diff --git a/.github/workflows/attest-release.yml b/.github/workflows/attest-release.yml
new file mode 100644
index 00000000..b4dd75c4
--- /dev/null
+++ b/.github/workflows/attest-release.yml
@@ -0,0 +1,109 @@
+# Manual build-provenance attestation, for a release whose run published the
+# assets but never reached release.yml's "Attest build provenance" step.
+#
+# v1.7.0 is the case this exists for: the size report after goreleaser failed,
+# the steps behind it were skipped, and the release shipped without
+# attestations. mise requires them once an earlier version of a tool had them,
+# so `mise upgrade` and `hey upgrade` via mise refused the release (#499).
+# Re-running the release job is no answer: goreleaser would either refuse the
+# existing release or rebuild and re-sign, and the new binaries would not be
+# the bytes users download.
+#
+# This workflow attests the published assets and nothing else. checksums.txt is
+# the list of subjects handed to attest-build-provenance, not a subject itself.
+# It is trusted only after the release run's own cosign bundle verifies against
+# release.yml at the tag, and each listed digest only if the published asset of
+# that name carries it. The attestation's signer is this workflow rather than
+# release.yml; mise does not pin the signer workflow, and the installers and
+# `hey upgrade`'s own verification do not read attestations at all.
+name: Attest a published release
+
+on:
+  workflow_dispatch:
+    inputs:
+      tag:
+        description: 'Published release tag to attest (e.g. v1.7.0)'
+        required: true
+        type: string
+
+permissions: {}
+
+concurrency:
+  group: attest-release-${{ inputs.tag }}
+  cancel-in-progress: false
+
+jobs:
+  attest:
+    name: Attest build provenance
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    environment: release
+    permissions:
+      contents: read
+      id-token: write
+      attestations: write
+    steps:
+      - name: Validate tag input
+        env:
+          TAG: ${{ inputs.tag }}
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          if [[ ! "$TAG" =~ ^v[0-9]+\.[0-9]+\.[0-9]+(-[0-9A-Za-z.-]+)?$ ]]; then
+            echo "::error::Invalid tag '${TAG}' — expected a release tag such as v1.7.0"
+            exit 1
+          fi
+          # A draft's assets are not what anyone downloads, so there is
+          # nothing there to attest yet.
+          draft=$(gh api "repos/${GITHUB_REPOSITORY}/releases/tags/${TAG}" --jq '.draft' 2>/dev/null) || {
+            echo "::error::No published release found for ${TAG}"
+            exit 1
+          }
+          if [ "$draft" != "false" ]; then
+            echo "::error::${TAG} is a draft release"
+            exit 1
+          fi
+
+      - name: Download the release's checksums and their signature
+        env:
+          TAG: ${{ inputs.tag }}
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          gh release download "$TAG" --repo "$GITHUB_REPOSITORY" \
+            --pattern checksums.txt --pattern checksums.txt.bundle
+
+      - name: Install Cosign
+        uses: sigstore/cosign-installer@6f9f17788090df1f26f669e9d70d6ae9567deba6 # v4.1.2
+
+      # The same identity the installers and `hey upgrade` pin: only the
+      # assets listed in a checksums.txt the release run for this tag signed
+      # are attested.
+      - name: Verify checksums.txt was signed by the release run
+        env:
+          TAG: ${{ inputs.tag }}
+        run: |
+          cosign verify-blob checksums.txt \
+            --bundle checksums.txt.bundle \
+            --certificate-identity "https://github.com/${GITHUB_REPOSITORY}/.github/workflows/release.yml@refs/tags/${TAG}" \
+            --certificate-oidc-issuer https://token.actions.githubusercontent.com
+
+      - name: Verify every checksum matches the published asset
+        env:
+          TAG: ${{ inputs.tag }}
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          gh api "repos/${GITHUB_REPOSITORY}/releases/tags/${TAG}" \
+            --jq '.assets[] | select(.digest != null) | "\(.digest | ltrimstr("sha256:"))  \(.name)"' \
+            | sort > published.txt
+          sort checksums.txt > signed.txt
+          missing=$(comm -23 signed.txt published.txt)
+          if [ -n "$missing" ]; then
+            echo "::error::checksums.txt lists entries no published asset matches:"
+            echo "$missing"
+            exit 1
+          fi
+          echo "All $(wc -l < signed.txt) signed checksums match published assets"
+
+      - name: Attest build provenance
+        uses: actions/attest-build-provenance@4d101475d8b20a2381f78447822ac1eab6504dd8 # v4.2.2
+        with:
+          subject-checksums: ./checksums.txt
diff --git a/.github/workflows/sensitive-change-gate.yml b/.github/workflows/sensitive-change-gate.yml
index 9a05d15c..0568095c 100644
--- a/.github/workflows/sensitive-change-gate.yml
+++ b/.github/workflows/sensitive-change-gate.yml
@@ -13,6 +13,7 @@ jobs:
       extra-patterns: |
         .goreleaser.yaml
         .github/workflows/release.yml
+        .github/workflows/attest-release.yml
         scripts/release.sh
         scripts/stamp-nix-version.sh
         scripts/sign-windows.sh
diff --git a/RELEASING.md b/RELEASING.md
index 72fc67e3..7e8347d2 100644
--- a/RELEASING.md
+++ b/RELEASING.md
@@ -260,6 +260,28 @@ it is idempotent and refuses downgrades.
