Arrows That Curve Around Things

Draw an arrow between two boxes with a third box in the way, and the arrow does not land as a straight line through it. It arrives with a gentle bow around the obstacle instead.

This is deliberate, and it is the answer to "why is my arrow curved when I drew a straight one?"

When it happens

Only at the moment you finish drawing a new arrow. The editor looks at the straight line it is about to leave behind and asks whether that line would read badly:

• It would cut through something. The line passes through another element's box, or close enough to graze it. The arrow bows around, on whichever side needs the smaller bend.
• It would run flush along its own boxes. Two stacked elements joined along one edge give a line that hugs their sides and is hard to see. The arrow bows outward, away from them.

If neither side can be cleared without an enormous bend, the arrow stays straight: a wild curve reads worse than the crossing it was avoiding.

When it does not

It is deliberately a one-shot at draw time, not a rule the diagram lives under:

• Arrows are never re-routed later. Move a box onto an existing arrow and the arrow stays exactly as it is. Nothing quietly reshapes work you have already arranged.
• Repositioning an endpoint never triggers it. Only a brand-new arrow's head placement does.
• Anything you chose wins. If the arrow already has a style, a curve, or bend points, that is left alone.
• Imported and generated diagrams keep their own geometry — Mermaid and Excalidraw imports, templates, AI authoring and auto layout all decide their own routing.

Changing it

What you get is an ordinary curved arrow: the same thing you would have made by dragging the curve handle yourself. Nothing about it is special afterwards, so every normal control applies.

• Drag its curve handle to bow it more, less, or the other way. See Curve and Elbow Handles.
• Set it back to Straight from the arrow's style controls, and it stays straight. See Arrow Styles.
• Undo removes the whole arrow, not just the bow. The curve is part of drawing the arrow, so one Ctrl/Cmd + Z takes you back to before you drew it rather than leaving a straight arrow through the obstacle behind.