fix: show tooltip during hidden periods for multiple choice questions

[SylvainChevalier]

Summary

Fixed the missing tooltip issue for multiple choice timeline charts during hidden periods.

Changes

• Tooltips now properly display during hidden periods (cpRevealsOn or isEmpty)
• User predictions column is always shown during hidden periods
• Forecasters count is hidden when community predictions are not available

Testing

• Linting passed
• TypeScript compilation successful
• Build completed without errors

Fixes #4112

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes

  • Improved tooltip rendering reliability in the multiple-choice chart to ensure tooltips appear correctly across more forecast and user-choice scenarios.

• New Features

  • Added a "Show Me" column in chart tooltips that appears when user choices, forecast reveals, or empty-forecast states are present.

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[SylvainChevalier]

@claude the number of forecasters should be shown during the hidden period.

[coderabbitai]

📝 Walkthrough

Walkthrough

Refines tooltip rendering in the multiple choices chart view: expands the tooltip active condition to include user choices and forecast availability flags, introduces a showMeColumn prop for the tooltip, and adds null-safe checks when computing these values.

Changes

Cohort / File(s)	Summary
Tooltip Rendering Logic front_end/src/app/(main)/questions/[id]/components/multiple_choices_chart_view/index.tsx	Adjusts tooltip visibility condition to `isTooltipActive && (tooltipChoices.length > 0

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Suggested reviewers

• hlbmtc

Poem

🐰 A tooltip hid in shadowed times,
I nibbled logic, tuned the lines.
Now columns peek where choices play,
Small fixes hop and brighten day. ✨

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The PR title accurately summarizes the main change: fixing tooltip visibility during hidden periods for multiple choice questions, which matches the code modifications.
Linked Issues check	✅ Passed	The code changes address issue #4112 by modifying tooltip rendering logic to display during hidden periods (cpRevealsOn/isEmpty) and show user predictions/placeholders as required.
Out of Scope Changes check	✅ Passed	Changes are narrowly focused on the tooltip visibility condition and showMeColumn logic for the multiple_choices_chart_view component, remaining within scope of fixing the hidden period tooltip issue.

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✨ Finishing touches

• 📝 Generate docstrings

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📜 Recent review details

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between caecb8e and cb091cb.

📒 Files selected for processing (1)

• front_end/src/app/(main)/questions/[id]/components/multiple_choices_chart_view/index.tsx

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🔇 Additional comments (2)

front_end/src/app/(main)/questions/[id]/components/multiple_choices_chart_view/index.tsx (2)

342-350: This review comment is incorrect—the component already safely handles undefined userPredictions.

The MCPredictionsTooltip component is designed defensively: it uses optional chaining (userPredictions?.find(...)) when accessing the predictions array and defaults to "?" for missing values via nullish coalescing. Even when showMeColumn is true and userPredictions is undefined, the component renders the "Me" column correctly without throwing or rendering nothing.

No change is needed.

Likely an incorrect or invalid review comment.

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330-334: The original review comment's concern about tooltip activation is incorrect. The useChartTooltip hook uses Floating UI's useHover interaction, which activates on DOM hover regardless of data points—not on chart cursor events. The reference element is properly attached (line 273-274), so tooltip activation will work in hidden periods.

The content condition check at lines 331-334 is separate from activation logic and intentional: it prevents rendering an empty tooltip when there's no data to display. This is correct behavior and not a bug.

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[claude]

Claude finished @SylvainChevalier's task in 53s —— View job

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Task Complete ✓

Task: Show the number of forecasters during the hidden period

Todo List:

• Read the modified file to understand current implementation
• Check for CLAUDE.md repository guidelines
• Modify code to show forecasters count during hidden periods
• Commit and push changes
• Update comment with completion status

Summary

I've updated the code to show the forecasters count during hidden periods. The change was made in front_end/src/app/(main)/questions/[id]/components/multiple_choices_chart_view/index.tsx:348-349.

What changed:

• Removed the conditions !forecastAvailability?.cpRevealsOn && !forecastAvailability?.isEmpty from the FooterRow display logic
• The forecasters count now displays whenever it has a valid value (not null/undefined), regardless of whether the period is hidden

The forecasters count will now be visible in the tooltip during hidden periods (cpRevealsOn or isEmpty states), while the user predictions column remains visible as intended.

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[github-actions]

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• Branch: claude/issue-4112-20260120-1651
• Fly App: metaculus-pr-4115-claude-issue-4112-20260120-165

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[SylvainChevalier]

@claude the fix does not work, the tooltip still does not appear on hover during the hidden period.

[claude]

Claude finished @SylvainChevalier's task in 2m 16s —— View job

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Task Complete ✓

Task: Fix tooltip not appearing on hover during hidden periods

Todo List:

• Read the modified file to understand current implementation
• Check for CLAUDE.md repository guidelines
• Analyze tooltip rendering logic to identify root cause
• Fix the tooltip rendering condition
• Commit and push changes
• Update comment with completion status

Solution

Modified the tooltip rendering condition in front_end/src/app/(main)/questions/[id]/components/multiple_choices_chart_view/index.tsx:330-334 to allow tooltips to appear during hidden periods.

What changed:
The tooltip now renders when any of these conditions are met:

• tooltipChoices.length > 0 (has community predictions)
• tooltipUserChoices?.length (has user predictions)
• forecastAvailability?.cpRevealsOn (community predictions hidden until reveal time)
• forecastAvailability?.isEmpty (no forecasts yet)

Previous behavior: Tooltip would only show if tooltipChoices had items, which could be empty during hidden periods.

New behavior: During hidden periods, the tooltip will appear showing:

• Placeholder text for community predictions (e.g., "Reveals on [date]" or "No forecasts yet")
• User's own predictions (if available)
• Forecasters count

This ensures users can always see their own predictions and understand the hidden period status when hovering over the chart.

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| Branch: claude/issue-4112-20260120-1651