docs: document plugin program cli helpers

src/cli/program/build-program.ts

@@ -1,3 +1,4 @@
+// Builds the root Commander program, context, help, hooks, and command registry.
 import process from "node:process";
 import { Command } from "commander";
 import { registerProgramCommands } from "./command-registry.js";

src/cli/program/command-registry-core.ts

@@ -1,3 +1,4 @@
+// Core command registry that lazily imports command groups based on parsed argv.
 import type { Command } from "commander";
 import { resolveCliArgvInvocation } from "../argv-invocation.js";
 import { shouldRegisterPrimaryCommandOnly } from "../command-registration-policy.js";
@@ -142,6 +143,7 @@ const coreEntrySpecs: readonly CommandGroupDescriptorSpec<
 ];
 
 function resolveCoreCommandGroups(ctx: ProgramContext, argv: string[]): CommandGroupEntry[] {
+  // Descriptor metadata and import specs stay separate so help can stay cheap.
   return buildCommandGroupEntries(
     getCoreCliCommandDescriptors(),
     coreEntrySpecs,

src/cli/program/config-guard.ts

@@ -1,3 +1,4 @@
+// CLI config readiness guard, legacy-state migration routing, and invalid-config allowances.
 import fs from "node:fs";
 import os from "node:os";
 import path from "node:path";
@@ -97,6 +98,7 @@ function hasBundledChannelLegacyStateMigrationInputs(stateDir: string, oauthDir:
 }
 
 function hasLegacyStateMigrationInputs(): boolean {
+  // Only run migration prompts when old state actually exists in known legacy locations.
   const stateDir = resolveStateDir(process.env, os.homedir);
   const oauthDir = resolveOAuthDir(process.env, stateDir);
   if (