ABI Layer 2: prove forbidden actions are never permitted (ethical safety) — flagship Idris2 proof#33
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Raises the Phronesiser Idris2 ABI to Layer 2 with a flagship, machine-checked
semantic proof of the repo's headline property ("provably safe ethical
constraints for AI agents").
Model: a deontic policy partitions agent actions into Allow/Deny. The
`ActionPermitted` proposition has NO constructor admitting a `Deny` verdict, so
a forbidden action is structurally uncertifiable.
Proven:
- decActionPermitted: sound + complete `Dec (ActionPermitted a)`.
- certifyPermittedSound: certifier soundness (Ok => ActionPermitted).
- safeInformPermitted: positive control (inhabited permission witness).
- forbiddenNeverPermitted: negative control / core safety theorem
`Not (ActionPermitted forbiddenDeploy)`.
- forbiddenNeverCertifiedOk: corollary that the forbidden action is never Ok.
Non-vacuity confirmed: a deliberately false witness
`PermitAllow Refl : ActionPermitted forbiddenDeploy` is rejected by idris2
(Allow vs Deny mismatch). Build is clean (exit 0, zero warnings).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01A6PSzJWpRxtzGDjUCEh7Mx
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Summary
Raises phronesiser's Idris2 ABI to Layer 2 with its first flagship semantic proof. phronesiser's headline is provably safe ethical constraints for AI agents; this proves the core safety property: a forbidden action can never be certified permitted.
ActionPermittedhas no inhabitant for a forbidden action, the certifier is proven sound (Permitted ⇒ ActionPermitted), andforbiddenNeverPermitted : Not (...)is the headline safety theorem.Mirrors the estate flagship-proof pattern: action/policy model, uninhabited bad case, sound+complete
Dec, certifier proven sound, positive + negative controls.Changes
src/interface/abi/Phronesiser/ABI/Semantics.idr—Action/policy,ActionPermitted, sound+complete decision,certifyPermitted/soundness, and the safety theoremforbiddenNeverPermitted.phronesiser-abi.ipkg.RSR Quality Checklist
Required
As Applicable
Testing
Verified with Idris2 0.7.0:
idris2 --build phronesiser-abi.ipkg→ exit 0, zero warnings. Adversarial check: a deliberately-false proof (certifying a forbidden action as permitted) was rejected.build/removed.🤖 Generated with Claude Code
https://claude.ai/code/session_01A6PSzJWpRxtzGDjUCEh7Mx
Generated by Claude Code