Design intent: rules that stay true

Parameters capture values. Design intent captures rules. "The wall is 2.4 mm" is a value. "No wall may ever be thinner than 1.6 mm" is a rule. "The holes stay centered no matter how wide the plate gets" is a rule too.

In other CAD tools these are called constraints. In Solid Vibes they are written in plain language and shown as small chips in a Design intent section.

How to create one

Say it with words like "keep", "always", or "no matter":

Keep these four holes centered on the plate, no matter how wide I make it.

Always keep the walls at least 1.6 mm thick.

The lid and the box must always have the same width.

The agent turns each sentence into a lasting rule. You will see it appear as a chip you can read, edit, or remove.

Two ways a rule is enforced

1. By construction. Most rules are enforced by writing dependent values as formulas. "Centered" becomes "hole position = width / 2", so there is nothing to break. The geometry cannot move off center, because its position is defined as the center.

2. By checking. Some rules cannot be built in. "Walls at least 1.6 mm" depends on the whole shape. For these, Solid Vibes re-evaluates a yes-or-no check after every rebuild and shows a green or red chip.

The checks can use a few measurements of the current model:

So "walls at least 1.6 mm" becomes min_wall() >= 1.6, and "fits on a 220 mm bed" becomes bbox_x() <= 220.

Kinds of intent

Each chip also records who made it (you or the agent) and which parameters or steps it is about, so clicking it highlights the relevant parts.

What a red chip means

A red chip is not an error in your model. It is the model telling you a rule you set has just stopped being true. Maybe you slid wall down to 1.2 and the min-wall rule says 1.6.

You then have a choice, and that choice is the useful part:

1. Undo the change. The rule was right.
2. Fix the design so the rule holds again (use a thicker wall).
3. Relax the rule on purpose, because you now know better.

Writing good intents

• Keep the list short. Five meaningful rules beat twenty obvious ones.
• Prefer positive, measurable statements. "Min wall 1.6 mm" works. "Strong enough" cannot be checked.
• Name the cause, not the symptom. "The lid is always the box width" is better than "the lid should fit".
• Pair rules with parameters. A fit_clearance parameter plus a rule that it stays between 0.15 and 0.4 mm is a safe design.

Intent and the agent

Intent also guides the agent. When you ask it to widen a plate, it knows the "holes stay centered" rule exists and writes the change so it keeps holding. It will mention it if a request would break a rule, rather than quietly breaking it.

You can ask what is currently protected:

List every design intent on this piece and tell me which ones are currently satisfied.

Try it

On the Enclosure template:

Add three rules. The walls are never thinner than 1.6 mm. The overall length stays under 150 mm. The screw bosses are always equally spaced from the corners.

Now drag the wall slider below 1.6 and watch the chip turn red. Drag it back and it turns green again.