feat (auth): CLI OAuth supports pasting callback URLs to complete login

- Added callback URL resolution and terminal prompt logic
  - Codex/Claude/iFlow/Antigravity/Gemini login supports callback URL or local callback completion
  - Update Gemini login option signature and manager call
  - CLI default prompt function is compatible with null input to continue waiting

internal/cmd/anthropic_login.go

@@ -24,12 +24,17 @@ func DoClaudeLogin(cfg *config.Config, options *LoginOptions) {
 		options = &LoginOptions{}
 	}
 
+	promptFn := options.Prompt
+	if promptFn == nil {
+		promptFn = defaultProjectPrompt()
+	}
+
 	manager := newAuthManager()
 
 	authOpts := &sdkAuth.LoginOptions{
 		NoBrowser: options.NoBrowser,
 		Metadata:  map[string]string{},
-		Prompt:    options.Prompt,
+		Prompt:    promptFn,
 	}
 
 	_, savedPath, err := manager.Login(context.Background(), "claude", cfg, authOpts)

internal/cmd/antigravity_login.go

@@ -15,11 +15,16 @@ func DoAntigravityLogin(cfg *config.Config, options *LoginOptions) {
 		options = &LoginOptions{}
 	}
 
+	promptFn := options.Prompt
+	if promptFn == nil {
+		promptFn = defaultProjectPrompt()
+	}
+
 	manager := newAuthManager()
 	authOpts := &sdkAuth.LoginOptions{
 		NoBrowser: options.NoBrowser,
 		Metadata:  map[string]string{},
-		Prompt:    options.Prompt,
+		Prompt:    promptFn,
 	}
 
 	record, savedPath, err := manager.Login(context.Background(), "antigravity", cfg, authOpts)

internal/cmd/iflow_login.go

@@ -20,13 +20,7 @@ func DoIFlowLogin(cfg *config.Config, options *LoginOptions) {
 
 	promptFn := options.Prompt
 	if promptFn == nil {
-		promptFn = func(prompt string) (string, error) {
-			fmt.Println()
-			fmt.Println(prompt)
-			var value string
-			_, err := fmt.Scanln(&value)
-			return value, err
-		}
+		promptFn = defaultProjectPrompt()
 	}
 
 	authOpts := &sdkAuth.LoginOptions{

internal/cmd/login.go

@@ -55,11 +55,17 @@ func DoLogin(cfg *config.Config, projectID string, options *LoginOptions) {
 
 	ctx := context.Background()
 
+	promptFn := options.Prompt
+	if promptFn == nil {
+		promptFn = defaultProjectPrompt()
+		options.Prompt = promptFn
+	}
+
 	loginOpts := &sdkAuth.LoginOptions{
 		NoBrowser: options.NoBrowser,
 		ProjectID: strings.TrimSpace(projectID),
 		Metadata:  map[string]string{},
-		Prompt:    options.Prompt,
+		Prompt:    promptFn,
 	}
 
 	authenticator := sdkAuth.NewGeminiAuthenticator()
@@ -76,7 +82,10 @@ func DoLogin(cfg *config.Config, projectID string, options *LoginOptions) {
 	}
 
 	geminiAuth := gemini.NewGeminiAuth()
-	httpClient, errClient := geminiAuth.GetAuthenticatedClient(ctx, storage, cfg, options.NoBrowser)
+	httpClient, errClient := geminiAuth.GetAuthenticatedClient(ctx, storage, cfg, &gemini.WebLoginOptions{
+		NoBrowser: options.NoBrowser,
+		Prompt:    promptFn,
+	})
 	if errClient != nil {
 		log.Errorf("Gemini authentication failed: %v", errClient)
 		return
@@ -90,11 +99,6 @@ func DoLogin(cfg *config.Config, projectID string, options *LoginOptions) {
 		return
 	}
 
-	promptFn := options.Prompt
-	if promptFn == nil {
-		promptFn = defaultProjectPrompt()
-	}
-
 	selectedProjectID := promptForProjectSelection(projects, strings.TrimSpace(projectID), promptFn)
 	projectSelections, errSelection := resolveProjectSelections(selectedProjectID, projects)
 	if errSelection != nil {

internal/cmd/openai_login.go

@@ -35,12 +35,17 @@ func DoCodexLogin(cfg *config.Config, options *LoginOptions) {
 		options = &LoginOptions{}
 	}
 
+	promptFn := options.Prompt
+	if promptFn == nil {
+		promptFn = defaultProjectPrompt()
+	}
+
 	manager := newAuthManager()
 
 	authOpts := &sdkAuth.LoginOptions{
 		NoBrowser: options.NoBrowser,
 		Metadata:  map[string]string{},
-		Prompt:    options.Prompt,
+		Prompt:    promptFn,
 	}
 
 	_, savedPath, err := manager.Login(context.Background(), "codex", cfg, authOpts)