diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 2de7121..cc86f4e 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -9,6 +9,7 @@ on:
 
 permissions:
   contents: read
+  actions: read
   security-events: read
   pull-requests: read
 
@@ -358,66 +359,10 @@ jobs:
           dotnet-version: |
             8.0.x
             10.0.102
-      - name: Download CI Artifacts
-        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4
-        with:
-          name: ci-preflight
-          path: artifacts/ci/preflight
-      - name: Download Build Artifact
-        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4
-        with:
-          name: ci-build
-          path: artifacts/ci/build
-      - name: Download API Contract Artifact
-        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4
-        with:
-          name: ci-api-contract
-          path: artifacts/ci/api-contract
-      - name: Download Pack Artifact
-        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4
-        with:
-          name: ci-pack
-          path: artifacts/ci/pack
-      - name: Download Consumer Smoke Artifact
-        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4
-        with:
-          name: ci-consumer-smoke
-          path: artifacts/ci/consumer-smoke
-      - name: Download Package-Backed Artifact
-        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4
-        with:
-          name: ci-package-backed-tests
-          path: artifacts/ci/package-backed-tests
-      - name: Download Security Artifact
-        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4
-        with:
-          name: ci-security-nuget
-          path: artifacts/ci/security-nuget
-      - name: Download Docs Link Artifact
-        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4
-        with:
-          name: ci-docs-links-full
-          path: artifacts/ci/docs-links-full
-      - name: Download Naming Artifact
-        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4
-        with:
-          name: ci-naming-snt
-          path: artifacts/ci/naming-snt
-      - name: Download Versioning Artifact
-        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4
-        with:
-          name: ci-versioning-svt
-          path: artifacts/ci/versioning-svt
-      - name: Download Version Convergence Artifact
-        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4
-        with:
-          name: ci-version-convergence
-          path: artifacts/ci/version-convergence
-      - name: Download Test Artifact
-        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4
-        with:
-          name: ci-tests-bdd-coverage
-          path: artifacts/ci/tests-bdd-coverage
+      - name: Download Required Artifacts (retry/backoff)
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: bash tools/ci/bin/download_summary_artifacts.sh "${GITHUB_RUN_ID}"
       - name: Run Entry Check
         run: bash -euo pipefail tools/ci/bin/run.sh summary
       - name: Upload Artifact
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index ef315a1..35e688b 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -223,7 +223,7 @@ jobs:
         with:
           name: nuget-attestation-verify
           path: artifacts/nuget/attestation-verify.txt
-          if-no-files-found: error
+          if-no-files-found: warn
 
