Security and trust boundary

MasterSeed authenticates bytes against a caller-provided seed_hash; it does not identify or sign a publisher. Structural validity (seed_size being a multiple of 32) is not trust. A consumer should obtain the expected hash and, for source verification, the source size through a trusted upper-layer protocol.

The seed contains no header or metadata, so it cannot carry its own provenance, filename, or source length. Treat an untrusted seed as input: run VerifySeed/verifySeed before membership checks, and use VerifySeedForSourceSize/verifySeedForSourceSize or complete source verification when a trusted size is available. Streaming inputs are consumed once; reopen them for independent passes. Errors and context cancellation are part of the boundary, not evidence that a hash is trustworthy.