diff --git a/packages/core/src/lib/designFile.ts b/packages/core/src/lib/designFile.ts
index 2b5b2231..63a19dac 100644
--- a/packages/core/src/lib/designFile.ts
+++ b/packages/core/src/lib/designFile.ts
@@ -12,7 +12,7 @@ import { dbSourceRefSchema, type DbSourceRef } from "../types/DataSource";
 import type { LabelObject } from "../types/Group";
 import { blockOverlaySchema, overlayText, type BlockOverlay } from "./zplOverlay/overlay";
 import { reconstructLegacyBlockHeads, storedFormatPathOf } from "./zplHeadScan";
-import { visitLeavesInPages, foldSerialLeaf, fixTlc39SlotsLeaf, bindSingleMarkerLeaf, safeUniqueNameById } from "./objectTree";
+import { visitLeavesInPages, foldSerialLeaf, fixTlc39SlotsLeaf, bindSingleMarkerLeaf, migrateGs1DatabarLeaf, safeUniqueNameById } from "./objectTree";
 import { sanitiseLoadedVariables } from "./loadedVariables";
 import { insertReverseBackingBoxes, pageNeedsReverseBacking } from "./reverseBacking";
 import { ok, err } from "./result";
@@ -20,11 +20,8 @@ import { schemaIssues } from "./schemaIssues";
 import { getEntry } from "../registry";
 import { propDomainIssue, truncateIntegerProps, type PropSpec } from "../types/propSpec";
 
-/** Current design-file schema version. Bump when the persisted shape
- *  changes in a way an older app cannot read. Add a vN schema +
- *  migrator below and dispatch on `schemaVersion` in `parseDesignFile`.
- *  The persist middleware in `labelStore` has its own independent
- *  version for localStorage state; do not conflate. */
+/** Bump when an older app could not read the persisted shape, with a hop in the migration chain
+ *  of `parseDesignFile`. The persist middleware in `labelStore` versions localStorage on its own. */
 export const CURRENT_DESIGN_SCHEMA_VERSION = 6;
 
 export type DesignFileError = "parse_error" | "invalid_schema" | "fn_slots_exhausted";
@@ -129,7 +126,7 @@ export function parseDesignFile(text: string): DesignFileResult {
   // Valid JSON that is not an object (null, true, "x") must reject, not throw.
   if (!json || typeof json !== "object") return err("invalid_schema");
 
-  migrateGs1databarModuleWidth(json);
+  visitLeavesInPages((json as { pages?: unknown }).pages, migrateGs1DatabarLeaf);
   visitLeavesInPages((json as { pages?: unknown }).pages, fixTlc39SlotsLeaf);
   migrateReverseTextBackground(json);
   migrateSerialToTextMode(json);
@@ -184,27 +181,6 @@ function migrateReverseTextBackground(json: unknown): void {
   j.schemaVersion = 2;
 }
 
-/** Rename gs1databar `props.moduleWidth` → `props.magnification` on
- *  legacy design files. Mirrors the persist-store v5→v6 hop in
- *  `labelStore.ts`. Idempotent. */
-function migrateGs1databarModuleWidth(json: unknown): void {
-  if (!json || typeof json !== "object") return;
-  const pages = (json as { pages?: unknown }).pages;
-  visitLeavesInPages(pages, (leaf) => {
-    if (
-      leaf.type === "gs1databar" &&
-      leaf.props &&
-      typeof leaf.props === "object" &&
-      "moduleWidth" in leaf.props &&
-      !("magnification" in leaf.props)
-    ) {
-      const props = leaf.props as Record<string, unknown>;
-      props.magnification = props.moduleWidth;
-      delete props.moduleWidth;
-    }
-  });
-}
-
 /** Convert the legacy standalone `serial` object type into a `text` field with
  *  a `serial` prop (the dissolved field-mode model). Keeps content/font/rotation
  *  and folds increment/zplMode into `props.serial`. Idempotent. */
diff --git a/packages/core/src/lib/designOps.test.ts b/packages/core/src/lib/designOps.test.ts
index ec743a76..1e87e914 100644
--- a/packages/core/src/lib/designOps.test.ts
+++ b/packages/core/src/lib/designOps.test.ts
@@ -42,22 +42,36 @@ describe("applyDesignOps", () => {
     const seen: { dpmm: number; variables: string[] }[] = [];
     const input = doc();
     input.pages[0]!.objects.push(rightBarcode("bc"));
-    const result = applyDesignOps(
-      input,
-      [{ op: "addVariable", variable: { name: "qty" } }, { op: "update", id: "bc", props: { content: "«qty»" } }],
-      (_o, ctx) => {
-        seen.push({ dpmm: ctx.label.dpmm, variables: ctx.variables.map((v) => v.name) });
-        return null;
-      },
-    );
+    input.variables.push(variable("qty", 2, "1"));
+    const result = applyDesignOps(input, [{ op: "update", id: "bc", props: { content: "«qty»" } }], (_o, ctx) => {
+      seen.push({ dpmm: ctx.label.dpmm, variables: ctx.variables.map((v) => v.name) });
+      return null;
+    });
     expect(result.ok).toBe(true);
     if (!result.ok) return;
     expect(result.doc.pages[0]?.objects[1]).toMatchObject({ dirty: true, props: { content: "«qty»" } });
     expect([...result.edited]).toEqual([0]);
+    expect([...result.touched]).toEqual([]);
+    expect(result.doc.pages.every((p) => p.overlay === overlay)).toBe(true);
     expect(seen.length).toBeGreaterThan(0);
     expect(seen.every((s) => s.dpmm === 8 && s.variables.includes("qty"))).toBe(true);
   });
 
