diff --git a/.crow/weekly-rebuild-reindex.yaml b/.crow/weekly-rebuild-reindex.yaml
index a67875d..bb00332 100644
--- a/.crow/weekly-rebuild-reindex.yaml
+++ b/.crow/weekly-rebuild-reindex.yaml
@@ -173,13 +173,13 @@ steps:
       OTEL_R_METRICS_EXPORTER: none
       BUNNYNET_API_KEY:
         from_secret: BUNNYNET_API_KEY
-      # All hostnames on the zone share this id, so one purge covers
-      # cran.devxy.io, cran.allianceswisspass.devxy.io and cran.rpkgs.com.
-      BUNNY_PULLZONE: '3857050'
+      # cran.rpkgs.com and cran.allianceswisspass.devxy.io are on separate
+      # Bunny pull zones, so both must be purged after the shared origin changes.
+      BUNNY_PULLZONES: '3857050 3265648'
     commands:
       - apk add --no-cache -q bash curl
       # Crow carries the checkout from the re-index step into this step.
-      - bash scripts/purge_cdn_zone.sh "$BUNNYNET_API_KEY" "$BUNNY_PULLZONE"
+      - bash scripts/purge_cdn_zone.sh "$BUNNYNET_API_KEY" $BUNNY_PULLZONES
     # Runs on every row rather than on one designated slot: a cron fires only
     # its own slot's row, so gating on a named slot would leave every other
     # slot unpurged. A manual "all" run therefore purges the zone 18 times,
diff --git a/cdn.tf b/cdn.tf
index 5e8899d..01191a5 100644
--- a/cdn.tf
+++ b/cdn.tf
@@ -32,7 +32,7 @@
 #   cache_stale           = ["offline", "updating"]
 #   use_background_update = true
 
-  # block_ips = var.cdn_block_ips
+# block_ips = var.cdn_block_ips
 
 #   # 50 TB
 #   limit_bandwidth = 50000000000000
@@ -82,7 +82,7 @@ resource "bunnynet_pullzone" "cran_rpkgs_com" {
 
   cache_expiration_time = 31919000
   websockets_enabled    = false
-  errorpage_whitelabel = true
+  errorpage_whitelabel  = true
 
   origin {
     type              = "OriginUrl"
@@ -147,6 +147,58 @@ resource "bunnynet_pullzone_hostname" "cran_rpkgs_com" {
   tls_enabled = true
 }
 
+# Alliance SwissPass historically used a separate, manually configured pull
+# zone. Adopt it so both public repositories use the same B2 origin, middleware
+# release and cache behavior.
+import {
+  to = bunnynet_pullzone.cran_allianceswisspass
+  id = "3265648"
+}
+
+resource "bunnynet_pullzone" "cran_allianceswisspass" {
+  name = "cran-allianceswisspass"
+
+  cache_errors          = false
+  cache_expiration_time = 31919000
+  websockets_enabled    = false
+  errorpage_whitelabel  = true
+
+  origin {
+    type              = "OriginUrl"
+    url               = "https://devxy-rpkgs-binaries.s3.eu-central-003.backblazeb2.com"
+    middleware_script = bunnynet_compute_script.rpkgs_router.id
+  }
+
+  routing {
+    filters = [
+      "scripting",
+    ]
+  }
+
+  s3_auth_enabled = true
+  s3_auth_key     = var.B2_S3_ACCESS_KEY
+  s3_auth_secret  = var.B2_S3_SECRET_KEY
+  s3_auth_region  = "eu-central-003"
+
+  cache_enabled              = true
+  request_coalescing_enabled = true
+  block_post_requests        = true
+  cache_vary_headers         = ["User-Agent"]
+
+  limit_requests    = 5000
+  limit_connections = 1000
+
+  safehop_enabled      = true
+  add_canonical_header = true
+  cache_stale          = ["offline", "updating"]
+  block_ips            = var.cdn_block_ips
+
+  # 50 TB
+  limit_bandwidth = 50000000000000
+
+  block_root_path = true
+}
+
 # resource "bunnynet_storage_zone" "devxy-r-binaries" {
 #   name      = "devxy-r-binaries-storage"
 #   region    = "DE"
diff --git a/edge/rpkgs-router.test.ts b/edge/rpkgs-router.test.ts
index 553185d..9493f8a 100644
--- a/edge/rpkgs-router.test.ts
+++ b/edge/rpkgs-router.test.ts
@@ -117,6 +117,13 @@ Deno.test('rpkgs-router', async (t) => {
       assertEquals(res.status, 200);
     });
 
