Isolate providers per client: add provider targets and a Codex-side form

internal/config/config.go

@@ -28,6 +28,13 @@ const (
 	LanguageEnglish = "en-US"
 )
 
+// Client targets. The Claude and Codex pages each manage their own
+// isolated set of providers.
+const (
+	TargetClaude = "claude"
+	TargetCodex  = "codex"
+)
+
 // Models maps requested model names onto upstream model names. The role
 // fields are matched by keyword (a request mentioning "haiku" uses Haiku);
 // Extra holds exact requested-model overrides and wins over everything.
@@ -49,6 +56,7 @@ type Provider struct {
 	Models           Models    `json:"models"`
 	EnabledForClaude bool      `json:"enabled_for_claude"`
 	EnabledForCodex  bool      `json:"enabled_for_codex"`
+	Target           string    `json:"target,omitempty"`
 	CreatedAt        time.Time `json:"created_at"`
 }
 
@@ -162,6 +170,13 @@ func (c *Config) normalize() {
 	}
 	for i := range c.Providers {
 		c.Providers[i].Models.normalize()
+		switch c.Providers[i].Target {
+		case TargetClaude, TargetCodex:
+		default:
+			// Providers created before targets existed belong to the
+			// Claude page.
+			c.Providers[i].Target = TargetClaude
+		}
 	}
 	switch c.Gateway.PortMode {
 	case PortModeAuto, PortModeFixed:
@@ -186,7 +201,7 @@ func (c *Config) clone() *Config {
 	return &out
 }
 
-func newProvider(name, preset, baseURL, apiKey string, models Models) (*Provider, error) {
+func newProvider(name, preset, baseURL, apiKey string, models Models, target string) (*Provider, error) {
 	name = strings.TrimSpace(name)
 	if name == "" {
 		return nil, errors.New("name is required")
@@ -204,6 +219,13 @@ func newProvider(name, preset, baseURL, apiKey string, models Models) (*Provider
 		return nil, errors.New("API key is required")
 	}
 	models.normalize()
+	switch target {
+	case TargetClaude, TargetCodex:
+	case "":
+		target = TargetClaude
+	default:
+		return nil, fmt.Errorf("target must be %q or %q", TargetClaude, TargetCodex)
+	}
 	return &Provider{
 		ID:        newID("p_"),
 		Name:      name,
@@ -211,6 +233,7 @@ func newProvider(name, preset, baseURL, apiKey string, models Models) (*Provider
 		BaseURL:   strings.TrimRight(baseURL, "/"),
 		APIKey:    apiKey,
 		Models:    models,
+		Target:    target,
 		CreatedAt: time.Now().UTC(),
 	}, nil
 }