feat(chat): view context — tell the assistant what you're looking at

An eye next to the paperclip shares what the user has open with their next
message: the page, the folder being browsed, the file open in the viewer and
any highlighted passage (line numbers where a source view exists), plus which
entity a detail page is about. The bag is client-authored {label, value} pairs
in English — the backend only clamps (chars, never bytes), neutralizes the
harness tag and renders one <system-extra> block per message, deduped
consecutively so it appears exactly when the view changed. On by default,
per-device toggle, hover/tap to preview, a chip on every sent message;
docs/view-context.md for users, an updated harness.md clause for the model.

web/components/connector-detail.js

@@ -1,6 +1,7 @@
 import { html, nothing } from 'lit';
 import { LightElement } from '../lib/base.js';
 import { t }            from '../lib/i18n.js';
+import { setSlice, clearSlice } from '../lib/view-context.js';
 import {
   announceChange, authLabel, connectorIconUrl, jf, normalizeSchema, parseJson, seedEnv, statusOf,
 } from './shared/connector-common.js';
@@ -23,6 +24,9 @@ import {
 const ADMIN_ID = 'admin';
 const PAGE_ID  = 'connector';
 
+/// The view-context slice this page owns (see `lib/view-context.js`).
+const VIEW_SLICE = 'entity@connector';
+
 function nameFromHash() {
   const m = location.hash.match(/^#connector\?name=(.*)$/);
   if (!m) return null;
@@ -82,7 +86,10 @@ export class ConnectorDetailPage extends LightElement {
       this._open = e.detail.page === PAGE_ID;
       this.style.display = this._open ? 'flex' : 'none';
       if (this._open) this._loadFromHash();
-      else this._stopQrPoll();   // never poll a connector's login off-screen
+      else {
+        this._stopQrPoll();        // never poll a connector's login off-screen
+        clearSlice(VIEW_SLICE);
+      }
     });
     window.addEventListener('hashchange', () => {
       if (this._open) this._loadFromHash();
@@ -92,6 +99,7 @@ export class ConnectorDetailPage extends LightElement {
   disconnectedCallback() {
     window.removeEventListener('locale-changed', this.__onLocaleChanged);
     this._stopQrPoll();
+    clearSlice(VIEW_SLICE);
     super.disconnectedCallback();
   }
 
@@ -106,13 +114,24 @@ export class ConnectorDetailPage extends LightElement {
 
   async _loadFromHash() {
     const name = nameFromHash();
-    if (!name) return;
+    if (!name) { clearSlice(VIEW_SLICE); return; }
     // A different connector must not inherit the previous one's typed secrets.
     if (name !== this._name) this._reset();
     this._name = name;
+    // Say which connector is open before the fetch lands — the status line is
+    // added by `_load` once the runtime rows are known.
+    this._publishViewContext(false);
     await this._load();
   }
 
+  // The entity slice: which connector this page is about, and — once loaded —
+  // its state. Never a config value or a credential: *which*, not *what's in it*.
+  _publishViewContext(withStatus) {
+    if (!this._name) return;
+    const value = withStatus ? `${this._name} (status: ${this._status})` : this._name;
+    setSlice(VIEW_SLICE, [{ label: 'Open connector', value }]);
+  }
+
   async _load() {
     this._error = null;
     try {
@@ -133,6 +152,7 @@ export class ConnectorDetailPage extends LightElement {
       this._entry = entry;
       this._glob  = glob;
       this._act   = act;
+      this._publishViewContext(true);
 
       const schema = normalizeSchema(parseJson(entry?.config_schema_json, []));
       this._schema = schema;