feat: add OpenAI image generation controls

backend/internal/service/openai_model_alias.go

@@ -0,0 +1,137 @@
+package service
+
+import "strings"
+
+func lastOpenAIModelSegment(model string) string {
+	model = strings.TrimSpace(model)
+	if model == "" {
+		return ""
+	}
+	if strings.Contains(model, "/") {
+		parts := strings.Split(model, "/")
+		model = parts[len(parts)-1]
+	}
+	return strings.TrimSpace(model)
+}
+
+func canonicalizeOpenAIModelAliasSpelling(model string) string {
+	model = strings.ToLower(lastOpenAIModelSegment(model))
+	if model == "" {
+		return ""
+	}
+
+	normalized := strings.ReplaceAll(model, "_", "-")
+	normalized = strings.Join(strings.Fields(normalized), "-")
+	for strings.Contains(normalized, "--") {
+		normalized = strings.ReplaceAll(normalized, "--", "-")
+	}
+
+	if strings.HasPrefix(normalized, "gpt5") {
+		normalized = "gpt-5" + strings.TrimPrefix(normalized, "gpt5")
+	}
+	if !strings.HasPrefix(normalized, "gpt-") && !strings.Contains(normalized, "codex") {
+		return ""
+	}
+
+	replacements := []struct {
+		from string
+		to   string
+	}{
+		{"gpt-5.4mini", "gpt-5.4-mini"},
+		{"gpt-5.4nano", "gpt-5.4-nano"},
+		{"gpt-5.3-codexspark", "gpt-5.3-codex-spark"},
+		{"gpt-5.3codexspark", "gpt-5.3-codex-spark"},
+		{"gpt-5.3codex", "gpt-5.3-codex"},
+	}
+	for _, replacement := range replacements {
+		normalized = strings.ReplaceAll(normalized, replacement.from, replacement.to)
+	}
+	return normalized
+}
+
+func normalizeKnownOpenAICodexModel(model string) string {
+	normalized := canonicalizeOpenAIModelAliasSpelling(model)
+	if normalized == "" {
+		return ""
+	}
+
+	if mapped := getNormalizedCodexModel(normalized); mapped != "" {
+		return mapped
+	}
+	if strings.HasSuffix(normalized, "-openai-compact") {
+		if mapped := getNormalizedCodexModel(strings.TrimSuffix(normalized, "-openai-compact")); mapped != "" {
+			return mapped
+		}
+	}
+
+	switch {
+	case strings.Contains(normalized, "gpt-5.5"):
+		return "gpt-5.5"
+	case strings.Contains(normalized, "gpt-5.4-mini"):
+		return "gpt-5.4-mini"
+	case strings.Contains(normalized, "gpt-5.4-nano"):
+		return "gpt-5.4-nano"
+	case strings.Contains(normalized, "gpt-5.4"):
+		return "gpt-5.4"
+	case strings.Contains(normalized, "gpt-5.2"):
+		return "gpt-5.2"
+	case strings.Contains(normalized, "gpt-5.3-codex-spark"):
+		return "gpt-5.3-codex-spark"
+	case strings.Contains(normalized, "gpt-5.3-codex"):
+		return "gpt-5.3-codex"
+	case strings.Contains(normalized, "gpt-5.3"):
+		return "gpt-5.3-codex"
+	case strings.Contains(normalized, "codex"):
+		return "gpt-5.3-codex"
+	case strings.Contains(normalized, "gpt-5"):
+		return "gpt-5.4"
+	default:
+		return ""
+	}
+}
+
+func appendUsageBillingModelCandidate(candidates []string, seen map[string]struct{}, model string) []string {
+	trimmed := strings.TrimSpace(model)
+	if trimmed == "" {
+		return candidates
+	}
+	add := func(candidate string) {
+		candidate = strings.TrimSpace(candidate)
+		if candidate == "" {
+			return
+		}
+		key := strings.ToLower(candidate)
+		if _, ok := seen[key]; ok {
+			return
+		}
+		seen[key] = struct{}{}
+		candidates = append(candidates, candidate)
+	}
+
+	add(trimmed)
+	if canonical := canonicalizeOpenAIModelAliasSpelling(trimmed); canonical != "" {
+		add(canonical)
+	}
+	if normalized := normalizeKnownOpenAICodexModel(trimmed); normalized != "" {
+		add(normalized)
+	}
+	return candidates
+}
+
+func usageBillingModelCandidates(primary string, alternates ...string) []string {
+	seen := make(map[string]struct{}, 1+len(alternates))
+	candidates := appendUsageBillingModelCandidate(nil, seen, primary)
+	for _, alternate := range alternates {
+		candidates = appendUsageBillingModelCandidate(candidates, seen, alternate)
+	}
+	return candidates
+}
+
+func firstUsageBillingModel(candidates []string) string {
+	for _, candidate := range candidates {
+		if trimmed := strings.TrimSpace(candidate); trimmed != "" {
+			return trimmed
+		}
+	}
+	return ""
+}