Invariant Ace

Mission

Turn "should never happen" into "cannot happen" with minimal, high-leverage changes: name the real state owner, define owned inductive predicates, prove a counterexample trace, choose the strongest cheap enforcement boundary, and attach verification that can falsify the invariant and the proposed enforcement.

This skill is discriminative, not decorative. An invariant proposal is a claim to adjudicate, not a mandate to add checks. A property may be true, useful, or reviewer-sounding and still be the wrong invariant, wrong owner, wrong scope, wrong phase, wrong witness, or wrong boundary.

Actuating composition

Within Actuating, the checked-in [invariant review lens](../actuating/references/lenses/invariant-review.md) owns the lane's scope and return shape. Use that evidence-only contract, not a second authority workflow. Return concrete invariant/transition witnesses to Review Fold; Actuating retains selection, implementation, proof, and closure. Do not launch authority fanout, emit clearance packets, or require the standalone Invariant Gate. This section takes precedence over the standalone modes, gates, output templates, and companion routing below only within Actuating. Standalone invocation is unchanged; no review lane or proof obligation is added or removed.

Default mode

Use Authority-Gated v1 when invariant analysis can affect implementation, review adjudication, proof closure, validation, or downstream handoff.

Authority-Gated v1 requires:

• stable candidate invariant IDs;
• artifact and direction state identity;
• counterexample trace or explicit no-current-counterexample classification;
• owner/scope/source-of-truth proof;
• transition/induction coverage;
• enforcement-boundary selection with why-not-weaker/why-not-stronger reasoning;
• exception and policy ownership checks;
• generator/validator/witness parity checks;
• fixture precondition alignment;
• verification plan tied to predicates;
• authority packet receipts and veto handling when the task is non-trivial or consequential;
• an Invariant Gate before implementation, review adjudication handoff, proof closure, or fixed-point routing.

Compact mode is allowed only for exploratory invariant sketches, and it must block implementation handoff unless the Invariant Gate passes.

Core doctrine

Operate in OWNER-FIRST, COUNTEREXAMPLE-DRIVEN, INDUCTIVE, AUTHORITY-GATED, SOURCE-OF-TRUTH-SEEKING, POLICY-OWNED, WITNESS-PARITY, FIXTURE-AWARE, FAIL-CLOSED, ACCRETIVE, and PROOF-BEARING mode.

• OWNER-FIRST: if you cannot name the state owner and mutation boundary, you do not yet have an enforceable invariant.
• COUNTEREXAMPLE-DRIVEN: every accepted invariant needs a concrete bad trace, or an explicit proof-only reason why no current trace exists.
• INDUCTIVE: accepted invariants must hold initially and be preserved by every allowed transition in scope.
• AUTHORITY-GATED: consequential invariants require independent clearances; unresolved vetoes block enforce-now.
• SOURCE-OF-TRUTH-SEEKING: enforce at the owner/source of truth, not at downstream local shortcuts.
• POLICY-OWNED: exceptions must be encoded in the policy owner, allowlist, capability, ACL, flag, or protocol that owns the invariant.
• WITNESS-PARITY: validation, generation, projection, certificate, source-map, replay, and proof paths must use the same identity/witness semantics or a named stricter refinement.
• FIXTURE-AWARE: tests must satisfy upstream preconditions when targeting downstream invariants; otherwise they prove the wrong boundary.
• FAIL-CLOSED: unsupported, unmodeled, or unknown cases must block or validate before certificate/proof/artifact construction.
• ACCRETIVE: prefer the smallest truthful boundary repair that removes the illegal state without broadening the system.

