diff --git a/src/features/store-admin/StoreOpenControl.tsx b/src/features/store-admin/StoreOpenControl.tsx
index 2d919ea..42a6d07 100644
--- a/src/features/store-admin/StoreOpenControl.tsx
+++ b/src/features/store-admin/StoreOpenControl.tsx
@@ -1,4 +1,4 @@
-import { useEffect, useState } from 'react';
+import { useEffect, useRef, useState } from 'react';
 import { useMutation, useQueryClient } from '@tanstack/react-query';
 import { Switch } from '@astryxdesign/core/Switch';
 import { Button } from '@astryxdesign/core/Button';
@@ -56,17 +56,35 @@ export function StoreOpenControl({
   const [until, setUntil] = useState('');
   const [error, setError] = useState<string | null>(null);
 
-  // Re-seed if the page refetches with a different answer, but never while the
-  // confirmation is up — that would move the switch under the shopkeeper's hand.
+  /*
+    Re-seed only when the PROP ITSELF changes.
+
+    This used to run whenever `confirming` flipped, and that undid its own
+    save: closing the branch set open to false and confirming to false, the
+    change of `confirming` re-ran the effect, and it wrote the prop — still
+    true, because the page behind had not refetched yet — straight back over
+    the answer. The switch snapped open the instant the shop was closed.
+
+    Comparing against the last value seen means a genuinely new answer from the
+    server still lands, and nothing else can reach in and overwrite what the
+    shopkeeper just did.
+  */
+  const lastSeen = useRef(isOpen);
   useEffect(() => {
-    if (!confirming) setOpen(isOpen);
-  }, [isOpen, confirming]);
+    if (lastSeen.current !== isOpen) {
+      lastSeen.current = isOpen;
+      setOpen(isOpen);
+    }
+  }, [isOpen]);
 
   const save = useMutation({
     mutationFn: (next: { isopen: boolean; closeduntil?: string }) =>
       tenantsApi.setStoreOpen({ tenantid, locationid, ...next }),
     onMutate: () => setError(null),
     onSuccess: (_data, next) => {
+      // Move the reference too. Otherwise the next render carrying the old
+      // prop reads as a change and reverts what was just saved.
+      lastSeen.current = next.isopen;
       setOpen(next.isopen);
       setConfirming(false);
       setUntil('');
@@ -75,6 +93,7 @@ export function StoreOpenControl({
     // A close that fails silently is the worst outcome here: the shopkeeper
     // walks away believing the shop is shut while it keeps taking orders.
     onError: (cause) => {
+      lastSeen.current = isOpen;
       setOpen(isOpen);
       setError(errorMessage(cause));
     },
diff --git a/src/features/store-admin/storeOpenControl.test.ts b/src/features/store-admin/storeOpenControl.test.ts
new file mode 100644
index 0000000..6b7de8f
--- /dev/null
+++ b/src/features/store-admin/storeOpenControl.test.ts
@@ -0,0 +1,82 @@
+/**
+ * The switch must not undo its own save.
+ *
+ * It shipped doing exactly that. Closing a branch set the local flag false and
+ * dismissed the confirmation, the change of `confirming` re-ran the seeding
+ * effect, and the effect wrote the prop — still `true`, because the page behind
+ * had not refetched — back over the answer. The shop closed and the switch
+ * snapped open, with nothing on screen to say the save had worked.
+ *
+ * A source-text guard rather than a render test: the defect was entirely in
+ * which values the effect watched, which is readable without a DOM, and this
+ * fails the moment somebody puts `confirming` back in the list.
+ */
+
+import { strict as assert } from 'node:assert';
+import { readFileSync } from 'node:fs';
+import { join } from 'node:path';
+import { describe, it } from 'node:test';
+
+const SOURCE = readFileSync(
+  join(process.cwd(), 'src/features/store-admin/StoreOpenControl.tsx'),
+  'utf8',
+);
+
+/** The dependency list of each useEffect in the file. */
+function effectDeps(source: string): string[] {
+  return [...source.matchAll(/useEffect\([\s\S]*?\}, \[([^\]]*)\]\)/g)].map((m) =>
+    (m[1] ?? '').trim(),
+  );
+}
+
+describe('StoreOpenControl seeding effect', () => {
+  it('does not re-run when the confirmation dialog opens or closes', () => {
+    for (const deps of effectDeps(SOURCE)) {
+      assert.ok(
+        !/\bconfirming\b/.test(deps),
+        `an effect watches "confirming" (deps: [${deps}]). Dismissing the ` +
+          'confirmation then re-seeds from the prop, which still holds the old ' +
+          'value, and the save is undone on screen.',
+      );
+    }
+  });
+
+  it('seeds from the prop only when the prop itself has changed', () => {
+    // A bare `setOpen(isOpen)` in an effect overwrites local state on every
+    // render that touches the dependencies. The guard is the comparison.
+    assert.match(
+      SOURCE,
+      /lastSeen\.current !== isOpen/,
+      'the seeding effect no longer compares against the last value seen, so ' +
+        'it can overwrite a save that has not reached the prop yet',
+    );
+  });
+
+  it('moves the reference when a save succeeds', () => {
+    // Without this the next render carrying the old prop reads as a change,
+    // and reverts what was just written.
+    assert.match(
+      SOURCE,
+      /onSuccess:[\s\S]{0,400}lastSeen\.current = next\.isopen/,
+      'onSuccess does not update lastSeen, so a stale prop will look like a ' +
+        'new answer and revert the switch',
+    );
+  });
+
+  it('surfaces a failed save', () => {
+    // A close that fails silently is the worst outcome: the shopkeeper walks
+    // away believing the shop is shut while it keeps taking orders.
+    assert.match(SOURCE, /onError:/, 'the mutation has no onError');
+    assert.match(SOURCE, /setError\(errorMessage\(cause\)\)/, 'the error is never shown');
+  });
+
+  it('asks before closing, and does not ask before reopening', () => {
+    // Closing stops the shop taking money; reopening is harmless.
+    assert.match(
+      SOURCE,
+      /save\.mutate\(\{ isopen: true \}\)/,
+      'reopening should happen on the tap, not behind a confirmation',
+    );
+    assert.match(SOURCE, /setConfirming\(true\)/, 'closing should ask first');
+  });
+});