diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 2cabb6da..e1d41ef6 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -22,9 +22,18 @@ jobs:
     runs-on: ubuntu-24.04
     steps:
       - name: Check out the tagged source
-        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
+          ref: ${{ github.sha }}
           fetch-depth: 0
+          persist-credentials: false
+      - name: Verify exact checkout
+        env:
+          INKSPAN_EXPECTED_HEAD_SHA: ${{ github.sha }}
+        run: |
+          set -euo pipefail
+          actual_head="$(git rev-parse HEAD)"
+          test "$actual_head" = "$INKSPAN_EXPECTED_HEAD_SHA"
       - name: Set up pnpm
         uses: pnpm/action-setup@0977fd99725f1db4007ccb2928dbb4e90d06cc86 # v6.0.10
       - name: Set up Node.js
@@ -468,7 +477,6 @@ jobs:
           gh release edit "$GITHUB_REF_NAME" \
             --repo "$GITHUB_REPOSITORY" \
             --draft=false
-
           release_immutable="$(gh release view "$GITHUB_REF_NAME" \
             --repo "$GITHUB_REPOSITORY" \
             --json isImmutable \
diff --git a/src/releaseExactCheckout.test.ts b/src/releaseExactCheckout.test.ts
new file mode 100644
index 00000000..bb7fd53b
--- /dev/null
+++ b/src/releaseExactCheckout.test.ts
@@ -0,0 +1,95 @@
+import { readFileSync } from 'node:fs';
+import { resolve } from 'node:path';
+
+import { describe, expect, it } from 'vitest';
+
+const RELEASE_CHECKOUT_ACTION =
+  'actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1';
+
+/** Read one authoritative repository file as UTF-8 text. */
+function repositoryFile(path: string): string {
+  return readFileSync(resolve(process.cwd(), path), 'utf8');
+}
+
+/** Extract one top-level workflow job without allowing another job to satisfy it. */
+function workflowJob(source: string, jobName: string, nextJobName: string): string {
+  const start = source.indexOf(`  ${jobName}:`);
+  const end = source.indexOf(`  ${nextJobName}:`, start + 1);
+  expect(start).toBeGreaterThan(-1);
+  expect(end).toBeGreaterThan(start);
+  return source.slice(start, end);
+}
+
+/** Extract one named workflow step so unrelated steps cannot satisfy its contract. */
+function workflowStep(source: string, stepName: string, nextStepName: string): string {
+  const start = source.indexOf(`      - name: ${stepName}`);
+  const end = source.indexOf(`      - name: ${nextStepName}`, start + 1);
+  expect(start).toBeGreaterThan(-1);
+  expect(end).toBeGreaterThan(start);
+  return source.slice(start, end);
+}
+
+describe('release artifact checkout authority', () => {
+  it('binds the artifact build to the repository checkout baseline and exact tag SHA before setup', () => {
+    const workflow = repositoryFile('.github/workflows/release.yml');
+    const buildJob = workflowJob(
+      workflow,
+      'build-release-artifacts',
+      'browser-release-evidence',
+    );
+    const checkoutStep = workflowStep(
+      buildJob,
+      'Check out the tagged source',
+      'Verify exact checkout',
+    );
+    const verifyStep = workflowStep(
+      buildJob,
+      'Verify exact checkout',
+      'Set up pnpm',
+    );
+
+    expect(checkoutStep).toContain(`uses: ${RELEASE_CHECKOUT_ACTION}`);
+    expect(checkoutStep).toContain('with:');
+    expect(checkoutStep).toContain('ref: ${{ github.sha }}');
+    expect(checkoutStep).toContain('fetch-depth: 0');
+    expect(checkoutStep).toContain('persist-credentials: false');
+    expect(verifyStep).toContain('INKSPAN_EXPECTED_HEAD_SHA: ${{ github.sha }}');
+    expect(verifyStep).toContain('actual_head="$(git rev-parse HEAD)"');
+    expect(verifyStep).toContain(
+      'test "$actual_head" = "$INKSPAN_EXPECTED_HEAD_SHA"',
+    );
+
+    expect(buildJob.indexOf('name: Verify exact checkout')).toBeLessThan(
+      buildJob.indexOf('name: Set up pnpm'),
+    );
+    expect(buildJob.indexOf('name: Verify exact checkout')).toBeLessThan(
+      buildJob.indexOf('name: Set up Node.js'),
+    );
+    expect(buildJob.indexOf('name: Verify exact checkout')).toBeLessThan(
+      buildJob.indexOf('name: Set up Python'),
+    );
+  });
+
+  it('preserves the established prerelease tag semantics while npm publication remains gated', () => {
+    const workflow = repositoryFile('.github/workflows/release.yml');
+    const buildJob = workflowJob(
+      workflow,
+      'build-release-artifacts',
+      'browser-release-evidence',
+    );
+    const identityStep = workflowStep(
+      buildJob,
+      'Verify release identity and current main tip',
+      'Install JavaScript dependencies',
+    );
+
+    expect(identityStep).toContain(
+      "if (!/^v(?:0|[1-9]\\d*)\\.(?:0|[1-9]\\d*)\\.(?:0|[1-9]\\d*)(?:-[0-9A-Za-z.-]+)?$/.test(releaseTag))",
+    );
+    expect(identityStep).toContain('Release tag is not valid semantic version syntax');
+    expect(identityStep).not.toContain('valid stable semantic version syntax');
+    expect(workflow).toContain(
+      "github.repository == 'ContextualWisdomLab/inkspan' && !contains(github.ref_name, '-')",
+    );
+  });
+});