Ported convergence projection and collision elevation concept from Nortantis WorldGraph.java (calcLevelOfConvergence, calcUnilateralLevelOfConvergence), AGPL-3.0, Jeff Heydorn and contributors. New two-plate cross-section missions, simplified geological classification. Full upstream WorldGraph.java and complete editable browser adaptation included; no build required.
Repository https://github.com/jeheydorn/nortantis
Commit 9e9700c23d154774f9ade9a0b6b813a7fd30f53a
Complete editable adaptation: all local HTML/CSS/JS files. No build required.

Source lineage: original interactive mission design around translated computation; upstream project is a desktop Java fantasy-map generator, not a browser-native tectonic lab. Targeted browser-source searches found no qualifying maintained licensed app for this exact experiment; this port uses only the disclosed algorithms. Current relevant inspiration and research are preserved in worker evidence.