Engineering notes from 9io.
How we build products, AI systems and trading infrastructure — and what we learn on the way. Written by the people who do the work, with the sources linked.
How much does it cost to build an AI agent or app in 2026?
How much does it cost to build an AI agent? A cost model that shows its working, from build hours and market rates to monthly running costs per 1,000 users.
8 October 2026 · 16 min read AI industryWhat EU and California law now require of AI-generated content
Article 50 of the EU AI Act and California’s AI Transparency Act took effect on 2 August 2026. What product teams must build, and by when.
8 October 2026 · 13 min read Product engineeringHow to take a vibe-coded app from Lovable to production safely
Moving a vibe-coded app from Lovable to production: the Supabase RLS, key, storage and webhook checks that matter, how to migrate, and when to rebuild.
4 October 2026 · 19 min read Product engineeringWhat a fractional CTO costs in 2026, and when an AI startup needs one
Fractional CTO cost in 2026: the market hourly rate, what a full-time CTO costs once employer costs are added, and a decision rule by startup stage.
3 October 2026 · 14 min read AI engineeringHow AI image pipelines fail quietly, and how to catch it
A Gemini try-on that took nearly two minutes to fail, product cutouts saved onto black, and the retry, cache and alpha fixes for each.
2 October 2026 · 11 min read TestingHow we pinned down four intermittent bugs in React 19 and Python
Four bugs in a React 19 and Python stack that failed only some of the time, the condition behind each, and how we made each one show up on demand.
30 September 2026 · 10 min read Next.jsHow redux-persist’s PersistGate emptied our Next.js server HTML
Our public Next.js pages returned 200 with full head tags, but each body was a 1 KB loading screen. Why PersistGate did it, the fix, and how to check yours.
26 September 2026 · 7 min read MCPMaking one MCP server work in Claude, ChatGPT, Cursor and VS Code
What broke when one remote MCP server met Claude, ChatGPT, Cursor, VS Code and command-line clients, and the OAuth and version fixes behind each.
26 September 2026 · 13 min read Product engineeringEncoding transparent WebM with WebCodecs when alpha isn’t supported
Chrome’s VideoEncoder rejects alpha. Encode colour and alpha as two VP9 streams and join them in WebM BlockAdditions with a small hand-written muxer.
25 September 2026 · 12 min read Algo tradingOrder safety by default in code that can place trades
How 9io Alpha keeps order code safe with paper ports, dry runs, order caps and broker-side exits, and the cancel-then-sell race we still have to fix.
15 September 2026 · 14 min read Product engineeringHow we built the 9io.ai blog on Markdown files and FastAPI
Markdown files and one Python module run the 9io.ai blog, with JSON-LD, canonical URLs, a sitemap, RSS and llms.txt built in. How it works and what we’d change.
10 September 2026 · 8 min read