fix: lock up top edge of the composer so suggestions list doesn't jump

[szymeo]

Problem

before.mp4

When new suggestions were added, centered content was jumping vertically, so the rows shifted under the cursor. While trying out a suggestion I ended up misclicking and starting a task I didn't intend to, which is easy to do on a surface people use to kick off work.

Changes

after.mp4

A small UI fix to keep the suggestions list stable and harder to misclick:

• Page navigation now slides horizontally with a single page mounted at a time, so the panel stays anchored and no longer jumps.
• Removed the clip that was cutting off rows mid-slide (any real overflow is still handled by the surrounding layout).
• Card dismissal scales down and fades with a synced layout shift, and the composer is centered with the suggestions anchored below it.
• Added a dev-only simulation harness (VITE_SIMULATE_SUGGESTIONS=1 env or the posthog-code:simulate-suggestions localStorage flag) so this can be exercised locally without waiting on real discovery.

How did you test this?

• pnpm --filter code typecheck and Biome pass (also enforced by the pre-commit hook).
• Confirmed manually in the running app: paging no longer shifts the list, and rows slide without being clipped — so the suggestion you click stays where you expect it.

Automatic notifications

• Publish to changelog?
• Alert Sales and Marketing teams?

[greptile-apps]

Prompt To Fix All With AI

Fix the following 2 code review issues. Work through them one at a time, proposing concise fixes.

---

### Issue 1 of 2
apps/code/src/renderer/features/setup/hooks/useSetupDiscovery.ts:27-30
Missing cleanup for the simulation interval. If `selectedDirectory` transitions from a real path to `null`/`undefined`, React re-runs the effect and exits early at `if (!selectedDirectory) return;` — the `startSuggestionSimulation` call that would have cleared the old timer is never reached. The interval keeps firing and accumulates tasks in the store for a directory that is no longer active. The normal non-simulation code path avoids this by returning a cleanup function.

```suggestion
    if (shouldSimulateSuggestions()) {
      service.startSuggestionSimulation(selectedDirectory);
      return () => {
        service.stopSuggestionSimulation();
      };
    }
```

### Issue 2 of 2
apps/code/src/renderer/features/setup/services/setupRunService.ts:312-325
The simulation interval runs forever and has no upper bound. Because every tick uses a unique id (`simulated-suggestion-${index}`), `addDiscoveredTaskIfMissing` never deduplicates and the `discoveredTasks` array in the store grows without limit. Since the purpose of the harness is to exercise the incoming-suggestions animation, capping it (e.g. after one full cycle through all categories) would make the simulation repeatable and predictable.

```suggestion
    const totalSuggestions = SIMULATED_SUGGESTION_CATEGORIES.length * 2;

    const addNextSuggestion = () => {
      useSetupStore
        .getState()
        .addDiscoveredTaskIfMissing(
          buildSimulatedSuggestion(directory, this.simulatedSuggestionsCount),
        );
      this.simulatedSuggestionsCount += 1;
      if (this.simulatedSuggestionsCount >= totalSuggestions) {
        this.stopSuggestionSimulation();
      }
    };

    addNextSuggestion();
    this.simulatedSuggestionsTimer = window.setInterval(
      addNextSuggestion,
      SIMULATED_SUGGESTION_INTERVAL_MS,
    );
```

_{Reviews (1): Last reviewed commit: "feat: smoother suggested-tasks list anim..." | Re-trigger Greptile}

[szymeo]

Resolved both Greptile comments in 32788c56: the simulation interval now has effect cleanup/self-stop behavior and is capped so it cannot grow persisted suggestions indefinitely.

[ablaszkiewicz]

@PostHog/team-posthog-code