diff --git a/.github/workflows/attestation-check.yml b/.github/workflows/attestation-check.yml
index 81ce0b8..2bf734b 100644
--- a/.github/workflows/attestation-check.yml
+++ b/.github/workflows/attestation-check.yml
@@ -24,6 +24,10 @@ jobs:
     permissions:
       contents: read
       issues: write
+    env:
+      # crates.io answers 403 to a generic user agent (verified — plain `curl/8.x`
+      # gets 403). One descriptive UA, shared by every crates.io call in this job.
+      CRATES_IO_UA: cachekit-core-attestation-check (+https://github.com/${{ github.repository }})
     steps:
       # github-script, not `gh`, for API calls — the convention release.yml documents
       # on its "Assign release PR" step. `gh` is confined to Sigstore verification below.
@@ -96,10 +100,9 @@ jobs:
         run: |
           mkdir -p release-assets
           ARTIFACT="release-assets/${CRATE}-${VERSION}.crate"
-          # -A is mandatory, not politeness: crates.io answers 403 to a generic user
-          # agent (verified — plain `curl/8.x` gets 403 on this exact URL).
+          # -A is mandatory, not politeness — see CRATES_IO_UA at the job level.
           curl -fsSL --retry 3 --retry-connrefused \
-            -A "cachekit-core-attestation-check (+https://github.com/${GITHUB_REPOSITORY})" \
+            -A "$CRATES_IO_UA" \
             "https://crates.io/api/v1/crates/${CRATE}/${VERSION}/download" \
             -o "$ARTIFACT"
           test -s "$ARTIFACT"
@@ -153,21 +156,142 @@ jobs:
             --format json \
             --jq '.[] | "verified SBOM: digest=\(.verificationResult.statement.subject[0].digest.sha256) predicate=\(.verificationResult.statement.predicateType) signer=\(.verificationResult.signature.certificate.buildSignerURI)"'
 
+      # Verification above proves the latest GitHub release's crate is authentic — but
+      # says nothing about whether that is the version `cargo add` actually resolves.
+      # A hand-published version, a prerelease-skipped release, or a yank all leave
+      # the steps above green while users install something this job never checked
+      # (LAB-1036). max_stable_version is what cargo resolves by default, so
+      # verified != max_stable is a false green and must go red — unconditionally.
+      #
+      # Deliberately NO tolerance for the release→publish window (release.yml tags
+      # before `cargo publish`): that window cannot reach this comparison. While it
+      # is open the crate is not on crates.io yet, so the job has already gone red at
+      # the download step above. And an "is release.yml in flight?" tolerance here
+      # would itself be a fail-open — release.yml runs on every push to main, so an
+      # unrelated queued run would green-light a dead publish or a yanked version
+      # (expert panel, LAB-1036). A crate that downloaded successfully but mismatches
+      # max_stable is always a real defect: yanked, hand-published, prerelease-
+      # skipped, or a publish that died after the tag.
+      - name: Check crates.io serves the verified version
+        if: steps.release.outputs.skip != 'true'
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        env:
+          CRATE: ${{ steps.release.outputs.crate }}
+          VERSION: ${{ steps.release.outputs.version }}
+        with:
+          script: |
+            const crate = process.env.CRATE;
+            const version = process.env.VERSION;
+            // try/catch so a network-level failure (DNS, connection reset) or a
+            // non-JSON body fails with a descriptive message instead of a raw
+            // unhandled-rejection trace. Red either way — diagnostics, not a swallow.
+            let data;
+            try {
+              const res = await fetch(`https://crates.io/api/v1/crates/${crate}`, {
+                headers: { 'User-Agent': process.env.CRATES_IO_UA },
+              });
+              if (!res.ok) {
+                core.setFailed(`crates.io API answered ${res.status} for crate '${crate}' — cannot confirm what users install.`);
+                return;
+              }
+              data = await res.json();
+            } catch (error) {
+              core.setFailed(`crates.io API request for '${crate}' failed: ${error.message} — cannot confirm what users install.`);
+              return;
+            }
+
+            // Fail closed if the response shape shifts under us: an error-shaped 200
+            // without a `crate` object, or a missing `versions` array, must fail with
+            // a message, not a TypeError — `|| []`/optional chaining here would
+            // silently degrade the checks to no-ops, `|| echo ""` in JS clothing.
+            if (!data.crate) {
+              core.setFailed(`crates.io response for '${crate}' has no crate object — cannot confirm what users install.`);
+              return;
+            }
+            if (!Array.isArray(data.versions)) {
+              core.setFailed(`crates.io response for '${crate}' has no versions array — cannot check yank status.`);
+              return;
+            }
+            // The explicit yank branch is not redundant with the mismatch below: it
+            // names the actual cause. Yanked crates stay downloadable, so the download
+            // step above cannot catch this case.
