feat(classifier): NanoGPT-backed category-classify fetcher (32-axis taxonomy)

[0motionguy]

Summary

Without a classifier, the 17 new chips shipped in C-CAT PR #3174 read "0 repos." This PR wires the missing piece: a daily NanoGPT-backed classifier that maps every consensus-trending repo into one of the 32 category ids.

Approach

• New fetcher apps/trendingrepo-worker/src/fetchers/category-classify/ — reads consensus-trending payload, batches the top-1000 fullNames into chunks of 20, sends each chunk to NanoGPT (Kimi-K2-Instruct via OpenAI-compatible chat) with strict response_format: { type: 'json_object' } and the full 32-id taxonomy embedded in the system prompt.
• Re-classification skip rule — any repo whose previous classification is fresher than 7 days is skipped. Bounds cost as the pool grows.
• Schedule — '17 3 * * *' UTC, well off the on-the-hour peaks where the other fetchers run.
• Cost discipline — ~$0.00003/call × (1000 / 20-per-batch) = $0.0015/day at full pool. Documented in code.
• No publicly stale batches rule — payload emits computedAt + staleness_seconds so UI consumers can drop the category facet when stale.

Companion PRs

• #3174 C-CAT — ships the 32 taxonomy entries
• #3181 per-category-landing-pages — renders /categories/<slug> with JSON-LD
• This PR — the classifier that ties them together so each chip lights up with real repos

Files

apps/trendingrepo-worker/src/fetchers/category-classify/
├── index.ts        — fetcher (batched LLM sweep, skip-fresh, write payload)
├── llm.ts          — NanoGPT primary + Kimi fallback (lifted from L1 PR #3172 pattern)
├── types.ts        — CategoryClassifyPayload, VALID_CATEGORY_IDS, CATEGORY_BRIEFS
└── __tests__/types.test.ts — 4 vitest tests asserting taxonomy schema
apps/trendingrepo-worker/src/lib/env.ts — NANOGPT_API_KEY/_BASE_URL/_MODEL + widen LLM_PROVIDER enum
apps/trendingrepo-worker/src/lib/llm/router.ts — narrows the wider enum back to 'kimi'|'openrouter' for the unrelated router
apps/trendingrepo-worker/src/registry.ts — register categoryClassify in FETCHERS
scripts/classify-categories.ts — one-shot seed script for post-deploy

Test plan

• pnpm --filter trendingrepo-worker tsc --noEmit — clean
• pnpm --filter trendingrepo-worker test src/fetchers/category-classify — 4/4 pass
• Operator sets NANOGPT_API_KEY and runs pnpm tsx scripts/classify-categories.ts once — verify ss:data:v1:repo-categories populates with assignments
• Verify per-category landing page (feat(seo): JSON-LD CollectionPage + schema graph for /categories/[slug] #3181) reads the assignments and lights up the new C-CAT chips

Evidence

Deep-crawl deltas v3: OSSInsight ships 102 curated collections to TrendingRepo's 15; C-CAT brought us to 32; this classifier makes those 32 actually useful. Toolbox PR #241 has the underlying delta.

🤖 Generated with Claude Code