+  it("measures under a variable the same batch adds, and that addition costs every capture", () => {
+    const seen: string[][] = [];
+    const input = doc();
+    input.pages[0]!.objects.push(rightBarcode("bc"));
+    const result = applyDesignOps(input, [{ op: "addVariable", variable: { name: "qty" } }, { op: "update", id: "bc", props: { content: "«qty»" } }], (_o, ctx) => {
+      seen.push(ctx.variables.map((v) => v.name));
+      return null;
+    });
+    expect(result.ok).toBe(true);
+    if (!result.ok) return;
+    expect(seen.length).toBeGreaterThan(0);
+    expect(seen.every((names) => names.includes("qty"))).toBe(true);
+    expect([...result.touched]).toEqual([0, 1]);
+  });
+
   it("renames a variable through every marker without costing the captures", () => {
     const result = applyDesignOps(doc(), [{ op: "updateVariable", name: "lot", newName: "batch", comment: "c" }], noProbe);
     expect(result.ok).toBe(true);
diff --git a/packages/core/src/lib/objectTree.ts b/packages/core/src/lib/objectTree.ts
index 2ccb63f9..a0c9d540 100644
--- a/packages/core/src/lib/objectTree.ts
+++ b/packages/core/src/lib/objectTree.ts
@@ -69,6 +69,15 @@ export function fixTlc39SlotsLeaf(leaf: UnknownNode): void {
   }
 }
 
+/** Legacy gs1databar `moduleWidth` is the ^BR magnification. */
+export function migrateGs1DatabarLeaf(leaf: UnknownNode): void {
+  if (leaf.type !== "gs1databar" || !leaf.props || typeof leaf.props !== "object") return;
+  const props = leaf.props as Record<string, unknown>;
+  if (!("moduleWidth" in props) || "magnification" in props) return;
+  props.magnification = props.moduleWidth;
+  delete props.moduleWidth;
+}
+
 /** Legacy standalone `serial` object type → `text` field with a `serial` prop. */
 export function foldSerialLeaf(leaf: UnknownNode): void {
   if (leaf.type !== "serial" || !leaf.props || typeof leaf.props !== "object") return;
diff --git a/packages/core/src/lib/zplOverlay/overlay.ts b/packages/core/src/lib/zplOverlay/overlay.ts
index b7b67914..eeb2eed5 100644
--- a/packages/core/src/lib/zplOverlay/overlay.ts
+++ b/packages/core/src/lib/zplOverlay/overlay.ts
@@ -10,8 +10,7 @@
 
 import { z } from "zod";
 
-/** Key identifying a labelConfig/printerProfile field a config command sets.
- *  Refined to a union as config linkage lands (later stage); string for now. */
+/** The labelConfig or printerProfile field a config command sets. */
 export type ConfigFieldKey = string;
 
 export type OverlaySegment =
diff --git a/src/store/labelStore.test.ts b/src/store/labelStore.test.ts
index cc6d4960..09a26815 100644
--- a/src/store/labelStore.test.ts
+++ b/src/store/labelStore.test.ts
@@ -988,6 +988,14 @@ describe('setPageStoredFormatPath', () => {
   });
 });
 
