---
summary: "Loopback WebChat static host and Gateway WS usage for chat UI"
read_when:
  - Debugging or configuring WebChat access
title: "WebChat"
---

# WebChat (Gateway WebSocket UI)

Status: the macOS/iOS SwiftUI chat UI talks directly to the Gateway WebSocket.

## What it is

- A native chat UI for the gateway (no embedded browser and no local static server).
- Uses the same sessions and routing rules as other channels.
- Deterministic routing: replies always go back to WebChat.

## Quick start

1. Start the gateway.
2. Open the WebChat UI (macOS/iOS app) or the Control UI chat tab.
3. Ensure a valid gateway auth path is configured (shared-secret by default,
   even on loopback).

## How it works (behavior)

- The UI connects to the Gateway WebSocket and uses `chat.history`, `chat.send`, and `chat.inject`.
- `chat.history` is bounded for stability: Gateway may truncate long text fields, omit heavy metadata, and replace oversized entries with `[chat.history omitted: message too large]`.
- `chat.inject` appends an assistant note directly to the transcript and broadcasts it to the UI (no agent run).
- Aborted runs can keep partial assistant output visible in the UI.
- Gateway persists aborted partial assistant text into transcript history when buffered output exists, and marks those entries with abort metadata.
- History is always fetched from the gateway (no local file watching).
- If the gateway is unreachable, WebChat is read-only.

## Control UI agents tools panel

- The Control UI `/agents` Tools panel has two separate views:
  - **Available Right Now** uses `tools.effective(sessionKey=...)` and shows what the current
    session can actually use at runtime, including core, plugin, and channel-owned tools.
  - **Tool Configuration** uses `tools.catalog` and stays focused on profiles, overrides, and
    catalog semantics.
- Runtime availability is session-scoped. Switching sessions on the same agent can change the
  **Available Right Now** list.
- The config editor does not imply runtime availability; effective access still follows policy
  precedence (`allow`/`deny`, per-agent and provider/channel overrides).

## Remote use

- Remote mode tunnels the gateway WebSocket over SSH/Tailscale.
- You do not need to run a separate WebChat server.

## Configuration reference (WebChat)

Full configuration: [Configuration](/gateway/configuration)

WebChat options:

- `gateway.webchat.chatHistoryMaxChars`: maximum character count for text fields in `chat.history` responses. When a transcript entry exceeds this limit, Gateway truncates long text fields and may replace oversized messages with a placeholder. Per-request `maxChars` can also be sent by the client to override this default for a single `chat.history` call.

Related global options:

- `gateway.port`, `gateway.bind`: WebSocket host/port.
- `gateway.auth.mode`, `gateway.auth.token`, `gateway.auth.password`:
  shared-secret WebSocket auth.
- `gateway.auth.allowTailscale`: browser Control UI chat tab can use Tailscale
  Serve identity headers when enabled.
- `gateway.auth.mode: "trusted-proxy"`: reverse-proxy auth for browser clients behind an identity-aware **non-loopback** proxy source (see [Trusted Proxy Auth](/gateway/trusted-proxy-auth)).
- `gateway.remote.url`, `gateway.remote.token`, `gateway.remote.password`: remote gateway target.
- `session.*`: session storage and main key defaults.
