Agents Forget Between Sessions. Leave Them a Handoff Note.

If you run agents on work that takes more than one sitting, here is the short answer.

At the end of every session, have the agent write a handoff note. At the start of the next one, have it read the note before it touches anything.

That's it. It sounds too simple to matter. It's often the difference between work that builds and work that starts over every morning.

Why agents forget

An agent works inside a window of context: the instructions, the files it opened, the tool results, the back-and-forth. When that session ends, the window closes. The next session starts cold.

Even inside one long session, the window fills up. Many tools handle that by summarizing older parts of the conversation to make room. A summary keeps the gist and drops the details. The detail it drops is often the one that mattered: the reason a choice was made, the file that was off-limits, the thing that was checked and turned out to be wrong.

None of this is a flaw you can prompt away. It's how the setup works. So plan for it the way you'd plan for a shift change.

What goes wrong without a note

When a fresh session picks up old work with no note, the same problems show up again and again.

It redoes finished work. It doesn't know step three is done, so it does step three again, sometimes differently.

It undoes decisions. You chose one approach for a good reason yesterday. Today it doesn't know the reason, sees a "better" option, and quietly switches.

It re-asks settled questions. You answered something once. Now you answer it again. And again.

It repeats a known mistake. The thing that failed yesterday looks like a fine idea today, because the failure isn't on the page.

It treats guesses as facts. This is the worst one. Yesterday's session wrote "the config probably lives in the settings folder." Today's session reads its own old summary and acts as if that line had been confirmed.

Every one of these costs time. The last one can cost a lot more.

What goes in the note

A good handoff note is short. It's written for a stranger who is smart, careful, and knows nothing about the last session. A handful of headings is enough:

• Goal: one or two sentences on what this work is for.
• Done: what's finished, and how you know.
• Not done: what's left, in the order it should happen.
• Decisions: what was chosen, and why, in a line each.
• Verified vs. assumed: which statements were checked, and which are still guesses.
• Open questions: what's waiting on a person, and on whom.
• Don't touch: files, systems, or steps that are off-limits, and why.
• Where things are: paths, links, branch names, anything the next session will need to find.
• Next step: the single first thing to do.

Put a date and time on it, with a time zone. "Updated Tuesday" stops meaning anything by Thursday.

The line that matters most

If you only add one heading, make it "verified vs. assumed."

Agents are confident writers. A guess and a fact look the same in a tidy summary. Once a guess has been written down and read back, it starts to feel like knowledge, both to the agent and to the person skimming the note.

So split them on purpose. "Verified: the test suite passes on the current branch (ran it at 3:40 PM)." "Assumed, not checked: the old endpoint has no other callers."

That one split can do more to stop bad work than a page of clever instructions. The next session can trust the first list and has to check the second before it builds on it.

Where the note lives

Keep it in the work, not in the chat.

A file in the project folder or the repo is best. One known path, same name every time. A chat history scrolls away. A file sits where the next session will look, and where you can read it too.

Two pieces work well together: a short current note that gets rewritten at the end of each session, and a running log that only grows. The current note says where things stand. The log says how they got there. When the two disagree, that's worth a look.

Don't let the note become a diary. If it takes more than a couple of minutes to read, the next session will skim it. So will you.

Read it first, then check it

Writing the note is half the habit. The other half is making the next session read it before it acts.

Put that in the instructions in plain words: read the handoff note first, then confirm the "verified" items still hold, then start on the next step.

The check matters because the world moves between sessions. Someone else may have changed a file. A deploy may have gone out. A question may have been answered somewhere else. A note is a starting point, not a promise that nothing changed overnight.

If the check turns something up, the first job is to fix the note. Then do the work.

It helps the people too

The note isn't only for the agent.

When you want to know where a piece of work stands, the handoff note is the fastest answer. You don't have to scroll a long transcript or ask the agent to summarize itself again. You open one file and read it in a minute.

It also makes problems visible early. If the "assumed" list keeps growing and nothing moves to "verified," something is off. If the same open question sits there for a week, someone needs to answer it. You can see that in the note without digging.

A short checklist

1. End every session with a note. No note, no session end.
2. Write for a stranger. Assume the next reader knows nothing.
3. Split verified from assumed. Every time.
4. Record decisions with reasons. One line each is enough.
5. List what's off-limits. Say why, so it stays off-limits.
6. Keep it in a file at a known path. Not in chat.
7. Date it, with a time zone.
8. Read it first, then check it. Fix the note before you do the work.

The short version

Agents don't remember yesterday. You can't change that, but you can make yesterday easy to pick up.

A short handoff note, read first and checked against reality, turns a string of cold starts into one piece of work that actually moves forward.

I spend a lot of my writing life with a man who wakes up with no memory and has to piece together who he was from the people around him. Agents get off easy by comparison. All they need is a good note. Allen Mercer's story starts in Shadows of the Forgotten, and the first three chapters are free: https://johndclay.com/free-chapters