diff --git a/packages/realm-server/handlers/handle-archive-realm.ts b/packages/realm-server/handlers/handle-archive-realm.ts
index bf278ceae8..93ee3d3cdf 100644
--- a/packages/realm-server/handlers/handle-archive-realm.ts
+++ b/packages/realm-server/handlers/handle-archive-realm.ts
@@ -1,6 +1,7 @@
 import type Koa from 'koa';
 import {
   archiveRealm,
+  cancelAllJobsInConcurrencyGroup,
   createResponse,
   logger,
   SupportedMimeType,
@@ -32,6 +33,16 @@ export default function handleArchiveRealm({
 
     try {
       await archiveRealm(dbAdapter, new URL(realmURL));
+      // Stop the realm's indexer: cancel any in-flight from-scratch /
+      // incremental-index job and drop the pending queue for this realm's
+      // concurrency group. Mirrors the realm-level cancel-jobs endpoint
+      // (Realm.handleCancelJobsRequest). `cancelAllJobsInConcurrencyGroup`
+      // marks jobs rejected and emits NOTIFY jobs_finished so peer
+      // replicas evict job-scoped search-cache rows. The unarchive flow
+      // rebuilds boxel_index from disk via the full-reindex enqueue, so
+      // any partial work left behind by an in-flight cancellation is
+      // discarded on restore.
+      await cancelAllJobsInConcurrencyGroup(dbAdapter, `indexing:${realmURL}`);
 
       let response = createResponse({
         body: JSON.stringify(
diff --git a/packages/realm-server/lib/full-reindex-realm-urls.ts b/packages/realm-server/lib/full-reindex-realm-urls.ts
index 91c00dc885..c9e0f96a2b 100644
--- a/packages/realm-server/lib/full-reindex-realm-urls.ts
+++ b/packages/realm-server/lib/full-reindex-realm-urls.ts
@@ -5,9 +5,16 @@ type RealmRegistryRow = {
   url: string;
 };
 
+// The system-wide full-reindex source list. Archived realms are sealed and
+// their contents can't drift while archived, so the sweep skips them — a
+// realm rejoins this list when unarchive clears archived_at, and the
+// unarchive handler separately enqueues the one-time reindex that brings
+// boxel_index back up to date.
 export async function getFullReindexRealmUrls(dbAdapter: DBAdapter) {
   let rows = (await query(dbAdapter, [
-    `SELECT url FROM realm_registry ORDER BY url`,
+    `SELECT url FROM realm_registry
+     WHERE url NOT IN (SELECT url FROM realm_metadata WHERE archived_at IS NOT NULL)
+     ORDER BY url`,
   ])) as RealmRegistryRow[];
 
   return rows.map(({ url }) => url);
diff --git a/packages/realm-server/tests/full-reindex-test.ts b/packages/realm-server/tests/full-reindex-test.ts
index 7fb7db6cb1..41770a2ca4 100644
--- a/packages/realm-server/tests/full-reindex-test.ts
+++ b/packages/realm-server/tests/full-reindex-test.ts
@@ -10,13 +10,19 @@ import type {
   VirtualNetwork,
 } from '@cardstack/runtime-common';
 import {
+  archiveRealm,
   fullReindex,
   insertPermissions,
   logger,
+  unarchiveRealm,
   uuidv4,
 } from '@cardstack/runtime-common';
 
-import { upsertPublishedRealmInRegistry } from '../lib/realm-registry-writes.ts';
+import { getFullReindexRealmUrls } from '../lib/full-reindex-realm-urls.ts';
+import {
+  insertSourceRealmInRegistry,
+  upsertPublishedRealmInRegistry,
+} from '../lib/realm-registry-writes.ts';
 import { setupDB } from './helpers/index.ts';
 
