Algorithm 4 Merkle-Batch Audit Anchoring
Require: evidence queue $\mathcal{Q}$, batch size B, flush interval $T_{\mathrm{flush}}$
1: while gateway is running do
2:       collect ${\mathcal{\ell }}_i=H\left(\mathrm{enc}(h_i,R_i,{\mathsf{Decision}}_i,{\mathsf{reason}}_i)\right)$ into buffer $\mathcal{E}$
3:        if $\left|\mathcal{E}\right|\ge B$ or elapsed $\ge T_{\mathrm{flush}}$ then
4:              $\mathsf{root}\leftarrow$ MerkleRoot$\left(\mathcal{E}\right)$
5:              $\mathsf{tx}\leftarrow$ Sign$n_{s{k}_G}(\mathsf{anchor},\mathsf{root},|\mathcal{E}|,[t_{\mathrm{start}},t_{\mathrm{end}}])$
6:              SubmitAsync$(\mathcal{L},\mathsf{tx})$	▹ non-blocking; edge path never waits
7:              persist $\mathcal{E}$ and proofs off-chain; $\mathcal{E}\leftarrow \varnothing$
8:        end if
9: end while