diff --git a/.github/workflows/deploy.yml b/.github/workflows/deploy.yml
index 2d12a6e..6b4edd3 100644
--- a/.github/workflows/deploy.yml
+++ b/.github/workflows/deploy.yml
@@ -19,14 +19,25 @@ jobs:
         with: { node-version: '22.19', cache: pnpm }
       - run: pnpm install --frozen-lockfile --ignore-scripts
       - run: pnpm cf:build
-      - uses: cloudflare/wrangler-action@v3
+      - name: Upload Worker version
+        id: upload
+        uses: cloudflare/wrangler-action@v3
         with:
           apiToken: ${{ secrets.CLOUDFLARE_API_TOKEN }}
           accountId: ${{ secrets.CLOUDFLARE_ACCOUNT_ID }}
           # Code releases preserve existing routes; route changes use a separately authorized credential.
-          command: |
-            versions upload --env="" --tag ${{ github.sha }}
-            versions deploy --env="" --version-tag ${{ github.sha }}@100% --yes
+          command: versions upload --env="" --tag ${{ github.sha }}
+      - name: Resolve this upload's version ID
+        id: uploaded-version
+        run: node scripts/uploaded-worker-version.mjs
+        env:
+          WORKER_UPLOAD_OUTPUT: ${{ steps.upload.outputs.command-output }}
+      - name: Deploy the uploaded version
+        uses: cloudflare/wrangler-action@v3
+        with:
+          apiToken: ${{ secrets.CLOUDFLARE_API_TOKEN }}
+          accountId: ${{ secrets.CLOUDFLARE_ACCOUNT_ID }}
+          command: versions deploy --env="" ${{ steps.uploaded-version.outputs.version-id }}@100% --yes
       - name: Smoke check production
         run: pnpm smoke:prod
 
diff --git a/__tests__/deploy-workflow.test.ts b/__tests__/deploy-workflow.test.ts
index 4ead4a3..51dd165 100644
--- a/__tests__/deploy-workflow.test.ts
+++ b/__tests__/deploy-workflow.test.ts
@@ -11,9 +11,14 @@ describe('deploy workflow', () => {
     expect(deployWorkflow).toContain('workflow_dispatch:');
     expect(deployWorkflow).toContain("if: github.event_name == 'workflow_dispatch'");
     expect(deployWorkflow).toContain('pnpm cf:build');
+    expect(deployWorkflow).toMatch(/versions upload --env="" --tag \$\{\{ github\.sha \}\}/);
     expect(deployWorkflow).toMatch(
-      /versions upload --env="" --tag \$\{\{ github\.sha \}\}\n\s+versions deploy --env="" --version-tag \$\{\{ github\.sha \}\}@100% --yes/
+      /WORKER_UPLOAD_OUTPUT: \$\{\{ steps\.upload\.outputs\.command-output \}\}/
     );
+    expect(deployWorkflow).toMatch(
+      /versions deploy --env="" \$\{\{ steps\.uploaded-version\.outputs\.version-id \}\}@100% --yes/
+    );
+    expect(deployWorkflow).not.toContain('--version-tag');
     expect(deployWorkflow).not.toMatch(
       /^[ \t]+(?:command: )?(?:wrangler )?(?:deploy|triggers deploy)(?:[ \t]|$)/m
     );
diff --git a/__tests__/uploaded-worker-version.test.ts b/__tests__/uploaded-worker-version.test.ts
new file mode 100644
index 0000000..92d2f3c
--- /dev/null
+++ b/__tests__/uploaded-worker-version.test.ts
@@ -0,0 +1,29 @@
+// A repeat deployment produced two versions with the same SHA tag. Resolve the
+// UUID from this upload's actual Wrangler output, never from a shared tag.
