research(track-a): trace post-serialization buffer boundary

[blakinio]

Draft-only Track A P2 research source from exact main@8fca1c3eee453d0d4ef8a47e0f15c9dbae491b45.

Coordinator disposition

ACCEPT_WITH_EDITS — source Draft closed unmerged after bounded promotion into coordinator PR #300.

Final release head: 7153ba4f0799a2c6b81eeeb62e4b1320e386c924
Code-bearing head: 34f73b0c48198ba452caa505b4c0f3ae7e5b61d7
Hardened semantic run: 31903490468 SUCCESS
Hardened artifact: 9251725866, digest sha256:f669df2ace3db0e269f60287d82c51b69eff11eaf7c7f5b932e049492632bd1e
Code-bearing CI: 31903493799 SUCCESS
Exact final release-head CI: 31903882606 SUCCESS

Promoted only:

• retained QDataStream serialization is concretely bound to a persistent QBuffer-backed QIODevice byte container;
• persistent QBuffer pair -> helper 0x1960340 -> TIODeviceWriter -> TProtocolWriter+0x18/+0x20 -> retained intermediate -> TProtocolClientMessageProcessor is proven by exact setup/disassembly bytes;
• local object lifecycle order is proven only as QBuffer/QDataStream binding constructed before serializer use.

Still canonical UNKNOWN:

• overall protocol-stage order;
• framing;
• sequence numbering;
• compression;
• encryption;
• final binary egress/socket ownership;
• causal local protocol harness.

Canonical promotion evidence: docs/agents/evidence/OTC-20260815-track-a-promotion-coordination/p2-buffer-boundary/20260815-pr308-disposition.md on coordinator branch docs/OTC-20260815-track-a-promotion-coordination.

No live traffic, login, credentials, gameplay, account state, Track B mutation, or final-socket shortcut was used.