## Typing indicators

`POST /send-typing-indicator`

Show the iMessage typing indicator (the three dots) to a recipient. Authenticate with a Bearer API key, same as every other endpoint.

> **iMessage only, existing conversation required**
>
> Typing indicators are iMessage-only — SMS recipients never see them. The number must already have a conversation on the sending line; there is no indicator without a prior thread.

### Request body

- `phoneNumber` (string (E.164), required) — Recipient phone number in E.164 (e.g. +15551234567). Must already have an existing conversation on the sending line.

- `lineId` (string (UUID v4)) — Optional sender line. Use the lineId from GET /get-lines. When omitted, uses the line that owns the existing conversation with this number.

The indicator auto-clears on the recipient's device after a short period or when a message arrives. The intended pattern is `send-typing-indicator` → wait about 2–4 seconds → `send-api-message`.

### Response

On success the endpoint returns HTTP `200` with `{ status: "SENT" | "ERROR", number, error_message }` — `error_message` is null when `status` is `SENT`. Auth and request-validation failures still use standard 4xx bodies with an `error` field. Treat device-level failures (`status: "ERROR"`) as fire-and-forget — do not retry.

**Request — Basic**

```bash
curl -X POST https://api.tryprojectblue.com/send-typing-indicator \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "phoneNumber": "+15551234567"
  }'
```

**Request — Humanized sending**

Show typing, wait 2–4 seconds, then send the message.

```bash
# 1. Show typing
curl -X POST https://api.tryprojectblue.com/send-typing-indicator \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"phoneNumber": "+15551234567"}'

# 2. Wait 2–4 seconds so the dots are visible
sleep 3

# 3. Send the message
curl -X POST https://api.tryprojectblue.com/send-api-message \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "message": "Hey — just following up on our conversation.",
    "phone": "+15551234567"
  }'
```

**Response — SENT**

```json
{
  "status": "SENT",
  "number": "+15551234567",
  "error_message": null
}
```

**Response — ERROR**

Fire-and-forget — do not retry on ERROR.

```json
{
  "status": "ERROR",
  "number": "+15551234567",
  "error_message": "No existing iMessage conversation with this number on the selected line"
}
```