Discover and propose payload content lengths

Discover calls to approved parser interfaces and their preceding length computations throughout the input source set. Derive source paths, program identities, both statement locations and COPY snapshots. Reuse the existing content-length correction proof to replace capacity measurements with trailing-trimmed content length. Keep existing range checks and failure behavior. Unknown effects, earlier consumers and unsupported interfaces prevent changes. Locate candidates by syntax identity after earlier replacements. Report every candidate and established conditional vulnerability witnesses separately. No source files, program IDs, statement lines or caller hashes are required. Padding semantics and parser requirements remain explicit approved policy. Application team review remains required.