test(benchmark): keep the a871f8f engine as a fixed calibration engine

The differential check's frozen bundle will be rebuilt for #302; the
relative gate keeps timing the unchanged a871f8f bundle so its ratios
stay comparable with the recorded history.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/benchmark/README.md

@@ -18,9 +18,11 @@ The relative gate replaces the 300-second acceptance protocol named in
 policy. This is an explicit policy change from #279/#285: runners differ in
 speed, so a fixed wall-clock limit was flaky.
 
-Before the protocol, in the same process, the spec times the frozen engine
-(`src/app/services/frozen-engine/leave-planner.core.frozen.mjs`, the engine at
-a871f8f) on the `two years` scenario, best of three, and prints the result.
+Before the protocol, in the same process, the spec times the calibration engine
+(`src/app/services/frozen-engine/leave-planner.core.calibration.mjs`, the engine at
+a871f8f) on the `two years` scenario, best of three, and prints the result. This
+bundle never changes, so ratios stay comparable with the recorded history; the
+differential check's frozen bundle can be rebuilt independently.
 Each scenario's budget is its multiplier times that calibration; the mean
 `planningMs` of its two measured repetitions must not exceed it. A scenario
 without a multiplier fails too. `#286` tightens the multipliers once the speed

src/app/benchmark/leave-planner-benchmark.spec.ts

@@ -1,5 +1,5 @@
 import { vi } from '../../testing/vitest-compat';
-import { calculatePlanningAsyncInternal } from '../services/frozen-engine/leave-planner.core.frozen.mjs';
+import { calculatePlanningAsyncInternal } from '../services/frozen-engine/leave-planner.core.calibration.mjs';
 import { createPlanningCalculation } from '../services/leave-planner.service';
 import {
 	BENCHMARK_BUDGET_MULTIPLIERS,
@@ -69,7 +69,7 @@ describe('leave planner benchmark protocol', () => {
 					),
 				).toHaveLength(2);
 			}
-			// Frozen engine (a871f8f) on 'two years', best of three: the runner-speed yardstick.
+			// Calibration engine (frozen at a871f8f) on 'two years', best of three: the runner-speed yardstick.
 			const calibrationRequest = scenarios.find((item) => item.name === 'two years')!.request;
 			let calibrationMs = Infinity;
 			for (let run = 0; run < 3; run++) {

src/app/services/frozen-engine/leave-planner.core.calibration.d.mts

@@ -0,0 +1,22 @@
+import type {
+	PlanningArtifactsCallback,
+	PlanningCheckpoint,
+	PlanningExplanationCallback,
+	PlanningOutcome,
+	PlanningOutcomeCallback,
+} from '../leave-planner.core';
+
+export function calculatePlanningInternal(
+	request: unknown,
+	checkpointCallback?: undefined,
+	artifactsCallback?: PlanningArtifactsCallback,
+): PlanningOutcome;
+
+export function calculatePlanningAsyncInternal(
+	request: unknown,
+	checkpointCallback?: PlanningCheckpoint,
+	artifactsCallback?: PlanningArtifactsCallback,
+	outcomeCallback?: PlanningOutcomeCallback,
+	explanationCallback?: PlanningExplanationCallback,
+	isCancelled?: () => boolean,
+): Promise<PlanningOutcome>;