fix(terrain): refresh cache recency when resolving warm batches

CHANGELOG.md

@@ -32,6 +32,7 @@
 - Tool string length validation counts Unicode characters correctly, including characters outside the basic multilingual plane.
 
 - Director timeline seeks cross the dateline along the short longitude arc.
+- Frequently reused terrain batches retain their cached heights ahead of unused cells.
 
 - Treat explicitly current, complete empty vessel coverage as a successful update,
   clearing obsolete contacts while retaining stale or incomplete snapshots.

docs/CURRENT-STATE.md

@@ -5326,3 +5326,8 @@ datacenters, dams and the Nepal locator retain that shared credit while displaye
 
 Military fragments stitch by source identity. Different mapped parcels merge only
 when their footprints touch or contain one another, never across a seam tolerance gap.
+
+
+### fix(terrain): refresh cache recency when resolving warm batches
+
+Use the existing LRU read path for batch lookups; provider requests, fallback cooldowns and bounded residency retain their current contracts.

src/services/terrain-warm-batch-lru.test.mjs

@@ -0,0 +1,24 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { createTerrainHeights } from './terrainHeights.js';
+test('warm batch consumers retain their terrain cells ahead of unused cells', async () => {
+  let calls = 0;
+  const terrain = createTerrainHeights({
+    maxCacheEntries: 2,
+    source: {
+      async getHeights(points) {
+        calls++;
+        return points.map((p) => ({ ellipsoid: 100 + p.lon }));
+      },
+    },
+  });
+  const p = (lon) => ({ lat: 0, lon });
+  await terrain.resolveEllipsoidalGround([p(1)]);
+  await terrain.resolveEllipsoidalGround([p(2)]);
+  await terrain.resolveEllipsoidalGround([p(1)]);
+  assert.equal(calls, 2);
+  await terrain.resolveEllipsoidalGround([p(3)]);
+  assert.equal(terrain.cachedEllipsoidalGround(0, 1), 101);
+  assert.equal(terrain.cachedEllipsoidalGround(0, 2), null);
+  assert.equal(calls, 3);
+});

src/services/terrainHeights.js

@@ -273,7 +273,7 @@ export function createTerrainHeights({
     const seenKeys = new Set();
     const now = Date.now();
     for (const item of work) {
-      const entry = cache.get(item.key);
+      const entry = cacheTouch(item.key);
       const fallbackCooling =
         entry?.source === 'geoid-fallback' &&
         Number.isFinite(entry.retryAt) &&