diff --git a/.changeset/protocol-version-13-lockstep.md b/.changeset/protocol-version-13-lockstep.md
new file mode 100644
index 0000000000..fbf2fb8814
--- /dev/null
+++ b/.changeset/protocol-version-13-lockstep.md
@@ -0,0 +1,11 @@
+---
+'@objectstack/spec': patch
+---
+
+fix(spec): bump PROTOCOL_VERSION 12.0.0 → 13.0.0 to match the spec major
+
+The version-packages roll (#2720) took `@objectstack/spec` to major `13.0.0`
+but left `PROTOCOL_VERSION` at `12.0.0`, so `protocol-version.test.ts` (the
+lockstep guard that asserts the protocol major equals the package major) failed
+on `main` — reddening Test Core for every PR. Restore the lockstep so the
+loader/installer handshake advertises the major the package actually ships.
diff --git a/.objectui-sha b/.objectui-sha
index e18aa26bfb..37dadd1210 100644
--- a/.objectui-sha
+++ b/.objectui-sha
@@ -1 +1 @@
-b0aa25129542504b81589ee95bb81a5d6003f998
+7a68d78f2a0c3c1f99dafd39b75b4f117a24917b
diff --git a/packages/spec/src/kernel/protocol-version.ts b/packages/spec/src/kernel/protocol-version.ts
index b5d0924ad8..874d60bfdc 100644
--- a/packages/spec/src/kernel/protocol-version.ts
+++ b/packages/spec/src/kernel/protocol-version.ts
@@ -15,7 +15,7 @@
  * Kept in lockstep with the package's own major; `protocol-version.test.ts`
  * asserts it against `package.json` so the two cannot drift.
  */
-export const PROTOCOL_VERSION = '12.0.0';
+export const PROTOCOL_VERSION = '13.0.0';
 
 /** The protocol major as an integer — the value the handshake compares. */
 export const PROTOCOL_MAJOR: number = Number.parseInt(PROTOCOL_VERSION.split('.')[0]!, 10);