Embedded Signup

You are helping me integrate WhatsApp into my product using the Intelli Partner API (base URL: https://api.intelliconcierge.dev/v1). Intelli hosts Meta's embedded signup, so my app never touches Meta credentials — everything goes through my Intelli API key.

Before writing code, ask me:
1. My backend framework/language (and frontend framework if relevant).
2. Whether the hosted signup should open as a popup or a full redirect.

Environment variables (server-side only — the API key must NEVER reach the browser):
- INTELLI_API_KEY: my secret key. ik_test_... keys validate everything but never deliver; ik_live_... delivers for real.
- INTELLI_WEBHOOK_SECRET: HMAC secret for verifying incoming webhooks (from the Intelli portal, Webhooks section).

Every API call: Authorization: Bearer <INTELLI_API_KEY>. Errors are JSON {"error": {"code": "...", "message": "...", "details": {...}}}.

Implement:

A) Client onboarding (Intelli-hosted embedded signup)
1. A server endpoint that creates a signup session:
   POST /embedded-signup/sessions with body {"client_ref": "<my unique id for this customer>"}
   -> 201 {"session_id": "...", "url": "https://...", "expires_in": 600}
   Sessions are single-use, valid 10 minutes. Handle 409 code "number_already_connected": that WhatsApp number is already connected (as one of my clients, or through another provider) — show the customer a clear message.
2. Frontend: open the returned url in a popup (about 600x720). Listen for a window "message" event where event.data = {type: "intelli:whatsapp", status: "success", client_ref: "..."}. Treat it as a hint only — it is untrusted.
3. Server-side confirmation: GET /clients/<client_ref>
   -> 200 {client_ref, channel, waba_id, phone_number_id, phone_number, business_name}
   Only mark the customer as connected once this succeeds. Persist client_ref — it identifies this customer in every later call.
4. Instagram variant: POST /instagram-connect/sessions works identically (same body, same 3 steps; completion message type is "intelli:instagram"). The resulting client has channel "instagram": "to" is the Instagram-scoped user ID from webhook events, and it carries text plus image/video/audio/document — media must be a public HTTPS URL in "link" (an uploaded media "id" returns "media_link_required"), and "caption"/"filename" come back under "warnings" because an Instagram attachment has nowhere to put them. Templates, sticker, location, contacts, interactive and reaction are WhatsApp-only and return "channel_type_unsupported".

B) Sending messages (server-side)
- POST /messages/send mirrors Meta's Cloud API: {"client_ref": "...", "to": "<E.164 digits, no +>", "type": "<t>", "<t>": {...}} where <t> is one of text, image, video, audio, document, sticker, location, contacts, interactive, reaction. Examples: text needs {"body": "..."}; media types need {"link": "<public https url>"} (or an uploaded media "id"), image/video/document accept "caption", document accepts "filename"; location needs {latitude, longitude}; interactive needs Meta's interactive object ({"type": "button" | "list" | ...}); reaction needs {message_id, emoji} (empty emoji removes it).
- Template: POST /messages/send-template with {"client_ref": "...", "to": "...", "template": {"name": "...", "language": {"code": "en_US"}, "components": [...]}}
- Free-form types require an open 24h customer-service window; outside it only templates deliver.
- Success: {"success": true, "message_id": "wamid..."}. With a test key the response includes "dry_run": true and nothing is delivered.

C) Webhook receiver
- A public POST endpoint in my app; I register its URL in the Intelli portal (Webhooks section).
- Verify the X-Intelli-Signature header: "sha256=" + hex(HMAC_SHA256(INTELLI_WEBHOOK_SECRET, raw request body)), constant-time comparison, reject mismatches.
- Payload: {"event": "...", "timestamp": "...", "client_ref": "...", "phone_number": "...", ...}. Event types: message.received (has messages[]), message.status (has statuses[]), message.reaction, template.status, user.preferences.
- Respond 2xx immediately and process asynchronously; failed deliveries are retried with backoff, and events can be redelivered manually — dedupe by message id.

D) Error handling
- 401 invalid/revoked key, 403 missing scope, 404 unknown client_ref, 409 number_already_connected, 429 rate-limited (respect Retry-After), 402 subscription required.

