fix playwright slides test, and fix sizing

[Light2Dark]

📝 Summary

1. Fix playwright test
2. For a notebook with very few cells, we didn't stretch the slide area fully. This fixes that. See the snapshot picture for reference.

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✅ Merge Checklist

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• Documentation has been updated where applicable, including docstrings for API changes.
• Tests have been added for the changes made.

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Project	Deployment	Actions	Updated (UTC)
marimo-docs	Ready	Preview, Comment	May 21, 2026 2:01pm

[cubic-dev-ai]

No issues found across 5 files

Architecture diagram

sequenceDiagram
    participant Playwright as Playwright Test
    participant Browser as Browser Page
    participant Reveal as Reveal.js Deck
    participant Slides as SlidesLayout
    participant Minimap as Slides Minimap

    Note over Playwright,Minimap: Slide Rendering & Keyboard Navigation Flow

    Playwright->>Browser: Navigate to slides page
    Browser->>Reveal: Initialize slide deck
    Reveal->>Reveal: Set tabIndex=-1 on .reveal wrapper
    Reveal->>Reveal: Focus .reveal wrapper (preventScroll: true)
    Reveal-->>Browser: Deck ready

    Browser->>Slides: Render slides layout
    Slides->>Slides: Apply flex-1 class for vertical stretching
    Slides->>Minimap: Pass cells with output
    Minimap-->>Slides: Render minimap
    Slides-->>Browser: Rendered slides container

    Playwright->>Browser: Query .slides > section elements
    Browser->>Reveal: Get slide sections
    Reveal-->>Browser: Return sections
    Browser-->>Playwright: 2 slides found
    Playwright->>Browser: Assert nth(0) has class .present

    Playwright->>Browser: Click slides container
    Browser->>Browser: Set document.activeElement to .reveal wrapper
    Browser-->>Playwright: Focus confirmed via polling

    Playwright->>Browser: Press ArrowRight key
    Browser->>Reveal: Dispatch keydown event
    alt document.activeElement is not input/textarea
        Reveal->>Reveal: Advance to next slide
        Reveal-->>Browser: nth(1) slide has class .present
    else document.activeElement is input/textarea (e.g., speaker notes)
        Reveal->>Reveal: Ignore keydown (no navigation)
    end
    Browser-->>Playwright: Assert nth(1) has class .present

    Playwright->>Browser: Press ArrowLeft key
    Browser->>Reveal: Dispatch keydown event
    alt document.activeElement is .reveal wrapper
        Reveal->>Reveal: Go to previous slide
        Reveal-->>Browser: nth(0) slide has class .present
    end
    Browser-->>Playwright: Assert nth(0) has class .present

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[Copilot]

Pull request overview

This PR stabilizes the slides Playwright E2E test by making slide selection and keyboard navigation more reliable, and adjusts the editor slides layout so the slide area properly stretches even for notebooks with very few cells.

Changes:

• Ensure Reveal’s deck wrapper receives focus on initialization so arrow-key navigation works without requiring a click (even when focus was previously restored to an input like speaker notes).
• Fix slides layout sizing by letting the editor slides container grow to fill available space.
• Update the Playwright slides test to identify slides positionally and verify focus/navigation behavior more robustly.

Reviewed changes

Copilot reviewed 3 out of 5 changed files in this pull request and generated no comments.

File	Description
frontend/src/components/slides/reveal-component.tsx	Forces focus onto the Reveal wrapper on deck ready to make keyboard navigation consistent.
frontend/src/components/editor/renderers/slides-layout/slides-layout.tsx	Adds flex-1 to ensure the slides layout stretches to fill the available vertical space.
frontend/e2e-tests/slides.spec.ts	Updates slide selection logic and adds a focus assertion to reduce flakiness in keyboard navigation.

[github-actions]

🚀 Development release published. You may be able to view the changes at https://marimo.app?v=0.23.7-dev73