diff --git a/docs/superpowers/plans/2026-05-17-files-overlay-rewrite.md b/docs/superpowers/plans/2026-05-17-files-overlay-rewrite.md
index fb7c02e..324d8fc 100644
--- a/docs/superpowers/plans/2026-05-17-files-overlay-rewrite.md
+++ b/docs/superpowers/plans/2026-05-17-files-overlay-rewrite.md
@@ -45,7 +45,7 @@ Direct-bind escape hatches (places we keep direct binding deliberately):
 
 Create the new directory. Move helpers (lines ~40-170 of the current file: `postJson`, `postForm`, `scheduleRefresh`, `parentOf`, `joinPath`, byte-count utility, manager-element detection, CSRF read). Add the file-row click delegation that currently lives at line 1054 — same selector match, but instead of switch-casing into local handlers, dispatch through a registry `window.__filesOverlay.handleAction(action, path, actionEl)` that feature modules register handlers into. Old `files-overlay.js` still has its own handlers for now — `core.js` dispatch is unused until subsequent steps wire features into it.
 
-base.html: add `<script src="files-overlay/core.js">` BEFORE `files-overlay.js` (so the registry exists when the old file runs).
+`overlay_detail.html` (NOT base.html): add `<script src="files-overlay/core.js" defer>` BEFORE the existing `files-overlay.js` script tag (currently at `overlay_detail.html:285`, also `defer`). The script tag lives in `overlay_detail.html` because `files-overlay.js` activates only when `.files-manager` exists (line 23-24 of the current file) — loading from `base.html` would pull the JS onto every page unnecessarily. **All new module script tags use `defer`** to match the existing pattern (the modules query the DOM at load time and need the body parsed first).
 
 Verification: existing functionality still works (click any file row → opens editor, +new-file → opens editor, +new-folder → opens new-folder modal, zip download works).
 
@@ -89,7 +89,7 @@ Convert upload-row cancel buttons (currently direct-bound at row creation, line
 
 Register file-row action handlers (`zip`) into `core.js` dispatch registry. (`zip` is just a navigation — could live in `core.js` directly; pick whichever reads cleaner.)
 
-Delete remaining migrated handlers from old `files-overlay.js`. After this step the old file is empty or near-empty. Replace with `<script src="files-overlay/uploads.js">` etc. in base.html (or delete the old `<script>` tag entirely if the file is empty). Initially leave the old file in place to avoid stretching this step further.
+Delete remaining migrated handlers from old `files-overlay.js`. After this step the old file is empty or near-empty. Add `<script src="files-overlay/uploads.js" defer>` etc. to `overlay_detail.html` alongside the (now-empty) `files-overlay.js` script tag (or delete the old `<script>` tag entirely if the file is empty). Initially leave the old file in place to avoid stretching this step further.
 
 Verification: drop a single file onto tree → uploads + appears; drop a folder onto tree → multiple uploads with progress; cancel in-flight upload → stops, row shows cancelled; click Clear → done rows removed; drag a file row to another folder → moves.
 
@@ -177,7 +177,7 @@ Verification: overlay detail page renders without the legacy dialog (DOM inspect
 
 **Step 10: delete `files-overlay.js` stub + update base.html**
 
-If `files-overlay.js` is empty or just an IIFE shell, delete it. Update `base.html` to load only the 4 new modules (`core.js`, `editor.js`, `dialogs.js`, `uploads.js`). Order doesn't strictly matter (each is an independent IIFE), but `core.js` first makes the registry-of-handlers pattern explicit.
+If `files-overlay.js` is empty or just an IIFE shell, delete it. Update `overlay_detail.html` (NOT base.html) to load only the 4 new modules (`core.js`, `editor.js`, `dialogs.js`, `uploads.js`), all with `defer`. Order doesn't strictly matter for execution (each is an independent IIFE), but `core.js` first makes the registry-of-handlers pattern explicit.
 
 Verification: full re-run of the URL-addressable-modals spec's verification matrix (10 checks); 4 new modules' features all work (editor text + binary + create-new; new-folder; conflict; delete-confirm; drag-drop; uploads cancel + clear).
 
@@ -224,7 +224,7 @@ End of Phase C: `routes/files_routes.py` ~450 lines (vs 640), no dead endpoints,
 | `l4d2web/l4d2web/static/js/files-overlay/dialogs.js` | A | New file |
 | `l4d2web/l4d2web/static/js/files-overlay/uploads.js` | A | New file |
 | `l4d2web/l4d2web/static/js/files-overlay.js` | A → B | Shrinks each step; deleted in step 10 |
-| `l4d2web/l4d2web/templates/base.html` | A, B | Script tag updates each phase end |
+| `l4d2web/l4d2web/templates/overlay_detail.html` | A, B | Script tag updates each phase end (currently loads files-overlay.js at line 285 with `defer`) |
 | `l4d2web/l4d2web/templates/overlay_file_editor.html` | B | Add new-file + binary-replace branches |
 | `l4d2web/l4d2web/templates/overlay_detail.html` | B | Delete legacy `<dialog id="files-editor-modal">` (step 9) |
 | `l4d2web/l4d2web/routes/files_routes.py` | B, C | Add `/files/new` route (step 5); extend `/files/edit` for binary (step 7); extract helpers (step 11); delete `/files/content` (step 12) |
@@ -259,6 +259,10 @@ After **each** commit, the working tree is in a known-good Chromium-verified sta
 
 Natural pause points: end of Phase A, end of Phase B, end of Phase C. Each phase delivers value independently — Phase A alone is a useful cleanup if the user doesn't want to do B and C.
 
+## Errata (pre-execution)
+
+- **Script tag location:** the plan's first draft incorrectly referenced `base.html` for the script tag updates. The actual location is `overlay_detail.html:285` (with `defer`). `files-overlay.js` and its replacement modules are page-scoped to overlay detail — loading from `base.html` would pull the JS onto every page when the `.files-manager` element only exists on overlay detail. All script tag references in this plan now correctly say `overlay_detail.html`. This errata is itself an example of the `feedback_validate_before_implementing` memory: probe the live state before trusting a plan claim.
+
 ## Out of scope
 
 - Adding a JS test framework (no JS tests in the project today; verification stays Chromium-driven).