 module(basename(import.meta.filename), function (hooks) {
@@ -174,4 +180,49 @@ module(basename(import.meta.filename), function (hooks) {
       'no jobs are enqueued for bot-owned realms',
     );
   });
+
+  module('getFullReindexRealmUrls', function () {
+    async function seedSourceRealm(realmURL: string) {
+      await insertSourceRealmInRegistry(dbAdapter, {
+        url: realmURL,
+        diskId: uuidv4(),
+        ownerUsername: '@owner:localhost',
+      });
+    }
+
+    test('returns only active realms from realm_registry', async function (assert) {
+      const activeA = 'http://example.com/active-a/';
+      const activeB = 'http://example.com/active-b/';
+      const archived = 'http://example.com/archived/';
+
+      await seedSourceRealm(activeA);
+      await seedSourceRealm(activeB);
+      await seedSourceRealm(archived);
+      await archiveRealm(dbAdapter, new URL(archived));
+
+      let urls = await getFullReindexRealmUrls(dbAdapter);
+      assert.deepEqual(
+        [...urls].sort(),
+        [activeA, activeB].sort(),
+        'archived realms are excluded from the sweep source',
+      );
+    });
+
+    test('an unarchived realm returns to the sweep source', async function (assert) {
+      const realmURL = 'http://example.com/restored/';
+
+      await seedSourceRealm(realmURL);
+      await archiveRealm(dbAdapter, new URL(realmURL));
+      assert.notOk(
+        (await getFullReindexRealmUrls(dbAdapter)).includes(realmURL),
+        'archived realm is absent',
+      );
+
+      await unarchiveRealm(dbAdapter, new URL(realmURL));
+      assert.ok(
+        (await getFullReindexRealmUrls(dbAdapter)).includes(realmURL),
+        'unarchived realm reappears',
+      );
+    });
+  });
 });
diff --git a/packages/realm-server/tests/server-endpoints/archive-realm-test.ts b/packages/realm-server/tests/server-endpoints/archive-realm-test.ts
index bbd917819c..5ed25bc71e 100644
--- a/packages/realm-server/tests/server-endpoints/archive-realm-test.ts
+++ b/packages/realm-server/tests/server-endpoints/archive-realm-test.ts
@@ -4,10 +4,12 @@ import { basename } from 'path';
 import { v4 as uuidv4 } from 'uuid';
 import {
   archiveRealm,
+  FROM_SCRATCH_JOB_TIMEOUT_SEC,
   insertPermissions,
   isRealmArchived,
   param,
   query,
+  systemInitiatedPriority,
   type RealmPermissions,
 } from '@cardstack/runtime-common';
 import { realmSecretSeed } from '../helpers/index.ts';
@@ -122,6 +124,44 @@ module(`server-endpoints/${basename(import.meta.filename)}`, function () {
       );
     });
 
+    test('POST /_archive-realm cancels pending indexing jobs for the realm', async function (assert) {
+      const owner = '@archive-owner:localhost';
+      const realmURL = makeRealmURL();
+      await seedSourceRealm(realmURL, {
+        [owner]: ['read', 'write', 'realm-owner'],
+      });
+
+      let pending = await context.publisher.publish<void>({
+        jobType: 'from-scratch-index',
+        concurrencyGroup: `indexing:${realmURL}`,
+        timeout: FROM_SCRATCH_JOB_TIMEOUT_SEC,
+        priority: systemInitiatedPriority,
+        args: {
+          realmURL,
+          realmUsername: 'archive-owner',
+          clearLastModified: false,
+        },
+      });
+
+      let response = await context.request
+        .post('/_archive-realm')
+        .set('Accept', 'application/vnd.api+json')
+        .set('Content-Type', 'application/json')
+        .set('Authorization', authHeader(owner))
+        .send(JSON.stringify({ data: { type: 'realm', id: realmURL } }));
+      assert.strictEqual(response.status, 200, 'HTTP 200 status');
+
+      let rows = (await context.dbAdapter.execute(
+        `SELECT status FROM jobs WHERE id = $1`,
+        { bind: [pending.id] },
+      )) as { status: string }[];
+      assert.strictEqual(
+        rows[0]?.status,
+        'rejected',
+        'the pending indexing job is marked rejected',
+      );
+    });
+
     test('POST /_archive-realm returns 403 for a non-owner', async function (assert) {
       const owner = '@archive-owner:localhost';
       const intruder = '@intruder:localhost';