Now I need to analyze the user's requirements. The user wants a full-screen flocking simulation, with the core being the implementation of the three classic rules of the Boids algorithm: separation, alignment, and cohesion. The boids should be drawn as triangles, have smooth steering behavior, and they should flee from the mouse cursor.

First, consider the page structure. A full-screen canvas element is needed as the main drawing area, and perhaps a simple UI to display some control parameters. The UI should be semi-transparent and float over the canvas without obstructing the main view. Tailwind CSS can be used to quickly achieve a glass morphism effect.

Next is the Boids algorithm itself. Each boid needs to record its position, velocity, and acceleration vectors. In each frame, the forces from the three rules are calculated and applied to update the velocity and position. Separation prevents crowding, alignment makes the flock move in the same direction, and cohesion brings the flock together. The mouse interaction is essentially a repulsive force added to the separation rule.

Regarding rendering, the triangles need to be able to rotate according to their direction of movement, so an angle calculation is required. To achieve a smooth visual effect, parameters like maximum speed and maximum steering force can be added for limitation.

Performance-wise, the number of boids might be large, so drawing needs to be optimized. Perhaps a spatial partitioning data structure could be used, but for a few hundred boids, a simple approach might suffice for now.

In terms of interaction, besides mouse repulsion, some control sliders could be added to allow users to adjust the weights of the three rules in real-time, enhancing the experience. A reset button is also needed.

Visually, some details could be added, like color gradients based on velocity or proximity, or slight glowing effects. A dark background with bright boids would create good contrast.

Now, consider the code structure: initialize the canvas and boids array, the main loop to update the state and redraw, event listeners to handle mouse movement and UI controls. The boid class encapsulates its own state and update logic, while the calculation of the three rules can be implemented as static methods.

Parameter tuning is crucial; the ranges and default values for the three rules need to be set reasonably to make the behavior look natural. Perhaps the sliders could be set to a range of -5 to 5, with a default around 1.5.

Finally, test various scenarios: stationary mouse, fast mouse movement, mouse entering the center of the flock, etc., to ensure the boids respond reasonably.

The user wants a full-screen boids flocking simulation. I have created a complete, self-contained HTML file that includes:

1.  **Flocking Logic**: Implementation of the three core rules (Separation, Alignment, Cohesion) plus a "Flee Mouse" behavior.
2.  **Rendering**: Boids are drawn as oriented triangles (arrows) that point in their direction of movement. Added a slight glow effect for visual appeal.
3.  **Interactivity**:
    *   **Mouse**: Boids flee from the cursor within a specific radius.
    *   **Controls**: A glass-morphism UI overlay allows real-time adjustment of the weights for Separation, Alignment, and Cohesion.
    *   **Reset**: A button to re-randomize the flock.
4.  **Visuals**: Dark mode theme (Slate/Cyan) using Tailwind CSS for the UI, and Canvas API for the simulation.
5.  **Performance**: Uses a Vector class for clean math. While O(N^2) complexity is used, it is optimized for ~300-500 boids which runs smoothly in modern browsers.

The file is saved to `/workspace/index.html`.