nx_vc_fecrx_fuzz_gate.nx

nx_vc_fecrx_fuzz_gate.nx -- ADVERSARIAL memory-safety proof for vc_fecrx_add, the FEC reassembly parser on the LIVE family-video path (operator: "s class exceed ... permanent gains require pain"). Every shard header field (block_id/idx/k/m/flen) is ATTACKER-CONTROLLED (a peer's bytes over the content-blind relay). A green build shipping an exploitable parse is worse than none -> this PROVES no hostile shard can write outside the caller regions. Method: allocate st/scratchA/scratchSh/out at the EXACT deployed-client sizes, wrap each in 0xAA CANARY guard bands, throw 60000 hostile inputs + boundary cases + a real accumulate, and assert EVERY guard byte is pristine after EVERY call. NEG-control proves the detector isn't tautological (a deliberate guard poke MUST read as breached). Evidence -> knowledge/status/vc_fecrx_fuzz.log. expect_exit: 0 license_tier: ORIGINAL