 One-time setup: `ssh-keygen -t ed25519 -f aur_key`, add the public key to the AUR
 account, store the private key as `AUR_KEY`.
 
+## Missing attestation
+
+mise refuses a version without GitHub build provenance once an earlier version
+of the tool had it, so a release whose run published but stopped before
+`Attest build provenance` cannot be installed or upgraded through mise (v1.7.0,
+#499). Do not re-run the release job: goreleaser would rebuild and re-sign, and
+the new digests are not what was published. Dispatch the `Attest a published
+release` workflow with the tag instead:
+
+```bash
+gh workflow run attest-release.yml -f tag=v1.7.0
+gh attestation verify hey_1.7.0_linux_amd64.tar.gz --repo basecamp/hey-cli
+```
+
+`checksums.txt` is the index of subjects, not the subject: the workflow
+attests each release asset it lists, by name and digest, which is why the check
+above names an archive. It does so only after the release run's
+`checksums.txt.bundle` verifies against `release.yml` at that tag and every
+listed digest matches the published asset of that name. The attestation's
+signer is `attest-release.yml` rather than `release.yml`; mise does not check
+the signer workflow.
+
 ## Skills sync
 
 Stable releases mirror `skills/` into [basecamp/skills](https://github.com/basecamp/skills),
diff --git a/tests/e2e/attest_release_workflow.bats b/tests/e2e/attest_release_workflow.bats
new file mode 100644
index 00000000..612b93e4
--- /dev/null
+++ b/tests/e2e/attest_release_workflow.bats
@@ -0,0 +1,42 @@
+#!/usr/bin/env bats
+# attest_release_workflow.bats - static contracts for the manual attestation
+# workflow. actionlint validates syntax; these assertions validate intent.
+
+setup() {
+  REPO_ROOT="$(cd "${BATS_TEST_DIRNAME}/../.." && pwd)"
+  WORKFLOW="$REPO_ROOT/.github/workflows/attest-release.yml"
+}
+
+step_order() {
+  grep -n -- "- name: $1" "$WORKFLOW" | head -1 | cut -d: -f1
+}
+
+@test "checksums are trusted only when the release run for the tag signed them" {
+  run cat "$WORKFLOW"
+  [[ "$output" == *'.github/workflows/release.yml@refs/tags/${TAG}'* ]]
+  [[ "$output" == *"--certificate-oidc-issuer https://token.actions.githubusercontent.com"* ]]
+}
+
+@test "attestation comes after both verifications" {
+  signed=$(step_order "Verify checksums.txt was signed by the release run")
+  published=$(step_order "Verify every checksum matches the published asset")
+  attest=$(step_order "Attest build provenance")
+  [ -n "$signed" ] && [ -n "$published" ] && [ -n "$attest" ]
+  [ "$signed" -lt "$attest" ]
+  [ "$published" -lt "$attest" ]
+}
+
+@test "it attests the release's own checksums, as release.yml does" {
+  run grep -c "subject-checksums: ./checksums.txt" "$WORKFLOW"
+  [ "$output" = "1" ]
+  expected=$(grep -o "actions/attest-build-provenance@[0-9a-f]*" "$REPO_ROOT/.github/workflows/release.yml")
+  actual=$(grep -o "actions/attest-build-provenance@[0-9a-f]*" "$WORKFLOW")
+  [ "$expected" = "$actual" ]
+}
+
+@test "it can read the release but cannot write to the repository" {
+  run grep -E "contents: write|actions: write" "$WORKFLOW"
+  [ "$status" -ne 0 ]
+  run grep -c "^      contents: read$" "$WORKFLOW"
+  [ "$output" = "1" ]
+}