Reaction Diagram with Blender Structure Insets

Level-line free-energy diagram where each state carries a circular-fade inset cropped from a Blender top-view render (no-box, transparent background), plus plain gas-phase molecule renders at the reactant/product ends.

REQUIRED BACKGROUND: matplotlib-scientific rules apply (Arial FontProperties, no grid, no tight_layout, audit text overlap). rxn-diagram conventions apply for levels/connectors/labels.

Core pattern

import sys
sys.path.insert(0, '/Users/sean/.claude/skills/matplotlib-scientific/rxn-diagram-inset')
from mol_inset import mol_circle, add_inset

img = mol_circle(f"{R}/state_nobox_top.png", ox=-140, oy=30)   # surface state
gas = mol_circle(f"{R}/gas_products_fs.png", gasmode=True)     # gas: NO fade
add_inset(ax, img, x, iy, zoom=0.36)

Full working exemplar: example_fig1_integrated.py (Fig 1, CeO2 ketonization 3-B path: 9 states, per-state table with label side, inset dx/dy, per-system center tweaks, largest-step highlight).

Layout recipe (what made Fig 1 work)

• Per-state table: (key, label, side, render, gasmode, label_dy, inset_dy_extra, inset_dx, (ox, oy), connector_gas_label).
• Inset goes on the SAME side as the state label, stacked beyond it: iy = y +/- (8 + label_dy + INSET_KJ + inset_dy_extra + (nlines-1)*16), INSET_KJ ~ 72 (in y-data units). Keep insets CLOSE to their label -- user rejects big vertical gaps.
• Crop half-size 460 px on 1600 px renders, out 400 px, zoom ~ 0.36. Two co-adsorbed fragments (PBC split): widen to ~500-560 px.
• Widen ylim (~+/-30%) to make room; subplots_adjust, not tight_layout.

Hard-won rules

1. Carbon centering is manual. Dark-pixel median lands mid-frame (surface shadow crevices dominate). Always render -> Read the PNG -> set per-system (ox, oy) in render px -> repeat (1-2 rounds).
2. Gas renders never get the fade -- plain alpha-bbox crop.
3. Crop must stay inside the render frame or the circle shows a flat clipped edge; shrink |oy|/size rather than accept padding.
4. Stagger neighboring insets (dx shift +/- up to 0.3 x-units, dy) so circles don't collide and don't cover the next state's label; e.g. move an inset left+up when its neighbor's label crowds it.
5. Labels: no over-compressed formulas -- write out species with line breaks ("CO$_2$* + CH$_2$C(CH$_3$)O*\n+ 2 H*"), keep off the connectors.
6. Save PNG (dpi ~ 220); AnnotationBbox images do not survive SVG text-editing workflows well.

Blender render inputs

Renders come from blender --background --python render_autoframe_v2.py -- in.xyz out.png top ... cz with cz=-1 (no box, atom framing) -> 1600x1600 RGBA *_nobox_top.png. Gas molecules: standalone gas_*_fs.png renders.