diff --git a/.github/scripts/run_notebook.py b/.github/scripts/run_notebook.py
index 94b66ee..db15e00 100644
--- a/.github/scripts/run_notebook.py
+++ b/.github/scripts/run_notebook.py
@@ -69,11 +69,54 @@ def run(cmd, **kw):
     return subprocess.run(cmd, capture_output=True, text=True, **kw)
 
 
+ANSI_RE = re.compile(r"\x1b\[[0-9;]*m")
+
+
+def execute_with_kernel(tmp_nb: Path, executed_path: Path, nb_dir: Path,
+                        timeout: int, log_path: Path, finalize) -> int:
+    """Run the notebook through a real kernel via nbconvert, keeping outputs.
+
+    --allow-errors keeps going past a failing cell so the executed notebook
+    shows reviewers exactly where and how it failed; the error outputs are
+    then scanned to decide pass/fail.
+    """
+    executed_path.parent.mkdir(parents=True, exist_ok=True)
+    cmd = ["jupyter", "nbconvert", "--to", "notebook", "--execute", "--allow-errors",
+           f"--ExecutePreprocessor.timeout={timeout}",
+           "--ExecutePreprocessor.kernel_name=python3",
+           "--output", str(executed_path.resolve()), str(tmp_nb.resolve())]
+    print(f"\n=== executing notebook through the kernel ===\n  {' '.join(cmd)}", flush=True)
+    r = run(cmd, cwd=str(nb_dir))
+    with log_path.open("a") as f:
+        f.write(f"\n=== nbconvert rc={r.returncode} ===\n{r.stderr[-4000:]}\n")
+    if r.returncode != 0 or not executed_path.exists():
+        return finalize("execute", False, error=r.stderr[-3000:])
+
+    executed = nbformat.read(str(executed_path), as_version=4)
+    for i, cell in enumerate(executed.cells):
+        if cell.cell_type != "code":
+            continue
+        for out in cell.get("outputs", []):
+            if out.get("output_type") == "error":
+                tb = ANSI_RE.sub("", "\n".join(out.get("traceback", [])))
+                print(tb, flush=True)
+                return finalize("execute", False,
+                                error=f"cell {i}: {out.get('ename')}: {out.get('evalue')}\n{tb}",
+                                executed_notebook=str(executed_path))
+    return finalize("done", True, executed_notebook=str(executed_path))
+
+
 def main() -> int:
     parser = argparse.ArgumentParser()
     parser.add_argument("notebook")
     parser.add_argument("--output-dir", default="/tmp/notebook-test")
     parser.add_argument("--timeout", type=int, default=3600)
+    parser.add_argument(
+        "--executed-output",
+        help="Execute through the real Jupyter kernel (nbconvert) instead of the "
+             "ipython script path and write the executed notebook, with outputs, "
+             "to this path. Used by the PR workflow to publish a reviewable copy.",
+    )
     args = parser.parse_args()
 
     nb_path = Path(args.notebook)
@@ -109,10 +152,10 @@ def finalize(stage: str, ok: bool, error: str | None = None, **extra) -> int:
 
     log_path.write_text("")
 
-    r = run(
-        ["uv", "pip", "install", "--system",
-         "ipython", "nbconvert", "nbformat", *pins]
-    )
+    harness_deps = ["ipython", "nbconvert", "nbformat"]
+    if args.executed_output:
+        harness_deps.append("ipykernel")
+    r = run(["uv", "pip", "install", "--system", *harness_deps, *pins])
     with log_path.open("a") as f:
         f.write(f"=== install rc={r.returncode} ===\n")
         f.write(f"--- stdout ---\n{r.stdout[-2000:]}\n")
@@ -142,6 +185,10 @@ def finalize(stage: str, ok: bool, error: str | None = None, **extra) -> int:
     tmp_nb = out_dir / f"{slug}.toexec.ipynb"
     nbformat.write(nb_for_exec, str(tmp_nb))
 
