feat(client): the desktop application keeps M and every node identity in its main process

keyring.js derives, opens, mints, seals, signs and agrees there; the page gets
public keys and a handle. Argon2 comes from the page's own WebAssembly build
(Electron's crypto has none). Without OS key storage the page keeps its keys as
a browser does. A node's bundle is settled after connecting, re-sealed when the
key changed.

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

1 files changed, 20 insertions, 2 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/keyderive.js b/packages/meshbay-hub/src/meshbay_hub/static/keyderive.js
index 8f820ec..d847aab 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/keyderive.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/keyderive.js
@@ -165,6 +165,24 @@ async function deriveBundleSessionKey(password, username, userId, pepperB64, pep
 }
 
 /**
+ * The session's bundle key wherever it is kept. In a browser, derived here. In
+ * the desktop application, derived and kept by its main process, and what
+ * comes back is a handle — `{ native, userId, pepperVersion }` — that opens
+ * nothing by itself: the transport asks the application for what it needs.
+ * `pending`: a passphrase change, held aside until the hub accepts it.
+ */
+async function sessionBundleKey(password, username, userId, pepperB64, pepperVersion,
+                                { pending = false } = {}) {
+  const P = typeof window !== 'undefined' && window.MeshBayPlatform;
+  if (P && P.nativeKeys && await P.nativeKeys()) {
+    if (!userId || !pepperB64) throw new Error('the hub did not provide the bundle pepper');
+    await P.keys.deriveSession({ password, username, userId, pepperB64, pepperVersion, pending });
+    return { native: true, userId, pepperVersion: pepperVersion || 1, pending };
+  }
+  return deriveBundleSessionKey(password, username, userId, pepperB64, pepperVersion);
+}
+
+/**
  * The key that seals this account's identity on ONE node. A leaked one opens
  * that node's bundle and no other.
  */
@@ -428,7 +446,7 @@ async function loginAndRecover(username, password) {
     refreshToken: data.refresh_token,
     // The pepper rides on the sign-in response, so this costs no extra call;
     // it is folded into the key here and not kept.
-    bundleKey: await deriveBundleSessionKey(
+    bundleKey: await sessionBundleKey(
       password, username, _subOf(data.access_token),
       data.bundle_pepper, data.bundle_pepper_version),
   };
@@ -457,7 +475,7 @@ window.MeshBayKeys = {
   deriveAuthKey,
   // The bundle key (docs/MESHBAY_DESIGN.md §3.1, §3.7): one session key per
   // sign-in, one derived key per node, one format.
-  deriveBundleSessionKey, nodeBundleKey, fetchBundlePepper,
+  deriveBundleSessionKey, sessionBundleKey, nodeBundleKey, fetchBundlePepper,
   encryptBundle, decryptBundle, bundleFormat,
   // Account recovery key (docs/MESHBAY_DESIGN.md §3.6).
   generateRecoveryKey, deriveRecoveryKey,