diff --git a/PLAN.md b/PLAN.md
index 02e815f..e43dd2e 100644
--- a/PLAN.md
+++ b/PLAN.md
@@ -113,7 +113,7 @@ Learned from the independent validation ([#45](https://github.com/QuantEcon/data
 | CPython — intro site notebooks, Colab, every other series | any resolving form; `github.com/…/raw/` is fine |
 | Browser — `lecture-wasm` code-cell reads | `raw.githubusercontent.com/QuantEcon/data-lectures/main/lectures/<file>`, or `media.githubusercontent.com/media/…` for LFS-tracked files |
 
-`{download}` targets and prose links are plain navigations — CORS does not apply, and the `github.com` form is fine there. The audit classifies references by org/repo across all URL forms, so both spellings count as the same pattern: the strict check **cannot enforce this rule**; the repoint PR has to. Quick test from any `quantecon.github.io` page console: `fetch('<url>')` — the bad form rejects, the good form resolves.
+`{download}` targets and prose links are plain navigations — CORS does not apply, and the `github.com` form is fine there. The audit classifies references by org/repo across all URL forms, so both spellings count as the same pattern — but the strict build now also checks the *form*: any `lecture-wasm` code-cell read via a `github.com/…` URL fails the audit. That is a **post-merge net, not a gate** — the scan reads each lecture repo's `main`, so a violation turns the dashboard red at the next audit run rather than blocking the offending PR; the repoint PR remains the place the rule is actually upheld. Quick test from any `quantecon.github.io` page console: `fetch('<url>')` — the bad form rejects, the good form resolves.
 
 Phase 4 inherits the requirement: `data.quantecon.org` must serve `access-control-allow-origin: *` before `lecture-wasm` can cut over to it — recorded as an acceptance criterion on [#37](https://github.com/QuantEcon/data-lectures/issues/37).
 
diff --git a/scripts/build_audit.py b/scripts/build_audit.py
index aa8ff50..c17f985 100644
--- a/scripts/build_audit.py
+++ b/scripts/build_audit.py
@@ -457,6 +457,21 @@ def scan(repos_dir: Path):
                     f"{fname}: in pending wave {wave.get('pilot')} but already "
                     f"read from data-lectures")
 
+    # Repoint rule 5 (PLAN): lecture-wasm executes code cells in the reader's
+    # browser, where the github.com/*/raw/ redirect fails CORS before it is
+    # followed — wasm reads must use raw.githubusercontent.com, or
+    # media.githubusercontent.com for LFS files. Only code-cell reads are
+    # scanned, so {download} and prose links (navigations, CORS-exempt) can
+    # never trip this.
+    for d in datasets:
+        for r in d["refs"]:
+            if (r["repo"] == "lecture-wasm"
+                    and (r.get("url_form") or "").startswith("github.com/")):
+                mig_problems.append(
+                    f"{d['file']}: lecture-wasm {r['lecture']} reads via "
+                    f"{r['url_form']} — fails CORS in the browser "
+                    f"(repoint rule 5)")
+
     audit = {
         "generated": date.today().isoformat(),
         "repos": {n: {"sha": repos[n]["sha"],