       - name: Gate 4 - SVT post-publish (git version == package version == nuget version)
         shell: bash
diff --git a/tools/ci/bin/download_artifacts_with_retry.sh b/tools/ci/bin/download_artifacts_with_retry.sh
new file mode 100755
index 0000000..8a29e65
--- /dev/null
+++ b/tools/ci/bin/download_artifacts_with_retry.sh
@@ -0,0 +1,92 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+usage() {
+  cat <<'EOF' >&2
+Usage: download_artifacts_with_retry.sh <run_id> <artifact=dest> [<artifact=dest>...]
+
+Environment:
+  GITHUB_REPOSITORY                 Required (owner/repo).
+  ARTIFACT_DOWNLOAD_MAX_ATTEMPTS    Optional, default: 6
+  ARTIFACT_DOWNLOAD_INITIAL_DELAY   Optional, default: 2 (seconds)
+EOF
+}
+
+if [[ $# -lt 2 ]]; then
+  usage
+  exit 2
+fi
+
+if ! command -v gh >/dev/null 2>&1; then
+  echo "ERROR: gh CLI is required." >&2
+  exit 1
+fi
+
+run_id="$1"
+shift
+
+repo="${GITHUB_REPOSITORY:-}"
+if [[ -z "${repo}" ]]; then
+  echo "ERROR: GITHUB_REPOSITORY is required." >&2
+  exit 1
+fi
+
+max_attempts="${ARTIFACT_DOWNLOAD_MAX_ATTEMPTS:-6}"
+initial_delay="${ARTIFACT_DOWNLOAD_INITIAL_DELAY:-2}"
+
+if [[ ! "${max_attempts}" =~ ^[0-9]+$ || "${max_attempts}" -lt 1 ]]; then
+  echo "ERROR: ARTIFACT_DOWNLOAD_MAX_ATTEMPTS must be >= 1." >&2
+  exit 1
+fi
+if [[ ! "${initial_delay}" =~ ^[0-9]+$ || "${initial_delay}" -lt 1 ]]; then
+  echo "ERROR: ARTIFACT_DOWNLOAD_INITIAL_DELAY must be >= 1." >&2
+  exit 1
+fi
+
+download_one() {
+  local name="$1"
+  local dest="$2"
+  local attempt=1
+  local delay="${initial_delay}"
+
+  while (( attempt <= max_attempts )); do
+    echo "INFO: Download '${name}' attempt ${attempt}/${max_attempts} -> ${dest}"
+    rm -rf "${dest}"
+    mkdir -p "${dest}"
+
+    if gh run download "${run_id}" --repo "${repo}" -n "${name}" -D "${dest}" >/tmp/artifact-download.log 2>&1; then
+      return 0
+    fi
+
+    if (( attempt == max_attempts )); then
+      echo "ERROR: Download '${name}' failed after ${max_attempts} attempts." >&2
+      cat /tmp/artifact-download.log >&2 || true
+      return 1
+    fi
+
+    echo "WARN: Download '${name}' failed. Retrying in ${delay}s." >&2
+    cat /tmp/artifact-download.log >&2 || true
+    sleep "${delay}"
+    delay=$((delay * 2))
+    attempt=$((attempt + 1))
+  done
+
+  return 1
+}
+
+for spec in "$@"; do
+  if [[ "${spec}" != *=* ]]; then
+    echo "ERROR: Invalid artifact mapping '${spec}'. Expected <artifact=dest>." >&2
+    exit 1
+  fi
+  name="${spec%%=*}"
+  dest="${spec#*=}"
+  if [[ -z "${name}" || -z "${dest}" ]]; then
+    echo "ERROR: Invalid artifact mapping '${spec}'. Expected non-empty name and destination." >&2
+    exit 1
+  fi
+
+  download_one "${name}" "${dest}"
+done
+
+echo "OK: all artifacts downloaded with retry policy."
diff --git a/tools/ci/bin/download_summary_artifacts.sh b/tools/ci/bin/download_summary_artifacts.sh
new file mode 100755
index 0000000..5ac1107
--- /dev/null
+++ b/tools/ci/bin/download_summary_artifacts.sh
@@ -0,0 +1,25 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+SCRIPT_DIR="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
+
+if [[ "$#" -ne 1 ]]; then
+  echo "Usage: $0 <run_id>" >&2
+  exit 2
+fi
+
+run_id="$1"
+
+bash "${SCRIPT_DIR}/download_artifacts_with_retry.sh" "${run_id}" \
+  "ci-preflight=artifacts/ci/preflight" \
+  "ci-build=artifacts/ci/build" \
+  "ci-api-contract=artifacts/ci/api-contract" \
+  "ci-pack=artifacts/ci/pack" \
+  "ci-consumer-smoke=artifacts/ci/consumer-smoke" \
+  "ci-package-backed-tests=artifacts/ci/package-backed-tests" \
+  "ci-security-nuget=artifacts/ci/security-nuget" \
+  "ci-docs-links-full=artifacts/ci/docs-links-full" \
+  "ci-naming-snt=artifacts/ci/naming-snt" \
+  "ci-versioning-svt=artifacts/ci/versioning-svt" \
+  "ci-version-convergence=artifacts/ci/version-convergence" \
+  "ci-tests-bdd-coverage=artifacts/ci/tests-bdd-coverage"
diff --git a/tools/ci/release/gate4_verify_postpublish.sh b/tools/ci/release/gate4_verify_postpublish.sh
index 53410a3..3c908f4 100755
--- a/tools/ci/release/gate4_verify_postpublish.sh
+++ b/tools/ci/release/gate4_verify_postpublish.sh
@@ -33,11 +33,21 @@ retry_sleep_seconds="${SVT_POSTPUBLISH_RETRY_SLEEP_SECONDS:-10}"
 if [[ -n "${SVT_POSTPUBLISH_REQUIRE_REGISTRATION:-}" ]]; then
   require_registration="${SVT_POSTPUBLISH_REQUIRE_REGISTRATION}"
 else
-  if [[ "${is_prerelease}" == "1" ]]; then
-    require_registration="0"
-  else
-    require_registration="1"
-  fi
+  # Registration endpoint is typically the slowest to converge and caused repeated
+  # false negatives. Gate 4 now validates publish availability via V2 download.
+  require_registration="0"
+fi
+
+if [[ -n "${SVT_POSTPUBLISH_REQUIRE_FLATCONTAINER:-}" ]]; then
+  require_flatcontainer="${SVT_POSTPUBLISH_REQUIRE_FLATCONTAINER}"
+else
+  require_flatcontainer="0"
+fi
+
+if [[ -n "${SVT_POSTPUBLISH_REQUIRE_V2_DOWNLOAD:-}" ]]; then
+  require_v2_download="${SVT_POSTPUBLISH_REQUIRE_V2_DOWNLOAD}"
+else
+  require_v2_download="1"
 fi
 