Contract

• Do not implement fixes here unless another skill explicitly owns implementation after this gate.
• Do not accept a candidate invariant without owner, scope, holds-when, source-of-truth, counterexample/trace status, transition coverage, enforcement boundary, and verification.
• Do not confuse invariants with preconditions, postconditions, liveness goals, local assertions, style rules, or reviewer preferences.
• Do not fix identity drift locally when the shared identity predicate belongs to another phase or owner.
• Do not add local explicit-input shortcuts around policy predicates.
• Do not trust generated, caller-provided, or fixture-typed witness fields when they should be recomputed or bound to an owning certificate/proof.
• Do not let stronger outer gates silently invalidate inner-invariant tests; choose whether to configure the outer gate to reach the inner failure or update the expected boundary deliberately.
• Do not route validate-only, proof-only, defer, no-change, or blocked invariant rows into implementation.
• Do not allow root to upgrade a vetoed or unresolved invariant to enforce-now; clear the veto or stay non-permissive.

Use When (Signals)

• Null/shape surprises, runtime validation sprawl, scattered input decoding, or "unreachable" branches reached in logs.
• Redundant stored facts drift: cache/index/denormalized columns/certificates/source maps/summaries.
• Descriptor identity differs from occurrence/site/route multiplicity.
• Validation accepts by one identity rule while generation/projection/certificate paths select by another.
• Policy-owned exceptions are bypassed by local explicit-input, explicit-port, shortcut, or allow flag paths.
• Tests drift because an outer policy gate rejects before the inner invariant under test.
• Generator/validator parity, certificate witness, proof-object, replay-frame, source-map, or blocked-state accounting issues.
• Races, duplicate/out-of-order events, retries, stale writes, idempotency, linearization, or loop invariants.

Authority fanout mode

For consequential invariant work, use custom Codex authority agents. They solve both bandwidth and authority: independent lanes gather evidence in parallel, and each lane owns a decision dimension.

Required lanes when an invariant can become implementation work or block closure:

Authority rules:

• Each required lane returns a packet; packets are not votes.
• Root remains the final synthesizer but may only downgrade without re-clearance.
• enforce-now requires all required authority lanes clear and the skeptic lane defeated.
• Any unresolved or veto packet blocks enforce-now.
• Missing authority packets require blocked unless a same-schema root-equivalent packet is emitted.
• Rejected packets are logged and cannot support accepted invariants.

See references/authority-fanout.md and references/CODEX_SUBAGENTS.md.

Immediate scan

Before declaring an invariant, record:

artifact_state_id:
  branch:
  base:
  head:
  diff_digest:
  proof_state:

direction_state_id:
  source:
  source_ref:
  same_objective:
  non_goals:
  compatibility_posture:

Then ask:

• State owner: where does truth live?
• Raw boundary: where does untrusted or derived state enter?
• Allowed transitions: which operations/events mutate the state?
• Failure today: what minimal trace reaches the bad state?
• Identity semantics: unique descriptor, occurrence, site, route, target, or witness?
• Exception owner: what policy/capability/allowlist authorizes exceptions?
• Witness owner: who proves downstream usability, not mere existence?
• Fixture preconditions: which upstream gates must be satisfied to test this boundary?
• Protection level: hope -> runtime -> construction-time -> type/compile-time -> persistence/protocol/atomicity.

Candidate classification

Classify each candidate:

• accepted: owned, inductive, enforceable, currently material, and cleared by authority lanes.
• candidate: plausible but missing route-changing evidence.
• downgraded: useful property, but it is a pre/postcondition, liveness goal, derived check, test-only guard, or non-material convention.
• rejected: wrong owner, wrong scope, wrong identity rule, ungrounded, duplicate boundary, or direction-conflicting.
• unresolved: material uncertainty; validation or artifact search required.
• blocked: missing artifact state, direction state, authority packet, identity proof, or verification path prevents safe routing.

Allowed routes:

• enforce-now: implement/handoff allowed only after gate passes.
• validate-only: add proof/probe/test before mutation.
• proof-only: current artifacts already satisfy the invariant; only cite proof.
• defer: real invariant but wrong owner/timing/scope.
• no-change: reject/downgrade; no implementation work.
• blocked: fail closed.

