Start here this week

If you only have a weekend, do these three things. They are the highest leverage per hour in the whole book.

1. Turn on Anthropic prompt caching

Effort: two hours. Impact: immediate and ongoing cost reduction, plus latency.

In agent.py, add cache_control to the system prompt so it hits Anthropic's prompt cache. system_prompt.md is 101 lines and ships on every turn. Caching it cuts token cost by a large factor. Invoke the claude-api skill when you do this, so the diff also handles model version hygiene.

2. Add TypeScript to the frontend

Effort: one weekend. Impact: catches most of the bugs you will hit in the next three months.

Add a tsconfig.json, rename the leaf components in frontend/src/components/ from .jsx to .tsx, and run openapi-typescript against the FastAPI server's /openapi.json to generate a typed client. Import those types into useChat.js and App.jsx as they get ported. You do not have to port everything in one pass. Leaving a few files as .jsx is fine.

3. Read Refactoring UI and do one design pass

Effort: one weekend. Impact: biggest visible-quality bump for the effort.

Read Refactoring UI cover to cover. Then spend one focused hour on MapSettingsPanel.jsx and RouteDetail.jsx applying what you just learned. Fix spacing, align on a grid, cut the number of gray shades, and pick a type scale. Only touch styles, do not refactor logic.

What comes next

Once these three are done, open TypeScript and React and work through the chapters in order. Persistence and auth is the chapter that unblocks paying customers. Everything before it is quality-of-life. Everything after it is scale and polish.