fix(desktop): preserve Welcome banner dismissal (#5406)

## Summary

- remove the complete Welcome guidance surface when dismissal reaches
`hidden`
- preserve dismissal across the private and starter Welcome channels for
the active identity
- assert the starter channel's actual `welcome-everyone` title on
re-entry

## Why

PR #5330 introduced two deterministic Desktop E2E failures:

- the inner banner unmounted, but `welcome-composer-guidance-layer`
remained
- the re-entry test expected case-sensitive `Welcome` while navigating
to `welcome-everyone`

The state hook also scoped completion to channel IDs while `ChannelPane`
remounts during navigation. The Welcome guidance is one experience
spanning both Welcome channels, so completion now survives that remount
while remaining identity-scoped.

## Validation

At `b577eb42edffe889f63566f2457eacea720f3593`:

- `pnpm -C desktop typecheck`
- focused Biome check for all four changed files
- E2E build
- both `welcome-everywhere banner` integration tests repeated three
times: **6/6 passed**
- mandatory pre-push desktop check, typecheck, and full desktop unit
suite: **4,535 passed**
- `git diff --check`

Signed-off-by: Wes <wesbillman@users.noreply.github.com>
Co-authored-by: Carl <c7ebe626f000404285d3686e1dc74cc07cc60a9754a150041ba132e14bd3e2ec@buzz.block.builderlab.xyz>

desktop/src/features/channels/ui/ChannelPane.tsx

@@ -216,7 +216,11 @@ export const ChannelPane = React.memo(function ChannelPane({
     bannerState: welcomeComposerBannerState,
     completeBanner: completeWelcomeComposerBanner,
     dismissBanner: handleDismissWelcomeBanner,
-  } = useWelcomeComposerBanner(activeChannelId, isActiveWelcomeChannel);
+  } = useWelcomeComposerBanner(
+    activeChannelId,
+    isActiveWelcomeChannel,
+    currentPubkey ?? null,
+  );
   const isEditInThread =
     editTarget != null &&
     threadHeadMessage != null &&

desktop/src/features/channels/ui/WelcomeComposerBanner.tsx

@@ -443,6 +443,10 @@ export function WelcomeComposerGuidanceLayer({
   settingUp,
   state,
 }: WelcomeComposerGuidanceLayerProps) {
+  if (state === "hidden") {
+    return null;
+  }
+
   return (
     <div className="relative" data-testid="welcome-composer-guidance-layer">
       <ComposerDockGlassBackdrop

desktop/src/features/channels/ui/useWelcomeComposerBanner.ts

@@ -8,11 +8,14 @@ import {
   type WelcomeComposerBannerState,
 } from "@/features/channels/ui/WelcomeComposerBanner";
 
+const completedWelcomeComposerIdentityPubkeys = new Set<string>();
+
 /**
  * Manages the Welcome-channel composer hint banner's state machine.
  *
- * Tracks which channels have been completed within the session so the banner
- * stays hidden on re-entry. Exposes three transitions:
+ * Remembers completion across the Welcome experience per identity for this app
+ * session, so the hint stays hidden while moving between the private and
+ * starter Welcome channels without leaking dismissal to another identity.
  * - `completeBanner`: agent-mention path — plays the "Nice work." success
  *   animation before auto-dismissing.
  * - `dismissBanner`: manual X-button path — immediately begins the slide-down
@@ -21,12 +24,12 @@ import {
 export function useWelcomeComposerBanner(
   activeChannelId: string | null,
   isActiveWelcomeChannel: boolean,
+  identityPubkey: string | null,
 ): {
   bannerState: WelcomeComposerBannerState;
   completeBanner: () => void;
   dismissBanner: () => void;
 } {
-  const completedChannelIdsRef = React.useRef(new Set<string>());
   const dismissTimerRef = React.useRef<number | null>(null);
   const hideTimerRef = React.useRef<number | null>(null);
   const [bannerState, setBannerState] =
@@ -48,15 +51,15 @@ export function useWelcomeComposerBanner(
   React.useEffect(() => {
     clearTimers();
     if (
-      activeChannelId &&
       isActiveWelcomeChannel &&
-      completedChannelIdsRef.current.has(activeChannelId)
+      identityPubkey &&
+      completedWelcomeComposerIdentityPubkeys.has(identityPubkey)
     ) {
       setBannerState("hidden");
       return;
     }
     setBannerState("prompt");
-  }, [activeChannelId, clearTimers, isActiveWelcomeChannel]);
+  }, [clearTimers, identityPubkey, isActiveWelcomeChannel]);
 
   const scheduleHide = React.useCallback(() => {
     hideTimerRef.current = window.setTimeout(
@@ -70,30 +73,42 @@ export function useWelcomeComposerBanner(
   }, []);
 
   const completeBanner = React.useCallback(() => {
-    if (!activeChannelId || !isActiveWelcomeChannel) {
+    if (!activeChannelId || !isActiveWelcomeChannel || !identityPubkey) {
       return;
     }
 
     clearTimers();
-    completedChannelIdsRef.current.add(activeChannelId);
+    completedWelcomeComposerIdentityPubkeys.add(identityPubkey);
     setBannerState("complete");
     dismissTimerRef.current = window.setTimeout(() => {
       setBannerState("dismissing");
       dismissTimerRef.current = null;
       scheduleHide();
     }, WELCOME_PERSONA_ROTATION_MS + WELCOME_COMPOSER_BANNER_SUCCESS_SETTLE_MS);
-  }, [activeChannelId, clearTimers, isActiveWelcomeChannel, scheduleHide]);
+  }, [
+    activeChannelId,
+    clearTimers,
+    identityPubkey,
+    isActiveWelcomeChannel,
+    scheduleHide,
+  ]);
 
   const dismissBanner = React.useCallback(() => {
-    if (!activeChannelId || !isActiveWelcomeChannel) {
+    if (!activeChannelId || !isActiveWelcomeChannel || !identityPubkey) {
       return;
     }
 
     clearTimers();
-    completedChannelIdsRef.current.add(activeChannelId);
+    completedWelcomeComposerIdentityPubkeys.add(identityPubkey);
     setBannerState("dismissing");
     scheduleHide();
-  }, [activeChannelId, clearTimers, isActiveWelcomeChannel, scheduleHide]);
+  }, [
+    activeChannelId,
+    clearTimers,
+    identityPubkey,
+    isActiveWelcomeChannel,
+    scheduleHide,
+  ]);
 
   return { bannerState, completeBanner, dismissBanner };
 }

desktop/tests/e2e/onboarding.spec.ts

@@ -3218,7 +3218,9 @@ test("welcome-everywhere banner: dismiss persists after channel re-entry", async
 
   // Return — banner must stay hidden.
   await page.getByTestId("channel-welcome-everyone").click();
-  await expect(page.getByTestId("chat-title")).toContainText("Welcome");
+  await expect(page.getByTestId("chat-title")).toContainText(
+    "welcome-everyone",
+  );
   await expect(banner).toHaveCount(0);
 });