v3.24.0 review: the ARR fetch retry and the DF-scope note

- pysimArrEnsure no longer caches a transient /api/arr fetch failure:
  the next file click retries instead of silently showing no ARR rules
  for the rest of the card session (a success is still cached per
  session, and a session change refetches).
- The help (EN/RU) and both AGENTS state the cache scope: only the MF
  (2F06) and ADF.USIM (6F06) ARR copies are read - a reference to
  another DF's copy is left unresolved.
- Test: the transient failure retries, a success is cached, a session
  change refetches.  869 frontend + 856 Python; sw cache simple-v423.

frontend/tests/profiler.test.js

@@ -34,7 +34,9 @@ code += extractFunc(html, 'profilerCardIccid', true) + '\n';
 code += extractFunc(html, 'profilerCheck', true) + '\n';
 code += extractFunc(html, 'profilerCheckSnapshot', true) + '\n';
 code += extractFunc(html, 'profilerScanSnapshot', true) + '\n';
+code += extractFunc(html, 'pysimArrEnsure', true) + '\n';
 code += "var _scanTarget = 'profile';\nvar profilerResults = null;\nvar profilerResultsHeader = null;\nvar profilerMismatchOnly = false;\n";
+code += "var _pysimArrCache = null;\nvar _pysimCardSession = null;\n";
 // the view-history hooks (the router lives in the page; this pure test stubs it)
 code += 'globalThis.navRecord = function() {};\nglobalThis.navReplace = function() {};\n';
 code += html.match(/const PROFILER_MASK_PREFIX4_FIDS = \{[\s\S]*?\n\};/)[0] + '\n';
@@ -902,6 +904,32 @@ test('pysimFsInfoHtml shows the referenced ARR rules when given the cache', () =
 	delete global.t;
 });
 
+test('pysimArrEnsure does not cache a transient failure', async () => {
+	_pysimArrCache = null;
+	_pysimCardSession = 7;
+	let calls = 0;
+	globalThis.pysimFetch = async () => {
+		calls++;
+		if (calls === 1) throw new Error('server down');
+		return { arrs: [{ fid: '2F06' }] };
+	};
+	// the failure is not cached: the next call retries and succeeds
+	assert.deepStrictEqual(await pysimArrEnsure(), []);
+	assert.strictEqual(_pysimArrCache, null);
+	assert.deepStrictEqual(await pysimArrEnsure(), [{ fid: '2F06' }]);
+	assert.strictEqual(calls, 2);
+	// the success is cached for the card session
+	assert.deepStrictEqual(await pysimArrEnsure(), [{ fid: '2F06' }]);
+	assert.strictEqual(calls, 2);
+	// a session change refetches
+	_pysimCardSession = 8;
+	await pysimArrEnsure();
+	assert.strictEqual(calls, 3);
+	delete globalThis.pysimFetch;
+	_pysimArrCache = null;
+	_pysimCardSession = null;
+});
+
 test('pysimFsInfoHtml embeds the symbolic name in the FCI border', () => {
 	global.t = s => s;
 	const hex = '6212800200098202412183026F078A0105880110';