+    await t.step('serves an archived binary when it exists', async () => {
+      const path = `${SLOT}/Archive/xml2/xml2_1.5.2.tar.gz`;
+      const res = await probe(path, UA_R45_MUSL);
+      assertEquals(res.status, 200);
+      assertEquals(res.location, null);
+    });
+
     await t.step('does not redirect a path already under a minor', async () => {
       const res = await probe(`${SLOT}/4.5/PACKAGES.gz`, UA_R45_MUSL);
       assertEquals(res.location, null);
diff --git a/edge/rpkgs-router.ts b/edge/rpkgs-router.ts
index 9cd410b..9278d4a 100644
--- a/edge/rpkgs-router.ts
+++ b/edge/rpkgs-router.ts
@@ -27,6 +27,7 @@ import * as BunnySDK from 'https://esm.sh/@bunny.net/edgescript-sdk@0.12';
 
 const PUBLIC_CDN_ORIGIN = 'https://cran.rpkgs.com';
 const CRAN_ORIGIN = 'https://cran.r-project.org';
+const PUBLIC_CDN_HOSTS = new Set(['cran.rpkgs.com', 'cran.allianceswisspass.devxy.io']);
 
 /** Slots ("<arch>/<os>", comma separated) whose per-minor index is a union. */
 const UNION_SLOTS = new Set(
@@ -47,6 +48,10 @@ const INDEX_FILE_REGEX = /^PACKAGES(\.gz|\.rds)?$/;
 
 const SRC_CONTRIB_REGEX = /^\/src\/contrib\/(.+)$/;
 
+/** A binary archive URL whose upstream source counterpart CRAN can serve. */
+const ARCHIVE_TARBALL_REGEX =
+  /^\/(?:amd64|arm64)\/[a-z0-9._-]+\/latest\/src\/contrib\/Archive\/([^/]+)\/([^/]+\.tar\.gz)$/;
+
 const MACOS_BIN_REGEX =
   /^\/bin\/macosx\/(big-sur-arm64|big-sur-x86_64|monterey-arm64|monterey-x86_64)\/contrib\/([0-9.]+)\/(.+)$/;
 
@@ -85,6 +90,10 @@ function redirectTo(location: string, status = 302): Response {
   });
 }
 
+function publicCdnOrigin(url: URL): string {
+  return PUBLIC_CDN_HOSTS.has(url.hostname) ? url.origin : PUBLIC_CDN_ORIGIN;
+}
+
 function extractRMinor(userAgent: string): string | null {
   for (const regex of R_MINOR_REGEXES) {
     const match = userAgent.match(regex);
@@ -181,15 +190,14 @@ BunnySDK.net.http
     const url = new URL(ctx.request.url);
     const path = normalizePathname(url.pathname);
     const userAgent = ctx.request.headers.get('User-Agent') || '';
+    const publicOrigin = publicCdnOrigin(url);
 
     // macOS clients are served from CRAN's own binary tree.
     const srcContrib = path.match(SRC_CONTRIB_REGEX);
     if (srcContrib && /darwin/.test(userAgent)) {
       const mac = parseMacUserAgent(userAgent);
       if (mac) {
-        return Promise.resolve(
-          redirectTo(`${PUBLIC_CDN_ORIGIN}/bin/macosx/${mac.os}/contrib/${mac.rver}/${srcContrib[1]}`),
-        );
+        return Promise.resolve(redirectTo(`${publicOrigin}/bin/macosx/${mac.os}/contrib/${mac.rver}/${srcContrib[1]}`));
       }
     }
 
@@ -213,7 +221,7 @@ BunnySDK.net.http
       if (target === path) {
         return Promise.resolve(ctx.request);
       }
-      return Promise.resolve(redirectTo(`${PUBLIC_CDN_ORIGIN}${target}`));
+      return Promise.resolve(redirectTo(`${publicOrigin}${target}`));
     }
 
