2025 AI Coding Toolchain: What to Use and When

What’s in the stack

• Agent runtimes: when to choose open-source vs hosted.
• Routers and fallbacks: choosing by latency, cost, and compliance.
• Observability: event replay, trace search, and prompt heatmaps that pass audits.

Quick starts

Downloadable templates for Next.js + Supabase, LangGraph + Postgres, and Temporal + open-weight ensembles.

What we’d avoid

Hidden vendor lock-in, opaque billing, and prompt code without tests.