fix(plist): decode XML data as CoreFoundation does

XML <data> used WHATWG atob, which pads an incomplete trailing quartet into bytes the native reader never produces and refuses non-alphabet characters that CFPropertyList skips. Decode at the shared XML value owner by skipping non-alphabet characters and emitting only completed quartets, shortened by the trailing padding run.

Fixes #4978

src/domain/propertyListXml.test.ts

@@ -24,6 +24,20 @@ it.each([
   },
 );
 
+it.each([
+  ["AQID", [1, 2, 3]],
+  [" A Q I D\n", [1, 2, 3]],
+  ["AQI", []],
+  ["AQ!ID", [1, 2, 3]],
+  ["AQ==", [1]],
+  ["AQI=", [1, 2]],
+  ["AQ= =\n", [1]],
+  ["", []],
+])("decodes data text %j as CFPropertyList does", (text, expected) => {
+  const parsed = parseXmlPropertyList(`<plist><data>${text}</data></plist>`);
+  expect(parsed.value).toEqual(Uint8Array.from(expected));
+});
+
 it("collects source integers and CDATA reals before rounding and duplicate assignment", () => {
   const parsed = parseXmlPropertyList(
     "<plist><dict><key>a</key><integer>0x20000000000001</integer><key>a</key><integer>9007199254740992</integer><key>b</key><real>9007199254<![CDATA[740992]]></real></dict></plist>",

src/domain/propertyListXml.ts

@@ -7,6 +7,32 @@ import {
   parsePlistNonFiniteRealLiteral,
 } from "./apple/plistNumbers.js";
 
+const BASE64_DIGITS =
+  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+const C_WHITESPACE = new Set([" ", "\t", "\n", "\v", "\f", "\r"]);
+
+// CFPropertyList skips non-alphabet characters and emits only completed
+// quartets; atob would pad or refuse data the native reader accepts.
+const decodePlistData = (text: string): Uint8Array => {
+  const bytes: number[] = [];
+  let quartet = 0;
+  let digits = 0;
+  let padding = 0;
+  for (const character of text) {
+    if (character === "=") padding += 1;
+    else if (!C_WHITESPACE.has(character)) padding = 0;
+    const digit = character === "=" ? 0 : BASE64_DIGITS.indexOf(character);
+    if (digit < 0) continue;
+    quartet = ((quartet << 6) | digit) & 0xffffff;
+    digits += 1;
+    if (digits % 4 !== 0) continue;
+    bytes.push(quartet >> 16);
+    if (padding < 2) bytes.push((quartet >> 8) & 0xff);
+    if (padding < 1) bytes.push(quartet & 0xff);
+  }
+  return Uint8Array.from(bytes);
+};
+
 /** Interpret an already validated, depth-bounded DOM, owning values and number facts together. */
 export const decodeXmlPropertyList = (document: Document) => {
   const root = document.documentElement;
@@ -132,10 +158,8 @@ export const decodeXmlPropertyList = (document: Document) => {
         if (literal.complete) numbers.real(value);
         return value;
       }
-      case "data": {
-        const binary = atob(content(node, textNode).text.replace(/\s+/gu, ""));
-        return Uint8Array.from(binary, (character) => character.charCodeAt(0));
-      }
+      case "data":
+        return decodePlistData(content(node, textNode).text);
       case "date": {
         const value = requireContent(node).nodeValue;
         return new Date(value === null ? 0 : value);

tests/acceptance/applications/keyedArchiveXmlNumbers.test.ts

@@ -34,8 +34,18 @@ cliTest.for([
     element: `<integer>1${"0".repeat(400)}</integer>`,
     expected: { $plist_type: "integer", decimal: `1${"0".repeat(400)}` },
   },
+  {
+    name: "incomplete data quartet",
+    element: "<data>AQI</data>",
+    expected: { $plist_type: "data", base64: "" },
+  },
+  {
+    name: "data with a non-alphabet character",
+    element: "<data>AQ!ID</data>",
+    expected: { $plist_type: "data", base64: "AQID" },
+  },
 ])(
-  "preserves $name XML numbers through CLI and MCP",
+  "preserves $name XML scalars through CLI and MCP",
   async (scenario, { cli }) => {
     const root = await createTestTempDirectory("rea-keyed-xml-numbers-");
     const bytes = Buffer.from(