Qualify BAR complete-prefix and raw-tail boundary evidence

[EHotwagner]

BARC-01.5f RP2 complete-prefix/raw-tail source

Source candidate 4f048bea0168e32df31680cf1f69029ea1c71238 / tree 8fda60908156463e2130d409f4380a8fd3275cfa, canonical protected base 87250d3d5d4ca48b25307228da595d1d7d6fc2ee.31 scoped RuntimeEvidence paths. ROOT owns admission, roadmap join and all native operations.

• Derive exact raw/complete-prefix/tail custody in F#, conservatively classify unfinished atlas tails, retain all previous unfinished bytes.
• Return candidates and require bounded final held-FD read/size L before a one-shot named receipt; every observed append reevaluates within the unchanged32-probe/3-evaluation/5-second budget. Post-L writes need the next boundary.
• Extend the existing canonical Quint state protocol and actual F# seam; preserve predecessor vectors and add real libc/full-state/ordered-effect qualification.

Validation

Canonical owning gate EXIT0: official locked SDK10.0.401 Release0warnings/errors; startup readiness;10Python/libc;2actual framed F# growth controls;38Quint;500×16 invariant run;14predecessorITFs;14actual successor scenarios and independent compiled replay;13semantic mutants rejected. Failed candidate logs and causal repairs retained in private handoff. git diff --check passed; working tree clean.

Remaining boundaries

Source-only qualification. No installed/default/protected-executable/native acceptance. Budget constants, Program.fs, engine/plugin/browser/NativeProof outer protocol and failed495/2639 packet unchanged. RP3/RP4/RP5 and useful play0/6 remain separate. ROOT adds exact native protected admission readbacks and required routine marker before push; this draft does not fabricate admission markers.

Root joined the owning roadmap on final head aaff077615908f57aa0cc239e27a402116b2b5e6. Its code/model/test tree is byte-identical to locally qualified 4f048bea0168e32df31680cf1f69029ea1c71238; the additional commit changes only the owning progress prose. Exact-head hosted qualification remains required.