Add the assistant: a chat that drives the MCP tools in-process

A provider set under Settings (OpenAI-compatible; key encrypted in
flow-data/ai.json) turns on an Assistant panel in the sidebar. Each turn runs
the FastMCP tools in-process as the person chatting, streams the rounds over
SSE and keeps one transcript per user. The panel floats on any screen and
shares the editor's lane: a settings panel keeps the top half, the chat the
bottom. The MCP client is now built once, for the endpoint and the chat.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

docs/code/agents.md

@@ -95,6 +95,25 @@ door could write one the canvas cannot open.
 The caller's token rides along on every hop, so the API sees the agent's own
 identity rather than a service account. The audit trail on Home names it.
 
+## The assistant
+
+The same tools drive the chat inside the dashboard. An operator sets a
+provider under **Settings → Assistant** (anything OpenAI-compatible: OpenAI,
+Anthropic, OpenRouter, a local Ollama), and an **Assistant** entry appears in
+the sidebar for everyone. The panel opens on any screen and keeps its place
+from screen to screen; on a flow, it knows which one you are looking at.
+
+The model calls the tools above, in-process, as **you**: every call carries
+your own token, so the chat can do nothing you could not do yourself, and its
+edits show up in the editor as drafts the moment they are saved. It is told to
+publish only when asked, but it has the tool, so read what it did before
+saying so. The trace under each answer lists every call it made.
+
+The conversation is one per person, kept on the instance beside the
+configuration, and the bin in the panel's header starts it over. `MCP_ENABLED`
+is not needed for it: the endpoint is for agents outside, the chat for the
+one inside.
+
 ## A note on working this way
 
 The pattern that works is the same one that works with a person: let the agent

docs/interface/index.md

@@ -25,7 +25,7 @@ phone the sidebar collapses to a sheet.
 | **Alerts** | where failures get sent |
 | **Admin** | users (superusers only) |
 | **Search** | anything in this instance, by name |
-| **Settings** | your account, appearance, and remote access |
+| **Settings** | your account, appearance, remote access, and the assistant |
 
 ### Search
 

docs/interface/operations.md

@@ -129,3 +129,10 @@ follow the system).
 **Remote access** is where an instance is paired with a portal, remote
 users are admitted, and the link is cut again. That has [its own
 page](portal.md).
+
+**Assistant** turns on the chat that builds and edits flows: pick a provider,
+paste a key, fetch the model list and choose one. The key is stored encrypted
+on the instance and never shown again. One provider serves everyone who signs
+in here, and until one is set nothing in the interface mentions the feature.
+How the chat works, and what it may do, is on the [agents
+page](../code/agents.md#the-assistant).