Output contract: Authority-Gated v1

Emit these sections, in order, for consequential runs:

1. Review Basis
2. Candidate Invariant Inventory
3. Counterexample Ledger
4. Invariant Ledger
5. Owner and Scope Ledger
6. Transition / Induction Matrix
7. Enforcement Boundary Decision
8. Policy / Exception Ledger
9. Witness and Fixture Parity Ledger
10. Verification Plan
11. Authority Packet Receipts
12. Authority Clearance Matrix
13. Authority Veto Ledger
14. Accepted Invariants
15. Validate Only
16. Proof Only
17. Defer / No Change
18. Change Agenda
19. Acceptance Skew Audit
20. All-Invariant Accepted Justification when every substantive candidate is accepted or enforce-now
21. Invariant Gate
22. Ace Bottom Line

Candidate Invariant Inventory

- candidate_count:
- accepted_count:
- validate_only_count:
- proof_only_count:
- defer_or_no_change_count:
- blocked_count:
- candidate_ids:
- accepted_ids:
- validate_only_ids:
- proof_only_ids:
- defer_or_no_change_ids:
- blocked_ids:
- missing_candidate_ids:
- duplicate_candidate_ids:

Invariant Ledger

Authority Clearance Matrix

Allowed clearance values: clear, veto, unresolved, not-needed, not-in-scope. Skeptic values: defeated, veto, unresolved, not-needed. Authority status: cleared-for-enforcement, cleared-for-validation, proof-only, defer, no-change, blocked.

Authority Veto Ledger

Veto classes include: no-counterexample, wrong-owner, wrong-scope, not-inductive, wrong-boundary, policy-bypass, identity-drift, witness-missing, fixture-precondition-mismatch, duplicate-boundary, validation-needed, proof-only, direction-conflicting, missing-packet.

Change Agenda

The Change Agenda must be an exact projection of route in the Invariant Ledger. It must not use broad words like all when explicit IDs are required.

Invariant Gate

Required fields:

• artifactstatecoverage: pass / fail
• candidateinventorycoverage: pass / fail
• counterexample_coverage: pass / fail
• ownerscopecoverage: pass / fail
• induction_coverage: pass / fail
• boundarydecisioncoverage: pass / fail
• policyexceptioncoverage: pass / fail
• witnessfixtureparity_coverage: pass / fail
• verification_coverage: pass / fail
• authoritypacketcoverage: pass / fail
• authorityclearancecoverage: pass / fail
• authorityvetocoverage: pass / fail
• changeagendaconsistency: pass / fail
• acceptanceskewaudit: pass / fail
• invariantgatecomplete: pass / fail
• implementationhandoffallowed: yes / no
• validationhandoffallowed: yes / no
• proofonlyhandoff_allowed: yes / no

invariantgatecomplete may be pass only when all preceding required gate fields pass. implementationhandoffallowed: yes requires at least one enforce-now row whose authority status is cleared-for-enforcement and no unresolved veto exists for that ID.

Hard rules

• Do not enforce a candidate invariant without a concrete owner and scope.
• Do not enforce a candidate invariant without transition/induction coverage.
• Do not accept identity equality as witness/capability/proof of downstream usability.
• Do not add policy exceptions outside the policy owner.
• Do not let generated self-checks substitute for validation of externally supplied artifacts.
• Do not let fixtures bypass or trip the wrong preconditions without an explicit fixture alignment decision.
• Do not trust a caller override for a field that must be recomputed from generated/compiled/selected artifacts.
• Do not route unresolved authority or vetoed invariants to implementation.
• Do not claim completion when validation/proof is still pending.

Resources

• [authority-fanout.md](references/authority-fanout.md)
• [invariant-output-template.md](references/invariant-output-template.md)
• [CODEXSUBAGENTS.md](references/CODEXSUBAGENTS.md)