b41f8a73

test: pin web selection lifecycle and interrupt behaviour

a73x 2026-08-18 12:27

Commit message

test: pin web selection lifecycle and interrupt behaviour

Four behaviours decisions.md already claims survived every check in
web/verify.js. Each pin was confirmed against its own mutation:

  - an existing-but-undecoded selection must not swallow Ctrl+C, or the
    shell gets no interrupt for up to the whole response timeout;
  - session exit and a non-`up` daemon leg each clear the retained
    selection, not just the pending scrollback request;
  - a wheel tick during an outstanding fetch is refused, so it cannot
    replace scrollRequest and its timer without clearing the old one.

Also renames the clipboard snapshot assertion to what it can actually
hold up. Swapping its `.slice` for `.subarray` leaves the whole file
green, because nothing runs between the copy and the decode; the check
pins the decode landing before the first await, and now says so.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

web/verify.js

Old		New
@@ -529,8 +529,16 @@ async function verifyClipboardShell(shell, html) {
529	const snapshotCalls = [];	529	const snapshotCalls = [];
530	h.navigator.clipboard = { writeText: (text) => { snapshotCalls.push(text); return snapshotWrite.promise; } };	530	h.navigator.clipboard = { writeText: (text) => { snapshotCalls.push(text); return snapshotWrite.promise; } };
531	const snapshotRun = snap.tile.onClipboardEffect();	531	const snapshotRun = snap.tile.onClipboardEffect();
		532	// The staging bytes are reused the instant that call returns, and the
		533	// pending text below is already the decoded value: the DECODE landed
		534	// before the first await. That is the whole of what this can pin. It is
		535	// deliberately NOT a claim about the `.slice` that takes the bytes —
		536	// nothing runs between the copy and `clipboardText`, so swapping in
		537	// `.subarray` is invisible to every check in this file (measured). The
		538	// copy is still correct, because a view is only safe while nothing can
		539	// grow linear memory; it is simply not a property a test can hold up.
532	new Uint8Array(snap.memory.buffer).fill('A'.charCodeAt(0), 17, 17 + snap.encoded.length);	540	new Uint8Array(snap.memory.buffer).fill('A'.charCodeAt(0), 17, 17 + snap.encoded.length);
533	check('zoomed effect snapshots clipboard bytes before await', snap.tile.pendingClipboard, 'snapshot ☃');	541	check('zoomed effect decodes clipboard text before any await', snap.tile.pendingClipboard, 'snapshot ☃');
534	check('zoomed effect starts automatic write', snapshotCalls.join('\|'), 'snapshot ☃');	542	check('zoomed effect starts automatic write', snapshotCalls.join('\|'), 'snapshot ☃');
535	check('zoomed effect advances version', snap.tile.clipboardVersion, 1);	543	check('zoomed effect advances version', snap.tile.clipboardVersion, 1);
536	snapshotWrite.resolve();	544	snapshotWrite.resolve();
@@ -985,6 +993,20 @@ async function verifySelectionShell(shell, html) {
985	check('session exit rolls pending scroll request back', exitLifecycle.tile.scrollRequest, null);	993	check('session exit rolls pending scroll request back', exitLifecycle.tile.scrollRequest, null);
986	check('session exit clears pending scroll timeout', exitTimeout?.cleared, true);	994	check('session exit clears pending scroll timeout', exitTimeout?.cleared, true);
987		995
		996	const controlClearsSelection = makeTile();
		997	controlClearsSelection.tile.selection = {
		998	anchor: { row: 1, col: 1 }, active: { row: 1, col: 2 }, requestId: 61, text: 'daemon leg dropped',
		999	};
		1000	controlClearsSelection.tile.onMessage(reconnectingControl);
		1001	check('daemon reconnect lifecycle clears the retained selection', controlClearsSelection.tile.selection, null);
		1002
		1003	const exitClearsSelection = makeTile();
		1004	exitClearsSelection.tile.selection = {
		1005	anchor: { row: 1, col: 1 }, active: { row: 1, col: 2 }, requestId: 62, text: 'outlived the shell',
		1006	};
		1007	exitClearsSelection.tile.onMessage(Uint8Array.from([0, 0x82, 1, 0, 0, 0, 0]));
