feat(config): add support for Fork in OAuth model mappings with alias handling

Implemented `Fork` flag in `ModelNameMapping` to allow aliases as additional models while preserving the original model ID. Updated the `applyOAuthModelMappings` logic, added tests for `Fork` behavior, and updated documentation and examples accordingly.

config.example.yaml

@@ -206,6 +206,7 @@ ws-auth: false
 #   gemini-cli:
 #     - name: "gemini-2.5-pro"          # original model name under this channel
 #       alias: "g2.5p"                  # client-visible alias
+#       fork: true                      # when true, keep original and also add the alias as an extra model (default: false)
 #   vertex:
 #     - name: "gemini-2.5-pro"
 #       alias: "g2.5p"

internal/config/config.go

@@ -145,11 +145,14 @@ type RoutingConfig struct {
 	Strategy string `yaml:"strategy,omitempty" json:"strategy,omitempty"`
 }
 
-// ModelNameMapping defines a model ID rename mapping for a specific channel.
-// It maps the original model name (Name) to the client-visible alias (Alias).
+// ModelNameMapping defines a model ID mapping for a specific channel.
+// It maps the upstream model name (Name) to the client-visible alias (Alias).
+// When Fork is true, the alias is added as an additional model in listings while
+// keeping the original model ID available.
 type ModelNameMapping struct {
 	Name  string `yaml:"name" json:"name"`
 	Alias string `yaml:"alias" json:"alias"`
+	Fork  bool   `yaml:"fork,omitempty" json:"fork,omitempty"`
 }
 
 // AmpModelMapping defines a model name mapping for Amp CLI requests.
@@ -551,7 +554,7 @@ func (cfg *Config) SanitizeOAuthModelMappings() {
 			}
 			seenName[nameKey] = struct{}{}
 			seenAlias[aliasKey] = struct{}{}
-			clean = append(clean, ModelNameMapping{Name: name, Alias: alias})
+			clean = append(clean, ModelNameMapping{Name: name, Alias: alias, Fork: mapping.Fork})
 		}
 		if len(clean) > 0 {
 			out[channel] = clean

internal/config/oauth_model_mappings_test.go

@@ -0,0 +1,27 @@
+package config
+
+import "testing"
+
+func TestSanitizeOAuthModelMappings_PreservesForkFlag(t *testing.T) {
+	cfg := &Config{
+		OAuthModelMappings: map[string][]ModelNameMapping{
+			" CoDeX ": {
+				{Name: " gpt-5 ", Alias: " g5 ", Fork: true},
+				{Name: "gpt-6", Alias: "g6"},
+			},
+		},
+	}
+
+	cfg.SanitizeOAuthModelMappings()
+
+	mappings := cfg.OAuthModelMappings["codex"]
+	if len(mappings) != 2 {
+		t.Fatalf("expected 2 sanitized mappings, got %d", len(mappings))
+	}
+	if mappings[0].Name != "gpt-5" || mappings[0].Alias != "g5" || !mappings[0].Fork {
+		t.Fatalf("expected first mapping to be gpt-5->g5 fork=true, got name=%q alias=%q fork=%v", mappings[0].Name, mappings[0].Alias, mappings[0].Fork)
+	}
+	if mappings[1].Name != "gpt-6" || mappings[1].Alias != "g6" || mappings[1].Fork {
+		t.Fatalf("expected second mapping to be gpt-6->g6 fork=false, got name=%q alias=%q fork=%v", mappings[1].Name, mappings[1].Alias, mappings[1].Fork)
+	}
+}

internal/watcher/diff/oauth_model_mappings.go

@@ -80,6 +80,9 @@ func summarizeOAuthModelMappingList(list []config.ModelNameMapping) OAuthModelMa
 			continue
 		}
 		key := name + "->" + alias
+		if mapping.Fork {
+			key += "|fork"
+		}
 		if _, exists := seen[key]; exists {
 			continue
 		}