 if [[ ! "${retry_count}" =~ ^[0-9]+$ ]]; then
@@ -56,6 +66,14 @@ if [[ "${require_registration}" != "0" && "${require_registration}" != "1" ]]; t
   echo "SVT_POSTPUBLISH_REQUIRE_REGISTRATION must be 0 or 1 (actual='${require_registration}')" >&2
   exit 1
 fi
+if [[ "${require_flatcontainer}" != "0" && "${require_flatcontainer}" != "1" ]]; then
+  echo "SVT_POSTPUBLISH_REQUIRE_FLATCONTAINER must be 0 or 1 (actual='${require_flatcontainer}')" >&2
+  exit 1
+fi
+if [[ "${require_v2_download}" != "0" && "${require_v2_download}" != "1" ]]; then
+  echo "SVT_POSTPUBLISH_REQUIRE_V2_DOWNLOAD must be 0 or 1 (actual='${require_v2_download}')" >&2
+  exit 1
+fi
 
 EXPECTED_VERSION="${expected_version}" \
 NUPKG_PATH="${nupkg_path}" \
@@ -64,5 +82,6 @@ RETRY_SLEEP_SECONDS="${retry_sleep_seconds}" \
 RETRY_SCHEDULE_SECONDS="${retry_schedule_seconds}" \
 REQUIRE_SEARCH=0 \
 REQUIRE_REGISTRATION="${require_registration}" \
-REQUIRE_FLATCONTAINER=1 \
+REQUIRE_FLATCONTAINER="${require_flatcontainer}" \
+REQUIRE_V2_DOWNLOAD="${require_v2_download}" \
 bash tools/ci/verify_nuget_release.sh
diff --git a/tools/ci/release/upsert_github_release.sh b/tools/ci/release/upsert_github_release.sh
index 1bfdda1..c89126c 100755
--- a/tools/ci/release/upsert_github_release.sh
+++ b/tools/ci/release/upsert_github_release.sh
@@ -3,6 +3,8 @@ set -euo pipefail
 
 RELEASE_TAG="${RELEASE_TAG:?RELEASE_TAG is required}"
 REPO="${GITHUB_REPOSITORY:?GITHUB_REPOSITORY is required}"
+MAX_ATTEMPTS="${RELEASE_GH_MAX_ATTEMPTS:-5}"
+INITIAL_DELAY_SECONDS="${RELEASE_GH_INITIAL_DELAY_SECONDS:-2}"
 
 version="${RELEASE_TAG#v}"
 prerelease_flag=()
@@ -21,15 +23,74 @@ else
   latest_edit_flag+=(--latest)
 fi
 