     // The bare `https://cran.rpkgs.com` form, resolved from the User-Agent.
@@ -224,12 +232,27 @@ BunnySDK.net.http
       }
 
       const rest = srcContrib ? srcContrib[1] : '';
-      return Promise.resolve(redirectTo(`${PUBLIC_CDN_ORIGIN}${contribPath(slot, rest, userAgent)}`));
+      return Promise.resolve(redirectTo(`${publicOrigin}${contribPath(slot, rest, userAgent)}`));
     }
 
     return Promise.resolve(ctx.request);
   })
-  .onOriginResponse((ctx) => {
+  .onOriginResponse(async (ctx) => {
+    const path = normalizePathname(new URL(ctx.request.url).pathname);
+    const archive = path.match(ARCHIVE_TARBALL_REGEX);
+
+    // Binary archives can be incomplete when an older build never succeeded.
+    // Preserve renv/remotes version restores by falling back to CRAN's source
+    // package only for an absent archived tarball. A requested version can be
+    // either archived upstream or still current, so probe the archive first.
+    // Other 404s remain visible.
+    if (ctx.response.status === 404 && archive) {
+      const archiveUrl = `${CRAN_ORIGIN}/src/contrib/Archive/${archive[1]}/${archive[2]}`;
+      const archiveResponse = await fetch(archiveUrl, { method: 'HEAD' });
+      const sourceUrl = archiveResponse.ok ? archiveUrl : `${CRAN_ORIGIN}/src/contrib/${archive[2]}`;
+      return redirectTo(sourceUrl);
+    }
+
     ctx.response.headers.append('X-Via', 'MyMiddleware');
     return Promise.resolve(ctx.response);
   });
diff --git a/scripts/purge_cdn_zone.sh b/scripts/purge_cdn_zone.sh
index 391a814..4853245 100755
--- a/scripts/purge_cdn_zone.sh
+++ b/scripts/purge_cdn_zone.sh
@@ -18,35 +18,38 @@
 # objects were replaced. The cost is a cold cache for everything else, which is
 # why this is not used by the daily update path.
 #
-# All hostnames on the zone (cran.devxy.io, cran.allianceswisspass.devxy.io,
-# cran.rpkgs.com) share pull zone 3857050, so one purge covers all of them.
+# The public hostnames currently use separate pull zones, so callers must pass
+# every zone that serves the repository.
 #
 # Usage:
-#   purge_cdn_zone.sh <BUNNYNET_API_KEY> <pull_zone_id>
+#   purge_cdn_zone.sh <BUNNYNET_API_KEY> <pull_zone_id> [<pull_zone_id>...]
 #
 set -euo pipefail
 
 if (($# < 2)); then
-  echo "usage: $0 <api_key> <pull_zone_id>" >&2
+  echo "usage: $0 <api_key> <pull_zone_id> [<pull_zone_id>...]" >&2
   exit 2
 fi
 
 api_key="$1"
-zone_id="$2"
+shift
 
-echo "Purging BunnyCDN pull zone ${zone_id}"
+for zone_id in "$@"; do
+  echo "Purging BunnyCDN pull zone ${zone_id}"
 
-status=$(
-  curl -sS -o /tmp/purge_zone_response.txt -w '%{http_code}' -X POST \
-    -H "AccessKey: ${api_key}" \
-    -H "Content-Length: 0" \
-    "https://api.bunny.net/pullzone/${zone_id}/purgeCache"
-)
+  response_file="/tmp/purge_zone_response_${zone_id}.txt"
+  status=$(
+    curl -sS -o "${response_file}" -w '%{http_code}' -X POST \
+      -H "AccessKey: ${api_key}" \
+      -H "Content-Length: 0" \
+      "https://api.bunny.net/pullzone/${zone_id}/purgeCache"
+  )
 
-if [[ "${status}" != "200" && "${status}" != "204" ]]; then
-  echo "Purge of pull zone ${zone_id} failed with HTTP ${status}:" >&2
-  cat /tmp/purge_zone_response.txt >&2
-  exit 1
-fi
+  if [[ "${status}" != "200" && "${status}" != "204" ]]; then
+    echo "Purge of pull zone ${zone_id} failed with HTTP ${status}:" >&2
+    cat "${response_file}" >&2
+    exit 1
+  fi
 
-echo "Purged pull zone ${zone_id} (HTTP ${status})"
+  echo "Purged pull zone ${zone_id} (HTTP ${status})"
+done