Verification Frontiers & Local Finality

Status: Draft / Notes Non-normative Builds on: Proof Availability & Deferred Verification

Motivation

Deferred verification introduces temporal uncertainty.

A verifier may observe:

• finalized global state transitions
• without possessing proofs
• across an unbounded timeline

Without constraints, this leads to unbounded waiting and ambiguous local state.

This note introduces verification frontiers and local finality as mechanisms for bounding verifier responsibility without compromising safety.

Verification Frontier

A verification frontier is the maximal boundary of state for which a verifier is willing to reason.

It defines:

• how far forward the verifier tracks unverified commitments
• how long the verifier will defer verification
• when refusal becomes terminal rather than temporary

The frontier is a local policy choice.

Frontier as a Set, Not a Point

A frontier is not a single block height or timestamp.

It is a set of accepted and pending commitments that define the verifier’s working view.

Elements outside the frontier are ignored, not rejected.

Frontier Advancement

The frontier advances when:

• proofs are verified
• lineage consistency is maintained
• resource constraints permit extension

Advancement is monotonic.

A verifier never retracts verified history.

Frontier Saturation

A frontier saturates when:

• too many unverified commitments accumulate
• proofs fail to arrive within policy bounds
• storage or computation limits are reached

Saturation does not cause failure.

It causes suspension of forward progress.

Local Finality

Local finality is the point at which a verifier considers a state transition irrevocable within its own view.

Local finality requires:

• verified proof
• lineage consistency
• inclusion within the verifier’s frontier

Global finality alone is insufficient.

Distinction from Network Finality

Network finality asserts that:

• the network will not revert a commitment

Local finality asserts that:

• the verifier accepts the commitment as part of its trusted state

The two are related but not equivalent.

Refusal Escalation

When frontier saturation persists, the verifier escalates from:

• deferred verification
• to permanent refusal

Permanent refusal is a stable state.

It signals:

• the verifier will not reason about further state
• without external intervention or reconfiguration

Reconfiguration and Recovery

A verifier may recover by:

• extending resource bounds
• importing external proofs
• reconnecting to new peers
• resetting its frontier policy

Recovery is explicit.

Implicit trust is never introduced.

Safety Guarantees

Verification frontiers preserve safety because:

• no unverified state is accepted
• no forced progression occurs
• no trust is introduced to bypass missing proofs

Liveness is intentionally sacrificed before safety.

Genesis-Anchored Boundaries

Genesis anchoring bounds the maximum meaningful frontier.

Even if a verifier discards all state beyond its frontier, it can always re-anchor to genesis and rebuild.

No infinite regress exists.

Implications

Verification frontiers enable:

• deterministic verifier behavior
• bounded memory usage
• explicit refusal semantics
• offline-tolerant systems
• heterogeneous verifier policies

They formalize verifier sovereignty.

What Follows

Once local finality exists, the system must define how verifiers interact with each other.

The next note introduces verifier composition:

0x06 — Multi-Verifier Consistency & Gossip Safety