fix(auth): improve default account hint and add reset-default command

- Change post-create hint from casual text to warning box
- Clearly state that running the command will SWITCH default account
- Add `ccs auth reset-default` command to restore original CCS behavior
- Add warnBox() UI helper for yellow-bordered warning boxes
- Update main help to show default/reset-default commands

Closes #106

src/auth/auth-commands.ts

@@ -30,6 +30,7 @@ import {
   info,
   table,
   infoBox,
+  warnBox,
 } from '../utils/ui';
 import { getClaudeCliInfo } from '../utils/claude-detector';
 import { escapeShellArg } from '../utils/shell-executor';
@@ -98,6 +99,9 @@ class AuthCommands {
     console.log(`  ${color('show <profile>', 'command')}         Show profile details`);
     console.log(`  ${color('remove <profile>', 'command')}       Remove saved profile`);
     console.log(`  ${color('default <profile>', 'command')}      Set default profile`);
+    console.log(
+      `  ${color('reset-default', 'command')}          Clear default (restore original CCS)`
+    );
     console.log('');
     console.log(subheader('Examples'));
     console.log(`  ${dim('# Create & login to work profile')}`);
@@ -106,6 +110,9 @@ class AuthCommands {
     console.log(`  ${dim('# Set work as default')}`);
     console.log(`  ${color('ccs auth default work', 'command')}`);
     console.log('');
+    console.log(`  ${dim('# Restore original CCS behavior')}`);
+    console.log(`  ${color('ccs auth reset-default', 'command')}`);
+    console.log('');
     console.log(`  ${dim('# List all profiles')}`);
     console.log(`  ${color('ccs auth list', 'command')}`);
     console.log('');
@@ -252,8 +259,17 @@ class AuthCommands {
           console.log(header('Usage'));
           console.log(`  ${color(`ccs ${profileName} "your prompt here"`, 'command')}`);
           console.log('');
-          console.log('To set as default (so you can use just "ccs"):');
-          console.log(`  ${color(`ccs auth default ${profileName}`, 'command')}`);
+          console.log(
+            warnBox(
+              `Running the command below will SWITCH your default\n` +
+                `CCS account to "${profileName}". After this, running\n` +
+                `"ccs" without a profile name will use this account.\n\n` +
+                `  ${color(`ccs auth default ${profileName}`, 'command')}\n\n` +
+                `To restore the original default, run:\n` +
+                `  ${color('ccs auth reset-default', 'command')}`,
+              'Set as Default?'
+            )
+          );
           console.log('');
           process.exit(0);
         } else {
@@ -611,6 +627,32 @@ class AuthCommands {
     }
   }
 
+  /**
+   * Reset default profile (clear the custom default, restore original CCS behavior)
+   */
+  async handleResetDefault(): Promise<void> {
+    await initUI();
+
+    try {
+      // Use unified or legacy based on config mode
+      if (this.isUnifiedMode()) {
+        this.registry.clearDefaultUnified();
+      } else {
+        this.registry.clearDefaultProfile();
+      }
+
+      console.log(ok('Default profile cleared'));
+      console.log('');
+      console.log('CCS will now use the original behavior:');
+      console.log(`  ${dim('# Uses your primary Claude account')}`);
+      console.log(`  ${color('ccs "your prompt"', 'command')}`);
+      console.log('');
+    } catch (error) {
+      console.log(fail((error as Error).message));
+      process.exit(1);
+    }
+  }
+
   /**
    * Route auth command to appropriate handler
    */
@@ -653,6 +695,10 @@ class AuthCommands {
         await this.handleDefault(commandArgs);
         break;
 
+      case 'reset-default':
+        await this.handleResetDefault();
+        break;
+
       case 'current':
         await initUI();
         console.log(warn('Command "current" has been removed'));

src/auth/profile-registry.ts

@@ -217,6 +217,15 @@ export class ProfileRegistry {
     this._write(data);
   }
 
+  /**
+   * Clear default profile (restore original CCS behavior)
+   */
+  clearDefaultProfile(): void {
+    const data = this._read();
+    data.default = null;
+    this._write(data);
+  }
+
   /**
    * Check if profile exists
    */
@@ -284,6 +293,15 @@ export class ProfileRegistry {
     saveUnifiedConfig(config);
   }
 
+  /**
+   * Clear default profile in unified config (restore original CCS behavior)
+   */
+  clearDefaultUnified(): void {
+    const config = loadOrCreateUnifiedConfig();
+    config.default = undefined;
+    saveUnifiedConfig(config);
+  }
+
   /**
    * Check if account exists in unified config
    */

src/commands/help-command.ts

@@ -141,6 +141,8 @@ Claude Code Profile & Model Switcher`.trim();
       ['ccs auth --help', 'Show account management commands'],
       ['ccs auth create <name>', 'Create new account profile'],
       ['ccs auth list', 'List all account profiles'],
+      ['ccs auth default <name>', 'Set default profile'],
+      ['ccs auth reset-default', 'Restore original CCS default'],
     ]
   );
 

src/utils/ui.ts

@@ -301,6 +301,18 @@ export function infoBox(content: string, title?: string): string {
   });
 }
 
+/**
+ * Render warning box (yellow border)
+ */
+export function warnBox(content: string, title = 'WARNING'): string {
+  return box(content, {
+    title,
+    borderColor: 'yellow',
+    borderStyle: 'round',
+    padding: 1,
+  });
+}
+
 // =============================================================================
 // TABLE RENDERING
 // =============================================================================
@@ -613,6 +625,7 @@ export const ui = {
   box,
   errorBox,
   infoBox,
+  warnBox,
   table,
 
   // Progress