architecture-and-stacklisted

# 05 — Architecture and Stack Default stack: `_kernel/standards.md#stack`. Override conditions below. ## Cloudflare-first decision tree **Compute**: Workers (default, every HTTP/cron/queue) · Pages (static-only marketing, rare) · Containers (non-JS runtimes: Playwright headful, ffmpeg, Python ML, build orchestration) · Sandbox SDK (generated/risky code before live promotion) **State**: D1 (default relational, ≤10GB/db, Sessions API read-replicas, Time Travel 30-day PIT) · KV (eventually-consistent, cache/sessions/feature-flags) · R2 (object storage, lifecycle Standard→IA after 30d) · Durable Objects (coordination + strongly-consistent SQLite storage since Apr 2025, chat rooms/builder sessions/rate-limiting) · Hyperdrive (front external Postgres/MySQL) · Vectorize (semantic search/RAG, 5M dim/index, topK 100, 10 metadata indexes) **Async**: Queues (best-effort, 5000 msg/sec, R2 event notifications) · Workflows v2 (deterministic, 50K concurrent, 300 creates/sec, 2M queued/workflow, `step.do` + `step.sleep` + `step.waitForEvent`) · Inngest (event-driven, better DX/observability) **AI**: Workers AI (Llama 3.3 70B FP8 free, Llama 3.1 8B FP8, Llama 4 Scout 17B vision) · AI Gateway (caching + rate-limit + fallback + logging for every LLM call) · Vectorize (embeddings + ANN search) ## Override conditions (when CF isn't enough) | Need | Fallback | Adapter | |---|---|---| | Advanced SQL (RLS, OLAP, partial indexes) | Neon Postgres via Hyperdrive | `SqlPort` | | Redis primitives