docs(tools): note tui and telegram session routing

TOOLS.md

@@ -45,6 +45,18 @@ Skills are shared. Your setup is yours. Keeping them apart means you can update
 - Tailscale IP:
   - `100.123.88.127`
 
+### Session routing notes
+
+- Current TUI conversations arrive with inbound metadata like:
+  - `channel: webchat`
+  - `provider: webchat`
+  - `surface: webchat`
+- Telegram DMs route into a separate main session when `session.dmScope = "per-channel-peer"`.
+- Verified 2026-03-10:
+  - TUI/webchat session remained separate from Telegram DM session
+  - Telegram outbound + inbound both worked
+  - Telegram inbound landed in its own main session file rather than the active TUI session
+
 ### Search routing
 
 - Default page-reading tool: native `web_fetch`