diff --git a/packages/cultmesh-ts/src/content.ts b/packages/cultmesh-ts/src/content.ts
index 3191a285..a0f3f06d 100644
--- a/packages/cultmesh-ts/src/content.ts
+++ b/packages/cultmesh-ts/src/content.ts
@@ -2,7 +2,7 @@ import { constants } from "node:fs";
 import { open } from "node:fs/promises";
 import type { IncomingMessage, ServerResponse } from "node:http";
 import { join } from "node:path";
-import { DEFAULT_CHUNK_SIZE_BYTES, EMPTY_SHA256, chunkRecordKey, parseSha256Hex, sha256Hex } from "cultnet-ts/content";
+import { DEFAULT_CHUNK_SIZE_BYTES, EMPTY_SHA256, chunkRecordKey, isNullOrWhiteSpaceCSharp, parseSha256Hex, sha256Hex } from "cultnet-ts/content";
 
 /** What the provider reads of a request. The path and the headers are never read: the route is the query alone. */
 export interface ContentChunkRequest { method: string; url: string; }
@@ -63,7 +63,7 @@ export function createContentChunkHandler(store: ContentChunkStore, options: Con
       const [hash, ...otherHashes] = query.getAll("chunkHash");
       const [key = "", ...otherKeys] = query.getAll("recordKey");
       hex = parseSha256Hex(hash ?? "");
-      if (otherHashes.length || otherKeys.length || (key.trim() !== "" && key !== chunkRecordKey(hex))) return refusal(400);
+      if (otherHashes.length || otherKeys.length || (!isNullOrWhiteSpaceCSharp(key) && key !== chunkRecordKey(hex))) return refusal(400);
     } catch { return refusal(400); }
     if (hex === EMPTY_SHA256) return chunkAnswer(new Uint8Array());
     let bytes: Uint8Array | undefined;
diff --git a/packages/cultnet-ts/src/content.ts b/packages/cultnet-ts/src/content.ts
index 8474c396..323a59e9 100644
--- a/packages/cultnet-ts/src/content.ts
+++ b/packages/cultnet-ts/src/content.ts
@@ -12,6 +12,9 @@ import { checkPayloadDepth } from "@gamecult/cultcache-ts/document";
 import { isNullOrWhiteSpaceCSharp, trimCSharp } from "./cultmesh-authority";
 import { wellFormed } from "./utf8-bound";
 
+/** C#'s `string.IsNullOrWhiteSpace`, the one blank rule every consumer of the content shapes shares. */
+export { isNullOrWhiteSpaceCSharp };
+
 export const CULTMESH_CDN_MANIFEST_SCHEMA = "gamecult.mesh.cdn_artifact_manifest.v1";
 export const DEFAULT_CHUNK_SIZE_BYTES = 4 * 1024 * 1024;
 export const EMPTY_SHA256 = "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855";