From 4cabbea0d463f981912d1acd7d4de0cf74db7804 Mon Sep 17 00:00:00 2001
From: Davide Scaini <davide.scaini@alumni.cern>
Date: Sun, 26 Apr 2026 15:19:39 +0200
Subject: [PATCH] fix(mobile): three-patch compat shim for Chrome <80 (Karoo
 WebView 61)
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Root causes identified via logcat:
  Chrome <71: globalThis not defined → ReferenceError in Pyodide factory,
              loadPyodide stays as {} (set by UMD wrapper), "not a function"
  Chrome <63: dynamic import() is a parse-time SyntaxError
  Chrome <63: for-await-of is a parse-time SyntaxError

Fix: when Chrome <80 is detected, fetch v0.18.1 pyodide.js as text and apply
three split/join patches before injecting via Blob URL:
  1. prepend globalThis polyfill
  2. import( → __loadScript(  (script-tag shim)
  3. for await( → for(        (getFsHandles is never called in our flow)

Chrome 80+ keeps the original clean <script>-tag path with v0.26.4.
---
 mobile/extraction/PyodideWebView.tsx | 54 ++++++++++++++++------------
 1 file changed, 32 insertions(+), 22 deletions(-)
diff --git a/mobile/extraction/PyodideWebView.tsx b/mobile/extraction/PyodideWebView.tsx
index d69d7c9..d531b21 100644
--- a/mobile/extraction/PyodideWebView.tsx
+++ b/mobile/extraction/PyodideWebView.tsx
@@ -2,9 +2,10 @@ import { StyleSheet } from 'react-native';
 import WebView from 'react-native-webview';
 import { handleWebViewMessage, pyodideRef } from './extractActivity';
 
-// v0.18.1: newest version whose pyodide.js is ES2017-compatible (no ??, no ?.)
-// Chrome 61 (Karoo WebView) throws SyntaxError on 0.19+ which uses nullish-coalescing.
-const CDN = 'https://cdn.jsdelivr.net/pyodide/v0.18.1/full/';
+const CDN        = 'https://cdn.jsdelivr.net/pyodide/v0.26.4/full/';
+// v0.18.1: last version whose JS wrapper avoids ??, ?., and other syntax
+// unavailable on Chrome <80 (e.g. Karoo WebView 61). Used in the compat path.
+const CDN_COMPAT  = 'https://cdn.jsdelivr.net/pyodide/v0.18.1/full/';
 
 // Python snippets embedded as JSON strings to avoid any JS/TS escaping issues.
 const PY_INSTALL_PACKAGES = [
@@ -64,7 +65,8 @@ const PYODIDE_HTML = `<!DOCTYPE html>
 var _PY_INSTALL_PACKAGES = ${JSON.stringify(PY_INSTALL_PACKAGES)};
 var _PY_INSTALL_WHEEL    = ${JSON.stringify(PY_INSTALL_WHEEL)};
 var _PY_EXTRACT          = ${JSON.stringify(PY_EXTRACT)};
-var _CDN = ${JSON.stringify(CDN)};
+var _CDN       = ${JSON.stringify(CDN)};
+var _CDN_COMPAT = ${JSON.stringify(CDN_COMPAT)};
 
 function _post(m) { window.ReactNativeWebView.postMessage(JSON.stringify(m)); }
 
@@ -77,17 +79,23 @@ var initError     = null;
   try {
     _post({ type: 'progress', msg: 'Loading Python runtime…' });
 