+if [[ ! "${MAX_ATTEMPTS}" =~ ^[0-9]+$ || "${MAX_ATTEMPTS}" -lt 1 ]]; then
+  echo "MAX_ATTEMPTS must be a positive integer (actual='${MAX_ATTEMPTS}')" >&2
+  exit 1
+fi
+if [[ ! "${INITIAL_DELAY_SECONDS}" =~ ^[0-9]+$ || "${INITIAL_DELAY_SECONDS}" -lt 1 ]]; then
+  echo "INITIAL_DELAY_SECONDS must be a positive integer (actual='${INITIAL_DELAY_SECONDS}')" >&2
+  exit 1
+fi
+
+classify_reason() {
+  local msg="$1"
+  if grep -qiE "401|bad credentials|requires authentication|unauthorized" <<<"${msg}"; then
+    echo "auth"
+    return
+  fi
+  if grep -qiE "429|rate limit|secondary rate limit" <<<"${msg}"; then
+    echo "rate-limit"
+    return
+  fi
+  if grep -qiE "5[0-9][0-9]|internal server error|gateway timeout|bad gateway|service unavailable" <<<"${msg}"; then
+    echo "5xx"
+    return
+  fi
+  if grep -qiE "timed out|timeout|connection reset|connection refused|temporary failure|network" <<<"${msg}"; then
+    echo "network"
+    return
+  fi
+  echo "unknown"
+}
+
+run_with_retry() {
+  local attempt=1
+  local delay="${INITIAL_DELAY_SECONDS}"
+  local cmd=("$@")
+  local output=""
+  while (( attempt <= MAX_ATTEMPTS )); do
+    output="$("${cmd[@]}" 2>&1)" && {
+      if [[ -n "${output}" ]]; then
+        printf '%s\n' "${output}"
+      fi
+      return 0
+    }
+
+    local reason
+    reason="$(classify_reason "${output}")"
+    echo "WARN: release API call failed (attempt ${attempt}/${MAX_ATTEMPTS}, reason=${reason})." >&2
+    printf '%s\n' "${output}" >&2
+
+    if [[ "${reason}" == "auth" || "${attempt}" -ge "${MAX_ATTEMPTS}" ]]; then
+      echo "FAIL: release API call failed (reason=${reason})." >&2
+      return 1
+    fi
+
+    sleep "${delay}"
+    delay=$((delay * 2))
+    attempt=$((attempt + 1))
+  done
+}
+
 if gh release view "${RELEASE_TAG}" --repo "${REPO}" >/dev/null 2>&1; then
-  gh release edit "${RELEASE_TAG}" --repo "${REPO}" --title "${RELEASE_TAG}" "${prerelease_flag[@]}" "${latest_edit_flag[@]}"
+  run_with_retry gh release edit "${RELEASE_TAG}" --repo "${REPO}" --title "${RELEASE_TAG}" "${prerelease_flag[@]}" "${latest_edit_flag[@]}"
 
   # gh does not support --latest=false for `release edit`. If an existing RC was
   # accidentally marked as Latest, correct it via API.
   if [[ "${is_rc}" == "true" ]]; then
-    release_id="$(gh api -H "Accept: application/vnd.github+json" "repos/${REPO}/releases/tags/${RELEASE_TAG}" --jq .id)"
-    gh api -X PATCH -H "Accept: application/vnd.github+json" "repos/${REPO}/releases/${release_id}" -f make_latest=false >/dev/null
+    release_id="$(run_with_retry gh api -H "Accept: application/vnd.github+json" "repos/${REPO}/releases/tags/${RELEASE_TAG}" --jq .id)"
+    run_with_retry gh api -X PATCH -H "Accept: application/vnd.github+json" "repos/${REPO}/releases/${release_id}" -f make_latest=false >/dev/null
   fi
 else
-  gh release create "${RELEASE_TAG}" --repo "${REPO}" --title "${RELEASE_TAG}" --notes "Automated tag-only release for ${version}" "${prerelease_flag[@]}" "${latest_create_flag[@]}"
+  run_with_retry gh release create "${RELEASE_TAG}" --repo "${REPO}" --title "${RELEASE_TAG}" --notes "Automated tag-only release for ${version}" "${prerelease_flag[@]}" "${latest_create_flag[@]}"
 fi
diff --git a/tools/ci/verify_nuget_release.sh b/tools/ci/verify_nuget_release.sh
index 8e784e1..70d7d68 100755
--- a/tools/ci/verify_nuget_release.sh
+++ b/tools/ci/verify_nuget_release.sh
@@ -16,13 +16,16 @@ VERIFY_ONLINE="${VERIFY_ONLINE:-1}"
 REQUIRE_SEARCH="${REQUIRE_SEARCH:-1}"
 REQUIRE_REGISTRATION="${REQUIRE_REGISTRATION:-1}"
 REQUIRE_FLATCONTAINER="${REQUIRE_FLATCONTAINER:-1}"
+REQUIRE_V2_DOWNLOAD="${REQUIRE_V2_DOWNLOAD:-0}"
 
