Never re-read what you have already read
by Andreas Tissen · · updated
An agent that starts every session by reading your whole outline is paying for the same knowledge again and again. I measured it. In this product's own logs, reading the tree cost 962,608 bytes. Asking what had changed since last time cost 1,060. Same knowledge, nine hundred times cheaper, and faster by the same order.
There is no trick in that gap. A snapshot and a feed are different things, and most agent integrations only have the first.
Read once, then ask what changed
Every write in Pando is one atomic mutation with a sequence number. An agent that remembers the last number it saw can ask a single question: what happened after this? The answer is the changes themselves, not the tree they happened in.
The habit is three lines in the agent's own memory:
- read the branch once, and write down the sequence number you reached;
- next session, ask for changes since that number;
- write down the new number.
That is all of it. An agent doing this arrives already knowing what moved while it was away, and what moved is usually the only thing that matters.
The other three cheap habits
Ask for the least that answers the question. Outline mode is the bare shape, without the notes and the timestamps, and that makes it about 80% smaller. If the question is "where does this live", the shape is the whole answer.
Write many things in one call. Eleven separate edits, sent as one batch, came back as 648 bytes. The same eleven edits, each echoing its whole bullet: 1,745. Sent one at a time: 2,157.
Change part of a line, never the whole line. Appending to a note without resending it cost 83 bytes. The rewrite cost 13,018. And the bytes are the smaller problem here, because a rewrite is also how an agent deletes a sentence you wrote while it was composing.
Why this belongs in the agent's memory, not in your prompt
These are habits, not instructions. Habits belong where the agent will find them without you. Written into its memory branch they survive every session and every context reset; written into a prompt they last exactly until the day you forget to paste it.
The test is simple. Ask your agent, at the start of a session, what it knows. If the answer arrives quickly and starts with what changed rather than with everything, the agent has the habits.
Try it on your own tree
Connect an agent at pando.ink, let it read one branch, and ask it tomorrow what changed since yesterday. The first session is the expensive one. Every session after that should not be.