GESI computes 8 stability metrics across Band 1 (Determinism Integrity: M1 Hash Match, M2 Reproducibility, M3 Canonical Stability), Band 2 (Governance Drift: M4 Drift Reduction, M5 Entropy Slope Shift), and Band 3 (Cascade Risk: M6 Amplification Factor, M7 Cascade Divergence). M8 produces a weighted composite score.
Every GESI computation produces a snapshot hash (SHA-256 of canonical metric output), a Merkle root (balanced binary tree of per-metric leaves), and a final root signed with Ed25519. This anchor can be verified independently across any language or platform.
GESI v1.0-D achieves bit-identical reproduction across Node.js and Python. The protocol enforces 8-decimal truncation and alphabetical key sorting before hashing. All 8 test vectors produce identical final roots and pass Ed25519 signature verification in both runtimes.
The GESI v1.0-D specification is frozen and normative. Any hash-affecting change requires a new major version. Partial compliance is not recognized. The reference hash set and reference vectors are immutable constants used to verify all compliant implementations.