Social preview image not working for OBBBA household-by-household tool

[MaxGhenis]

Problem

The OBBBA household-by-household tool at https://policyengine.org/us/obbba-household-by-household shows the default PolicyEngine logo for social media previews instead of the specific OBBBA image.

Current Behavior

• The page shows social_cards/main_logo.png for both Twitter and Open Graph meta tags
• The correct image obbba-household-by-household.png exists in the app but isn't being used

Root Cause

The backend social card generation (in gcp/social_card_tags.py or API) doesn't handle external_url posts properly. It only knows how to generate social cards for traditional blog posts with markdown files.

Expected Behavior

The page should show the OBBBA household-by-household image for social media previews when shared on Twitter, LinkedIn, etc.

Related Issues

• This is part of the larger architectural issue where tools/interactives need proper structure separate from blog posts
• Related to the previous 502 errors fixed in Fix 502 errors: Add posts.json validation test and dummy filename for OBBBA #2726

Potential Solutions

1. Short-term: Add special handling for external_url posts in the social card generation
2. Long-term: Create proper structure for non-blog posts/tools as discussed in Add checkboxes to toggle parameters and variables in explorer #2707
3. Alternative: Move social card generation to edge functions (Vercel/Supabase) as suggested by the team

Impact

When people share the OBBBA tool on social media, it doesn't show the appropriate preview image, reducing engagement and click-through rates.