+    if args.executed_output:
+        return execute_with_kernel(tmp_nb, Path(args.executed_output), nb_dir,
+                                   args.timeout, log_path, finalize)
+
     r = run(["jupyter", "nbconvert", "--to", "script", "--stdout", str(tmp_nb)])
     if r.returncode != 0:
         return finalize("convert", False, error=r.stderr[-3000:])
diff --git a/.github/workflows/index_workflow.yml b/.github/workflows/index_workflow.yml
index d35c56d..ea1e20f 100644
--- a/.github/workflows/index_workflow.yml
+++ b/.github/workflows/index_workflow.yml
@@ -14,7 +14,7 @@ on:
 
 # Deploys push to the same gh-pages branch; never run two at once.
 concurrency:
-  group: index-deploy
+  group: gh-pages-deploy
   cancel-in-progress: false
 
 jobs:
diff --git a/.github/workflows/pr_preview.yml b/.github/workflows/pr_preview.yml
index e20fcca..19e5ba3 100644
--- a/.github/workflows/pr_preview.yml
+++ b/.github/workflows/pr_preview.yml
@@ -15,6 +15,11 @@ jobs:
     permissions:
       contents: write
       pull-requests: write
+    # Every gh-pages deploy across workflows shares this group so pushes to
+    # the branch never race.
+    concurrency:
+      group: gh-pages-deploy
+      cancel-in-progress: false
     steps:
       - uses: actions/checkout@v4
 
@@ -61,6 +66,9 @@ jobs:
     permissions:
       contents: write
       pull-requests: write
+    concurrency:
+      group: gh-pages-deploy
+      cancel-in-progress: false
     steps:
       - name: Checkout gh-pages
         uses: actions/checkout@v4
diff --git a/.github/workflows/test-changed-notebooks.yml b/.github/workflows/test-changed-notebooks.yml
index c52cadb..6eade39 100644
--- a/.github/workflows/test-changed-notebooks.yml
+++ b/.github/workflows/test-changed-notebooks.yml
@@ -67,11 +67,38 @@ jobs:
         run: pip install --no-cache-dir uv nbformat
 
       - name: Run notebook
+        id: run
+        # Executes through the real kernel and keeps the executed notebook so
+        # reviewers can see the outputs.
         run: |
+          slug=$(python -c "import sys; sys.path.insert(0, '.github/scripts'); from run_notebook import slugify; print(slugify(sys.argv[1]))" "${{ matrix.notebook }}")
+          echo "slug=$slug" >> "$GITHUB_OUTPUT"
           python .github/scripts/run_notebook.py \
             "${{ matrix.notebook }}" \
             --output-dir "$RUNNER_TEMP/notebook-test" \
-            --timeout 3600
+            --timeout 3600 \
+            --executed-output "$RUNNER_TEMP/executed/$slug.ipynb"
+
+      - name: Render executed notebook to HTML
+        if: always() && steps.run.outputs.slug != ''
+        run: |
+          slug='${{ steps.run.outputs.slug }}'
+          if [ -f "$RUNNER_TEMP/executed/$slug.ipynb" ]; then
+            jupyter nbconvert --to html "$RUNNER_TEMP/executed/$slug.ipynb" \
+              --output "$slug.html" --output-dir "$RUNNER_TEMP/executed"
+            if [ '${{ job.status }}' = 'success' ]; then status=pass; else status=fail; fi
+            printf '%s\t%s\t%s\n' "$slug" "${{ matrix.notebook }}" "$status" \
+              > "$RUNNER_TEMP/executed/$slug.status.tsv"
+          fi
+
+      - name: Upload executed notebook
+        if: always() && steps.run.outputs.slug != ''
+        uses: actions/upload-artifact@v4
+        with:
+          name: executed-${{ steps.run.outputs.slug }}
+          path: ${{ runner.temp }}/executed/
+          retention-days: 14
+          if-no-files-found: ignore
 
