fix(hub): re-read the roster before saying a key changed

A member invited after the roster was read showed "key changed" on each
message until a reload. Read it again once per account and device on the
connection, shared by concurrent messages, and pin only the final verdict.

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

1 files changed, 30 insertions, 0 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/transport-roster.js b/packages/meshbay-hub/src/meshbay_hub/static/transport-roster.js
index cac3b52..d2e8c94 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/transport-roster.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/transport-roster.js
@@ -103,6 +103,36 @@ async function _writePinnedAccount(nodePk, userId, keys) {
 }
 
 /**
+ * How `devicePk` stands against what is pinned for its account (`known`, null
+ * at first sight) and what the roster lists for it (`entry`): `{ status, pin }`,
+ * `pin` being the keys to keep if that answer stands. Decides and writes
+ * nothing, so a verdict reached on a stale roster can be taken again on a fresh
+ * one without having pinned half a set first. The statuses are
+ * `accountDeviceStatus`'s.
+ */
+function _judgeDevice(known, entry, devicePk) {
+  if (known && known.includes(devicePk)) return { status: 'pinned', pin: null };
+  if (!known) {
+    // First sight, so **everything the node says** is pinned — not only what
+    // a chain reaches. There is nothing to compare against yet: that is what
+    // trust-on-first-use means, and pinning only the verified subset would
+    // raise "key changed" on a legitimate second device whose
+    // countersignature simply predates it being kept. What TOFU buys is that
+    // a substitution *later* is visible; it cannot buy anything now.
+    const pin = entry ? entry.all : null;
+    return { status: entry && entry.all.includes(devicePk) ? 'first' : 'changed', pin };
+  }
+  if (entry && entry.verified.includes(devicePk)
+      && entry.chain.get(devicePk)
+      && known.includes(entry.chain.get(devicePk))) {
+    // Countersigned by a key we already trust for this account: a second
+    // device of someone we know, admitted without anybody comparing digits.
+    return { status: 'linked', pin: [...new Set([...known, devicePk])] };
+  }
+  return { status: 'changed', pin: null };
+}
+
+/**
  * A wire payload as text.
  *
  * A plaintext message arrives as a string from the node; msgpack `bin` arrives