Update chat/session docs

fern/call-forwarding.mdx

@@ -386,6 +386,7 @@ In this mode, Vapi dials the destination number and places the caller on hold (w
   - Provide a `message` to be spoken to the operator when they answer.
   - Optionally define a `summaryPlan` that will take precedence over the message if enabled.
   - Configure a `fallbackPlan` with a message and whether to end the call if transfer fails.
+  - Optionally provide a `holdAudioUrl` to play custom hold music to the customer during the transfer.
   - Configure `voicemailDetectionType` to customize how human voice detection is performed (only applies when the provider is Google or OpenAI):
     - `"audio"` (default): Supports a wide range of machine detection including beep detection and other audio cues
     - `"transcript"`: Uses transcript-based detection with the lowest latency and faster transfer processing times
@@ -397,6 +398,7 @@ In this mode, Vapi dials the destination number and places the caller on hold (w
 "transferPlan": {
   "mode": "warm-transfer-experimental",
   "message": "Transferring a customer to you.",
+  "holdAudioUrl": "https://api.twilio.com/cowbell.mp3",
   "voicemailDetectionType": "transcript",
   "fallbackPlan": {
     "message": "Could not transfer your call, goodbye.",
@@ -436,6 +438,7 @@ Here is a full example of a `transferCall` payload using the experimental warm t
       "transferPlan": {
         "mode": "warm-transfer-experimental",
         "message": "Transferring a customer to you.",
+        "holdAudioUrl": "https://assets.example.com/music.mp3",
         "voicemailDetectionType": "audio",
         "fallbackPlan": {
           "message": "Could not transfer your call, goodbye.",
@@ -465,6 +468,7 @@ Here is a full example of a `transferCall` payload using the experimental warm t
 **Notes:**
 
 - In all warm transfer modes, the `{{transcript}}` variable contains the full transcript of the call and can be used within the `summaryPlan`.
+- The `holdAudioUrl` property (available only in `warm-transfer-experimental` mode) allows you to specify a custom MP3 file URL that will be played to the customer while they are on hold during the transfer. If not provided, the default hold audio will be used.
 - The `voicemailDetectionType` parameter allows you to optimize the detection method based on your needs:
   - Use `"transcript"` for the fastest transfer processing with lowest latency
   - Use `"audio"` (default) for comprehensive machine detection including beep detection and other audio cues

fern/chat/quickstart.mdx

@@ -318,6 +318,18 @@ We'll create a customer support chat for "TechFlow", a software company that wan
 - Server webhook events (status updates, end-of-call reports, etc.) are not supported
 </Note>
 
+## Webhook Support
+
+<Note>
+The chat API supports the following webhook events through server messaging:
+- **`chat.created`** - Triggered when a new chat conversation is initiated
+- **`chat.deleted`** - Triggered when a chat conversation is deleted
+
+To receive these webhooks, go to your Assistant page in the Dashboard and navigate to "Server Messaging" and select the events you want to receive.
+
+These webhooks are useful for tracking conversation analytics, maintaining conversation history in your own database, and triggering follow-up actions.
+</Note>
+
 ## Next Steps
 
 Take your chat bot to the next level:

fern/chat/session-management.mdx

@@ -132,6 +132,11 @@ Create a persistent session that groups multiple chats.
   </Step>
 </Steps>
 
+<Note>
+- Sessions expire automatically after 24 hours by default. After expiration, you'll need to create a new session to continue conversations.
+- Web chat widget and SMS conversations automatically manage session creation and expiration. You don't need to manually create or manage sessions when using these channels.
+</Note>
+
 Here's a TypeScript implementation of the session manager:
 
 ```typescript title="session-manager.ts"
@@ -234,6 +239,21 @@ await sendToAssistant("billing_agent", "Can you help with this?");
 
 ---
 
+## Webhook Support
+
+<Note>
+Sessions support the following webhook events through server messaging:
+- **`session.created`** - Triggered when a new session is created
+- **`session.updated`** - Triggered when a session is updated
+- **`session.deleted`** - Triggered when a session is deleted
+
+To receive these webhooks, go to your Assistant page in the Dashboard and navigate to "Server Messaging" and select the events you want to receive.
+
+These webhooks are useful for tracking session lifecycle, managing session state in your own database, and triggering workflows based on session changes.
+</Note>
+
+---
+
 ## Next Steps
 
 * **[Streaming responses](/chat/streaming)** - Add real-time responses to session-managed chats

fern/docs.yml

@@ -963,3 +963,5 @@ redirects:
     destination: /workflows/examples/lead-qualification
   - source: /fern/api-reference
     destination: /api-reference/calls/list
+  - source: /documentation/chat/chat
+    destination: /api-reference/chats