Devin runs longer than most agents. A session can span hours and touch dozens of files without you watching each step.
That is exactly the situation where a design drift compounds. One wrong grey in hour one becomes the house style by hour three.
Two places to put the rule
Devin reads repository files like any other agent, so AGENTS.md in your root works and is portable across tools.
Devin also has a Knowledge feature in its web interface. Knowledge entries persist across sessions and apply to the repositories you scope them to. For a design contract that a whole team relies on, that is the more durable home.
Use both. The repo file keeps the rule versioned, the Knowledge entry makes sure it survives even when a session starts somewhere unexpected.
The repository side
Put DESIGN.md in your root and reference it from AGENTS.md:
## Design
All UI work follows DESIGN.md in the repository root. Read it before creating
or editing any component, page, or stylesheet.
- Colors, spacing, radius, and type come only from DESIGN.md tokens.
- Component states and density follow its component rules.
- No new font family, shadow, or gradient.
- If a token is missing, open a question rather than inventing a value.The Knowledge side
In the Devin web app, open Knowledge and add an entry scoped to the repository.
Keep it short and operational:
Title: Design contract
Before any UI work in this repo, read DESIGN.md at the root. Use only the
tokens it defines for color, spacing, radius, and type. Do not add fonts,
shadows, or gradients. If a value is missing, ask in the session summary
instead of choosing one.Devin pulls matching Knowledge into its context automatically, so you do not have to repeat it in the prompt.
Ask for a design checkpoint
Here is the habit that has helped me most with long sessions.
Add one line to your task description:
Before you start UI work, post the DESIGN.md tokens you plan to use.You get a checkpoint early in the run. If the tokens are wrong, you correct one message instead of reviewing a 40 file pull request.
Verify it worked
Start a session and ask before assigning work:
Summarise the color and type rules for this repository and cite the file.A correct summary that names DESIGN.md means both layers are working.
Common mistakes
- Only using Knowledge. Knowledge lives in Devin. Your teammates on Cursor get nothing. Keep the file in the repo too.
- Writing Knowledge as description rather than instruction. "Our brand is confident and minimal" is not actionable. Token rules are.
- Letting a long session run unchecked. The early checkpoint costs a minute and saves an afternoon.
What this means for you
Autonomy is only comfortable when the guardrails are set before the work starts. A design contract in both the repo and Knowledge is a guardrail that does not depend on you being at the keyboard.
If you need a DESIGN.md, the library has documented systems ready to adapt.