diff --git a/.changeset/22080-v18-line-opens.md b/.changeset/22080-v18-line-opens.md
new file mode 100644
index 00000000000..91b1263e9b6
--- /dev/null
+++ b/.changeset/22080-v18-line-opens.md
@@ -0,0 +1,14 @@
+---
+"@objectstack/spec": major
+---
+
+The v18 line opens (ADR-0131; #22050). Every release from here is an `18.0.0-next.N` prerelease on the npm dist-tag `next`, until 18.0 GA.
+
+Clause-②: no
+
+- **What this marks.** Changesets is in pre mode with the tag `next`. Every `@objectstack/*` package versions together, so this one `major` takes all of them to 18, and the first version cut is `18.0.0-next.0`. `PROTOCOL_VERSION` follows `@objectstack/spec`'s major at version time, so it reads `18.0.0` from that prerelease on. The marker itself changes no code, key, export or stored shape.
+- **What the line carries.** ADR-0131 (organization ownership is total: no NULL `organization_id`) lands on this line in stages. Each stage that breaks something says so in its own changeset, with its own migration.
+- **Who receives it.** A plain install still resolves the dist-tag `latest`, which stays on 17.x until 18.0 GA. A prerelease is installed only on request: `@objectstack/spec@next`, or an exact `18.0.0-next.N`.
+- **What ends it.** 18.0 GA exits pre mode and publishes to `latest`.
+
+<!-- adr-0087: not-required (no-migration-prescription) the v18 line's opening marker: Changesets pre mode plus one major on the fixed group, so the train versions 18.0.0-next.N. No authorable key, spelling, export, type or stored shape moves in this diff, and no stored row is read, rewritten or converted; each breaking stage of the line states its own disposition in its own changeset. The other categories are closed on facts: the package publishes (not unpublished); no ADR-0087 id is named or touched (not registered or already-registered); and no TypeScript declaration moves (not runtime-interface-only or type-surface-only). -->
diff --git a/.changeset/pre.json b/.changeset/pre.json
new file mode 100644
index 00000000000..d20efa9e7db
--- /dev/null
+++ b/.changeset/pre.json
@@ -0,0 +1,4 @@
+{
+  "mode": "pre",
+  "tag": "next"
+}
diff --git a/scripts/check-adr-0087-registration.mjs b/scripts/check-adr-0087-registration.mjs
index 7362b91033f..c961391c805 100644
--- a/scripts/check-adr-0087-registration.mjs
+++ b/scripts/check-adr-0087-registration.mjs
@@ -533,7 +533,8 @@ const isChangesetFile = (p) => p.startsWith('.changeset/') && p.endsWith('.md')
  * audit surfaces is a readability fix; filtering the verdict would be a bypass,
  * and `PRE2` in the self-test pins the difference.
  */
-const isConsumedPrerelease = (p) => p.startsWith('.changeset/pre/');
+const CONSUMED_PRERELEASE_EXCLUDED = '.changeset/pre/';
+const isConsumedPrerelease = (p) => p.startsWith(CONSUMED_PRERELEASE_EXCLUDED);
 
 /**
  * Split a changeset into its frontmatter bump entries and its body.