fix(cliproxy): fix edit dialog empty model and composite guidance

- P2: Edit dialog no longer seeds empty model string
  Changed `variant.model || ''` to `variant.model ?? undefined`
  Added payload filtering to exclude undefined/empty values before API call
  Prevents unintended model overwrites when user only changes other fields

- P3: Composite --config guidance now uses variant name
  Added profileName to ExecutorConfig interface
  Error message now shows correct variant name instead of default tier provider
  e.g., "ccs cliproxy edit my-mix" instead of "ccs cliproxy edit gemini"

src/ccs.ts

@@ -611,6 +611,7 @@ async function main(): Promise<void> {
         isComposite: profileInfo.isComposite,
         compositeTiers: profileInfo.compositeTiers,
         compositeDefaultTier: profileInfo.compositeDefaultTier,
+        profileName: profileInfo.name,
       });
     } else if (profileInfo.type === 'copilot') {
       // COPILOT FLOW: GitHub Copilot subscription via copilot-api proxy

src/cliproxy/executor/index.ts

@@ -434,10 +434,11 @@ export async function execClaudeWithCLIProxy(
   if (forceConfig && supportsModelConfig(provider)) {
     // Block --config for composite variants (per-tier models in config.yaml)
     if (cfg.isComposite) {
+      const variantName = cfg.profileName || provider;
       console.log(
         warn('Composite variants use per-tier config. Edit config.yaml to change tier models.')
       );
-      console.error(`    Use "ccs cliproxy edit ${provider}" to modify composite variants`);
+      console.error(`    Use "ccs cliproxy edit ${variantName}" to modify composite variants`);
       process.exit(1);
     } else {
       await configureProviderModel(provider, true, cfg.customSettingsPath);

src/cliproxy/types.ts

@@ -193,6 +193,8 @@ export interface ExecutorConfig {
   };
   /** Composite variant: which tier is the default */
   compositeDefaultTier?: 'opus' | 'sonnet' | 'haiku';
+  /** Original profile/variant name (e.g., "my-mix" for composite variants) */
+  profileName?: string;
 }
 
 /**

ui/src/components/cliproxy/cliproxy-edit-dialog.tsx

@@ -90,16 +90,20 @@ export function CliproxyEditDialog({ variant, open, onOpenChange }: CliproxyEdit
     } else {
       singleForm.reset({
         provider: variant.provider,
-        model: variant.model || '',
+        model: variant.model ?? undefined,
-        account: variant.account || '',
+        account: variant.account ?? undefined,
       });
     }
   }, [variant, isComposite, singleForm, compositeForm]);
 
   const onSubmitSingle = async (data: SingleProviderFormData) => {
     if (!variant) return;
+    // Filter out undefined values - backend interprets undefined as "no change"
+    const payload = Object.fromEntries(
+      Object.entries(data).filter(([, v]) => v !== undefined && v !== '')
+    ) as SingleProviderFormData;
     try {
-      await updateMutation.mutateAsync({ name: variant.name, data });
+      await updateMutation.mutateAsync({ name: variant.name, data: payload });
       onOpenChange(false);
     } catch (error) {
       console.error('Failed to update variant:', error);