A long session with a model produces a scroll that feels like documentation. It is not. It mixes rejected ideas, outdated file paths, and answers to prompts you later narrowed. The next morning you will not remember which paragraph was the decision.
Keep a working log in the repository or in the issue, and keep it dull. One line for the decision: what you chose and what you refused. One line for the command you ran. One line for the result you saw, especially when it failed. Link the diff. Do not paste the whole conversation.
Update the log when the plan changes, not at the end. A log written afterward tends to describe the code you wish you had. A log written at the time describes the constraint you actually hit, which is the part worth keeping.
When you start a new chat, paste the log, not the previous transcript. The model then continues from the decisions instead of from its own earlier digressions. That is also how a person joins the work. Five lines of log beat fifty lines of chat.