Not every handover has a second person. You finish a side project, a client pauses an engagement, a product goes on the shelf while you chase the next thing. Six months later you open the folder, and the developer who wrote none of it and remembers less inherits everything. That developer is you, and they deserve better than what you usually leave them.
Agent-built projects decay in memory faster than hand-built ones, because you never held the whole thing in your head to begin with. The agent held it, per session, and the sessions scrolled away. Coming back cold means rediscovering how to run it, which environment variables it silently needs, whether the tests ever meant anything, and why on earth the auth works the way it does. That re-entry cost is why shelved projects stay shelved: the afternoon of curiosity that might revive one gets spent on archaeology instead, and curiosity does not survive archaeology.
The day you shelve a project, spend ten minutes closing it properly:
The passport that lands in the repository is the letter to your future self, written by evidence instead of good intentions. Setup that was executed, not remembered. The environment variables that actually matter, including the undocumented one the scan will find. The decision log pulled from your agent sessions while they still exist, which matters doubly here, because session histories on your own machine are one OS reinstall away from gone. And the unknowns listed, so returning you knows exactly where the dragons were.
When you come back, do not start by reading code. Run npx mantyl receive first: it checks the project against its own passport and re-executes the recorded checks in a fresh sandbox. Everything reproducing means you are exactly where you left off, with a map. A named divergence means something rotted on the shelf, a dependency, a platform, a file you fiddled with and forgot, and you know what it was before you have invested an hour. Either way, re-entry costs an afternoon instead of a lost weekend, which is often the difference between a project reviving and not.
This is the lowest-stakes seat on this site, and the best place to build the habit, because a passport at every shelving point means every project you own is permanently one command from provably runnable. When one of those shelved projects turns out to matter, someone wants to buy it, use it, or build on it, you are already holding the artifact every other page here tells people to go and make; from there, selling it or delivering itstarts warm. The habit’s full version, including the credentials and services notes that future you also forgets, is the handover checklist.