Merge branch 'main' into chore/build-toolchain-20260812

app/game-api/src/services/readModelDeltaCache.ts

@@ -52,6 +52,11 @@ export const buildReadModelDeltaCacheKey = (
 const canPatch = (value: unknown): value is Record<string, unknown> | unknown[] =>
     value !== null && typeof value === 'object';
 
+const snapshotByteLength = (revision: string, serialized: string): number =>
+    Buffer.byteLength(`{"kind":"snapshot","revision":${JSON.stringify(revision)},"data":`) +
+    Buffer.byteLength(serialized) +
+    1;
+
 const storeSnapshot = async (store: ReadModelDeltaCacheStore, key: string, serialized: string): Promise<void> => {
     try {
         await store.set(key, serialized, { EX: CACHE_TTL_SECONDS });
@@ -91,7 +96,7 @@ export const createReadModelDelta = async <T>(request: ReadModelDeltaRequest<T>)
                     };
                     const snapshot = { kind: 'snapshot' as const, revision, data: canonicalValue };
                     await storeSnapshot(request.store, currentKey, serialized);
-                    return Buffer.byteLength(JSON.stringify(patch)) < Buffer.byteLength(JSON.stringify(snapshot))
+                    return Buffer.byteLength(JSON.stringify(patch)) < snapshotByteLength(revision, serialized)
                         ? patch
                         : snapshot;
                 }

app/game-api/test/readModelDeltaCache.test.ts

@@ -89,6 +89,31 @@ describe('createReadModelDelta', () => {
         );
     });
 
+    it('keeps the snapshot fallback when a positional patch is larger', async () => {
+        const store = new MemoryStore();
+        const initialValue = { values: Array.from({ length: 24 }, () => 'old') };
+        const initial = await createReadModelDelta({
+            store,
+            profile: 'hwe:default',
+            viewerId: 'user-1',
+            slice: 'context',
+            value: initialValue,
+            forceSnapshot: true,
+        });
+        const nextValue = { values: Array.from({ length: 24 }, () => 'new') };
+
+        const changed = await createReadModelDelta({
+            store,
+            profile: 'hwe:default',
+            viewerId: 'user-1',
+            slice: 'context',
+            value: nextValue,
+            knownRevision: initial.revision,
+        });
+
+        expect(changed).toMatchObject({ kind: 'snapshot', data: nextValue });
+    });
+
     it('falls back to a snapshot when Redis is unavailable', async () => {
         const store: ReadModelDeltaCacheStore = {
             get: async () => {