diff --git a/.changeset/promote-to-v1-stable.md b/.changeset/promote-to-v1-stable.md
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+---
+"@hypercerts-org/lexicon": major
+---
+
+Promote `@hypercerts-org/lexicon` to v1.0.0 — first stable release.
+
+This changeset contributes no schema or type changes of its own; it
+exists solely to force a major version bump so the package crosses the
+0.x → 1.0 line. From v1.0.0 onward, the lexicons, TypeScript types,
+and generated exports are considered stable for downstream consumers,
+and the package follows standard SemVer semantics: breaking changes
+bump the major version, non-breaking additions the minor version, and
+fixes the patch version. (Prior to v1.0.0, breaking changes were
+allowed under `minor` per the SemVer 0.x convention — see
+`.claude/skills/writing-changesets/SKILL.md`.)
+
+Any other changesets pending at the time this one is consumed are
+folded into the same v1.0.0 release; see the other entries below for
+those contributions.