ABI Layer 3: transition soundness of linear free (state + address preservation)#45
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Flagship semantic proof: a pointer with explicit Live/Freed state; an `Accessible` permission with a constructor only for Live pointers, so use-after-free and double-free are unrepresentable. `free` consumes a Live pointer (with its witness) into a Freed one. Sound+complete Dec, certifier soundness, positive + negative controls. Verified with idris2 0.7.0 (build clean, zero warnings) + adversarial false-proof rejection. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01A6PSzJWpRxtzGDjUCEh7Mx
Adds Atsiser.ABI.Invariants over the existing Semantics model (Ptr/ PtrState/Accessible/free, imported not redefined). Proves the dynamic soundness of the linear state machine's free transition, distinct from the Layer-2 static accessibility theorem: - freeYieldsFreed: progress — state (free p Acc) = Freed - freePreservesAddr: frame — addr (free p Acc) = addr p - freedResultUnusable: no reuse — free's result is never Accessible (composes the transition with Layer 2's freedNotAcc) - noFurtherFree: terminality of the Freed fixed point - AtTerminal predicate with sound+complete decAtTerminal and a certifier proven sound (certifyTerminalSound) - positive controls (concrete free witnesses) and negative/non-vacuity controls (Not Accessible, Not AtTerminal, certifier rejects live) Clean build, zero warnings; adversarial false statements rejected. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01A6PSzJWpRxtzGDjUCEh7Mx
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Summary
Layer 3 (second, deeper invariant): proves transition soundness of the linear
freeoperation —freealways yields aFreedpointer and preserves its address — so the pointer state machine is sound. Distinct from and deeper than the Layer-2 accessibility property.New module
Atsiser.ABI.Invariants(imports the Layer-2Semanticsmodel). 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