diff --git a/js/accessControl.js b/js/accessControl.js
index 0d31e511..f03f254c 100644
--- a/js/accessControl.js
+++ b/js/accessControl.js
@@ -749,7 +749,39 @@ class AccessControl {
       }
     }
 
-    const normalized = normalizeNpub(npub);
+    let normalized = normalizeNpub(npub);
+
+    // Cross-derive the missing representation. `whitelistPubkeys`/`blacklistPubkeys`
+    // are hex-keyed while `whitelist`/`blacklist` are npub-keyed; both are built
+    // from the same admin lists, but a format mismatch between the caller's input
+    // and how a given entry was stored must NOT read as "not allowed". Filling in
+    // both forms lets the checks below consult both sets.
+    const accessTools =
+      (typeof window !== "undefined" ? window?.NostrTools : null) ||
+      (typeof globalThis !== "undefined" ? globalThis?.NostrTools : null) ||
+      null;
+    if (normalized && !hex && typeof accessTools?.nip19?.decode === "function") {
+      try {
+        const decoded = accessTools.nip19.decode(normalized);
+        if (decoded?.type === "npub") {
+          hex = normalizeHexKey(
+            typeof decoded.data === "string"
+              ? decoded.data
+              : bytesToHex(decoded.data)
+          );
+        }
+      } catch (error) {
+        // ignore — fall back to the npub-only checks
+      }
+    }
+    if (hex && !normalized && typeof accessTools?.nip19?.npubEncode === "function") {
+      try {
+        normalized = normalizeNpub(accessTools.nip19.npubEncode(hex));
+      } catch (error) {
+        // ignore — fall back to the hex-only checks
+      }
+    }
+
     if (!normalized) {
       if (!hex) {
         return false;
diff --git a/js/app/playbackCoordinator.js b/js/app/playbackCoordinator.js
index 37bae812..08a9c8f2 100644
--- a/js/app/playbackCoordinator.js
+++ b/js/app/playbackCoordinator.js
@@ -677,6 +677,18 @@ export function createPlaybackCoordinator(deps) {
       }
       const authorNpub = this.safeEncodeNpub(video.pubkey) || video.pubkey;
       if (!accessControl.canAccess(authorNpub)) {
+        // Dev diagnostic: pinpoint WHY access was denied (format mismatch vs the
+        // author genuinely not being on the list vs lists not loaded).
+        devLogger.warn("[playback] access denied — whitelist diagnostic", {
+          pubkey: video.pubkey,
+          authorNpub,
+          foreign: video.foreign === true || video.source === "nip71-ingest",
+          whitelistMode: accessControl.whitelistMode?.(),
+          whitelistNpubSize: accessControl.whitelist?.size,
+          whitelistHexSize: accessControl.whitelistPubkeys?.size,
+          inNpubSet: accessControl.whitelist?.has?.(authorNpub),
+          inHexSet: accessControl.whitelistPubkeys?.has?.(video.pubkey),
+        });
         if (accessControl.isBlacklisted(authorNpub)) {
           this.showError("This content has been removed or is not allowed.");
         } else if (accessControl.whitelistMode()) {
diff --git a/tests/access-control-canaccess.test.mjs b/tests/access-control-canaccess.test.mjs
new file mode 100644
index 00000000..71d8c755
--- /dev/null
+++ b/tests/access-control-canaccess.test.mjs
@@ -0,0 +1,61 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import * as nostrTools from "nostr-tools";
+
+import { accessControl } from "../js/accessControl.js";
+
+// Bug: a genuinely whitelisted author was blocked at playback because canAccess
+// checks the hex set when given hex and the npub set when given an npub, without
+// cross-deriving. If an entry lands in only one representation (e.g. hex decode
+// hadn't run when the list loaded), querying in the other format read as "not
+// allowed". The fix cross-derives both forms and checks both sets.
+
+// canAccess resolves NostrTools from window/globalThis for the cross-derive.