-    // Chrome <63 cannot parse dynamic import() — a parse-time SyntaxError
-    // prevents loadPyodide from ever being defined.  Detect this once and
-    // use a patched loader only for those old WebViews.
-    var chromeVer = (navigator.userAgent.match(/Chrome\\/([0-9]+)/) || [])[1];
-    var needsPatch = chromeVer && parseInt(chromeVer) < 63;
+    // Chrome <80 is missing features that modern Pyodide uses in its JS wrapper:
+    //   Chrome <71: no globalThis  →  factory throws ReferenceError immediately
+    //   Chrome <63: no dynamic import() / for-await-of  →  parse/runtime failure
+    // Detection: read Chrome version from UA; absent means non-Chrome (assume modern).
+    var _chromeVer = (navigator.userAgent.match(/Chrome\\/([0-9]+)/) || [])[1];
+    var _needsPatch = _chromeVer && parseInt(_chromeVer) < 80;
 
-    if (needsPatch) {
-      // Fetch pyodide.js as text and replace every "import(" with a
-      // script-tag shim before injecting via Blob URL.  Using split/join
-      // avoids regex escape sequences, which template literals corrupt.
-      // Node.js import("path") calls are guarded by IN_NODE and never run.
+    if (_needsPatch) {
+      // Use v0.18.1 — its JS wrapper avoids ??, ?., and other Chrome-80+ syntax.
+      // Then apply three text patches before injecting via Blob URL (Blob scripts
+      // bypass the browser's module pre-scanner, so patched keywords are invisible).
+      //
+      // Patches (split/join avoids regex escapes, which template literals corrupt):
+      //   1. globalThis polyfill prepended  — Chrome <71 lacks globalThis entirely
+      //   2. import( → __loadScript(        — Chrome <63 cannot parse dynamic import
+      //   3. for await( → for(              — Chrome <63 lacks async iteration;
+      //      the only affected fn (getFsHandles/NativeFS) is never called by us
       window.__loadScript = function(url) {
         return new Promise(function(res, rej) {
           var s = document.createElement('script');
@@ -97,19 +105,22 @@ var initError     = null;
           document.head.appendChild(s);
         });
       };
-      var pyResp = await fetch(_CDN + 'pyodide.js');
-      if (!pyResp.ok) throw new Error('Could not fetch pyodide.js (' + pyResp.status + ')');
-      var pyCode = await pyResp.text();
-      pyCode = pyCode.split('import(').join('__loadScript(');
+      var _pyResp = await fetch(_CDN_COMPAT + 'pyodide.js');
+      if (!_pyResp.ok) throw new Error('Could not fetch pyodide.js (' + _pyResp.status + ')');
+      var _pyCode = await _pyResp.text();
+      _pyCode = 'var globalThis=typeof globalThis!=="undefined"?globalThis:self;\n' + _pyCode;
+      _pyCode = _pyCode.split('import(').join('__loadScript(');
+      _pyCode = _pyCode.split('for await(').join('for(');
       await new Promise(function(res, rej) {
-        var blob = new Blob([pyCode], { type: 'application/javascript' });
+        var blob = new Blob([_pyCode], { type: 'application/javascript' });
         var blobUrl = URL.createObjectURL(blob);
         var s = document.createElement('script');
         s.src = blobUrl;
         s.onload = function() { URL.revokeObjectURL(blobUrl); res(); };
-        s.onerror = function() { URL.revokeObjectURL(blobUrl); rej(new Error('Failed to execute patched pyodide.js')); };
+        s.onerror = function() { URL.revokeObjectURL(blobUrl); rej(new Error('Failed to inject patched pyodide.js')); };
         document.head.appendChild(s);
       });
+      pyodide = await loadPyodide({ indexURL: _CDN_COMPAT });
     } else {
       await new Promise(function(res, rej) {
         var s = document.createElement('script');
@@ -117,10 +128,9 @@ var initError     = null;
         s.onload = res; s.onerror = rej;
         document.head.appendChild(s);
       });
+      pyodide = await loadPyodide({ indexURL: _CDN });
     }
 
-    pyodide = await loadPyodide({ indexURL: _CDN });
-
     _post({ type: 'progress', msg: 'Loading packages…' });
     await pyodide.loadPackage(['lxml', 'pyyaml', 'micropip']);
 
