package service
 
 import (
-	_ "embed"
 	"strings"
 )
 
-//go:embed prompts/codex_cli_instructions.md
-var codexCLIInstructions string
-
 var codexModelMap = map[string]string{
 	"gpt-5.4":                    "gpt-5.4",
 	"gpt-5.4-none":               "gpt-5.4",
@@ -230,72 +226,13 @@ func getNormalizedCodexModel(modelID string) string {
 	return ""
 }
 
-func getOpenCodeCodexHeader() string {
-	// 兼容保留：历史上这里会从 opencode 仓库拉取 codex_header.txt。
-	// 现在我们与 Codex CLI 一致，直接使用仓库内置的 instructions，避免读写缓存与外网依赖。
-	return getCodexCLIInstructions()
-}
-
-func getCodexCLIInstructions() string {
-	return codexCLIInstructions
-}
-
-func GetOpenCodeInstructions() string {
-	return getOpenCodeCodexHeader()
-}
-
-// GetCodexCLIInstructions 返回内置的 Codex CLI 指令内容。
-func GetCodexCLIInstructions() string {
-	return getCodexCLIInstructions()
-}
-
-// applyInstructions 处理 instructions 字段
-// isCodexCLI=true: 仅补充缺失的 instructions（使用内置 Codex CLI 指令）
-// isCodexCLI=false: 优先使用内置 Codex CLI 指令覆盖
+// applyInstructions 处理 instructions 字段：仅在 instructions 为空时填充默认值。
 func applyInstructions(reqBody map[string]any, isCodexCLI bool) bool {
-	if isCodexCLI {
-		return applyCodexCLIInstructions(reqBody)
-	}
-	return applyOpenCodeInstructions(reqBody)
-}
-
-// applyCodexCLIInstructions 为 Codex CLI 请求补充缺失的 instructions
-// 仅在 instructions 为空时添加内置 Codex CLI 指令（不依赖 opencode 缓存/回源）
-func applyCodexCLIInstructions(reqBody map[string]any) bool {
 	if !isInstructionsEmpty(reqBody) {
-		return false // 已有有效 instructions，不修改
-	}
-
-	instructions := strings.TrimSpace(getCodexCLIInstructions())
-	if instructions != "" {
-		reqBody["instructions"] = instructions
-		return true
-	}
-
 		return false
-}
-
-// applyOpenCodeInstructions 为非 Codex CLI 请求应用内置 Codex CLI 指令（兼容历史函数名）
-// 优先使用内置 Codex CLI 指令覆盖
-func applyOpenCodeInstructions(reqBody map[string]any) bool {
-	instructions := strings.TrimSpace(getOpenCodeCodexHeader())
-	existingInstructions, _ := reqBody["instructions"].(string)
-	existingInstructions = strings.TrimSpace(existingInstructions)
-
-	if instructions != "" {
-		if existingInstructions != instructions {
-			reqBody["instructions"] = instructions
-			return true
 	}
-	} else if existingInstructions == "" {
-		codexInstructions := strings.TrimSpace(getCodexCLIInstructions())
-		if codexInstructions != "" {
-			reqBody["instructions"] = codexInstructions
+	reqBody["instructions"] = "You are a helpful coding assistant."
 	return true
-		}
-	}
-
-	return false
 }
 
 // isInstructionsEmpty 检查 instructions 字段是否为空

backend/internal/service/openai_codex_transform_test.go

@@ -234,20 +234,19 @@ func TestApplyCodexOAuthTransform_CodexCLI_SuppliesDefaultWhenEmpty(t *testing.T
 	require.True(t, result.Modified)
 }
 
-func TestApplyCodexOAuthTransform_NonCodexCLI_OverridesInstructions(t *testing.T) {
-	// 非 Codex CLI 场景：使用内置 Codex CLI 指令覆盖
+func TestApplyCodexOAuthTransform_NonCodexCLI_PreservesExistingInstructions(t *testing.T) {
+	// 非 Codex CLI 场景：已有 instructions 时保留客户端的值，不再覆盖
 
 	reqBody := map[string]any{
 		"model":        "gpt-5.1",
 		"instructions": "old instructions",
 	}
 
-	result := applyCodexOAuthTransform(reqBody, false, false) // isCodexCLI=false
+	applyCodexOAuthTransform(reqBody, false, false) // isCodexCLI=false
 
 	instructions, ok := reqBody["instructions"].(string)
 	require.True(t, ok)
-	require.NotEqual(t, "old instructions", instructions)
-	require.True(t, result.Modified)
+	require.Equal(t, "old instructions", instructions)
 }
 
 func TestIsInstructionsEmpty(t *testing.T) {

backend/internal/service/openai_gateway_service.go

@@ -1597,13 +1597,11 @@ func (s *OpenAIGatewayService) Forward(ctx context.Context, c *gin.Context, acco
 		patchDisabled = true
 	}
 
-	// 非透传模式下，保持历史行为：非 Codex CLI 请求在 instructions 为空时注入默认指令。
-	if !isCodexCLI && isInstructionsEmpty(reqBody) {
-		if instructions := strings.TrimSpace(GetOpenCodeInstructions()); instructions != "" {
-			reqBody["instructions"] = instructions
+	// 非透传模式下，instructions 为空时注入默认指令。
+	if isInstructionsEmpty(reqBody) {
+		reqBody["instructions"] = "You are a helpful coding assistant."
 		bodyModified = true
-			markPatchSet("instructions", instructions)
-		}
+		markPatchSet("instructions", "You are a helpful coding assistant.")
 	}
 
 	// 对所有请求执行模型映射（包含 Codex CLI）。