diff --git a/plugins/kapso/skills/integrate-whatsapp/SKILL.md b/plugins/kapso/skills/integrate-whatsapp/SKILL.md
index d38dd09..c9ee1df 100644
--- a/plugins/kapso/skills/integrate-whatsapp/SKILL.md
+++ b/plugins/kapso/skills/integrate-whatsapp/SKILL.md
@@ -232,6 +232,16 @@ Send-time:
 
 Use Flows to build native WhatsApp forms. Read `references/whatsapp-flows-spec.md` before editing Flow JSON.
 
+### Prerequisite: a connected number
+
+A Flow always belongs to a connected WhatsApp number, so confirm one exists **before** starting the builder:
+
+```bash
+node scripts/list-platform-phone-numbers.mjs
+```
+
+If the list is empty, do **not** proceed into the Flow builder with an empty number selection — that is a dead end. Route the user to connect a number first via embedded signup (`kapso setup`, or generate a setup link with `POST /platform/v1/customers/:id/setup_links`), then return to create the Flow. See `references/getting-started.md` and `references/setup-links.md`. `create-flow.js` enforces this: called without `--phone-number-id`, it lists the connected numbers to pick from, or tells you to connect one first when none exist.
+
 ### Create and publish a flow
 
 1. Create flow: `node scripts/create-flow.js --phone-number-id <id> --name <name>`
diff --git a/plugins/kapso/skills/integrate-whatsapp/scripts/create-flow.js b/plugins/kapso/skills/integrate-whatsapp/scripts/create-flow.js
index d894178..eaafad6 100644
--- a/plugins/kapso/skills/integrate-whatsapp/scripts/create-flow.js
+++ b/plugins/kapso/skills/integrate-whatsapp/scripts/create-flow.js
@@ -3,11 +3,62 @@ const { parseArgs, getStringFlag, getBooleanFlag, readFlagJson } = require('./li
 const { platformRequest } = require('./lib/http');
 const { run } = require('./lib/run');
 
+function summarizeNumbers(response) {
+  const configs = response?.data;
+  if (!Array.isArray(configs)) return [];
+  return configs.map((config) => ({
+    name: config.name,
+    display_phone_number: config.display_phone_number,
+    phone_number_id: config.phone_number_id || config.id,
+    business_account_id: config.business_account_id
+  }));
+}
+
+// A Flow always belongs to a connected WhatsApp number. When the caller did not
+// pass one, look at what is actually connected so we never dead-end the way an
+// empty "WhatsApp number" picker would: route to embedded signup if nothing is
+// connected, or list the choices if some are.
+async function resolvePhoneNumberGuidance() {
+  let numbers;
+  try {
+    const response = await platformRequest({
+      method: 'GET',
+      path: '/platform/v1/whatsapp/phone_numbers'
+    });
+    numbers = summarizeNumbers(response);
+  } catch {
+    // Listing failed (auth/network); fall back to the plain requirement.
+    throw new Error(
+      'Missing required flag --phone-number-id. Discover connected numbers with ' +
+        '`node scripts/list-platform-phone-numbers.mjs`; if none are connected, connect ' +
+        'a WhatsApp number first via embedded signup (`kapso setup`) before creating a Flow.'
+    );
+  }
+
+  if (numbers.length === 0) {
+    throw new Error(
+      'No WhatsApp numbers are connected, so a Flow cannot be created yet. ' +
+        'Connect a WhatsApp number first via embedded signup (`kapso setup`, or generate a ' +
+        'setup link with `POST /platform/v1/customers/:id/setup_links`), then re-run with ' +
+        '--phone-number-id <id>. See references/getting-started.md and references/setup-links.md.'
+    );
+  }
+
+  const choices = numbers
+    .map((n) => `${n.display_phone_number || n.name || 'number'} -> --phone-number-id ${n.phone_number_id}`)
+    .join('\n  ');
+  throw new Error(
+    'Missing required flag --phone-number-id. Connected numbers:\n  ' +
+      choices +
+      '\nRe-run create-flow.js with one of the phone_number_id values above.'
+  );
+}
+
 run(async () => {
   const { flags } = parseArgs(process.argv.slice(2));
   const phoneNumberId = getStringFlag(flags, 'phone-number-id') || getStringFlag(flags, 'phone_number_id');
   if (!phoneNumberId) {
-    throw new Error('Missing required flag --phone-number-id');
+    await resolvePhoneNumberGuidance();
   }
 
   const name = getStringFlag(flags, 'name');