[examples] Add Slack Socket Mode integration demo

slack/.env.example

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+SLACK_BOT_TOKEN=
+SLACK_SIGNING_SECRET=
+SLACK_WEBSOCKET_TOKEN=

slack/app.py

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+# This is a simple example to test the slack websocket handler.
+# To initiate the websocket dont forget to set the variables:
+#   - SLACK_BOT_TOKEN
+#   - SLACK_SIGNING_SECRET
+#   - SLACK_WEBSOCKET_TOKEN <- this one dictates if websocket or http handler
+
+from chainlit import Message, on_message, user_session
+
+
+@on_message
+async def main(message: Message):
+    client_type = user_session.get("client_type")
+    if client_type == "slack":
+        user_email = user_session.get("user").metadata.get("email")
+        print(f"Received a message from: {user_email}")
+        await Message(
+            content=f"Hi {user_email}, I have received the following message:\n{message.content}",
+        ).send()

slack/readme.md

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+# Slack Socket Mode Example
+
+A minimal, self‑contained demo that shows how to connect a **Chainlit** app to Slack via **Socket Mode** (WebSockets). It echoes each user message and greets the sender by e‑mail.
+
+---
+
+## Prerequisites
+
+| Requirement | Notes |
+|-------------|-------|
+| Python ≥ 3.9 | Any recent 3.x works. |
+| Slack workspace | You need permission to create and install an app. |
+| Slack app tokens | *Bot* token (`SLACK_BOT_TOKEN`), *Socket‑mode* token (`SLACK_WEBSOCKET_TOKEN`), and *Signing Secret* (`SLACK_SIGNING_SECRET`). |
+
+> **Tip:** In the Slack dashboard, enable **Socket Mode** and add the *`connections:write`* scope to generate the websocket token.
+
+---
+
+## Project layout
+
+```
+examples/slack_socket_mode/
+│ .env.example          # placeholder for the three Slack tokens
+│ app.py                # Chainlit echo bot
+│ requirements.txt      # exact Python deps
+└ README.md             # this file
+```
+
+---
+
+## Quick start
+
+```bash
+# 1 – enter the example directory (from repo root)
+cd examples/slack_socket_mode
+
+# 2 – create and activate a virtualenv (optional but recommended)
+python -m venv .venv
+source .venv/bin/activate  # Windows: .venv\Scripts\activate
+
+# 3 – install deps
+pip install -r requirements.txt
+
+# 4 – add your real tokens
+cmp .env.example .env      # then edit .env
+
+# 5 – run the bot
+python app.py
+```
+
+Invite the bot to a channel or send it a direct message in Slack. It should reply with something like:
+
+> *Hi [email protected], I have received the following message:* **hello!**
+
+---
+
+## How it works
+
+`app.py` spins up a Chainlit application and, if `SLACK_WEBSOCKET_TOKEN` is present, it starts Slack’s `AsyncSocketModeHandler`. Messages received over the websocket are handled in the `@on_message` function, which:
+
+1. Detects the client is Slack (`client_type == "slack"`).
+2. Reads the sender’s e‑mail from the metadata.
+3. Sends an acknowledgement back to the same channel.
+
+The HTTP event‑based handler remains available when only `SLACK_BOT_TOKEN` & `SLACK_SIGNING_SECRET` are defined.
+
+---
+
+## Troubleshooting
+
+* **`xoxb-*** or **`xapp-*** token invalid** – make sure the app is installed in the workspace and the token is copied correctly.
+* **Bot doesn’t respond** – check that it’s added to the channel and has the chat:write scope.
+* **Firewall / proxy issues** – Socket Mode uses outbound WebSocket connections on port 443; ensure they’re not blocked.
+
+---
+
+## License
+
+This example inherits the repository’s license.

slack/requirements.txt

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+chainlit