v3.30.4 follow-up: the suite delete re-resolves the selection by id

The independent re-check of the v3.30.4 identity fixes found a
pre-existing gap in testSuiteDelete: it cleared the selection only when
the deleted suite WAS the selected one, so deleting a suite BEFORE the
selection left _testSuiteIdx pointing at whatever moved into that slot
(or out of range when the list shrank).

The delete now captures the selected suite's id just before the store
refresh and re-resolves the index after it, which also keeps a selection
the user made while the dialog was open (the modal no longer freezes the
page).

Test: a behavioural test drives the real function through the four cases
(the selected suite deleted; a suite before it deleted; the selection
moved during the dialog; nothing selected) - mutation-checked to fail
without the re-resolution.  946 frontend + 952 Python.

frontend/tests/testsuites.test.js

@@ -191,6 +191,47 @@ test('role rows cannot be moved and the i18n refresh redraws the test views', ()
 	assert.match(i18n, /isViewVisible\('phone-sub-test'\)\) testRender\(\)/);
 });
 
+test('deleting a suite re-resolves the selection by id, not by index', async () => {
+	// The delete shifts every index after it and the list may be reordered
+	// while the confirmation is open (the modal does not block the page).
+	const del = extractFunc(html, 'testSuiteDelete', true);
+	const make = state => new Function('state', `
+		var _testSuiteIdx = state.selIdx;
+		var _testSuiteSaveTimer = null;
+		var testSuites = () => state.suites;
+		var testCurrentSuite = () => state.suites[_testSuiteIdx];
+		var pysimConfirm = async () => {
+			if (state.moveTo !== undefined && state.moveTo !== null) _testSuiteIdx = state.moveTo;
+			return true;
+		};
+		var pysimFetch = async (path, body) => { state.deleted = body.id; return {}; };
+		var testStoresFetch = async () => {
+			state.suites = state.suites.filter(x => x.id !== state.deleted);
+		};
+		var testViewShow = v => { state.view = v; };
+		var ioStatus = (id, msg) => { state.status = msg; };
+		var t = x => x;
+		${del}
+		return { run: testSuiteDelete, idx: () => _testSuiteIdx };
+	`)(state);
+	// deleting the SELECTED suite clears the selection
+	let app = make({ suites: [{id: 'SA'}, {id: 'SB'}, {id: 'SC'}], selIdx: 2 });
+	await app.run(2);
+	assert.strictEqual(app.idx(), -1);
+	// deleting a suite BEFORE the selection keeps it selected (the index shifts)
+	app = make({ suites: [{id: 'SA'}, {id: 'SB'}, {id: 'SC'}], selIdx: 2 });
+	await app.run(0);
+	assert.strictEqual(app.idx(), 1);
+	// a selection made while the dialog was open wins
+	app = make({ suites: [{id: 'SA'}, {id: 'SB'}, {id: 'SC'}], selIdx: 0, moveTo: 1 });
+	await app.run(2);
+	assert.strictEqual(app.idx(), 1);
+	// nothing selected stays nothing selected
+	app = make({ suites: [{id: 'SA'}], selIdx: -1 });
+	await app.run(0);
+	assert.strictEqual(app.idx(), -1);
+});
+
 test('the report keeps an expanded run log open across the live polls', () => {
 	// A live suite run re-renders the member blocks on every poll; replacing
 	// innerHTML creates fresh <details>, so the open state is carried over