Update version and release notes for the next feature release, Mesa 3.1.3.

Draft release available here.

@projectmesa/maintainers please especially check the release notes for about continuous space, and the feedback topic.

3.1.3 (2025-01-11)

Highlights

Mesa 3.1.3 introduces a major reimplementation of Mesa's continuous space, providing an intuitive agent-centric API and significant performance improvements. The new implementation supports n-dimensional spaces and offers streamlined methods for agent movement and neighbor calculations.

New Continuous Space Features

• Agent-centric movement API similar to cell spaces
• Efficient neighbor calculations and position updates
• Support for n-dimensional spaces
• Improved memory management with dynamic array resizing

Here's a quick look at the new API:

# Create a 2D continuous space
space = ContinuousSpace(
    dimensions=[[0, 1], [0, 1]],
    torus=True,
    random=model.random
)

# Create and position an agent
agent = ContinuousSpaceAgent(space, model)
agent.position = [0.5, 0.5]

# Move agent using vector arithmetic
agent.position += [0.1, 0.1]

# Get neighbors within radius
neighbors, distances = agent.get_neighbors_in_radius(radius=0.2)

# Find k nearest neighbors
nearest, distances = agent.get_nearest_neighbors(k=5)

The new implementation particularly benefits models requiring frequent position updates and neighbor queries, such as flocking simulations or particle systems. Note that this is an API-breaking change, and existing models using continuous space will need to be updated to use the new agent-centric approach. See #2584 for more details. We would love to get feedback on the new Continuous Space in #2611.

Other improvements in this release include consistent visualization behavior across space types with the reimplementation of draw_voronoi #2608, and a new render interval slider for controlling visualization update frequency in SolaraViz, which helps improve performance when working with complex visualizations #2596.