sdk/cliproxy/service.go

@@ -1231,7 +1231,13 @@ func applyOAuthModelMappings(cfg *config.Config, provider, authKind string, mode
 	if len(mappings) == 0 {
 		return models
 	}
-	forward := make(map[string]string, len(mappings))
+
+	type mappingEntry struct {
+		alias string
+		fork  bool
+	}
+
+	forward := make(map[string]mappingEntry, len(mappings))
 	for i := range mappings {
 		name := strings.TrimSpace(mappings[i].Name)
 		alias := strings.TrimSpace(mappings[i].Alias)
@@ -1245,7 +1251,7 @@ func applyOAuthModelMappings(cfg *config.Config, provider, authKind string, mode
 		if _, exists := forward[key]; exists {
 			continue
 		}
-		forward[key] = alias
+		forward[key] = mappingEntry{alias: alias, fork: mappings[i].Fork}
 	}
 	if len(forward) == 0 {
 		return models
@@ -1260,10 +1266,45 @@ func applyOAuthModelMappings(cfg *config.Config, provider, authKind string, mode
 		if id == "" {
 			continue
 		}
-		mappedID := id
-		if to, ok := forward[strings.ToLower(id)]; ok && strings.TrimSpace(to) != "" {
-			mappedID = strings.TrimSpace(to)
+		key := strings.ToLower(id)
+		entry, ok := forward[key]
+		if !ok {
+			if _, exists := seen[key]; exists {
+				continue
 			}
+			seen[key] = struct{}{}
+			out = append(out, model)
+			continue
+		}
+		mappedID := strings.TrimSpace(entry.alias)
+		if mappedID == "" {
+			if _, exists := seen[key]; exists {
+				continue
+			}
+			seen[key] = struct{}{}
+			out = append(out, model)
+			continue
+		}
+
+		if entry.fork {
+			if _, exists := seen[key]; !exists {
+				seen[key] = struct{}{}
+				out = append(out, model)
+			}
+			aliasKey := strings.ToLower(mappedID)
+			if _, exists := seen[aliasKey]; exists {
+				continue
+			}
+			seen[aliasKey] = struct{}{}
+			clone := *model
+			clone.ID = mappedID
+			if clone.Name != "" {
+				clone.Name = rewriteModelInfoName(clone.Name, id, mappedID)
+			}
+			out = append(out, &clone)
+			continue
+		}
+
 		uniqueKey := strings.ToLower(mappedID)
 		if _, exists := seen[uniqueKey]; exists {
 			continue

sdk/cliproxy/service_oauth_model_mappings_test.go

@@ -0,0 +1,58 @@
+package cliproxy
+
+import (
+	"testing"
+
+	"github.com/router-for-me/CLIProxyAPI/v6/sdk/config"
+)
+
+func TestApplyOAuthModelMappings_Rename(t *testing.T) {
+	cfg := &config.Config{
+		OAuthModelMappings: map[string][]config.ModelNameMapping{
+			"codex": {
+				{Name: "gpt-5", Alias: "g5"},
+			},
+		},
+	}
+	models := []*ModelInfo{
+		{ID: "gpt-5", Name: "models/gpt-5"},
+	}
+
+	out := applyOAuthModelMappings(cfg, "codex", "oauth", models)
+	if len(out) != 1 {
+		t.Fatalf("expected 1 model, got %d", len(out))
+	}
+	if out[0].ID != "g5" {
+		t.Fatalf("expected model id %q, got %q", "g5", out[0].ID)
+	}
+	if out[0].Name != "models/g5" {
+		t.Fatalf("expected model name %q, got %q", "models/g5", out[0].Name)
+	}
+}
+
+func TestApplyOAuthModelMappings_ForkAddsAlias(t *testing.T) {
+	cfg := &config.Config{
+		OAuthModelMappings: map[string][]config.ModelNameMapping{
+			"codex": {
+				{Name: "gpt-5", Alias: "g5", Fork: true},
+			},
+		},
+	}
+	models := []*ModelInfo{
+		{ID: "gpt-5", Name: "models/gpt-5"},
+	}
+
+	out := applyOAuthModelMappings(cfg, "codex", "oauth", models)
+	if len(out) != 2 {
+		t.Fatalf("expected 2 models, got %d", len(out))
+	}
+	if out[0].ID != "gpt-5" {
+		t.Fatalf("expected first model id %q, got %q", "gpt-5", out[0].ID)
+	}
+	if out[1].ID != "g5" {
+		t.Fatalf("expected second model id %q, got %q", "g5", out[1].ID)
+	}
+	if out[1].Name != "models/g5" {
+		t.Fatalf("expected forked model name %q, got %q", "models/g5", out[1].Name)
+	}
+}