+import { describe, expect, it } from 'vitest';
+import { uploadedWorkerVersionId } from '../scripts/uploaded-worker-version.mjs';
+
+const version = '11111111-2222-4333-8444-555555555555';
+
+describe('uploaded Worker identity', () => {
+  it('selects the uploaded version despite other IDs and a reused SHA tag', () => {
+    const output = `Bucket ID: aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee\nUploaded resume-tailor (6.17 sec)\nWorker Version ID: ${version}\nTag: ${'a'.repeat(40)}\n`;
+    expect(uploadedWorkerVersionId(output)).toBe(version);
+  });
+
+  it('accepts Wrangler ANSI formatting without changing the UUID', () => {
+    expect(uploadedWorkerVersionId(`\u001b[32mWorker Version ID: ${version}\u001b[0m`)).toBe(
+      version
+    );
+  });
+
+  it.each([
+    '',
+    `Version ID: ${version}`,
+    'Worker Version ID: not-a-version',
+    `Worker Version ID: ${version} trailing-command`,
+    `Worker Version ID: ${version}\nWorker Version ID: aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee`,
+  ])('refuses missing or ambiguous upload identity (%s)', (output) => {
+    expect(() => uploadedWorkerVersionId(output)).toThrow();
+  });
+});
diff --git a/scripts/uploaded-worker-version.mjs b/scripts/uploaded-worker-version.mjs
new file mode 100644
index 0000000..133e007
--- /dev/null
+++ b/scripts/uploaded-worker-version.mjs
@@ -0,0 +1,21 @@
+import { appendFileSync } from 'node:fs';
+import { resolve } from 'node:path';
+import { pathToFileURL } from 'node:url';
+
+export function uploadedWorkerVersionId(output) {
+  const ansi = new RegExp(`${String.fromCharCode(27)}\\[[0-9;]*m`, 'g');
+  const plain = String(output).replace(ansi, '');
+  const matches = [
+    ...plain.matchAll(
+      /^\s*Worker Version ID:\s*([0-9a-f]{8}(?:-[0-9a-f]{4}){3}-[0-9a-f]{12})\s*$/gim
+    ),
+  ];
+  if (matches.length !== 1) throw new Error('Expected exactly one uploaded Worker Version ID.');
+  return matches[0][1].toLowerCase();
+}
+
+if (process.argv[1] && import.meta.url === pathToFileURL(resolve(process.argv[1])).href) {
+  const versionId = uploadedWorkerVersionId(process.env.WORKER_UPLOAD_OUTPUT ?? '');
+  if (!process.env.GITHUB_OUTPUT) throw new Error('GITHUB_OUTPUT is required.');
+  appendFileSync(process.env.GITHUB_OUTPUT, `version-id=${versionId}\n`);
+}
diff --git a/src/__tests__/resume-oauth.test.ts b/src/__tests__/resume-oauth.test.ts
index 9c22cd3..027d1d5 100644
--- a/src/__tests__/resume-oauth.test.ts
+++ b/src/__tests__/resume-oauth.test.ts
@@ -185,7 +185,13 @@ it('qualifies registration, consent, PKCE, replay resistance, owner identity, re
   expect(valid.status).toBe(200);
   expect(await valid.json()).toEqual({ user: 'oauth-owner' });
   expect((await invoke(tokens.access_token, '/api/resume')).status).toBe(401);
-  expect((await invoke(`${tokens.access_token.slice(0, -2)}XX`)).status).toBe(401);
+  // Base64url's unused trailing bits can make an XX suffix decode to the same
+  // signature. Change the first signature character so the bytes always differ.
+  const parts = tokens.access_token.split('.');
+  const signature = parts[2];
+  parts[2] = `${signature[0] === 'A' ? 'B' : 'A'}${signature.slice(1)}`;
+  expect(Buffer.from(parts[2], 'base64url')).not.toEqual(Buffer.from(signature, 'base64url'));
+  expect((await invoke(parts.join('.'))).status).toBe(401);
   expect((await token({ ...grant, code: freshCode })).status).toBeGreaterThanOrEqual(400);
   const refreshed = await token({
     grant_type: 'refresh_token',