The user wants a single-page web app with:
1. A heptagon (7-sided polygon) that spins 360° every 5 seconds
2. 20 numbered balls (1-20) dropping from the center
3. Balls affected by gravity and friction
4. Balls collide with each other
5. Balls bounce off the rotating walls realistically
6. Each ball shows its number, and the number rotates to show the ball's spin

Let me build this step by step:

1. Draw a heptagon on canvas
2. Rotate it every 5 seconds
3. Simulate physics for 20 balls


4. Handle collisions between balls and the heptagon walls, apply gravity and friction forces, and render the spinning numbers on each ball

Now I'm setting up the canvas dimensions and defining the heptagon with its 7 vertices. I'll track each ball's position, velocity, spin angle, and friction coefficients. The physics will update each frame by applying gravity, detecting collisions between balls and the heptagon walls, then resolving those collisions with proper impulse calculations.

For ball-to-ball collisions, I'm checking when they overlap and applying elastic collision physics that accounts for their masses and velocities. When the balls hit the heptagon walls, I need to find the nearest point on each edge and reflect their velocity with a bounciness coefficient, also factoring in the wall's motion from the rotation. Now I'll implement this in JavaScript using canvas to render everything.

Writing canvas physics code... Writing collision detection... Writing the complete app... Writing canvas physics code... I'm accounting for the wall's rotational velocity by calculating the tangential velocity at the contact point, then resolving the collision by decomposing the relative velocity into normal and tangential components with separate coefficients for restitution and friction. The ball's angular velocity gets updated based on the tangential force applied during the collision.

I'm realizing this physics approach is getting unwieldy, so I should step back and build something that works rather than chase perfect accuracy. For the visuals, I'll render the balls as circles with numbers that rotate as they spin, and the heptagon as a spinning shape with a fixed viewport while the physics operate in the rotating frame.

Writing the canvas code... Building the canvas app now with a physics loop that handles the heptagon walls and ball interactions. Still writing physics code... Still writing collision code...

Now I'm thinking about the spin mechanics—when balls collide or hit walls, the friction should transfer angular velocity. I'll calculate the surface velocity by combining the ball's translational motion with its spin radius, then use the tangential component of the collision impulse to update the spin. For the visual effect, I'll rotate each ball's number based on its cumulative spin angle. I should also consider how the spinning heptagon affects collisions—the moving walls impart additional impulse to the balls, so I'll need to factor in the wall's velocity at the contact point when calculating the relative velocity.

Writing the complete simulation... Writing the physics engine... I'm simplifying the physics for stability—keeping bounce coefficients reasonable and treating friction-induced spin as a secondary effect rather than trying to perfectly model the full coupling. For wall collisions, I need to account for the wall's velocity at the contact point and decompose the relative velocity into normal and tangential components to apply the right forces.

Writing collision response code... Writing collision response code...

Now I'm working through the ball-to-ball collision physics with friction, calculating the normal impulse from the restitution coefficient, then using that to determine the friction impulse based on the tangential velocity component and Coulomb friction limit.

Still writing collision logic...

I'm thinking through how to render everything—the heptagon as a dark gray polygon, balls as colored circles with numbered labels, and I need to calculate the interior angles correctly for the polygon geometry.

Now I'm ready to write the full implementation. Setting up the canvas and UI with a dark background, then building out the physics simulation for the bouncing balls. I'm settling on a white background with dark gray walls for the heptagon, and using distinct colors for each of the 20 balls—cycling through reds, blues, greens, and purples to keep them visually separated.

Writing the complete implementation... Writing the complete implementation... Writing the complete code...

Actually, I'm realizing the initial drop needs some thought—all 20 balls starting at the center would just stack on top of each other. I should spread them out a bit, maybe with slight offsets and random initial velocities, so they don't all collide immediately. me stagger the ball creation over time to avoid a chaotic initial collision—releasing one ball every few frames lets them spread out naturally under gravity before they start colliding. I'll implement this with a queue system that adds balls gradually, each dropping from slightly different positions near the center.

Writing the HTML file now... Writing canvas setup and physics engine... Still writing collision detection... Writing the collision response... Still writing collision logic... Writing the animation loop...

The file has been written. Let me verify it exists and looks correct.

The file is written correctly. Let me review it once more to make sure everything is right.