fix: an identity signs a named kind, and a device approval answers a request

The desktop main process builds every transcript itself from fields
(transcripts.js) and signs no raw bytes; the page's identity has the same
contract (crypto.js transcriptFor). The keyring seals no bundle while browser
access is off. On the node, device_add must redeem a pending request filed by
the same keys, and device_revoke is signed under its own prefix
(meshbay:device_revoke:v1), so a retirement signature admits nothing.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 5 insertions, 2 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/transport-chat.js b/packages/meshbay-hub/src/meshbay_hub/static/transport-chat.js
index f0604ce..e49eb4c 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/transport-chat.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/transport-chat.js
@@ -172,8 +172,11 @@ extendTransport(class {
     const { nonce, ct } = await C.sealChat(
       epochKey, gid, epoch, this.devicePk, plaintext);
     const device = C.b64decode(this.devicePk);
-    const sig = C.b64decode(await this._identity.sign(
-      C.chatSigningTranscript(gid, epoch, device, nonce, ct)));
+    // The transcript names the signing device as this identity's own key,
+    // which is what `devicePk` is once the node has been told (device_hello).
+    const sig = C.b64decode(await this._identity.signAs('chat', {
+      groupId: gid, epoch, nonce: C.b64encode(nonce), ct: C.b64encode(ct),
+    }));
 
     const msg = await this._sendAndWait({
       type: 'chat_msg',