fix(cli): fast-path bare channels help (#77659)

* fix(cli): fast-path bare channels help

* fix(cli): normalize channels add argv gating

* fix(cli): restore channel add completion flags

src/cli/program/parent-default-help.ts

@@ -1,5 +1,21 @@
 import type { Command } from "commander";
 
+const parentDefaultHelpCommands = new WeakSet<Command>();
+
+function outputParentHelpWithoutStartupBanner(parent: Command): void {
+  const previous = process.env.OPENCLAW_SUPPRESS_HELP_BANNER;
+  process.env.OPENCLAW_SUPPRESS_HELP_BANNER = "1";
+  try {
+    parent.outputHelp();
+  } finally {
+    if (previous === undefined) {
+      delete process.env.OPENCLAW_SUPPRESS_HELP_BANNER;
+    } else {
+      process.env.OPENCLAW_SUPPRESS_HELP_BANNER = previous;
+    }
+  }
+}
+
 /**
  * Wire a parent command so that invoking it without a subcommand prints the
  * parent's own help and exits with status `0`.
@@ -15,8 +31,13 @@ import type { Command } from "commander";
  * callers keep that ownership explicit instead of probing private internals.
  */
 export function applyParentDefaultHelpAction(parent: Command): void {
+  parentDefaultHelpCommands.add(parent);
   parent.action(() => {
-    parent.outputHelp();
+    outputParentHelpWithoutStartupBanner(parent);
     process.exitCode = 0;
   });
 }
+
+export function isParentDefaultHelpAction(parent: Command): boolean {
+  return parentDefaultHelpCommands.has(parent);
+}