chore(boot): sweep orphan migration flags from localStorage

Two one-shot bootstraps left a per-user flag in localStorage so they
wouldn't run twice — and after F7 deleted the helpers themselves
(2a8e8ff98), the flags pointed at code that no longer existed:

  mana.profile.silentTwinRepair.<userId>
  mana.profile.avatarMigration.<userId>

New \`cleanupOrphanMigrationFlags()\` runs once per page load from the
(app) layout's onMount, right after \`restoreClientIdFromDexie()\`.
Cheap (single localStorage scan), idempotent (no-op once swept),
silent on private-mode / quota errors. The known-orphan prefix list
lives in the helper file with deletion-commit refs so it's clear
when each entry can be retired.

Future migration deletions: append the prefix to ORPHAN_KEY_PREFIXES
in the same commit that drops the helper, and the next page load
on every device cleans up.

Closes Punkt 8 of the F1-F7 follow-up audit.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/mana/apps/web/src/lib/data/migrations-cleanup.ts

@@ -0,0 +1,66 @@
+/**
+ * One-shot cleanup of orphan localStorage keys left behind by deleted
+ * migration helpers.
+ *
+ * When a one-shot bootstrap (e.g. `repairSilentTwinAvatarRows`) finishes
+ * the first time, it sets a per-user `mana.profile.<name>.<uid>` flag in
+ * localStorage so it doesn't run again. After the helper itself is
+ * deleted (F7 of docs/plans/sync-field-meta-overhaul.md), the flag stays
+ * behind forever — a small chunk of dead state that piles up if more
+ * helpers come and go.
+ *
+ * This module sweeps the known orphan prefixes and removes any matching
+ * key on every page load. Cheap (a single localStorage scan, capped by
+ * the browser's quota) and idempotent — calling it twice is a no-op
+ * the second time because the keys are already gone.
+ *
+ * Add a new prefix here whenever a migration helper is deleted in a
+ * future commit, then remove the prefix again once enough time has
+ * passed that no live device still carries the orphan flag.
+ */
+
+/**
+ * Known dead localStorage prefixes. Keep in chronological order with a
+ * comment naming the deletion commit so it's clear when the entry can
+ * be removed once enough time has passed.
+ */
+const ORPHAN_KEY_PREFIXES: readonly string[] = [
+	// F7: `repair-silent-twin.ts` deleted in 2a8e8ff98 (sync field-meta
+	// overhaul). The helper guarded itself with this flag so it'd only
+	// run once per user; the flag now points at code that no longer
+	// exists.
+	'mana.profile.silentTwinRepair.',
+	// F7: `legacy-avatar.ts` deleted in the same commit, same flag
+	// pattern, same orphan situation.
+	'mana.profile.avatarMigration.',
+];
+
+/**
+ * Remove every localStorage key matching one of {@link ORPHAN_KEY_PREFIXES}.
+ *
+ * Best-effort: failures (private mode, quota errors, locked storage on
+ * some browsers) are swallowed silently — orphan flags are cosmetic, not
+ * load-bearing.
+ */
+export function cleanupOrphanMigrationFlags(): void {
+	if (typeof localStorage === 'undefined') return;
+	const toRemove: string[] = [];
+	try {
+		for (let i = 0; i < localStorage.length; i++) {
+			const key = localStorage.key(i);
+			if (!key) continue;
+			if (ORPHAN_KEY_PREFIXES.some((prefix) => key.startsWith(prefix))) {
+				toRemove.push(key);
+			}
+		}
+	} catch {
+		return;
+	}
+	for (const key of toRemove) {
+		try {
+			localStorage.removeItem(key);
+		} catch {
+			// Storage locked / private mode — next reload retries.
+		}
+	}
+}

apps/mana/apps/web/src/routes/(app)/+layout.svelte

@@ -70,6 +70,7 @@
 		stopMemoroLlmWatcher,
 	} from '$lib/modules/memoro/llm-watcher.svelte';
 	import { createUnifiedSync, restoreClientIdFromDexie } from '$lib/data/sync';
+	import { cleanupOrphanMigrationFlags } from '$lib/data/migrations-cleanup';
 	import { syncBilling } from '$lib/stores/sync-billing.svelte';
 	import { networkStore } from '$lib/stores/network.svelte';
 	import { db } from '$lib/data/database';
@@ -632,6 +633,9 @@
 			// so the next push/pull keeps the same identity the server
 			// already knows.
 			await restoreClientIdFromDexie();
+			// Sweep stale localStorage flags from migration helpers that
+			// have since been deleted (F7 + future cleanups).
+			cleanupOrphanMigrationFlags();
 			const getToken = () => authStore.getValidToken();
 			unifiedSync = createUnifiedSync(SYNC_SERVER_URL, getToken, syncBilling.active);
 			// Expose on window for SYNC_DEBUG.md (Schritt C). Not a security