+describe('migrateLegacy: v5 gs1databar moduleWidth', () => {
+  it('becomes the magnification', () => {
+    const persisted = { pages: [{ objects: [{ id: 'g', type: 'gs1databar', x: 0, y: 0, rotation: 0, props: { moduleWidth: 4 } }] }] };
+    const migrated = migrateLegacy(persisted, 5) as { pages: { objects: { props: Record<string, unknown> }[] }[] };
+    expect(migrated.pages[0]?.objects[0]?.props).toEqual({ magnification: 4 });
+  });
+});
+
 describe('migrateLegacy: a main-era ^DF that only the overlay bytes carried', () => {
   it('lands on the page and its head, so naming the page rewrites instead of doubling', () => {
     const imported = importZplText(['^XA', '^DFE:OLD.ZPL', '^FO10,10^A0N,30,30^FDa^FS', '^XZ'].join('\n'), 8);
diff --git a/src/store/labelStore.ts b/src/store/labelStore.ts
index cb8b32a9..5abb359f 100644
--- a/src/store/labelStore.ts
+++ b/src/store/labelStore.ts
@@ -8,6 +8,7 @@ import {
   visitLeavesInPages,
   foldSerialLeaf,
   fixTlc39SlotsLeaf,
+  migrateGs1DatabarLeaf,
   bindSingleMarkerLeaf,
   safeUniqueNameById,
 } from '@zplab/core/lib/objectTree';
@@ -165,11 +166,9 @@ export function migrateLegacy(persistedState: unknown, version: number): unknown
     s = { ...s, printerProfile: {} };
   }
 
-  // v5→v6: gs1databar props.moduleWidth → props.magnification. The
-  // value was always semantically the ^BR magnification multiplier
-  // (1-10), not a dot quantity; the rename clarifies that.
+  // v5→v6: gs1databar props.moduleWidth → props.magnification.
   if (version < 6) {
-    s = { ...s, pages: migrateGs1DatabarInPages(s.pages) };
+    visitLeavesInPages(s.pages, migrateGs1DatabarLeaf);
   }
 
   // v6→v7: ^MA/^MI type codes corrected to match spec (R/C instead of
@@ -230,17 +229,6 @@ export function migrateLegacy(persistedState: unknown, version: number): unknown
     }
   }
 
-  // v15→v16: TLC39 props move to the real ^BT slots (w2/h2, wideRatio);
-  // emit and canvas read the new shape unguarded.
-  if (version < 16 && Array.isArray(s.pages)) {
-    visitLeavesInPages(s.pages, fixTlc39SlotsLeaf);
-  }
-
-  // v17→v18: the same drive pin the .zpld lane applies at schema v6.
-  if (version < 18 && Array.isArray(s.pages)) {
-    visitLeavesInPages(s.pages, pinBareFontDriveLeaf);
-  }
-
   // v9→v10: reverse text dropped its synthesized self-background ^GB for a
   // spec-true ^FR knockout. Give every legacy reverse text a real black box
   // behind it so the white-on-black look survives the model change.
@@ -353,6 +341,17 @@ export function migrateLegacy(persistedState: unknown, version: number): unknown
     }
   }
 
+  // v15→v16: TLC39 props move to the real ^BT slots (w2/h2, wideRatio);
+  // emit and canvas read the new shape unguarded.
+  if (version < 16 && Array.isArray(s.pages)) {
+    visitLeavesInPages(s.pages, fixTlc39SlotsLeaf);
+  }
+
+  // v17→v18: the same drive pin the .zpld lane applies at schema v6.
+  if (version < 18 && Array.isArray(s.pages)) {
+    visitLeavesInPages(s.pages, pinBareFontDriveLeaf);
+  }
+
   // v18→v19: the print target moves from loose browser keys into the session. Persist writes the
   // merged state back only after a migration, so the takeover has to run here and not at slice init.
   if (version < 19 && !('printTarget' in s)) {
@@ -415,21 +414,6 @@ function migrateSingleBindInPages(
   return pages;
 }
 
-function migrateGs1DatabarInPages(pages: unknown): unknown {
-  visitLeavesInPages(pages, (leaf) => {
-    if (
-      leaf.type !== 'gs1databar' ||
-      !leaf.props ||
-      typeof leaf.props !== 'object'
-    ) return;
-    const props = leaf.props as Record<string, unknown>;
-    if (!('moduleWidth' in props) || 'magnification' in props) return;
-    props.magnification = props.moduleWidth;
-    delete props.moduleWidth;
-  });
-  return pages;
-}
-
 function migrateCirclesInPages(pages: unknown): unknown {
   if (!Array.isArray(pages)) return pages;
   return pages.map((page) => {