diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 3037b2f0e9..02f16b4fd7 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -168,7 +168,11 @@ jobs:
 
           echo "Cross-platform CI passed for ${GITHUB_SHA}: ${ci_url}"
 
-          # Notes / service baseline:
+          # Service baseline (lineage-relative): merged tags only, so the
+          # changed-files gate compares against the last release actually
+          # reachable from this commit. The release-notes baseline below uses the
+          # full tag set instead, so a stable on another lineage can anchor the
+          # changelog range.
           # - Preview: newest prior release of either channel (stable or preview). A
           #   preview→preview-only baseline skips a shipped stable and restates it.
           # - Stable: newest prior stable only (matching preview carry adjusts the
@@ -310,8 +314,14 @@ jobs:
 
           # Channel previous tag for Full Changelog + default notes baseline.
           # Preview baselines any prior release; stable baselines prior stable only.
+          # Read the FULL tag set: stable tags live on main's lineage, which the
+          # preview branch does not carry, and a trailing same-core preview
+          # (vX.Y.Z-preview.* shipped after vX.Y.Z) must not hide the stable from
+          # the compare range. The helper's semver ordering already ranks the
+          # stable above its own trailing preview, so the full tag list yields
+          # v2.9.1 → v2.10.0-preview instead of v2.9.1-preview → v2.10.0-preview.
           previous_tag="$(
-            git tag --merged HEAD --list 'v[0-9]*' |
+            git tag --list 'v[0-9]*' |
               bun scripts/release-notes.ts previous-release-tag "$RELEASE_VERSION"
           )"
           npm_metadata="Published to npm as \`@bitkyc08/opencodex@${RELEASE_VERSION}\` with dist-tag \`${NPM_DIST_TAG}\`."
diff --git a/scripts/release-notes.ts b/scripts/release-notes.ts
index 24d24a3d5f..98aa308731 100644
--- a/scripts/release-notes.ts
+++ b/scripts/release-notes.ts
@@ -109,6 +109,14 @@ export function matchingPreviewTags(version: string, tags: string[]): string[] {
  *   that stable's changelog (e.g. 2.7.41-preview → 2.7.43-preview after 2.7.42).
  * - Stable releases: newest prior stable only. Matching preview carry adjusts the
  *   notes range start separately when assembling latest notes.
+ *
+ * Callers must pass the FULL repo tag set, not `git tag --merged HEAD`. Stable
+ * tags live on main's lineage, which the preview branch does not carry, and a
+ * trailing same-core preview (vX.Y.Z-preview.* shipped after vX.Y.Z) must not
+ * hide the stable: for `2.10.0-preview.*` after `v2.9.1` + `v2.9.1-preview.*`,
+ * the baseline must be `v2.9.1`, not the trailing preview. Semver ordering
+ * already ranks the stable above its own trailing preview, so the full set is
+ * sufficient; restricting to merged tags is what reintroduces the bug.
  */
 export function previousReleaseNotesTag(version: string, tags: string[]): string | null {
   if (!version) return null;
diff --git a/tests/ci-workflows.test.ts b/tests/ci-workflows.test.ts
index 2ca6f48f88..fe56a09ddd 100644
--- a/tests/ci-workflows.test.ts
+++ b/tests/ci-workflows.test.ts
@@ -629,6 +629,18 @@ describe("GitHub Actions hardening", () => {
     expect(createStep.indexOf("gh api")).toBeGreaterThan(-1);
     expect(createStep.indexOf('git tag "$release_tag"')).toBeGreaterThan(-1);
     expect(createStep.indexOf("gh api")).toBeLessThan(createStep.indexOf('git tag "$release_tag"'));
+    // The notes baseline must read the FULL tag set, not `--merged HEAD`: stable
+    // tags live on main's lineage, which the preview branch does not carry, and a
+    // trailing same-core preview must not hide the stable from the range
+    // (v2.9.1-preview → v2.10.0-preview is wrong; the range must start at v2.9.1).
+    expect(createStep).toContain("git tag --list 'v[0-9]*' |");
+    expect(createStep).not.toContain("--merged HEAD");
+    // The merged-only restriction remains on the service gate, whose
+    // changed-files comparison is deliberately lineage-relative.
+    const ciGateStep = workflow
+      .split("- name: Require successful Cross-platform CI for this commit")[1]!
+      .split(/\n {6}- name:/)[0]!;
+    expect(ciGateStep).toContain("--merged HEAD");
     // First-channel releases must not call generate-notes without an explicit baseline
     // (GitHub would otherwise pick the newest repo tag, possibly from the other channel).
     // Scope to the single if-block that owns generate-notes; createStep has two
diff --git a/tests/release-notes.test.ts b/tests/release-notes.test.ts
index ed853635e9..e9a0562c82 100644
--- a/tests/release-notes.test.ts
+++ b/tests/release-notes.test.ts
@@ -105,6 +105,19 @@ describe("previousReleaseNotesTag", () => {
       "v2.7.42",
     ])).toBe("v2.7.42");
   });
+
+  test("a trailing same-core preview does not hide the stable (2.9.1 → 2.10.0-preview)", () => {
+    // v2.9.1-preview.20260802 shipped after the v2.9.1 stable on another lineage;
+    // the next preview train must still baseline the stable, not the trailing
+    // preview. This is the workflow's `git tag --list` (full set) contract: the
+    // same input restricted to `--merged HEAD` would drop v2.9.1 and wrongly
+    // return v2.9.1-preview.20260802.
+    expect(previousReleaseNotesTag("2.10.0-preview.20260802", [
+      "v2.9.1-preview.20260802",
+      "v2.9.1",
+      "v2.10.0-preview.20260802",
+    ])).toBe("v2.9.1");
+  });
 });
 
 describe("stripCarriedReleaseNotes", () => {