Molecule Graph Validity - deterministic chemical validity check (no AI)

What it is

Compute CHEMICAL VALIDITY over an explicit atom-bond GRAPH - the headline "validity %" that molecular-generation pipelines report - with NO model, NO training, and NO AI. Give a molecule as { atoms:[{element}], bonds:[{a,b,order}], charges? } (0-indexed atoms; bond order in 1, 1.5, 2, 3). The plugin sums each atom's incident bond orders, applies formal charge, and flags any atom whose valence is not allowed by the cited standard-valence table (C=4, N=3, O=2, H=1, S=2/4/6, P=3/5, halogens=1, B=3); it also requires a single connected graph. A molecule is VALID iff every atom is well-formed and the graph is connected, and over a list it reports the batch validity %. All arithmetic is exact integer (bond orders carried in half-bond units, so aromatic 1.5 bonds sum exactly). HONEST: "valid" means WELL-FORMED under the octet/valence model - NOT that the molecule is real, stable, or synthesizable. This is a VERIFIABLE REFERENT for the validity check that generators headline; it does not generate molecules and makes no "beats/matches <generator>" claim (that would need a matched-frame benchmark we have not run). The graph is a defined geometric embedding; real GMDBS mesh57/HVP substrate integration is a flagged next step.

Honest scope

Authorities cited

• Standard main-group valences: N. N. Greenwood and A. Earnshaw, "Chemistry of the Elements", 2nd ed., Butterworth-Heinemann, 1997.
• Octet rule and formal charge: any general chemistry text (e.g. Atkins & de Paula, "Physical Chemistry"; IUPAC Nomenclature of Inorganic Chemistry, 2005 Recommendations).
• Validity as a deterministic post-hoc check is standard in molecular-generation evaluation (valence/connectivity check, not a learned quantity). This plugin provides that check as a verifiable referent; it does not generate molecules and runs no comparison benchmark.
• Graph connectivity: single connected component via breadth/depth-first traversal (standard graph algorithm).