ABI Layer 4: prove the FFI result-code seam is injective + faithful#41
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Add Dafniser.ABI.Semantics raising the Idris2 ABI to Layer 2 with a genuine,
machine-checked semantic proof of the repo's headline ("correct-by-construction
code generation").
Model: a Dafny spec as the postcondition MaxPost a b r — a real proposition
inhabited only when r dominates both inputs and equals one of them. The
generated body genMax returns its result paired with a MaxPost proof
(correct-by-construction). genMaxCorrect derives all three ensures conjuncts
(result>=a, result>=b, result==a||result==b) for all inputs; noUndershootLeft
refutes the bad case. A sound certifier (certifyMax/certifyMaxSound) emits the
ABI's VerificationResult. Positive control maxPositive : MaxPost 7 3 7 and
negative control maxNegative : Not (MaxPost 7 3 2) are machine-checked; an
adversarial false proof (MaxPost 7 3 2) is rejected by idris2, confirming
non-vacuity.
Builds clean (idris2 0.7.0, exit 0, zero warnings).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01A6PSzJWpRxtzGDjUCEh7Mx
…max duality Adds Dafniser.ABI.Invariants over the existing Layer-2 model (Dafniser.ABI.Semantics, reused unchanged). Three distinct, deeper machine-checked properties: 1. Relational commutativity of the max contract (MaxPost a b r <-> MaxPost b a r), with an involution proof ruling out vacuity. 2. A dual correct-by-construction generated function `min` (MinPost / genMin), with sound+complete decision procedure (decMinPost), certifier (certifyMin) and certifier soundness. 3. The min/max duality law max a b + min a b = a + b, proven relationally over any correct results and lifted to the generated bodies (genMaxMinSum). Positive controls (minPositive, commPositive, dualityConcrete, certifyMinAccepts) and negative/non-vacuity controls (minNegative, certifyMinRejects, dualityNonVacuous) all machine-checked. No believe_me/postulate/assert_total; %default total; builds with zero warnings; adversarial false statements rejected by the checker. Registers Dafniser.ABI.Invariants last in dafniser-abi.ipkg. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01A6PSzJWpRxtzGDjUCEh7Mx
…fiSeam) Prove the FFI result-code encoding is sound: - intToResult decoder + resultRoundTrip (lossless/faithful encoding) - resultToIntInjective derived from the round-trip (no collisions on the wire) - positive controls (decode 0=Ok, 4=NullPointer, 5=Nothing) - machine-checked negative/non-vacuity control (Ok and Error differ) Genuine total proof: no believe_me / postulate / assert_total / %hint. Wires Dafniser.ABI.FfiSeam into dafniser-abi.ipkg. Builds clean, zero warnings. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01A6PSzJWpRxtzGDjUCEh7Mx
Signed-off-by: Jonathan D.A. Jewell <6759885+hyperpolymath@users.noreply.github.com>
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Summary
Layer 4 (seal the ABI↔FFI seam): proves the FFI result-code encoding (
resultToInt) is a sound, lossless wire encoding — decoderintToResultwithresultRoundTrip, from whichresultToIntInjectiveis derived. Distinct ABI outcomes never collide on the C wire. Complements the structuralabi-ffi-gate.py.New module
*.ABI.FfiSeam(importsTypes). Positive + non-vacuity controls.Testing
Idris2 0.7.0
--build→ exit 0, zero warnings. Adversarial rejection confirmed.build/removed. Nobelieve_me/postulate/sorry.🤖 Generated with Claude Code
https://claude.ai/code/session_01A6PSzJWpRxtzGDjUCEh7Mx
Generated by Claude Code