# Separate C++ CORE callback-entry baseline

The actual matched review identified a tick-span mismatch: the original CORE
generation timestamps receive before parsing, while NexusFIX timestamps the
application callback entry before extraction. A separate compile-time baseline
now stamps the first instruction of `Application::ParseMsg`, before capture,
field extraction or business checks. The prepared-wire send remains unchanged.
It has the distinct identity `libhft-cpp-callback-canonical` and an explicit
reader policy. The default identity/policy and all frozen originals remain intact.

## Actual independent qualification

A complete 843-file stripped source archive, content pin
`d86d663653bedebffa6f2a94bc02fa72fa97bd6a4fe31563c8629e348fd84f68`, independently
builds both callback and default variants against the already qualified public
C++ SDK on HP and SCAN. Both SDK and producer source byte/mode inventories
remain unchanged; no SDK patch is applied. Each outer build/functional suite
holds an `isol` CPU-slot lease, high priority on HP and normal on SCAN. Shared
work may run concurrently, so no timing grade is inferred.

Each host passes twelve actual callback pairs and twelve default pairs. Together:
**48 actual pairs, 960 primary samples, 960 delay samples and 2,800 original
application frames per peer**. Each variant's cold vectors independently verify
120 canonical bodies and four typed owner vectors.

Independent SDK-free callback readers on BEELINK2 reproduce all twelve original
receipts per host and refuse **75 copied-evidence changes per host**, including
an old before-parser clock declaration in the new callback policy. Original
bytes and modes remain unchanged. The initial cold helper's old `actual/` path
was absent; its failed output and the corrected separate v2 helper are retained.

## Remaining admission

The full quiet local matrices, independently pinned runtime/controller and
root namespace entry, physical matrices, exact cold replay and matched NexusFIX
comparison remain required. This source/functional qualification does not grant
a four-flow C++ headline or alter the earlier producer grades.

[Full original qualification, binaries, source inventory and cold controls](evidence/cpp-callback-canonical-20261014/retention-seal.json)
are retained in a new immutable seal.