ABI Layer 2: prove counter-node bound invariant + determinism — flagship Idris2 proof#38
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Add Lustreiser.ABI.Semantics, raising the Idris2 ABI to Layer 2 with a machine-checked flagship proof of the repo headline (formally verified real-time embedded code via Lustre). Faithful model: a synchronous saturating bounded-counter Lustre node with Tick/Reset inputs, a static cap, and one-tick state memory; step/run give the synchronous execution semantics. Properties proven (no believe_me/postulate/assert): - Invariant preservation per tick: WithinBound c -> WithinBound (step i c) for every input, lifted to whole runs via runPreservesBound (no overflow). - Determinism (synchronous hypothesis): equal input streams from equal state yield equal output streams. - Sound+complete Dec (decWithinBound) + sound certifier (certifyBoundSound). - Positive controls (explicit witnesses, incl. a run that saturates) and a machine-checked negative control (overflowNotWithinBound) ensuring non-vacuity; a deliberately false witness is rejected by idris2. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01A6PSzJWpRxtzGDjUCEh7Mx
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Summary
Raises lustreiser's Idris2 ABI to Layer 2 with its first flagship semantic proof. Lustreiser's headline is generating formally verified real-time embedded code via Lustre; the correctness obligation is a per-tick invariant preserved by the synchronous node. This models a saturating-counter node and proves its bound invariant is preserved across every tick (and across a run), with output determinism.
Mirrors the estate flagship-proof pattern: stream/node model, invariant-preservation lemmas,
decWithinBound : Dec, certifier proven sound, negative control.Changes
src/interface/abi/Lustreiser/ABI/Semantics.idr—CounterNode/WithinBound,stepPreservesBound/runPreservesBound,decWithinBound : Dec,certifyBoundSound, and negative controloverflowNotWithinBound : Not (WithinBound (MkCounter 2 5))..ipkg.RSR Quality Checklist
Required
As Applicable
Testing
Verified with Idris2 0.7.0:
idris2 --build lustreiser-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