diff --git a/third_party/x/.cursor-plugin/plugin.json b/third_party/x/.cursor-plugin/plugin.json
index 7fa9076c3..19725139c 100644
--- a/third_party/x/.cursor-plugin/plugin.json
+++ b/third_party/x/.cursor-plugin/plugin.json
@@ -1,7 +1,7 @@
 {
   "name": "x",
   "displayName": "X",
-  "version": "2.8.0",
+  "version": "2.8.1",
   "minClientVersions": {
     "cursor": "3.13.0"
   },
diff --git a/third_party/x/CHANGELOG.md b/third_party/x/CHANGELOG.md
index 7e6afd41c..4315c4b35 100644
--- a/third_party/x/CHANGELOG.md
+++ b/third_party/x/CHANGELOG.md
@@ -2,6 +2,11 @@
 
 All notable changes to this plugin will be documented here.
 
+## 2.8.1 — Stop on UNAUTHORIZED_REQUESTING_USER from add_conversation_keys
+
+- `UNAUTHORIZED_REQUESTING_USER` from `add_conversation_keys` means the other person can't receive encrypted chats from the owner, almost always because they don't follow the owner. It is final for that conversation for the session: don't re-post, re-prepare keys, or send. Tell the owner the other person has to follow them first, and both accounts need X Chat keys.
+- A prepared `add_conversation_keys` body is single-use and must never be saved and re-posted.
+
 ## 2.8.0 — Livestreams
 
 - Requested `broadcast.read` and `broadcast.write` so agents can manage the owner's X livestreams on `https://api.x.com/mcp`.
diff --git a/third_party/x/skills/x-api-mcp-guide/SKILL.md b/third_party/x/skills/x-api-mcp-guide/SKILL.md
index 6401e16df..e4e416b1e 100644
--- a/third_party/x/skills/x-api-mcp-guide/SKILL.md
+++ b/third_party/x/skills/x-api-mcp-guide/SKILL.md
@@ -261,7 +261,7 @@ Do not tell them to create a Project or App. Do not ask for a Bearer token. Afte
 
 > I'll retry in a minute.
 
-400 `invalid-request`: fix params, don't retry unchanged.
+400 `invalid-request`: fix params, don't retry unchanged. A prepared `add_conversation_keys` body is single-use and must never be saved and re-posted.
 
 5xx / **503** / **`get_usage_credits` missing while other X tools work**: backoff once or twice. Do not treat it as $0 credits, a missing app, or [error 2](#2-account-not-ready). Other endpoints may still work. Then say:
 
@@ -645,7 +645,7 @@ Do not accept while you are still paging the list.
 
 **No conversation key yet** (first message, or only unencrypted messages): self + peer public keys (`public_key` = identity, `key_version` = `public_key_version`) → `session-encrypt` with `prepare` set → MCP `add_conversation_keys` (conversation `id` = thread id from inbox when known) → MCP `send_chat_message` → confirm.
 
-If `add_conversation_keys` returns `UNAUTHORIZED_REQUESTING_USER` or similar: you likely cannot rotate/init keys for that conversation, or the peer is not on XChat — stop and report; do not send ciphertext under an unpublished key.
+If `add_conversation_keys` returns `UNAUTHORIZED_REQUESTING_USER`, the other person can't receive encrypted chats from the owner, almost always because they don't follow the owner. This code is final for that conversation for this session: don't re-post, re-prepare keys, or send. Tell the owner the other person has to follow them first, and both accounts need X Chat keys.
 
 ### Chat safety