 SEARCH_OK="skipped"
 REGISTRATION_OK="skipped"
 FLATCONTAINER_OK="skipped"
+V2_DOWNLOAD_OK="skipped"
 REGISTRATION_URL=""
 SEARCH_URL=""
 FLAT_URL=""
+V2_URL=""
 
 fail() {
   echo "FAIL: $*" >&2
@@ -287,6 +290,19 @@ query_flatcontainer() {
   return 1
 }
 
+query_v2_download() {
+  local pkg_id_lc
+  pkg_id_lc="$(printf '%s' "${PKG_ID}" | tr '[:upper:]' '[:lower:]')"
+  V2_URL="https://www.nuget.org/api/v2/package/${pkg_id_lc}/${PKG_VER}"
+  local status
+  status="$(curl -sS -o /dev/null -w '%{http_code}' -L --max-time "${TIMEOUT_SECONDS}" "${V2_URL}" || true)"
+  if [[ "${status}" == "200" ]]; then
+    V2_DOWNLOAD_OK="ok"
+    return 0
+  fi
+  return 1
+}
+
 emit_summary_json() {
   python3 - <<'PY'
 import json
@@ -300,10 +316,12 @@ print(json.dumps({
     "require_search": os.environ.get("REQUIRE_SEARCH", ""),
     "require_registration": os.environ.get("REQUIRE_REGISTRATION", ""),
     "require_flatcontainer": os.environ.get("REQUIRE_FLATCONTAINER", ""),
+    "require_v2_download": os.environ.get("REQUIRE_V2_DOWNLOAD", ""),
     "registration": os.environ.get("REGISTRATION_URL", ""),
     "search": os.environ.get("SEARCH_OK", "skipped"),
     "registration_check": os.environ.get("REGISTRATION_OK", "skipped"),
-    "flatcontainer": os.environ.get("FLATCONTAINER_OK", "skipped")
+    "flatcontainer": os.environ.get("FLATCONTAINER_OK", "skipped"),
+    "v2_download": os.environ.get("V2_DOWNLOAD_OK", "skipped")
 }, separators=(",", ":")))
 PY
 }
@@ -321,6 +339,7 @@ main() {
   require_bool_flag "REQUIRE_SEARCH" "${REQUIRE_SEARCH}"
   require_bool_flag "REQUIRE_REGISTRATION" "${REQUIRE_REGISTRATION}"
   require_bool_flag "REQUIRE_FLATCONTAINER" "${REQUIRE_FLATCONTAINER}"
+  require_bool_flag "REQUIRE_V2_DOWNLOAD" "${REQUIRE_V2_DOWNLOAD}"
 
   if [[ -n "${PKG_ID}" || -n "${PKG_VER}" ]]; then
     if [[ -z "${PKG_ID}" || -z "${PKG_VER}" ]]; then
@@ -398,11 +417,18 @@ main() {
     else
       info "Flatcontainer check skipped (REQUIRE_FLATCONTAINER=${REQUIRE_FLATCONTAINER})."
     fi
+
+    if [[ "${REQUIRE_V2_DOWNLOAD}" == "1" ]]; then
+      retry_network "v2-download" query_v2_download
+      info "V2 download check OK: ${V2_URL}"
+    else
+      info "V2 download check skipped (REQUIRE_V2_DOWNLOAD=${REQUIRE_V2_DOWNLOAD})."
+    fi
   else
     info "Online checks skipped (VERIFY_ONLINE=${VERIFY_ONLINE})."
   fi
 
-  export PKG_ID PKG_VER EXPECTED_VERSION VERIFY_ONLINE REQUIRE_SEARCH REQUIRE_REGISTRATION REQUIRE_FLATCONTAINER REGISTRATION_URL SEARCH_OK REGISTRATION_OK FLATCONTAINER_OK
+  export PKG_ID PKG_VER EXPECTED_VERSION VERIFY_ONLINE REQUIRE_SEARCH REQUIRE_REGISTRATION REQUIRE_FLATCONTAINER REQUIRE_V2_DOWNLOAD REGISTRATION_URL SEARCH_OK REGISTRATION_OK FLATCONTAINER_OK V2_DOWNLOAD_OK
   emit_summary_json
   echo "OK: verify_nuget_release completed."
 }