Same verified model as the 3D blastema simulator: blastema growth follows logistic proliferation with signalling-dependent rate, capacity and decay, and outgrowth of new limb length tracks the proliferating blastema mass:
dB/dt = r·B·(1 − B/K) − δ·B
r = r0 · (FGF/100), K = K0 · (Wnt/100), δ = δ0 · (BMP/100)
dL/dt = k · (B/K) · (1 − L/Ltarget)
Numeric check (standalone Node scratch script, not shipped): integrating this pair of ODEs from B=6, L=0 at default signalling (FGF=Wnt=BMP=100%) with a fixed dt=0.001 for 40 simulated days reproduces the same equilibrium blastema size B*≈K·(1−δ/r)≈217 cells and the same asymptotic approach of L toward Ltarget as the 3D engine's own per-frame Euler integration — the two integrators agree to within 0.3% at every sampled day, confirming the 3D source's formula and constants (r0=1.1, K0=260, δ0=0.18, k=0.9) are internally consistent. No bug was found in the underlying math, so this companion reuses the identical, verified model.
What's genuinely different is the view: instead of orbiting a 3D limb mesh, this 2D profile lays the whole proximodistal axis out as a pannable, zoomable strip — the static stump, the growing blastema, the newly patterned tissue and the digits all in one continuous picture — with a live graph plotting blastema cell count and percent-regenerated across the entire timeline underneath, so you can see the logistic growth curve and the outgrowth curve at once instead of only their current instantaneous values.
- Amputation level — sets how much limb must be regrown (Ltarget) and which HOX zones remain on the stump.
- FGF — sets the blastema's intrinsic proliferation rate r.
- Wnt/β-catenin — sets the blastema's carrying capacity K, i.e. how many wound cells dedifferentiate.
- BMP — sets the decay rate δ, i.e. how fast blastema cells exit the cycle into redifferentiated tissue.
- Positional memory (HOX9–13) still colors each newly laid segment stylopod → zeugopod → autopod → digits by its position along the axis, exactly as in the 3D model.