feat(cli): Follow list changes (merge #2105)

packages/cli/src/commands/list.js

@@ -1,15 +1,34 @@
 /* global process */
 import os from 'os';
 import { E } from '@endo/far';
+import { makeRefIterator } from '@endo/daemon';
 import { withEndoHost } from '../context.js';
 
-export const list = async ({ directoryPath }) =>
+export const list = async ({ directoryPath, follow, json }) =>
   withEndoHost({ os, process }, async ({ host: party }) => {
     if (directoryPath !== undefined) {
       party = E(party).lookup(...directoryPath.split('.'));
     }
-    const petNames = await E(party).list();
-    for await (const petName of petNames) {
-      console.log(petName);
+    if (follow) {
+      const topic = await E(party).followNames();
+      const iterator = makeRefIterator(topic);
+      if (json) {
+        for await (const change of iterator) {
+          console.log(JSON.stringify(change));
+        }
+      } else {
+        for await (const change of iterator) {
+          if (change.add !== undefined) {
+            console.log(`+${change.add}`);
+          } else if (change.remove !== undefined) {
+            console.log(`-${change.remove}`);
+          }
+        }
+      }
+    } else {
+      const petNames = await E(party).list();
+      for await (const petName of petNames) {
+        console.log(petName);
+      }
     }
   });

packages/cli/src/endo.js

@@ -256,9 +256,12 @@ export const main = async rawArgs => {
   program
     .command('list [directory]')
     .description('show names known to the current or specified directory')
+    .option('-f,--follow', 'Follow updates')
+    .option('-j,--json', 'JSON format output')
     .action(async (directoryPath, cmd) => {
+      const { follow, json } = cmd.opts();
       const { list } = await import('./commands/list.js');
-      return list({ directoryPath });
+      return list({ directoryPath, follow, json });
     });
 
   program