Core documentation

11. The host supplies before-state for incremental evaluation

Specification metadata

adr: 11
title: The host supplies before-state for incremental evaluation
status: accepted
date: 2026-06-16

§Context

introduced is after \ before by fingerprint, which implies evaluating both states — O(2×) on every gate call, punishing for wrapped tools with no incremental API (review SI-4). The incremental capability existed but had no mechanism.

§Decision

judge/evaluate MAY carry priorDiagnostics: the host-cached before-state findings for the changeset’s before blobs.

A server that advertised incremental MAY treat priorDiagnostics as the before-set and evaluate only the after-state, diffing by fingerprint.
If priorDiagnostics is absent (cold/first call, or a non-incremental server), the server computes both states.
The host populates it from a per-server diagnostic cache keyed by (server, blob-set) — safe to cache forever because blobs are immutable. The host caches the full after-state findings of each evaluated blob-set (running an all pass once if needed), so the before-set handed back is complete, not merely the previously-introduced subset.

§Consequences

Warm gate calls drop to ~1× for incremental servers; naive servers still work unchanged.
Adds a host-side, content-hash-keyed diagnostic cache. Correctness is exact (same fingerprint space, same before blobs).