feat(dweb): user kill switch to shut down all dweb networking

extension/background/routes/dweb.js

@@ -201,6 +201,22 @@ export const makeDwebRoutes = (deps) => {
       await ensureOffscreen();
       return browser.runtime.sendMessage({ type: 'dweb/base-host/start' });
     },
+    // The master OFF — the user-facing kill switch, symmetric to start
+    // (docs/specs/FEATURE-FIRST-CLASS-MESSAGING.md §2). Persist the preference
+    // FIRST so it won't auto-restart on the next unlock (maybeStartBaseNetwork
+    // gates on dwebEnabled), then tear down a live host. NOT gated on dwebOn():
+    // we must be able to stop precisely as we flip the setting off. Gated only on
+    // DWEB_ENABLED — the store package prunes this module entirely.
+    'dweb/base/stop': async () => {
+      if (!DWEB_ENABLED) return { ok: false, error: 'dweb-disabled' };
+      await settingsStore.update({ dwebEnabled: false });
+      // Never SPAWN the offscreen just to stop it: if it isn't up, there is no
+      // live network to tear down. The offscreen stop handler closes every room,
+      // drops the mesh + lobby, and clears the re-sub timer (dweb-base.js).
+      const contexts = await browser.runtime.getContexts({ contextTypes: /** @type {any} */ (['OFFSCREEN_DOCUMENT']) });
+      if (contexts.length) await browser.runtime.sendMessage({ type: 'dweb/base-host/stop' });
+      return { ok: true, running: false };
+    },
     'dweb/base/status': async () => {
       if (!dwebOn()) return { ok: false, error: 'dweb-disabled' };
       await ensureOffscreen();

extension/home/network-section.js

@@ -381,6 +381,7 @@ export const NetworkSection = () => {
   /** @type {string | null} */
   let error = null;
   let starting = false;
+  let stopping = false;
   /** @type {ReturnType<typeof setInterval> | number} */
   let timer = 0;
   let dead = false;      // set on unmount — an in-flight poll must not redraw
@@ -406,6 +407,17 @@ export const NetworkSection = () => {
     await refresh(send);
   };
 
+  /** The kill switch: shut down ALL dweb networking + persist it off. @param {Send} send */
+  const stop = async (send) => {
+    // Destructive — drops every live connection — so confirm before the kill.
+    if (typeof confirm === 'function'
+      && !confirm('Shut down all peer-to-peer networking? This drops every live connection and keeps it off (it won’t come back on unlock) until you start it again.')) return;
+    stopping = true; if (!dead) m.redraw();
+    try { await send({ type: 'dweb/base/stop' }); } catch (e) { error = /** @type {{ message?: string }} */ (e)?.message || String(e); }
+    stopping = false;
+    await refresh(send);
+  };
+
   return {
     /** @param {{ attrs: { send: Send } }} vnode */
     oninit(vnode) { refresh(vnode.attrs.send); },
@@ -460,6 +472,14 @@ export const NetworkSection = () => {
               m('span.peerd-net-path', { class: `peerd-net-path--${pi.kind}` }, pi.label),
             ]);
           })),
+        // Kill switch — symmetric to "Start the network" in the offline view.
+        // Drops every live connection and persists dweb off (won't auto-restart
+        // on unlock) — docs/specs/FEATURE-FIRST-CLASS-MESSAGING.md §2.
+        m('button.peerd-net-btn', {
+          disabled: stopping,
+          style: 'margin-top:10px; font-size:12px; opacity:.75;',
+          onclick: () => stop(send),
+        }, stopping ? 'Stopping…' : 'Stop the network'),
       ]);
     },
   };