Context Engineering
The 30-Day Claude Code Playbook
Hour one, Claude Code is brilliant. Hour six, it's guessing. Build the 11 tools that stop the fade: a context inventory, a repeatable test that proves whether a change helped, a handoff packet a dead session passes to a fresh one, and a token budget with a measured before and after.
There are roughly 35 context engineering books on Amazon. The best-reviewed one has 17 ratings. One is 42 pages. One promises to cut your token costs by 40 percent and never shows the math. None of them let you check.
All eleven tools ship as a free companion repo: one folder per chapter, the scripts transcribed from the book, and a first command that reads your own session logs with no key and no account.
What You'll Build
Why the sixth hour is worse than the first, and what is actually degrading.
A context inventory that shows what is eating your window, line by line.
Build the test first. Every technique after this has to beat your own baseline or it does not ship.
A live gauge with three thresholds: watch, hand off, stop.
Cut the file down until every surviving rule has a number behind it.
A rot detector that catches your agent reasoning off its own failed attempts.
A dead session hands off to a fresh one, checked against your repo before it continues.
A subagent split that keeps your main window flat while the work still gets done.
Profile your sessions. One builder found a single file read 118 times and cut $15,000.
Ship your context system to teammates so it survives more than one machine.
The cases where a bigger window, a different model, or plain code beats every tool in this book.
The whole system on your calendar, with a token bill that has a before and an after.