ABI Layer 3: rest-for-one restart strategy (idempotence + child-set preservation)#36
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Add Otpiser.ABI.Semantics: a faithful Idris2 model of a one-for-one OTP
supervisor (children keyed by id, each Running/Failed) and a restart step,
with machine-checked proofs of the headline fault-tolerance invariant:
- restartPreservesChildSet: restarting any child leaves the ordered set
of supervised child ids unchanged (real propositional equality).
- restartLeavesOthersUntouched: every sibling whose id differs from the
target survives the restart byte-for-byte identical (Elem soundness).
- restartHeadRuns / RestartedRunning: the targeted child is set Running.
Positive controls exhibit concrete witnesses over a 3-worker supervisor;
the negative control (negativeSiblingNotReset) refutes, by machine, the
OneForAll-style claim that a failed sibling is reset — establishing the
property is non-vacuous. No believe_me / postulate / assert_total.
Registered in otpiser-abi.ipkg; ABI builds clean with zero warnings.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01A6PSzJWpRxtzGDjUCEh7Mx
…hed)
Add Otpiser.ABI.Invariants, a second machine-checked theorem distinct from
and deeper than the Layer-2 one-for-one flagship. Reuses the Semantics model
(Child/ChildStatus/Supervisor) and reasons about the rest_for_one transition:
T1 IDEMPOTENCE (algebraic law): restForOne target . restForOne target
= restForOne target -- a genuine fixpoint, proven via a triggered-branch
lemma; not a restatement of "siblings untouched".
T2 child-id-set preservation across the rest-for-one transition.
T3 prefix-untouched: children strictly before the target survive identically
(the directional core of rest-for-one), via a BeforeTarget certificate.
T4 sound+complete Dec (decIsTargetHead) + certifier.
Five positive controls (concrete witnesses incl. Refl-checked transition shape
and idempotence) and three negative/non-vacuity controls (Not-Elem refutation,
decision refutation, not-the-identity). No believe_me/postulate/assert_total;
%default total; SPDX MPL-2.0. Registered last in otpiser-abi.ipkg. Clean build
(0 warnings); adversarial false-equality check 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): models the OTP
rest_for_onestrategy and proves idempotence (restForOne t . restForOne t = restForOne t— an algebraic fixpoint law), child-id-set preservation, and prefix-untouched (children before the target survive identically). Distinct from and deeper than the Layer-2 one-for-one "siblings untouched" theorem.New module
Otpiser.ABI.Invariants(imports the Layer-2Semanticsmodel). Sound+completeDec, 5 positive + 3 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