From 1ebfc42db2ffdfa2cdc5949cebef364465deae49 Mon Sep 17 00:00:00 2001
From: Anthony Stirling <77850077+Frooodle@users.noreply.github.com>
Date: Sun, 30 Aug 2026 10:44:09 +0100
Subject: [PATCH] Extend touch-scroll rule to the global pointer layer and
 harden the pan config canary

---
 .../core/components/viewer/RedactionAPIBridge.tsx    |  2 ++
 .../components/viewer/ViewerPointerProviders.tsx     |  2 ++
 .../core/components/viewer/viewerPanConfig.test.ts   | 12 ++++++------
 .../src/core/components/viewer/viewerPanConfig.ts    |  2 ++
 frontend/editor/src/core/styles/theme.css            |  2 ++
 .../stubbed/viewer-touch-device-selection.spec.ts    | 10 ++++++++++
 6 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/frontend/editor/src/core/components/viewer/RedactionAPIBridge.tsx b/frontend/editor/src/core/components/viewer/RedactionAPIBridge.tsx
index 49c350f4ee..5f86253aa2 100644
--- a/frontend/editor/src/core/components/viewer/RedactionAPIBridge.tsx
+++ b/frontend/editor/src/core/components/viewer/RedactionAPIBridge.tsx
@@ -43,6 +43,8 @@ function RedactionAPIBridgeInner({ documentId }: { documentId: string }) {
     };
   }, [setBridgeReady]);
 
+  // The interaction mode is viewer-global, so a stranded redaction mode would block
+  // selection for the next document.
   useEffect(() => {
     return () => {
       try {
diff --git a/frontend/editor/src/core/components/viewer/ViewerPointerProviders.tsx b/frontend/editor/src/core/components/viewer/ViewerPointerProviders.tsx
index 38a10125c0..14a3cf8551 100644
--- a/frontend/editor/src/core/components/viewer/ViewerPointerProviders.tsx
+++ b/frontend/editor/src/core/components/viewer/ViewerPointerProviders.tsx
@@ -33,6 +33,7 @@ export function ViewerGlobalPointerProvider({
   return (
     <GlobalPointerProvider
       documentId={documentId}
+      // Consumed by the touch-action rule in core/styles/theme.css.
       data-viewer-touch-scroll={mode === POINTER_MODE ? "on" : "off"}
     >
       {children}
@@ -53,6 +54,7 @@ export function ViewerPagePointerProvider({
     <PagePointerProvider
       documentId={documentId}
       pageIndex={pageIndex}
+      // Consumed by the touch-action rule in core/styles/theme.css.
       className="pdf-page-pointer-layer"
     >
       {children}
diff --git a/frontend/editor/src/core/components/viewer/viewerPanConfig.test.ts b/frontend/editor/src/core/components/viewer/viewerPanConfig.test.ts
index 03412137b7..f239cbca32 100644
--- a/frontend/editor/src/core/components/viewer/viewerPanConfig.test.ts
+++ b/frontend/editor/src/core/components/viewer/viewerPanConfig.test.ts
@@ -3,12 +3,12 @@ import { PanPluginPackage } from "@embedpdf/plugin-pan";
 import { VIEWER_PAN_CONFIG } from "@app/components/viewer/viewerPanConfig";
 
 describe("viewer pan plugin config", () => {
-  it("resolves defaultMode to never so pan never becomes the interaction default", () => {
-    const resolved = {
-      ...PanPluginPackage.manifest.defaultConfig,
-      ...VIEWER_PAN_CONFIG,
-    };
+  it("overrides the plugin default so pan never becomes the interaction default", () => {
+    expect(VIEWER_PAN_CONFIG.defaultMode).toBe("never");
+  });
 
-    expect(resolved.defaultMode).toBe("never");
+  // Canary: if upstream ever ships a safe default, this override can go.
+  it("still needs the override because the plugin ships defaultMode mobile", () => {
+    expect(PanPluginPackage.manifest.defaultConfig.defaultMode).toBe("mobile");
   });
 });
diff --git a/frontend/editor/src/core/components/viewer/viewerPanConfig.ts b/frontend/editor/src/core/components/viewer/viewerPanConfig.ts
index 101284594c..7024378b79 100644
--- a/frontend/editor/src/core/components/viewer/viewerPanConfig.ts
+++ b/frontend/editor/src/core/components/viewer/viewerPanConfig.ts
@@ -1,5 +1,7 @@
 import type { PanPluginConfig } from "@embedpdf/plugin-pan";
 
+// The plugin's own defaultConfig is "mobile", which makes pan the global default
+// mode on any touch-capable device and locks activateDefaultMode into pan (#5175).
 export const VIEWER_PAN_CONFIG: PanPluginConfig = {
   defaultMode: "never",
 };
diff --git a/frontend/editor/src/core/styles/theme.css b/frontend/editor/src/core/styles/theme.css
index cd2c5013cc..fe29e9ce27 100644
--- a/frontend/editor/src/core/styles/theme.css
+++ b/frontend/editor/src/core/styles/theme.css
@@ -602,6 +602,8 @@
   background-color: var(--p-gray-500) !important;
 }
 
+/* !important beats the inline touch-action:none the interaction manager writes for pointerMode. */
+[data-viewer-touch-scroll="on"],
 [data-viewer-touch-scroll="on"] .pdf-page-pointer-layer {
   touch-action: pan-y pinch-zoom !important;
 }
diff --git a/frontend/editor/src/core/tests/stubbed/viewer-touch-device-selection.spec.ts b/frontend/editor/src/core/tests/stubbed/viewer-touch-device-selection.spec.ts
index 5029f391e6..9fa9e12947 100644
--- a/frontend/editor/src/core/tests/stubbed/viewer-touch-device-selection.spec.ts
+++ b/frontend/editor/src/core/tests/stubbed/viewer-touch-device-selection.spec.ts
@@ -249,6 +249,16 @@ test.describe("touch-primary device", () => {
       }),
     ).toBe("pan-y pinch-zoom");
 
+    // The global provider is an ancestor of the scroller, so its inline none would veto pinch-zoom.
+    expect(
+      await page.evaluate(() => {
+        const el = document.querySelector<HTMLElement>(
+          '[data-viewer-touch-scroll="on"]',
+        );
+        return el ? getComputedStyle(el).touchAction : null;
+      }),
+    ).toBe("pan-y pinch-zoom");
+
     const cdp = await page.context().newCDPSession(page);
     const touchDrag = async (x: number, y: number, dx: number, dy: number) => {
       await cdp.send("Input.dispatchTouchEvent", {