Audit: Mesa-examples compatibility with Mesa 3.x — tracking issue

[annapurna-gupta]

Summary

This issue tracks the compatibility of all mesa-examples with Mesa 3.x.
Each example has been manually tested.

The goal is to:

1. Identify every broken example and WHY it is broken
2. Fix each one with a separate PR

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Error types found so far

Type	Error message	Root cause
A	AttributeError: module 'mesa' has no attribute 'visualization'	Uses removed Mesa 2.x API (CanvasGrid, ModularServer, ChartModule)
B	ValueError: Unknown space type: NoneType	Space not initialized correctly for Mesa 3.x
C	ImportError: attempted relative import with no known parent package	Relative imports break when running with solara run directly

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Examples checklist

examples/

• aco_tsp — ✅ Working
• bank_reserves — status: ?
• boltzmann_wealth_model_network — status: ?
• caching_and_replay — ❌ BROKEN — Type A (AttributeError: module 'mesa' has no attribute 'visualization')
• color_patches — status: ?
• conways_game_of_life_fast — ❌ BROKEN — Type B (ValueError: Unknown space type: NoneType)
• deffuant_weisbuch — status: ?
• dining_philosophers — status: ?
• el_farol — status: ?
• emperor_dilemma — status: ?
• forest_fire — status: ?
• hex_ant — ❌ BROKEN — Type C (ImportError: attempted relative import with no known parent package)
• hotelling_law — status: ?
• humanitarian_aid_distribution — status: ?
• rumor_mill — status: ?
• virus_antibody — status: ?
• warehouse — status: ?
• termites — status: ?

gis/

• geo_schelling — status: ?
• geo_schelling_points — status: ?
• geo_sir — status: ?
• agents_and_networks — status: ?
• rainfall — status: ?
• urban_growth — status: ?
• population — status: ?

rl/

• boltzmann_money — status: ?
• epstein_civil_violence — status: ?
• wolf_sheep — status: ?

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Progress

Status	Count
✅ Working	1
❌ Broken	3
❓ Not tested yet	23

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Environment

• Mesa version: 3.5.0
• Python: 3.13
• OS: Ubuntu
• venv: activated

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Next steps

• Finish testing all remaining examples
• Update this checklist with results
• Open individual fix PRs for each broken example