fix(agents): keep list selection unbroken in agent replies

Draw list markers as non-selectable pseudo-elements instead of native
markers. WebKit paints a selection box around each native marker, which
left a broken stripe down the list gutter when a reply was selected.

src/features/agents/Session.module.css

@@ -471,6 +471,31 @@
 .markdown :global(ol) {
   margin: 0 0 8px;
   padding-left: 20px;
+  list-style: none;
+}
+/* Markers are drawn as pseudo-elements: WebKit paints a selection box around a native marker,
+   leaving a broken stripe down the gutter when a list is selected. */
+.markdown :global(li) {
+  position: relative;
+}
+.markdown :global(li)::before {
+  position: absolute;
+  right: calc(100% + 6px);
+  -webkit-user-select: none;
+  user-select: none;
+}
+.markdown :global(ul > li)::before {
+  content: "•";
+}
+.markdown :global(ul ul > li)::before {
+  content: "◦";
+}
+.markdown :global(ul ul ul > li)::before {
+  content: "▪";
+}
+.markdown :global(ol > li)::before {
+  content: counter(list-item) ".";
+  font-variant-numeric: tabular-nums;
 }
 .markdown :global(a) {
   color: var(--link);
@@ -521,7 +546,9 @@
 }
 .markdown :global(li:has(> input[type="checkbox"])) {
   margin-left: -20px;
-  list-style: none;
+}
+.markdown :global(li:has(> input[type="checkbox"]))::before {
+  content: none;
 }
 .markdown > :global(:first-child) {
   margin-top: 0;

src/features/plugins/PluginsPage.tsx

@@ -129,15 +129,6 @@ export function catalogState(
 
 const vendorOf = (authors: readonly string[]) => authors.join(", ");
 
-/** The marketplace's newer version of an installed plugin, if there is one this IDE can load. */
-function useMarketUpdate(plugin: PluginInfo): MarketPlugin | undefined {
-  return usePlugins((s) =>
-    plugin.source === "installed"
-      ? s.market?.find((m) => m.id === plugin.id && m.compatible && compareVersions(m.version, plugin.version) > 0)
-      : undefined,
-  );
-}
-
 function PluginIcon({ id, icon, large }: { id: string; icon: PluginIconData | null | undefined; large?: boolean }) {
   return (
     <span className={clsx(styles.icon, large && styles.iconLarge)} aria-hidden>
@@ -157,7 +148,6 @@ function ListHeader({ title, count }: { title: string; count: number }) {
 
 function InstalledRow({ plugin, selected, onSelect }: { plugin: PluginInfo; selected: boolean; onSelect: () => void }) {
   const busy = usePlugins((s) => !!s.busy[plugin.id]);
-  const update = useMarketUpdate(plugin);
   return (
     <li className={clsx(styles.row, selected && styles.rowSelected, !plugin.enabled && styles.rowDisabled)}>
       <button
@@ -176,7 +166,6 @@ function InstalledRow({ plugin, selected, onSelect }: { plugin: PluginInfo; sele
             {plugin.source !== "installed" && (
               <span className={styles.devTag}>{plugin.source === "linked" ? tx("linked") : tx("dev")}</span>
             )}
-            {update && <Badge tone="accent">{tx("Update")}</Badge>}
             {plugin.status === "failed" && (
               <Badge dot tone="danger">
                 <T>Failed</T>
@@ -555,8 +544,6 @@ function Homepage({ value }: { value: string }) {
 
 function InstalledDetails({ plugin }: { plugin: PluginInfo }) {
   const busy = usePlugins((s) => !!s.busy[plugin.id]);
-  const installing = usePlugins((s) => s.installing);
-  const update = useMarketUpdate(plugin);
   const status = STATUS[plugin.status];
   const [confirmUninstall, setConfirmUninstall] = useState(false);
 
@@ -659,16 +646,6 @@ function InstalledDetails({ plugin }: { plugin: PluginInfo }) {
         </div>
         <div className={styles.headerActions}>
           {busy && <Spinner size={14} label="Working" />}
-          {update && (
-            <Button
-              size="small"
-              variant="primary"
-              disabled={busy || installing}
-              onClick={() => void installFromMarket(update.id)}
-            >
-              {tx`Update to ${update.version}`}
-            </Button>
-          )}
           <Button
             size="small"
             variant={plugin.enabled ? "secondary" : "primary"}

src/features/plugins/__tests__/plugins.test.tsx

@@ -1354,19 +1354,6 @@ describe("marketplace", () => {
       await waitFor(() => expect(consents.map(([id]) => id)).toEqual(["a", "b"]));
     });
 
-    it("marks installed plugins with updates and updates one from its details", async () => {
-      setConsentPrompt(async () => ({ optional: [] }));
-      const consents = updatesBackend({ a: preview("a", "1.1.0"), b: preview("b", "2.0.0") });
-      const user = userEvent.setup();
-      render(<PluginsPage />);
-      await waitFor(() => expect(usePlugins.getState().market).toHaveLength(3));
-      const list = screen.getByRole("list", { name: "Installed plugins" });
-      expect(within(list).getAllByText("Update")).toHaveLength(2);
-      await user.click(within(list).getAllByRole("button", { name: /^b/i })[0]!);
-      await user.click(await screen.findByRole("button", { name: "Update to 2.0.0" }));
-      await waitFor(() => expect(consents.map(([id]) => id)).toEqual(["b"]));
-    });
-
     it("announces updates with actions to install them or show the plugins", async () => {
       updatesBackend({ a: preview("a", "1.1.0"), b: preview("b", "2.0.0") });
       handlePluginEvent({