+            const entry = data.versions.find((v) => v.num === version);
+            if (entry && entry.yanked) {
+              core.setFailed(
+                `Verified version ${version} is YANKED on crates.io — this check just green-lit ` +
+                'a version users are steered away from, so the latest GitHub release no longer matches a servable crate.',
+              );
+              return;
+            }
+
+            const maxStable = data.crate.max_stable_version;
+            if (!maxStable) {
+              core.setFailed(`crates.io reports no stable version of '${crate}' at all (every version yanked or prerelease).`);
+              return;
+            }
+            if (maxStable !== version) {
+              core.setFailed(
+                `crates.io max_stable_version is ${maxStable} but this check verified ${version}. ` +
+                `Users running 'cargo add ${crate}' get ${maxStable}, a version this job never verified — a false green (LAB-1036).`,
+              );
+              return;
+            }
+            core.info(`crates.io max_stable_version ${maxStable} == verified ${version} — the verified crate is what 'cargo add ${crate}' installs.`);
+
+      # GitHub silently disables `schedule:` triggers in public repos after ~60 days
+      # without repository activity — after which this job's failure mode becomes
+      # "not running at all", indistinguishable from passing quietly (LAB-1036). Fail
+      # while the schedule is still alive so the auto-disable is preceded by a red run
+      # and a tracking issue instead of a quiet death. The threshold is 43 days: the
+      # cron is weekly AND GitHub documents that scheduled runs can be delayed or
+      # dropped under load, so the margin must fit TWO weekly attempts, not one —
+      # 60 − 43 = 17 days ≥ two cron periods, so even one dropped Monday still leaves
+      # a red run before the disable. (A margin under 7 days could be jumped over
+      # entirely: green at day 54, disabled before the next run at day 61.) No `if:`
+      # on the release skip output: liveness is independent of whether releases exist.
+      - name: Assert schedule liveness
+        id: liveness
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { data: repo } = await github.rest.repos.get({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+            });
+            const staleDays = (Date.now() - Date.parse(repo.pushed_at)) / 86400000;
+            // `!(x <= 43)`, not `x > 43`: Date.parse of a malformed pushed_at is NaN,
+            // and NaN must fail closed, not log "not at risk" and pass.
+            if (!(staleDays <= 43)) {
+              core.setFailed(
+                `Last repository push was ${staleDays.toFixed(1)} days ago; GitHub auto-disables this schedule at ` +
+                '~60 days of inactivity, after which the check stops running with no signal at all. ' +
+                'Push activity (or re-enable the workflow) before it goes dark.',
+              );
+              return;
+            }
+            core.info(`Last push ${staleDays.toFixed(1)} days ago — schedule is not at risk of the 60-day auto-disable.`);
+
       # Weekly job: without dedupe one unfixed break files a fresh issue every Monday,
       # and a muted `bug` label is itself a fail-open alert channel. The marker is
-      # per-tag, so a NEW tag's failure still alerts instead of hiding behind the open
-      # issue for the old one. Matched on body, not title or label, so a human
-      # retitling or relabelling the issue cannot break dedupe. The 100-issue page is
-      # ample here; worst case is a duplicate issue, never a missed alert.
+      # per-failure-class: per-tag for verification breaks (a NEW tag's failure still
+      # alerts instead of hiding behind the open issue for the old one), and a
+      # dedicated `liveness` marker for staleness — the two classes are mutually
+      # exclusive in one run (liveness only executes after verification succeeded),
+      # and a shared marker would let an open staleness issue swallow a later real
+      # attestation break for the same tag. Matched on body, not title or label, so a
+      # human retitling or relabelling the issue cannot break dedupe. The 100-issue
+      # page is ample here; worst case is a duplicate issue, never a missed alert.
       - name: Open issue on failure
         if: failure()
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           TAG: ${{ steps.release.outputs.tag }}
+          LIVENESS_OUTCOME: ${{ steps.liveness.outcome }}
         with:
           script: |
             const tag = process.env.TAG || 'unresolved-release';
-            const marker = `<!-- attestation-check:${tag} -->`;
+            const liveness = process.env.LIVENESS_OUTCOME === 'failure';
+            const marker = liveness ? '<!-- attestation-check:liveness -->' : `<!-- attestation-check:${tag} -->`;
             const runUrl = `${context.serverUrl}/${context.repo.owner}/${context.repo.repo}/actions/runs/${context.runId}`;
             const { data: open } = await github.rest.issues.listForRepo({
               owner: context.repo.owner,
@@ -183,16 +307,23 @@ jobs:
             const { data: created } = await github.rest.issues.create({
               owner: context.repo.owner,
               repo: context.repo.repo,
-              title: `Attestation verification failed for ${tag}`,
+              title: liveness
+                ? 'Attestation health check schedule is at risk of auto-disable'
+                : `Attestation verification failed for ${tag}`,
               body: [
                 marker,
-                `The weekly attestation health check failed for \`${tag}\`.`,
+                liveness
+                  ? 'The repository has had no push activity for >43 days; GitHub auto-disables this workflow\'s `schedule:` trigger at ~60 days, after which the check silently stops running.'
+                  : `The weekly attestation health check failed for \`${tag}\`.`,
                 '',
                 `Run: ${runUrl}`,
                 '',
                 'Check that release.yml produced valid SLSA provenance and CycloneDX SBOM',
-                'attestations for the published `.crate`, that it ran on `main`, and that',
-                'the crate actually reached crates.io for this tag.',
+                'attestations for the published `.crate`, that it ran on `main`, that the',
+                'crate actually reached crates.io for this tag, that crates.io\'s',
+                '`max_stable_version` still matches this release (nothing hand-published,',
+                'yanked, or prerelease-skipped), and that the repository has push activity',
+                'within the last 43 days (GitHub auto-disables the schedule at ~60).',
               ].join('\n'),
               labels: ['bug'],
             });