+const priorTools = globalThis.NostrTools;
+globalThis.NostrTools = { nip19: nostrTools.nip19 };
+
+const sk = nostrTools.generateSecretKey();
+const HEX = nostrTools.getPublicKey(sk);
+const NPUB = nostrTools.nip19.npubEncode(HEX);
+
+const otherSk = nostrTools.generateSecretKey();
+const OTHER_HEX = nostrTools.getPublicKey(otherSk);
+const OTHER_NPUB = nostrTools.nip19.npubEncode(OTHER_HEX);
+
+function seed({ whitelist = [], whitelistHex = [] } = {}) {
+  accessControl.whitelistEnabled = true;
+  accessControl.whitelist = new Set(whitelist);
+  accessControl.whitelistPubkeys = new Set(whitelistHex);
+  accessControl.blacklist = new Set();
+  accessControl.blacklistPubkeys = new Set();
+  accessControl.editors = new Set(); // ensure the author isn't treated as admin
+}
+
+test.after(() => {
+  globalThis.NostrTools = priorTools;
+});
+
+test("whitelisted by HEX only is recognized when queried by npub (cross-derive)", () => {
+  seed({ whitelistHex: [HEX] }); // npub set deliberately empty
+  assert.equal(accessControl.canAccess(NPUB), true, "npub query finds the hex-set author");
+  assert.equal(accessControl.canAccess(HEX), true, "hex query still works");
+});
+
+test("whitelisted by NPUB only is recognized when queried by hex (cross-derive)", () => {
+  seed({ whitelist: [NPUB] }); // hex set deliberately empty
+  assert.equal(accessControl.canAccess(HEX), true, "hex query finds the npub-set author");
+  assert.equal(accessControl.canAccess(NPUB), true, "npub query still works");
+});
+
+test("a non-whitelisted author is still denied in both formats (no over-allow)", () => {
+  seed({ whitelist: [NPUB], whitelistHex: [HEX] });
+  assert.equal(accessControl.canAccess(OTHER_NPUB), false);
+  assert.equal(accessControl.canAccess(OTHER_HEX), false);
+});
+
+test("with whitelist mode OFF, any author is allowed regardless of sets", () => {
+  seed({});
+  accessControl.whitelistEnabled = false;
+  assert.equal(accessControl.canAccess(OTHER_NPUB), true);
+  assert.equal(accessControl.canAccess(OTHER_HEX), true);
+});
diff --git a/todo/TODO_2026-06-20_pre-launch.md b/todo/TODO_2026-06-20_pre-launch.md
index 174868b4..4c3c61d2 100644
--- a/todo/TODO_2026-06-20_pre-launch.md
+++ b/todo/TODO_2026-06-20_pre-launch.md
@@ -599,6 +599,29 @@ SILENT one: `handleEventDetailsAction` only opened the modal `if (… && payload
 - [ ] **VERIFY live**: click ⋯ → Event Details AND ⋯ → Popularity in the video
       modal AND on a grid/channel card; both should open the correct video.
 
+### 32. Whitelisted author's video won't play — "not from a whitelisted author" (BUG)
+Reported 2026-06-25: a video from a known-whitelisted author refused to play
+("This content is not from a whitelisted author." at `playbackCoordinator
+.playVideoByEventId`). The source URL was confirmed 100% healthy (HTTP 200,
+video/mp4, range + CORS `*`) — the block is the whitelist gate, not the source.
+- [x] **Root cause + fix: `canAccess` format asymmetry.** `accessControl` keeps the
+      whitelist in TWO sets — `whitelistPubkeys` (hex) and `whitelist` (npub) — and
+      `canAccess` checked only ONE based on the caller's input format (npub→npub set,
+      hex→hex set) without cross-deriving. `playbackCoordinator` passes the author's
+      **npub**, so it consulted only the npub set; if the entry was present in only
+      the hex set (e.g. the hex decode hadn't run / a normalization mismatch), a
+      genuinely whitelisted author read as "not allowed." Fixed `canAccess` to
+      cross-derive both forms and check BOTH sets (false-negatives only; a
+      non-whitelisted author is still denied). Tests:
+      `tests/access-control-canaccess.test.mjs`.
+- [x] Added a dev-gated diagnostic at the playback rejection
+      (`playbackCoordinator`) logging hex/npub, whitelistMode, set sizes, and
+      `inNpubSet`/`inHexSet` — so if it still denies, we know instantly whether the
+      author is genuinely off the list (→ then it's the separate "ingested foreign
+      content shown in a whitelist-mode feed but unplayable" question) vs a load race.
+- [ ] **VERIFY live**: replay the failing nevent. If it plays → fixed. If it still
+      denies, paste the new `[playback] access denied — whitelist diagnostic` line.
+
 ### 28. Beacon torrent app stuck — spinner never resolves (BUG) — FIXED 2026-06-24
 - [x] **Root cause:** the processing overlay (`torrent/app.js`) was gated on
       WebTorrent's metadata-ready callback (`client.add(magnet, opts, cb)` /