diff --git a/src/app/TerminalApp.ts b/src/app/TerminalApp.ts
index 2cf3ca81..b2631b64 100644
--- a/src/app/TerminalApp.ts
+++ b/src/app/TerminalApp.ts
@@ -345,7 +345,7 @@ import {liveSessionRows} from '../sessions/LiveSessionView.js';
 import {createResumeBrowser, describeArchivedRow, describeLiveRow, LIVE_ROW_LABELS, liveRowAgent, liveRowState, navigateResume, resumeDayLabel, resumeRowCount, resumeSelection,
   visibleLiveSessions, visibleResumeSessions, type ResumeBrowserState} from '../sessions/ResumeBrowser.js';
 import {dismissSessionNotice, listLiveSessions, listSessionNotices} from '../session/connectSession.js';
-import {OLDER_SERVICE_SWITCH, serviceBuildNotice} from '../session/SocketSessionClient.js';
+import {OLDER_SERVICE_SWITCH, serviceBuildNotice, serviceInputNotice} from '../session/SocketSessionClient.js';
 import {killAndArchive} from '../session/liveSessions.js';
 import {recoverEndedSessions} from '../session/recovery.js';
 import {AgentSessions, normalizeProfiles, type AgentProfile} from '../agents/sessions/manager.js';
@@ -1086,6 +1086,8 @@ export class TerminalApp {
     if (connection?.notice) this.output.addFrontendInteraction('session', connection.notice, ERROR);
     const stale = connection?.mode === 'service' ? serviceBuildNotice(this.session.serviceBuild, this.buildIdentity) : undefined;
     if (stale) this.output.addFrontendInteraction('session', stale, INFO);
+    const routing = connection?.mode === 'service' ? serviceInputNotice(this.session.features) : undefined;
+    if (routing) this.output.addFrontendInteraction('session', routing, WARNING);
     this.beginStartupWatch(connection?.attached);
     this.session.start();
     void this.loadInstalledPacks();
diff --git a/src/session/SocketSessionClient.ts b/src/session/SocketSessionClient.ts
index 287b10d9..ee11c314 100644
--- a/src/session/SocketSessionClient.ts
+++ b/src/session/SocketSessionClient.ts
@@ -144,6 +144,18 @@ export function serviceBuildNotice(serviceBuild: string | undefined, own: {versi
     + 'so fixes to how shells start are not in it yet. The service restarts by itself once every NMSh window and live session has ended.';
 }
 
+/**
+ * A session service without this release's look result (an older NMSh's, e.g. v0.20.0's) still decides who gets what
+ * is typed while a command runs, the way it did then: #426's and #436's protections are not active in its sessions.
+ * Said once per window, with when it ends; undefined for a service that has them.
+ */
+export function serviceInputNotice(features: ReadonlySet<string>): string | undefined {
+  if (features.has('input-look-result')) return undefined;
+  return 'This session\'s service is from an older NMSh, so what you type while a command runs is routed as that version did: '
+    + 'a password typed before a program asks for it can be shown, queued or run as a command. '
+    + 'The service restarts by itself once every NMSh window and live session has ended; new sessions then get the current protections.';
+}
+
 export const OLDER_SERVICE_SWITCH = 'The session service running this session is an older NMSh build without shell switching. '
   + 'Its live sessions keep running; once they end, the next nmsh launch starts the current service.';
 
diff --git a/tests/sessionService.test.ts b/tests/sessionService.test.ts
index e1cd94ca..249843b4 100644
--- a/tests/sessionService.test.ts
+++ b/tests/sessionService.test.ts
@@ -277,6 +277,18 @@ test('a shell from an older session service is called out, because the service b
   assert.match(serviceBuildNotice(undefined, own) ?? '', /build not reported/u, 'a service too old to report its build');
 });
 
+test('a session service without this release\'s typing protections says so, and when that ends (#426)', async () => {
+  const {serviceInputNotice} = await import('../src/session/SocketSessionClient.js');
+  const {SERVICE_FEATURES} = await import('../src/session/SessionProtocol.js');
+  assert.equal(serviceInputNotice(new Set(SERVICE_FEATURES)), undefined, 'this release\'s service: nothing to say');
+  // v0.20.0's service: the same protocol, without the look result #426's protections are built on.
+  const v020 = new Set(['shell-switch', 'shell-backends', 'notices', 'input-state', 'queue', 'queue-conditions', 'background-tasks', 'input-look', 'queue-timeline', 'queue-history']);
+  const notice = serviceInputNotice(v020) ?? '';
+  assert.match(notice, /what you type while a command runs is routed as that version did/u);
+  assert.match(notice, /password/u, 'says what can happen, plainly');
+  assert.match(notice, /restarts by itself once every NMSh window and live session has ended/u);
+});
+
 
 test('transported queue reviews expire at manual submission and controller reattachment', async () => {
   const runtimeDir = scratch('nmsh-queue-review-');