ABI Layer 2: prove operation reversibility (round-trip law) — flagship Idris2 proof#31
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Add Oblibeniser.ABI.Semantics, a machine-checked proof of oblibeniser's
headline domain property: operations are reversible.
Models a faithful family of structurally-invertible operations (FlipAll,
XorMask, Rev, Nop, Seq) over a bit-register state (List Bool), and proves
the round-trip law as a real propositional equality:
reversible : (op : Op) -> (s : State) -> unapply op (apply op s) = s
Also proved: the dual direction (apply . unapply = id, so each op is a
genuine bijection), closure under sequencing, and an unforgeable
IsReversible certificate tied to the ABI Result code. Positive controls
exhibit inhabited witnesses; negative controls machine-refute the bad
case (a wrong inverse). No believe_me / postulate / assert — Integer was
deliberately avoided since its primitive ops do not reduce symbolically;
the bit-register model gives honest, reduction-friendly involutions.
Adversarial check: a deliberately false round-trip (= [True] instead of
[False]) is rejected by idris2, confirming non-vacuity.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01A6PSzJWpRxtzGDjUCEh7Mx
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Summary
Raises oblibeniser's Idris2 ABI to Layer 2 with its first flagship semantic proof. oblibeniser's headline is making operations reversible and auditable; this discharges the reversible half as a genuine round-trip law: for structurally-invertible operations (mask XOR, global flip, reverse),
unapply (apply x) = x.Mirrors the estate flagship-proof pattern: faithful
Opmodel, the reversibility equality proven, certifier, controls.Changes
src/interface/abi/Oblibeniser/ABI/Semantics.idr—Opwithapply/unapplyand the round-trip reversibility theorem.oblibeniser-abi.ipkg.RSR Quality Checklist
Required
As Applicable
Testing
Verified with Idris2 0.7.0:
idris2 --build oblibeniser-abi.ipkg→ exit 0, zero warnings. Adversarial check: a deliberately-false proof was rejected.build/removed.🤖 Generated with Claude Code
https://claude.ai/code/session_01A6PSzJWpRxtzGDjUCEh7Mx
Generated by Claude Code