       - name: Upload artifacts on failure
         if: failure()
@@ -80,3 +107,66 @@ jobs:
           name: failure-${{ strategy.job-index }}
           path: ${{ runner.temp }}/notebook-test/
           retention-days: 14
+
+  publish-executed:
+    name: Publish executed notebooks to the PR preview
+    needs: [detect, test]
+    # Fork PRs only get a read-only token, so they keep the artifacts but
+    # cannot deploy to gh-pages; same-repo PRs get clickable previews.
+    if: always() && needs.detect.outputs.any_changed == 'true' && github.event.pull_request.head.repo.full_name == github.repository
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      pull-requests: write
+    concurrency:
+      group: gh-pages-deploy
+      cancel-in-progress: false
+    steps:
+      - name: Download executed notebooks
+        uses: actions/download-artifact@v4
+        with:
+          pattern: executed-*
+          path: executed
+          merge-multiple: true
+
+      - name: Assemble preview files and comment
+        id: assemble
+        run: |
+          mkdir -p publish
+          cp executed/*.html publish/ 2>/dev/null || true
+          base="https://notebooks.dandiarchive.org/pr-preview/${{ github.event.pull_request.number }}/notebooks"
+          {
+            echo "## Executed notebooks"
+            echo
+            echo "CI executed the notebooks changed in this PR through a Jupyter kernel. Review the outputs here (each link is the notebook with its outputs, as a reader would see it):"
+            echo
+            for f in executed/*.status.tsv; do
+              [ -f "$f" ] || continue
+              IFS=$'\t' read -r slug notebook status < "$f"
+              if [ "$status" = pass ]; then mark="✅"; else mark="❌"; fi
+              echo "- $mark [\`$notebook\`]($base/$slug.html)"
+            done
+            echo
+            echo "_Last updated: commit \`${{ github.event.pull_request.head.sha }}\`. The executed copies live only in the preview and are removed when the PR closes; nothing is committed to the branch._"
+          } > comment.md
+          cat comment.md
+          if ls publish/*.html >/dev/null 2>&1; then echo "has_files=true" >> "$GITHUB_OUTPUT"; else echo "has_files=false" >> "$GITHUB_OUTPUT"; fi
+
+      - name: Deploy executed notebooks to gh-pages
+        if: steps.assemble.outputs.has_files == 'true'
+        uses: peaceiris/actions-gh-pages@v3
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          publish_dir: ./publish
+          destination_dir: pr-preview/${{ github.event.pull_request.number }}/notebooks
+          keep_files: true
+          commit_message: "Deploy executed notebooks for PR #${{ github.event.pull_request.number }}"
+          user_name: 'github-actions[bot]'
+          user_email: 'github-actions[bot]@users.noreply.github.com'
+
+      - name: Comment PR with executed notebook links
+        if: steps.assemble.outputs.has_files == 'true'
+        uses: marocchino/sticky-pull-request-comment@v2
+        with:
+          header: executed-notebooks
+          path: comment.md
diff --git a/docs/adding-notebooks.md b/docs/adding-notebooks.md
index 77d8178..b0b16a3 100644
--- a/docs/adding-notebooks.md
+++ b/docs/adding-notebooks.md
@@ -52,6 +52,14 @@ on an `ubuntu-latest` runner with Python 3.12. That script:
 > imports something the install cell doesn't pin, CI fails (even if it "works on
 > Colab," where that package happens to be preinstalled).
 
+For pull requests, CI also executes each changed notebook through a real
+Jupyter kernel and publishes the executed copy, outputs included, to the PR's
+preview site, linking it from a comment on the PR so reviewers can read the
+rendered results without running anything. The executed copies live only in
+the preview and are removed when the PR closes; nothing is committed to the
+branch. (PRs from forks get the executed notebooks as workflow artifacts
+instead, since fork workflows cannot deploy the preview.)
+
 `test-changed-notebooks.yml` only tests notebooks **changed in the PR**. A
 notebook already on `master` that would fail today is not re-run until it is
 touched again (or until the weekly sweep catches it). Don't assume "it's on