fix: guard paper grid view transitions

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Bug and impact

Past-paper course pages render CoursePaperGrid, which wrapped every paper card in React's experimental <ViewTransition>. In the current runtime (react@19.2.7), React.ViewTransition is not exported, so rendering a course page with papers can pass undefined as a component and crash the page instead of showing the paper grid.

Root cause

A previous fix guarded one ViewTransition usage, but CoursePaperGrid still rendered the experimental component unconditionally.

Fix

Added a small PaperCardTransition wrapper that renders <ViewTransition> only when typeof ViewTransition === "function"; otherwise it renders children directly so the grid remains usable on runtimes without the experimental API.

Validation

• node -e "const React=require('react'); ..." confirmed react 19.2.7, ViewTransition type undefined, has ViewTransition false.
• ./node_modules/.bin/tsx scripts/test-global-error-reload-guard.ts
• ./node_modules/.bin/tsx scripts/test-pdf-download-page-edits.ts

Notes: corepack pnpm install --frozen-lockfile --prefer-offline is currently blocked by the repo's pre-existing pnpm override/lockfile config mismatch. Direct tsc --noEmit still hits the repo's known standalone SVG/generated-data declaration failures unrelated to this change.

  

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Greptile Summary

This PR guards the past-paper grid card transition so the page still renders without React’s experimental transition export. The main changes are:

• Adds a PaperCardTransition wrapper around each paper card.
• Uses ViewTransition only when it is available as a function.
• Falls back to rendering card children directly when the API is unavailable.

Confidence Score: 5/5

Safe to merge with minimal risk.

The change is narrowly scoped to replacing an unconditional experimental React component render with a runtime type guard and transparent children fallback. No correctness or security issues were found in the changed path.

No files require special attention.

T-Rex Logs

What T-Rex did

• The first offline link attempt was aborted due to pnpm's non-TTY modules purge confirmation.
• The CI retry rebuilt node_modules but failed with ERR_PNPM_NO_OFFLINE_META while resolving @capacitor/cli from the package mirror.
• The React viewtransition check failed because node_modules/react/package.json was missing, causing MODULE_NOT_FOUND when requiring react.
• The explicit tsx validations could not run because the ./node_modules/.bin/tsx binary was absent.

_{Ran code and verified through T-Rex}

Important Files Changed

Filename	Overview
app/components/past_papers/course-paper-grid.tsx	Adds a guarded wrapper so paper cards use ViewTransition only when React exports it, otherwise rendering children directly.

Sequence Diagram

%%{init: {'theme': 'neutral'}}%%
sequenceDiagram
participant Grid as CoursePaperGrid
participant Wrapper as PaperCardTransition
participant React as React.ViewTransition
participant Card as CoursePaperCard

Grid->>Wrapper: render paper card children
Wrapper->>React: check typeof ViewTransition
alt ViewTransition is a function
    Wrapper->>React: render transition with enter/exit/update props
    React->>Card: render card content
else ViewTransition unavailable
    Wrapper->>Card: render children directly
end

Loading

%%{init: {'theme': 'base', 'themeVariables': {"darkMode": true, "background": "#0d1117", "primaryColor": "#21262d", "primaryTextColor": "#e6edf3", "primaryBorderColor": "#8b949e", "lineColor": "#8b949e", "textColor": "#e6edf3", "edgeLabelBackground": "#161b22", "actorBkg": "#21262d", "actorBorder": "#8b949e", "actorTextColor": "#e6edf3", "actorLineColor": "#8b949e", "signalColor": "#8b949e", "signalTextColor": "#e6edf3", "noteBkgColor": "#373320", "noteBorderColor": "#d4a72c", "noteTextColor": "#f0e6c0", "labelBoxBkgColor": "#21262d", "labelBoxBorderColor": "#8b949e", "labelTextColor": "#e6edf3", "loopTextColor": "#e6edf3", "activationBkgColor": "#30363d", "activationBorderColor": "#8b949e"}}}%%
sequenceDiagram
participant Grid as CoursePaperGrid
participant Wrapper as PaperCardTransition
participant React as React.ViewTransition
participant Card as CoursePaperCard

Grid->>Wrapper: render paper card children
Wrapper->>React: check typeof ViewTransition
alt ViewTransition is a function
    Wrapper->>React: render transition with enter/exit/update props
    React->>Card: render card content
else ViewTransition unavailable
    Wrapper->>Card: render children directly
end

Loading

_{Reviews (1): Last reviewed commit: "fix: guard paper grid view transitions" | Re-trigger Greptile}

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Project	Deployment	Actions	Updated (UTC)
examcooker-dev	Error		Jul 15, 2026 11:03am