The situation
You have explained the same project preference several times: where a feature lives, how to test it, what not to touch, or how you want changes described. The next chat or agent session does not reliably remember that conversation.
The idea in one paragraph
An instruction file is a project file containing stable guidance for people and tools working there. It gives a fresh session a place to look for the local rules. Good instructions are short, specific, and relevant to many tasks; a temporary request belongs in the current task, not in permanent project guidance.
| Keep in the file | Keep in the task | Leave out |
|---|---|---|
| Test command | Today's outcome | Private secrets |
| File boundaries | Current constraint | Old chat history |
| Style rules | Acceptance check | Vague preferences |
How it actually works
An AI tool may be configured to read named instruction files when it enters a project. That makes the file a durable starting point, not magic memory: the tool can still misunderstand it, and different tools may read different file names. Put the most important rules near the top, state the reason when it helps judgement, and remove instructions that no longer match the project.
What this changes for you
- Write down rules you repeat across unrelated tasks.
- Make each rule observable, such as a check to run or an area to avoid.
- Review the file when the project's workflow changes.
Where it breaks
A long instruction file becomes background noise. Conflicting rules make an agent choose rather than follow. It also cannot safely hold credentials or turn a risky action into an approved one. Keep sensitive details out and give time-sensitive direction in the task itself.
Terms used on this page
Instruction file: A file that records durable guidance for work in a project.
Stable guidance: A rule likely to matter across many future tasks.
Task: The bounded piece of work currently being requested.
Read next
Continue to Resumable work.