docs(track-a): repair final P2 f50090 promotion

[blakinio]

Final source-head lifecycle repair for completed Track A task OTC-20260817-track-a-p2-f50090-downstream.

Merged promotion #489 used source head 76460840.... Before researcher #488 reached its terminal closed state, its final durable head advanced to ebda1b1c01a801e749d3ec2ed5973705e8140969 with stronger but same-scope exact evidence. This PR preserves that unique validated result without reopening research or creating a new task.

Final source validation:

• Track A governance 32038034263 = SUCCESS;
• CI 32038034467 = SUCCESS;
• CI / Required job 95412354038 = SUCCESS;
• final source diff exactly 3 durable P2 files;
• unresolved threads 0; one-shot workflow/script absent.

Independent current-canonical/type and immutable-artifact checks establish:

• current canonical report maps TIODeviceWriter to RTTI 0x3080718 / AP 0x2f69d48 and TProtocolWriter : TIODeviceWriter;
• research(track-a): trace post-serialization buffer boundary #308 exact artifact 9251725866, independently re-hashed to sha256:f669df2ace3db0e269f60287d82c51b69eff11eaf7c7f5b932e049492632bd1e, resolves helper 0x1960340 QIODevice→QDataStream binding and 0x4dd250 = QDataStream::writeRawData(char const*, qint64);
• nested-vcall artifact 9290498273, independently re-hashed to sha256:4aa991a9912c3fb56cc08863ba94ac9e73e78a466a966c00353e85ce39a85323, proves b4b273 -> 0x1960340 and binds that helper object as receiver this+0x08 for the 0xf50090 object.

Final promoted result:
canonical same message -> 0xf50090 -> structured fields -> TIODeviceWriter -> QDataStream -> QDataStream::writeRawData@0x4dd250 -> bound QIODevice concrete type UNKNOWN.

0xf50090 direct socket sink is DISPROVEN; 0xf50090 as proven final binary egress is DISPROVEN in that stated form. Final binary egress/socket ownership, framing, sequence, compression and encryption remain UNKNOWN.

This is same-task closeout repair only. No new active task/frontier is created. E2E: NOT_APPLICABLE — static exact-file/disassembly evidence only.

Merge only after exact-head governance/CI, full three-file diff review, review hygiene and current-main freshness pass.

[blakinio]

Final promotion-repair audit: PASS_BOUNDED, material findings open 0.

Reviewed the complete three-file diff against current main@5068b220aef571805a72c4d8f9293dcaa43ee90c, final source #488 head ebda1b1c01a801e749d3ec2ed5973705e8140969, current canonical type report, immutable #308 artifact digest, and independently re-hashed nested-vcall artifact 9290498273.

Scope is lifecycle-only: two final promotion evidence files plus correction of the existing archived task. No active task, workflow, script, binary, runtime, world-map, protocol implementation or unrelated path is added.

The stronger promoted facts are supported directly: TIODeviceWriter AP 0x2f69d48 / RTTI 0x3080718; constructor b4b273 -> 0x1960340 binds that helper at the 0xf50090 receiver this+0x08; helper QDataStream object is retained at +0x18; exact target 0x4dd250 is QDataStream::writeRawData(char const*, qint64). The concrete bound QIODevice and final network/socket semantics remain UNKNOWN.

No semantic overpromotion found. 0xf50090 direct socket sink and 0xf50090 as proven terminal binary egress are correctly DISPROVEN only for that exact function/stated role; downstream QIODevice effects remain explicitly unclassified.

E2E: NOT_APPLICABLE — documentation promotion of static exact-file/disassembly evidence only.

[blakinio]

Final exact-head gate note: the repair head bcebee08c8081cf83c94c65692d4e0d54ef24321 has CI / Required = SUCCESS in ready-state run 32038797722 / job 95414347401. The Track A runtime-governance workflow does not trigger for this lifecycle-only diff because its path filter covers governance, tasks/active/**, Track-A scripts/workflows and runtime bridge surfaces; #491 changes only two docs/agents/evidence/** files and one docs/agents/tasks/archive/** file. Therefore repair-head Track A governance is NOT_APPLICABLE_BY_WORKFLOW_PATH_FILTER, while the final source head #488 governance remains independently green (32038034263 = SUCCESS). Full diff audit PASS, material findings 0, unresolved threads 0, current main still 5068b220aef571805a72c4d8f9293dcaa43ee90c.