		1008	check('session exit clears the retained selection', exitClearsSelection.tile.selection, null);
		1009
988	const countMismatch = makeTile();	1010	const countMismatch = makeTile();
989	countMismatch.tile.viewStartRow = 30;	1011	countMismatch.tile.viewStartRow = 30;
990	countMismatch.tile.requestedViewStartRow = 30;	1012	countMismatch.tile.requestedViewStartRow = 30;
@@ -1229,6 +1251,21 @@ async function verifySelectionShell(shell, html) {
1229	check('matching scrollback echo becomes the displayed start row', scrolling.tile.viewStartRow, 25);	1251	check('matching scrollback echo becomes the displayed start row', scrolling.tile.viewStartRow, 25);
1230	check('scrollback echo paints the history viewport', paintedScroll, 1);	1252	check('scrollback echo paints the history viewport', paintedScroll, 1);
1231		1253
		1254	// A wheel tick arriving while a fetch is outstanding must not replace
		1255	// scrollRequest and scrollRequestTimer without clearing the old timer:
		1256	// that leaks one setTimeout per tick and leaves a rollback armed for a
		1257	// request nobody is waiting on any more.
		1258	const wheelDuringFetch = makeTile();
		1259	wheelDuringFetch.tile.viewStartRow = 30;
		1260	wheelDuringFetch.tile.changeScrollPages(1);
		1261	const inFlightScroll = wheelDuringFetch.tile.scrollRequest;
		1262	const inFlightScrollTimer = wheelDuringFetch.tile.scrollRequestTimer;
		1263	wheelDuringFetch.tile.onWheel({ deltaY: -1 });
		1264	check('a wheel tick during a pending fetch sends nothing', wheelDuringFetch.sent.length, 1);
		1265	check('a wheel tick during a pending fetch keeps the one request', wheelDuringFetch.tile.scrollRequest, inFlightScroll);
		1266	check('a wheel tick during a pending fetch keeps its one timer', wheelDuringFetch.tile.scrollRequestTimer, inFlightScrollTimer);
		1267	check('a wheel tick during a pending fetch does not move page intent', wheelDuringFetch.tile.scrollPages, 1);
		1268
1232	const failedStage = makeTile();	1269	const failedStage = makeTile();
1233	failedStage.tile.scrollPages = 1;	1270	failedStage.tile.scrollPages = 1;
1234	failedStage.tile.viewStartRow = 30;	1271	failedStage.tile.viewStartRow = 30;
@@ -1940,6 +1977,24 @@ async function verifySelectionShell(shell, html) {
1940	check('Ctrl+C without selection sends one PTY frame', terminalCopy.sent[0]?.type, 0x02);	1977	check('Ctrl+C without selection sends one PTY frame', terminalCopy.sent[0]?.type, 0x02);
1941	check('Ctrl+C fake encoder emits ETX byte', terminalCopy.sent[0]?.payload[0], 3);	1978	check('Ctrl+C fake encoder emits ETX byte', terminalCopy.sent[0]?.payload[0], 3);
1942		1979
		1980	// The retained selection exists but its reply has not decoded (or came
		1981	// back non-ok), so copySelection would return at its own text === null
		1982	// guard. Treating "a selection object exists" as "there is something to
		1983	// copy" swallows the interrupt for up to the whole response timeout.
		1984	const undecodedCopy = makeTile();
		1985	undecodedCopy.tile.selection = authoritativeSelection(null);
		1986	undecodedCopy.tile.core.mux_key_encode = () => 1;
		1987	undecodedCopy.tile.core.mux_output_len = () => 1;
		1988	h.setZoomedTile(undecodedCopy.tile);
		1989	const undecodedWrites = [];
		1990	h.navigator.clipboard = { writeText: (text) => { undecodedWrites.push(text); return Promise.resolve(); } };
		1991	const undecodedCtrlC = keyEvent({ key: 'c', ctrlKey: true });
		1992	h.document.dispatchEvent('keydown', undecodedCtrlC);
		1993	await flushPromises();
		1994	check('Ctrl+C with an undecoded selection still reaches the shell', undecodedCopy.sent[0]?.type, 0x02);
		1995	check('Ctrl+C with an undecoded selection sends exactly one frame', undecodedCopy.sent.length, 1);
		1996	check('Ctrl+C with an undecoded selection writes no clipboard', undecodedWrites.length, 0);
		1997
1943	const altCopy = makeTile();	1998	const altCopy = makeTile();
1944	const altKeys = [];	1999	const altKeys = [];
1945	altCopy.tile.selection = authoritativeSelection('must not copy');	2000	altCopy.tile.selection = authoritativeSelection('must not copy');