A test that waits for a deadline somebody guessed is waiting for the wrong thing, so it waits for the editor (#93)

The suite spent 88% of its step time asleep: 564 s of steps, 496 s of
them in sleep(n) - fixed spans estimated by hand and then copied from
step to step. That is why it was slow, and why it flickered.

The signal is afterFrames(count, timeout) in ui/render.ts, exposed as
__gm.afterFrames(). It wakes the loop itself, because an editor that
draws nothing would never redeem a promise of a frame, and it gives up
after a timeout instead of hanging the run. settle() in the harness
waits two drawn frames (~32 ms) instead of 150-300 ms and falls back to
sleep(150) when the hook is missing (an old build): silently not
waiting would make every later check a coin toss.

Every action goes through it now - click, doubleClick, wheel, drag,
dragAsset, press, typeText, select, mutate, undo, redo - and with that
about 550 sleep() calls behind those actions became redundant, helpers
that are nothing but a mutate in a coat included. What a frame cannot
answer got its own condition instead: waitUntil(expr), play()/stop()
waiting on __gm.state.mode rather than on 300 ms, saved() for the
autosave (the two hand-written polling loops sampled at 300 ms for
something that arrives after a second), and showTab() as a real tool -
47 places called evaluate("__gm.showTab(...)") raw, and 24 of them
waited for nothing at all and read the old panel.

564 s -> 243 s of step time, the waiting share 88% -> 76%. Three kinds
of wait were kept, and each one bit when it was taken away: loading
bytes (textures, fonts), game time that a repaint cannot stand in for
(time scale, shader and particle clocks, the live values a running
graph carries), and the inertia the scroll step measures on purpose.

Two things the new speed uncovered, both real: 25-animation read the
frame menu unfiltered and had frozen an incomplete list (the CI failure
on c990dbc), and 33-render-on-change measured idleness while the
autosave of the step before was still painting - it waits for
saveStatus to leave dirty/saving now, so it measures that nothing
happens any more instead of that it waited long enough.

tools/e2e/18-pause.mjs

@@ -46,6 +46,7 @@ export async function pause(t) {
     select,
     evaluate,
     asset,
+    showTab,
   } = t;
   const playInfo = () => json('__gm.playInfo()');
   const boxX = async () => (await entity('p-box'))?.x ?? NaN;
@@ -78,7 +79,6 @@ export async function pause(t) {
   // 18b. The toolbar button holds it. Both the clock and the box have to stop – a world that keeps
   //      ticking while the picture happens to look the same would pass a position check alone.
   await clickText('❚❚  Pause');
-  await sleep(200);
   const held = await playInfo();
   const heldX = await boxX();
   await sleep(1000);
@@ -108,11 +108,9 @@ export async function pause(t) {
   const hitsWhilePaused = await keyHits();
   await press('ArrowRight');
   await press('ArrowRight');
-  await sleep(200);
 
   // 18d. Ctrl+Enter resumes, the same shortcut that started play.
   await press('Enter', { ctrl: true });
-  await sleep(400);
   const resumed = await playInfo();
   const resumedX = await boxX();
   check(
@@ -132,7 +130,6 @@ export async function pause(t) {
   );
   // Without this the check above would also pass on a graph that never logs anything at all.
   await press('ArrowRight');
-  await sleep(300);
   check(
     'the same key does fire once the game is running again',
     (await keyHits()) === hitsBefore + 1,
@@ -142,7 +139,6 @@ export async function pause(t) {
   // 18e. A hold must never outlive its play: Esc stops from a paused game, and the next run starts
   //      moving. A pause left standing would leave the editor unable to run anything.
   await press('Enter', { ctrl: true });
-  await sleep(200);
   check('Ctrl+Enter holds it again', (await playInfo()).paused === true);
   await stop();
   const afterStop = await playInfo();
@@ -162,7 +158,9 @@ export async function pause(t) {
   // 18f. The graph stays editable while the game runs, with the mouse as in edit mode: a click
   //      selects the Move node, Delete removes it, and the running world stops drifting the box.
   await select({ kind: 'asset', assetId: 'pauser' });
-  await evaluate(`__gm.showTab('graph')`);
+  await showTab('graph');
+  // The live values are not drawn, they are carried: the running graph has to execute once while
+  // this tab is open before a node output holds anything. That is game time, not frames.
   await sleep(150);
   const outputs = (id) => json(`__gm.graph.nodeOutputs(${JSON.stringify(id)})`);
   const live = {
@@ -193,7 +191,6 @@ export async function pause(t) {
   );
   const beforeKey = await beadsOn('p-e4');
   await press('ArrowRight');
-  await sleep(80);
   const onKey = await beadsOn('p-e4');
   await sleep(500);
   const afterKey = await beadsOn('p-e4');
@@ -204,7 +201,6 @@ export async function pause(t) {
   );
   const movePos = await json(`__gm.graph.nodeAt('p-move')`);
   await click(movePos.x, movePos.y);
-  await sleep(100);
   check(
     'a click selects a node while playing',
     JSON.stringify(await json('__gm.graph.selected()')) === '["p-move"]',
@@ -212,17 +208,14 @@ export async function pause(t) {
   );
   const area = await json('__gm.graph.canvasRect()');
   await click(area.x + area.w - 15, area.y + area.h - 15, 'right');
-  await sleep(100);
   check('right-clicking the canvas opens the node palette while playing', await has('Search nodes…'));
   await press('Escape');
-  await sleep(100);
   check(
     'Escape closes the palette and leaves the game running',
     !(await has('Search nodes…')) && (await playInfo()).playing === true,
   );
   await click(movePos.x, movePos.y);
   await press('Delete');
-  await sleep(150);
   const stoppedAt = await boxX();
   await sleep(500);
   check(
@@ -232,7 +225,6 @@ export async function pause(t) {
     `x ${stoppedAt} → ${await boxX()}`,
   );
   await stop();
-  await sleep(200);
   check(
     'stopping takes the values off the nodes',
     JSON.stringify(await outputs('p-owner')) === '["object"]',
@@ -267,7 +259,6 @@ export async function pause(t) {
   await sleep(400);
   const runningClock = await clock();
   await clickText('❚❚  Pause');
-  await sleep(150);
   const heldClock = await clock();
   await sleep(800);
   const stillHeldClock = await clock();
@@ -283,7 +274,6 @@ export async function pause(t) {
   // Twice the scale has to move the clock and the world by the same factor: the delta a behavior
   // reads is the step the clock took, not a second measurement of the wall clock.
   await press('Enter', { ctrl: true });
-  await sleep(150);
   const slowFrom = { t: await clock(), x: await boxX() };
   await sleep(600);
   const slowTo = { t: await clock(), x: await boxX() };