Sumo App

Sumo App started as “I want to follow a basho and the official sites are kind of awful,” and quickly turned into “what if the entire visual identity were generated from prompts.” It tracks live tournament standings (via sumo-api.com), wrestler rankings, day-by-day matches, and the 86 finishing techniques (kimarite) that decide them.

Stack is Next.js 16 + React 19 with TanStack Query doing the server-state caching and a thin SSE layer pushing webhook updates from the upstream API straight into the query cache (with HMAC signature verification, because that’s table stakes).

~/sumo-app [ASSETS]

The AI bit (the actual reason this exists)

There’s no LLM call at runtime — every visual asset is pre-generated at build time by a small Python pipeline in /scripts. Two pipelines, both producing sumi-e ink-brush illustrations because that’s the only style that wouldn’t look ridiculous next to centuries-old sumo terminology.

Kimarite illustrations (86 techniques):

• A 291-line hand-written prompt file, one entry per technique, describing the pose, contact point, and intent
• A unified style suffix appended to all 86 prompts so the set holds together visually
• Generated through FLUX.1 Dev locally (28 inference steps) or OpenAI gpt-image-1 as the cloud option
• White background → transparent post-process so they composite cleanly into the UI

~/sumo-app/kimarite [ASSETS]

Rikishi portraits (191 wrestlers):

• Source photo from sumo.or.jp, watermark cropped
• IP-Adapter v2 extracts facial identity from the source
• Rank-conditional prompting: yokozuna get the tsuna rope and a katana; everyone else gets a kesho-mawashi (ceremonial apron)
• Kanji ring-name rendered in calligraphy in the corner
• --ip-scale knob trades likeness for artistic freedom — settled around 0.65 after a lot of A/B testing

~/sumo-app/portraits [ASSETS]

The result is a growing custom illustration set that would have cost real money to commission, generated for the price of a few GPU hours and a lot of prompt iteration.

Other bits

• Hybrid SSR + client-side TanStack Query — server fetches, hydrates initialData, client takes over with stale-while-revalidate
• A cmdk command palette for jumping between tournaments, wrestlers, and techniques (because everything is named in romanized Japanese and nobody can spell anything correctly on the first try)
• Real-time webhooks that invalidate exactly the right queries — matchResults invalidates ["matches", bashoId] and ["banzuke", bashoId], not the world

~/lighthouse [REPORT]

> mobile > desktop

88

performance

100

accessibility

96

best practices

100

seo