Sub2API v1.0 - AI API 网关（二开初始版本，基于上游 Wei-Shaw/sub2api）

backend/internal/pkg/openai/constants.go

@@ -0,0 +1,104 @@
+// Package openai provides helpers and types for OpenAI API integration.
+package openai
+
+import (
+	_ "embed"
+	"strings"
+)
+
+// Model represents an OpenAI model
+type Model struct {
+	ID          string `json:"id"`
+	Object      string `json:"object"`
+	Created     int64  `json:"created"`
+	OwnedBy     string `json:"owned_by"`
+	Type        string `json:"type"`
+	DisplayName string `json:"display_name"`
+}
+
+// DefaultModels OpenAI models list
+var DefaultModels = []Model{
+	{ID: "gpt-5.6-sol", Object: "model", Created: 1780876800, OwnedBy: "openai", Type: "model", DisplayName: "GPT-5.6 Sol"},
+	{ID: "gpt-5.6", Object: "model", Created: 1780876800, OwnedBy: "openai", Type: "model", DisplayName: "GPT-5.6 (Sol)"},
+	{ID: "gpt-5.6-terra", Object: "model", Created: 1780876800, OwnedBy: "openai", Type: "model", DisplayName: "GPT-5.6 Terra"},
+	{ID: "gpt-5.6-luna", Object: "model", Created: 1780876800, OwnedBy: "openai", Type: "model", DisplayName: "GPT-5.6 Luna"},
+	{ID: "gpt-5.5", Object: "model", Created: 1776873600, OwnedBy: "openai", Type: "model", DisplayName: "GPT-5.5"},
+	{ID: "gpt-5.4", Object: "model", Created: 1738368000, OwnedBy: "openai", Type: "model", DisplayName: "GPT-5.4"},
+	{ID: "gpt-5.4-mini", Object: "model", Created: 1738368000, OwnedBy: "openai", Type: "model", DisplayName: "GPT-5.4 Mini"},
+	{ID: "gpt-5.3-codex-spark", Object: "model", Created: 1735689600, OwnedBy: "openai", Type: "model", DisplayName: "GPT-5.3 Codex Spark"},
+	{ID: "codex-auto-review", Object: "model", Created: 1776902400, OwnedBy: "openai", Type: "model", DisplayName: "Codex Auto Review"},
+	{ID: "gpt-5.2", Object: "model", Created: 1733875200, OwnedBy: "openai", Type: "model", DisplayName: "GPT-5.2"},
+	{ID: "gpt-image-1", Object: "model", Created: 1733875200, OwnedBy: "openai", Type: "model", DisplayName: "GPT Image 1"},
+	{ID: "gpt-image-1.5", Object: "model", Created: 1735689600, OwnedBy: "openai", Type: "model", DisplayName: "GPT Image 1.5"},
+	{ID: "gpt-image-2", Object: "model", Created: 1738368000, OwnedBy: "openai", Type: "model", DisplayName: "GPT Image 2"},
+}
+
+// DefaultModelIDs returns the default model ID list
+func DefaultModelIDs() []string {
+	ids := make([]string, len(DefaultModels))
+	for i, m := range DefaultModels {
+		ids[i] = m.ID
+	}
+	return ids
+}
+
+// DefaultTestModel default model for testing OpenAI accounts
+const DefaultTestModel = "gpt-5.4"
+
+// CodexUsageProbeModel is the model used for OAuth Codex usage probes.
+const CodexUsageProbeModel = "codex-auto-review"
+
+// DefaultInstructions default instructions for non-Codex CLI requests.
+// 内容为真实 Codex CLI 的 GPT-5-Codex base prompt（codex 系模型默认）。
+//
+//go:embed instructions.txt
+var DefaultInstructions string
+
+// instructionsGPT51 / instructionsGPT52 / instructionsGPT55 为 gpt-5.1 / gpt-5.2 / gpt-5.5
+// 非 codex 模型对应的真实 Codex 编码 agent base prompt，用于模型感知的 instructions 选择。
+// GPT-5.5 同时作为最新版本的 fallback（覆盖 5.3 / 5.4 等未单独维护 prompt 的版本）。
+//
+//go:embed instructions_gpt5_1.txt
+var instructionsGPT51 string
+
+//go:embed instructions_gpt5_2.txt
+var instructionsGPT52 string
+
+//go:embed instructions_gpt5_5.txt
+var instructionsGPT55 string
+
+// latestCodexInstructions 返回当前已知最新版本的 Codex base instructions，
+// 当前为 GPT-5.5；若 5.5 prompt 意外为空则回退到 DefaultInstructions 保证非空。
+func latestCodexInstructions() string {
+	if v := strings.TrimSpace(instructionsGPT55); v != "" {
+		return instructionsGPT55
+	}
+	return DefaultInstructions
+}
+
+// CodexBaseInstructionsForModel 按模型返回最匹配的真实 Codex base instructions：
+//   - 含 "codex" 的模型（gpt-5-codex / gpt-5.x-codex / codex-max / spark 等）→ GPT-5-Codex prompt
+//   - gpt-5.5 系非 codex 模型 → GPT-5.5 prompt
+//   - gpt-5.2 系非 codex 模型 → GPT-5.2 prompt
+//   - gpt-5.1 系非 codex 模型 → GPT-5.1 prompt
+//   - 其它（含 gpt-5.3 / gpt-5.4 / 裸 gpt-5 / 未知模型）→ 回退到最新版本（当前 GPT-5.5）
+//
+// 任一专用 prompt 意外为空时回退链最终落到 DefaultInstructions，保证返回非空。
+func CodexBaseInstructionsForModel(model string) string {
+	m := strings.ToLower(strings.TrimSpace(model))
+	switch {
+	case strings.Contains(m, "codex"):
+		return DefaultInstructions
+	case strings.HasPrefix(m, "gpt-5.5"):
+		return latestCodexInstructions()
+	case strings.HasPrefix(m, "gpt-5.2"):
+		if v := strings.TrimSpace(instructionsGPT52); v != "" {
+			return instructionsGPT52
+		}
+	case strings.HasPrefix(m, "gpt-5.1"):
+		if v := strings.TrimSpace(instructionsGPT51); v != "" {
+			return instructionsGPT51
+		}
+	}
+	return latestCodexInstructions()
+}