From b082101c784f44a9910222f95f56ffe4cfb38ee9 Mon Sep 17 00:00:00 2001
From: Libby <libby@minds.libby.gamecult.org>
Date: Mon, 9 Nov 2026 10:22:15 +0000
Subject: [PATCH] cultnet-ts: a blank text in a raw frame is Unicode
 White_Space, not trim()

validateBinaryMessageRoot, requireNonEmptyString and requireOptionalStringArray
used String.prototype.trim(), which takes U+FEFF and misses U+0085, so the TS
decoder and the servers disagreed on what names nothing (write-receipt rule 5).

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
---
 packages/cultnet-ts/src/contracts.ts          | 11 ++++++++---
 .../cultnet-ts/test/write-receipt.test.ts     | 19 +++++++++++++++++++
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/packages/cultnet-ts/src/contracts.ts b/packages/cultnet-ts/src/contracts.ts
index 6e05c9a5..3cc87dcd 100644
--- a/packages/cultnet-ts/src/contracts.ts
+++ b/packages/cultnet-ts/src/contracts.ts
@@ -1422,7 +1422,7 @@ function validateBinaryMessageRoot(
   if (candidate.schemaVersion !== schemaVersion) {
     throw new Error(`Validation failed for ${schemaVersion}: /schemaVersion: must equal ${schemaVersion}`);
   }
-  if (typeof candidate.messageId !== "string" || candidate.messageId.trim().length === 0) {
+  if (typeof candidate.messageId !== "string" || isBlank(candidate.messageId)) {
     throw new Error(`Validation failed for ${schemaVersion}: /messageId: must be a non-empty string`);
   }
 
@@ -1460,8 +1460,13 @@ function validateRawDocumentRecord(
   requireOptionalStringArray(candidate.tags, `${instancePath}/tags`);
 }
 
+/** Blank is empty or only Unicode White_Space (write-receipt.md, rule 5), not `trim()`: JS trims U+FEFF and keeps U+0085. */
+function isBlank(value: string): boolean {
+  return /^\p{White_Space}*$/u.test(value);
+}
+
 function requireNonEmptyString(input: unknown, instancePath: string): void {
-  if (typeof input !== "string" || input.trim().length === 0) {
+  if (typeof input !== "string" || isBlank(input)) {
     throw new Error(`Validation failed for raw CultNet document record: ${instancePath}: must be a non-empty string`);
   }
 }
@@ -1477,7 +1482,7 @@ function requireOptionalStringArray(input: unknown, instancePath: string): void
   if (typeof input === "undefined" || input === null) {
     return;
   }
-  if (!Array.isArray(input) || input.some((item) => typeof item !== "string" || item.trim().length === 0)) {
+  if (!Array.isArray(input) || input.some((item) => typeof item !== "string" || isBlank(item))) {
     throw new Error(`Validation failed for raw CultNet document record: ${instancePath}: must be an array of non-empty strings`);
   }
 }
diff --git a/packages/cultnet-ts/test/write-receipt.test.ts b/packages/cultnet-ts/test/write-receipt.test.ts
index 83c31411..efab1c28 100644
--- a/packages/cultnet-ts/test/write-receipt.test.ts
+++ b/packages/cultnet-ts/test/write-receipt.test.ts
@@ -227,3 +227,22 @@ test("a write whose own send failed settles local_send_failed even when its wind
   tracker.sendFailed("w1", 1000);
   assert.deepEqual(tracker.state("w1"), { outcome: "unconfirmed", reason: "local_send_failed" });
 });
+
+// Blank is Unicode White_Space (write-receipt.md, rule 5), not what String.prototype.trim() trims: trim() takes U+FEFF and
+// misses U+0085. Every frame decoder that rejects a blank text must agree with the servers that do.
+test("a blank messageId, record key or tag is exactly Unicode White_Space, not trim()", () => {
+  const put = (document: Record<string, unknown>, messageId = "p1") => ({
+    schemaVersion: "cultnet.document_put_raw.v0", messageId,
+    document: { schemaId: "note.v0", recordKey: "note:1", storedAt: "2026-11-08T00:00:00Z", payloadEncoding: "messagepack", payload: Uint8Array.of(0x81, 0xa1, 0x61, 0x01), ...document },
+  });
+  for (const blank of ["\u0085", "  ", "　"]) {
+    assert.throws(() => parseCultNetMessage(put({}, blank)), `messageId ${JSON.stringify(blank)}`);
+    assert.throws(() => parseCultNetMessage(put({ recordKey: blank })), `recordKey ${JSON.stringify(blank)}`);
+    assert.throws(() => parseCultNetMessage(put({ tags: [blank] })), `tag ${JSON.stringify(blank)}`);
+  }
+  for (const named of ["", "​", "\u001c", "᠎"]) {
+    parseCultNetMessage(put({}, named));
+    parseCultNetMessage(put({ recordKey: named }));
+    parseCultNetMessage(put({ tags: [named] }));
+  }
+});