Start with my ik_test_ key end-to-end, then switch to live. Write idiomatic, production-quality code for my stack.

You are helping me integrate Instagram DMs into my product using the Intelli Partner API (base URL: https://api.intelliconcierge.dev/v1). Intelli hosts the Instagram connect flow, so my app never touches Meta credentials — everything goes through my Intelli API key.

Before writing code, ask me:
1. My backend framework/language (and frontend framework if relevant).
2. Whether the hosted connect should open as a popup or a full redirect.

Environment variables (server-side only — the API key must NEVER reach the browser):
- INTELLI_API_KEY: my secret key. ik_test_... keys validate everything but never deliver; ik_live_... delivers for real.
- INTELLI_WEBHOOK_SECRET: HMAC secret for verifying incoming webhooks (from the Intelli portal, Webhooks section).

Every API call: Authorization: Bearer <INTELLI_API_KEY>. Errors are JSON {"error": {"code": "...", "message": "...", "details": {...}}}.

Implement:

A) Client onboarding (Intelli-hosted Instagram connect)
1. A server endpoint that creates a connect session:
   POST /instagram-connect/sessions with body {"client_ref": "<my unique id for this customer>"}
   -> 201 {"session_id": "...", "url": "https://...", "expires_in": 600}
   Sessions are single-use, valid 10 minutes. Handle 409 code "account_already_connected": that Instagram account is already connected (as one of my clients, or through another provider) — show the customer a clear message.
2. Frontend: open the returned url in a popup (about 600x720). The page walks the customer through Instagram's login/consent, then posts a window "message" event where event.data = {type: "intelli:instagram", status: "success", client_ref: "..."}. Treat it as a hint only — it is untrusted.
3. Server-side confirmation: GET /clients/<client_ref>
   -> 200 {client_ref, channel: "instagram", business_name, ...}
   Only mark the customer as connected once this succeeds. Persist client_ref.

B) Sending messages (server-side)
- POST /messages/send with {"client_ref": "...", "to": "<Instagram-scoped user ID>", "type": "text", "text": {"body": "..."}}
- "to" is the IGSID that arrives in webhook events (sender.id) — you cannot derive it from a username. Text is capped at 1000 characters.
- Media: types "image", "video", "audio" and "document" also work. Pass a public HTTPS URL, e.g. {"type": "image", "image": {"link": "https://..."}}. Instagram fetches the file itself, so an uploaded media "id" is rejected with code "media_link_required". A "caption" or "filename" has nowhere to go on an Instagram attachment: the send succeeds and the response lists it under "warnings" — send the caption as its own text message if you need it.
- Not available on Instagram (code "channel_type_unsupported"): templates, sticker, location, contacts, interactive (buttons/lists) and reaction.
- Instagram allows replies within 24 hours of the customer's last message — send outside that window and Meta rejects the call.
- Success: {"success": true, "message_id": "..."}, plus "warnings": [...] when a field could not be carried. With a test key the response includes "dry_run": true and nothing is delivered — a test key rejects exactly what a live key would.

C) Webhook receiver
- A public POST endpoint in my app; I register its URL in the Intelli portal (Webhooks section).
- Verify the X-Intelli-Signature header: "sha256=" + hex(HMAC_SHA256(INTELLI_WEBHOOK_SECRET, raw request body)), constant-time comparison, reject mismatches.
- Payload: {"event": "...", "channel": "instagram", "timestamp": "...", "client_ref": "...", ...}. Event types: message.received (has messages[] — each with sender.id = the IGSID to reply to), message.echo, message.reaction, message.read, message.postback.
- Respond 2xx immediately and process asynchronously; failed deliveries are retried with backoff, and events can be redelivered manually — dedupe by message id.

D) Error handling
- 401 invalid/revoked key, 403 missing scope, 404 unknown client_ref, 409 account_already_connected, 429 rate-limited (respect Retry-After), 402 subscription required, 400 channel_type_unsupported (type the channel does not carry), 400 media_link_required (media sent as an id instead of a URL).

Start with my ik_test_ key end-to-end, then switch to live. Write idiomatic, production-quality code for my stack.